Liren Large Software Subsidy 10/10.iso/l/l391/2.ddi/CHART.BA$/CHART.bin

Text File | 1992-08-19 | 140.0 KB | 4,649 lines

' ------------------------------------------------------------------------
' Visual Basic for MS-DOS Presentation Graphics ToolKit
'
' The Presentation Graphics ToolKit (CHART.BAS, CHARTASM.ASM,
' FONT.BAS, and FONTASM.ASM) provides support for adding
' charts, graphs, and fonts to your programs.
'
' To use the Presentation Graphics routines in your
' program either include CHART.BAS and FONT.BAS in
' your program or use the supplied library (CHART.LIB)
' and Quick Library (CHART.QLB) and call the appropriate
' procedures.  An Alternate Math version of the
' Presentation Graphics Toolkit (for use with programs
' compiled /FPA) can be created as follows:
'     BC /X /E /O /FPa font.bas;
'     BC /X /E /O /FPa Chart.bas;
'     DEL Charta.lib
'     LIB Charta.Lib + Chart.Obj + Font.Obj + ChartAsm.Obj + FontAsm.Obj + vbdos.lib;
'
' The charting routines cannot be used without the
' font support routines.
'
' Note, if you include CHART.BAS and FONT.BAS in your
' program, you will also have to create and use a
' library and Quick Library containing the low-level
' support routines found in CHARTASM.ASM and FONTASM.ASM.
' This is done as follows:
'       LIB chartasm.lib + chartasm + fontasm + VBDOS.LIB;
'       LINK /Q chartasm.lib, chartasm.qlb,, VBDOSQLB.LIB;
'
' Copyright (C) 1982-1992 Microsoft Corporation
'
' You have a royalty-free right to use, modify, reproduce
' and distribute the sample applications and toolkits provided with
' Visual Basic for MS-DOS (and/or any modified version)
' in any way you find useful, provided that you agree that
' Microsoft has no warranty, obligations or liability for
' any of the sample applications or toolkits.
' ------------------------------------------------------------------------

' CHART.BI contains all of the TYPE definitions and SUB declarations
' that are accessible to the library user as well as CONST definitions for
' some routine parameters and error messages:
'$INCLUDE: 'CHART.BI'

' FONT.BI contains all of the TYPE definitions and SUB declarations
' required for graphics text:
'$INCLUDE: 'FONT.BI'

CONST cTicSize = .02            ' Percent of axis length to use for tic length
CONST cMaxChars = 255           ' Maximum ASCII value allowed for character
CONST cBarWid = .8              ' Percent of category width to use for bar
CONST cPiVal = 3.141592         ' A value for PI
CONST cFalse = 0                ' Logical false
CONST cTrue = NOT cFalse        ' Logical true

' Below are TYPE definitions local to this module:

' TYPE for recording information on title spacing:
TYPE TitleLayout
    Top         AS INTEGER        ' Space above first title
    TitleOne    AS INTEGER        ' Height of first title
    Middle      AS INTEGER        ' Space between first and second titles
    TitleTwo    AS INTEGER        ' Height of second title
    Bottom      AS INTEGER        ' Space below second title
    TotalSize   AS INTEGER        ' Sum of all the above
END TYPE

' TYPE for recording information on the legend layout:
TYPE LegendLayout
    NumCol      AS INTEGER        ' Number of columns in legend
    NumRow      AS INTEGER        ' Number of rows in legend
    SymbolSize  AS INTEGER        ' Height of symbol
    LabelOffset AS INTEGER        ' Space between start of symbol and label
    RowSpacing  AS INTEGER        ' Space between tops of rows
    ColSpacing  AS INTEGER        ' Spacing between beginnings of columns
    HorizBorder AS INTEGER        ' Top and bottom border
    VertBorder  AS INTEGER        ' Left and right border
END TYPE

' TYPE for a group of global parameters:
TYPE GlobalParams
    SysFlag     AS INTEGER        ' cYes means Analyze call is from system
    Initialized AS INTEGER        ' cYes means clInitChart has been called

    PaletteScrn AS INTEGER        ' Screen mode for which palette is set
    PaletteBits AS INTEGER        ' Bits per pixel for current screen mode
    PaletteSet  AS INTEGER        ' cYes means palette has been initialized
    White       AS INTEGER        ' White attribute in current screen mode

    Aspect      AS SINGLE         ' Current screen aspect
    MaxXPix     AS INTEGER        ' Screen size along X axis
    MaxYPix     AS INTEGER        ' Screen size along Y axis
    MaxColor    AS INTEGER        ' Maximum color number for current screen

    ChartWid    AS INTEGER        ' Width of chart window
    ChartHgt    AS INTEGER        ' Height of chart window
    CwX1        AS INTEGER        ' Left side of chart window
    CwY1        AS INTEGER        ' Top edge of chart window
    CwX2        AS INTEGER        ' Right side of chart window
    CwY2        AS INTEGER        ' Bottom edge of chart window

    XStagger    AS INTEGER        ' Boolean, true if category labels overflow
    ValLenX     AS INTEGER        ' Maximum length of value labels on X-axis
    ValLenY     AS INTEGER        ' Maximum length of value labels on Y-axis

    NVals       AS INTEGER        ' Number of data values in data series
    NSeries     AS INTEGER        ' Number of series of data
    MSeries     AS INTEGER        ' If multiple-series chart then cYes, else
                                            ' cNo
    XMode       AS INTEGER        ' Axis mode of x axis
    YMode       AS INTEGER        ' Axis mode of y axis
END TYPE

' FUNCTION and SUB declarations for procedures local to this module:

DECLARE FUNCTION clBuildBitP$ (Bits%, c%, InP$)
DECLARE FUNCTION clBuildPlaneP$ (Bits%, c%, InP$)
DECLARE FUNCTION clColorMaskL% (Bits%, Colr%)
DECLARE FUNCTION clGetStyle% (StyleNum%)
DECLARE FUNCTION clMaxVal (A, B)
DECLARE FUNCTION clMap2Pal% (N%)
DECLARE FUNCTION clMap2Attrib% (N%)
DECLARE FUNCTION clMaxStrLen% (Txt$(), First%, Last%)
DECLARE FUNCTION clVal2Str$ (X, Places%, Format%)

DECLARE SUB clAdjustScale (Axis AS AxisType)
DECLARE SUB clAnalyzeC (Cat$(), N%, SLabels$(), First%, Last%)
DECLARE SUB clAnalyzeS (N%, SLabels$(), First%, Last%)
DECLARE SUB clBuildPalette (ScrnMode%, Bits%)
DECLARE SUB clChkInit ()
DECLARE SUB clChkFonts ()
DECLARE SUB clChkForErrors (Env AS ChartEnvironment, TypeMin%, TypeMax%, N%, First%, Last%)
DECLARE SUB clChkChartWindow (Env AS ChartEnvironment)
DECLARE SUB clChkPalettes (c%(), s%(), P$(), Char%(), B%())
DECLARE SUB clClearError ()
DECLARE SUB clColorMaskH (Bits%, Colr%, CMask%())
DECLARE SUB clDrawAxes (Cat$())
DECLARE SUB clDrawDataWindow ()
DECLARE SUB clDrawChartWindow ()
DECLARE SUB clDrawTitles ()
DECLARE SUB clDrawLegend (SeriesLabel$(), First AS INTEGER, Last AS INTEGER)
DECLARE SUB clDrawBarData ()
DECLARE SUB clDrawColumnData ()
DECLARE SUB clDrawLineData ()
DECLARE SUB clDrawPieData (value(), Expl%(), N%)
DECLARE SUB clDrawScatterData ()
DECLARE SUB clFilter (A AS AxisType, AxisMode%, D1(), D2(), N%)
DECLARE SUB clFilterMS (A AS AxisType, AxisMode%, D1(), D2(), N%, First%, Last%)
DECLARE SUB clFlagSystem ()
DECLARE SUB clFormatTics (A AS AxisType)
DECLARE SUB clHPrint (X%, Y%, Txt$)
DECLARE SUB clInitChart ()
DECLARE SUB clInitStdStruc ()
DECLARE SUB clLabelXTics (Axis AS AxisType, Cat$(), TicX, TicTotX%, TicY, YBoundry%)
DECLARE SUB clLabelYTics (Axis AS AxisType, Cat$(), TicX, TicY, TicTotY%)
DECLARE SUB clLayoutTitle (TL AS ANY, T1 AS ANY, T2 AS ANY)
DECLARE SUB clPrintTitle (TitleVar AS TitleType, Y%)
DECLARE SUB clRenderBar (X1, Y1, X2, Y2, c%)
DECLARE SUB clRenderWindow (W AS RegionType)
DECLARE SUB clScaleAxis (A AS AxisType, AxisMode%, D1())
DECLARE SUB clSelectChartWindow ()
DECLARE SUB clSelectRelWindow (W AS RegionType)
DECLARE SUB clSetAxisModes ()
DECLARE SUB clSetChartFont (N AS INTEGER)
DECLARE SUB clSetError (ErrNo AS INTEGER)
DECLARE SUB clSetCharColor (N%)
DECLARE SUB clSetGlobalParams ()
DECLARE SUB clSizeDataWindow (Cat$())
DECLARE SUB clLayoutLegend (SeriesLabel$(), First%, Last%)
DECLARE SUB clSpaceTics ()
DECLARE SUB clSpaceTicsA (A AS AxisType, AxisMode%, AxisLen%, TicWid%)
DECLARE SUB clTitleXAxis (A AS AxisType, X1%, X2%, YBoundry%)
DECLARE SUB clTitleYAxis (A AS AxisType, Y1%, Y2%)
DECLARE SUB clUnFlagSystem ()
DECLARE SUB clVPrint (X%, Y%, Txt$)


' Variable definitions local to this module:

DIM PaletteC%(0 TO cPalLen)            ' List of colors     for drawing data
DIM PaletteS%(0 TO cPalLen)            ' List of styles     for drawing data
DIM PaletteP$(0 TO cPalLen)            ' List of patterns   for drawing data
DIM PaletteCh%(0 TO cPalLen)           ' List of plot chars for drawing data
DIM PaletteB%(0 TO cPalLen)            ' List of patterns   for borders

DIM StdChars%(0 TO cPalLen)            ' Holds default plot characters

DIM DAxis         AS AxisType          ' Default axis settings
DIM DWindow       AS RegionType        ' Default window settings
DIM DLegend       AS LegendType        ' Default legend settings
DIM DTitle        AS TitleType         ' Default title settings

DIM XTitleLayout  AS TitleLayout       ' X-axis layout information
DIM YTitleLayout  AS TitleLayout       ' Y-axis layout information
DIM TTitleLayout  AS TitleLayout       ' Main/Sub layout information

DIM LLayout       AS LegendLayout      ' Legend layout information

DIM GFI           AS FontInfo          ' Global font information
DIM GE            AS ChartEnvironment  ' An internal global chart environment
DIM GP            AS GlobalParams      ' Holds a number of global parameters
                                                    ' used in the charting routines.  See
                                                    ' TYPE definition for details.

'$DYNAMIC
DIM V1(1, 1), V2(1, 1)                 ' Internal dynamic data arrays.
'$STATIC


' Module level code:

' This error trap is set in the ChartScreen routine and will
' be evoked if an invalid screen mode is used:
ScreenErr:
    clSetError cBadScreen
    RESUME NEXT

' This error trap should catch all errors that arise in using
' the charting library that are not expected:
UnexpectedErr:
    clSetError cCLUnexpectedOff + ERR
    RESUME NEXT

'=== AnalyzeChart - Sets up scales and data window sizes
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     Cat$(1)    - One-dimensional array of category labels
'
'     Value(1)   - One-dimensional array of values to chart
'
'     N%         - The number of data values in data series
'
'  Return Values:
'     Scale and Data-Window values are changed as appropriate.
'
'=================================================================
SUB AnalyzeChart (Env AS ChartEnvironment, Cat$(), value(), N AS INTEGER)

SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED V1()
REDIM V1(1 TO N%, 1 TO 1)
DIM Dum$(1 TO 1)

    ' Check initialization and fonts:
    clClearError
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Set a global flag to indicate that this isn't a multiple-series chart:
    GP.MSeries = cNo

    ' Check for obvious parameter and ChartEnvironment errors:
    clChkForErrors Env, 1, 3, N, 0, 0
    IF ChartErr > 100 THEN EXIT SUB

    ' Make a copy of the user's ChartEnvironment variable to the library's
    ' global environment variable:
    GE = Env

    ' Set the correct axis modes for the type of chart specified in the
    ' chart environment:
    clSetAxisModes

    ' Transfer the input data to the dynamic working data array.  Do this
    ' for each axis because, depending on the chart type, either one may be
    ' the value axis.  The Filter routine automatically ignores the call if
    ' the axis is a category axis:
    clFilter GE.XAxis, GP.XMode, value(), V1(), N
    clFilter GE.YAxis, GP.YMode, value(), V1(), N

    ' Analyze the data for scale-maximum and -minimum and set the scale-
    ' factor, etc. depending on the options set in the chart environment:
    clAnalyzeC Cat$(), N, Dum$(), 1, 1

    ' Copy the global chart environment back to the user's ChartEnvironment
    ' variable so that the settings that were calculated by the library are
    ' accessible.  Then, if this routine wasn't called by the library itself,
    ' in the course of drawing a bar, column or line chart, deallocate the
    ' working data array:
    Env = GE
    IF GP.SysFlag = cNo THEN ERASE V1

END SUB

'=== AnalyzeChartMS - Analyzes multiple-series data for scale/window size.
'
'  Arguments:
'     Env             - ChartEnvironment variable
'
'     Cat$(1)         - One-dimensional array of category labels
'
'     Value(2)        - Two-dimensional array of values to chart.  First
'                       dimension (rows) represents different values within
'                       a series.  Second dimension (columns) represents
'                       different series.
'
'     N%              - Number of values (beginning with 1) to chart per
'                       series.
'
'     First%          - First series to analyze
'
'     Last%           - Last series to analyze
'
'     SeriesLabel$(1) - Labels for the different series
'
'  Return Values:
'     Various settings in the Env variable are altered in accordance with
'     the analysis.
'
'=================================================================
SUB AnalyzeChartMS (Env AS ChartEnvironment, Cat$(), value() AS SINGLE, N AS INTEGER, First AS INTEGER, Last AS INTEGER, SeriesLabel$())

SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED V1()
REDIM V1(1 TO N, 1 TO Last - First + 1)

    ' Check initialization and fonts:
    clClearError
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Set a global flag to indicate that this is a multiple-series chart:
    GP.MSeries = cYes

    ' Check for obvious parameter and ChartEnvironment errors:
    clChkForErrors Env, 1, 3, N, 0, 0
    IF ChartErr > 100 THEN EXIT SUB

    ' Make a copy of the user's ChartEnvironment variable to the library's
    ' global environment variable:
    GE = Env

    ' Set the correct axis modes for the type of chart specified in the
    ' chart environment:
    clSetAxisModes

    ' Transfer the input data to the dynamic working data array.  Do this
    ' for each axis because, depending on the chart type, either one may be
    ' the value axis.  The Filter routine automatically ignores the call if
    ' the axis is a category axis:
    clFilterMS GE.XAxis, GP.XMode, value(), V1(), N, First, Last
    clFilterMS GE.YAxis, GP.YMode, value(), V1(), N, First, Last

    ' Analyze the data for scale maximums and minimums and set the scale
    ' factor, etc. depending on the options set in the chart environment:
    clAnalyzeC Cat$(), N, SeriesLabel$(), First, Last

    ' Copy the global chart environment back to the user's ChartEnvironment
    ' variable so that the settings that were calculated by the library are
    ' accessible.  Then, if this routine wasn't called by the library itself,
    ' in the course of drawing a bar, column or line chart, deallocate the
    ' working data array:
    Env = GE
    IF GP.SysFlag = cNo THEN ERASE V1

END SUB

'=== AnalyzePie - Analyzes data for a pie chart
'
'  Arguments:
'     Env      - A ChartEnvironment variable
'
'     Cat$()   - One-dimensional array of category names
'
'     Value()  - One-dimensional array of values to chart
'
'     Expl()   - One dimensional array of flags indicating whether slices
'                are to be "exploded" (0 means no, 1 means yes).
'                Ignored if Env.ChartStyle <> 1.
'
'     N        - The number of values to chart
'
'  Return Values:
'     None.
'
'=================================================================
SUB AnalyzePie (Env AS ChartEnvironment, Cat$(), value() AS SINGLE, Expl() AS INTEGER, N AS INTEGER)
SHARED GE AS ChartEnvironment
SHARED GP AS GlobalParams
SHARED TTitleLayout AS TitleLayout
SHARED XTitleLayout AS TitleLayout
SHARED YTitleLayout AS TitleLayout
SHARED V1()
DIM EmptyTitle AS TitleType

    ' Check initialization and fonts:
    clClearError
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' This is a multiple series chart (a pie chart is treated as a
    ' multiple series chart with each series having one value):
    GP.MSeries = cYes
    GP.NSeries = N

    ' Check for obvious parameter and ChartEnvironment errors:
    clChkForErrors Env, cPie, cPie, 2, 1, N
    IF ChartErr > 100 THEN EXIT SUB

    ' Make a copy of the user's ChartEnvironment variable to the library's
    ' global environment variable:
    GE = Env

    ' Set the correct axis modes for the type of chart specified in the
    ' chart environment:
    clSetAxisModes

    ' Set global parameters and layout main title:
    clSetGlobalParams

    ' Layout titles (ignore X and Y axis titles):
    clLayoutTitle TTitleLayout, GE.MainTitle, GE.SubTitle
    EmptyTitle.Title = ""
    clLayoutTitle XTitleLayout, EmptyTitle, EmptyTitle
    clLayoutTitle YTitleLayout, EmptyTitle, EmptyTitle

    ' Calculate the size for LegendWindow and DataWindow:
    clLayoutLegend Cat$(), 1, N
    IF ChartErr > 100 THEN EXIT SUB
    clSizeDataWindow Cat$()
    IF ChartErr > 100 THEN EXIT SUB

    ' Copy the global chart environment back to the user's ChartEnvironment
    ' variable so that the settings that were calculated by the library are
    ' accessible.  Then, if this routine wasn't called by the library itself,
    ' in the course of drawing a pie chart, deallocate the working data array:
    Env = GE

END SUB

'=== AnalyzeScatter - Sets up scales and data-window sizes for scatter chart
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     ValX(1)    - One-dimensional array of values for X axis
'
'     ValY(1)    - One-dimensional array of values for Y axis
'
'     N%         - The number of data values in data series
'
'  Return Values:
'     Scale and data-window values are changed as appropriate.
'
'=================================================================
SUB AnalyzeScatter (Env AS ChartEnvironment, ValX() AS SINGLE, ValY() AS SINGLE, N AS INTEGER)

SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED V1(), V2()
REDIM V1(1 TO N, 1 TO 1), V2(1 TO N, 1 TO 1)
DIM Dum$(1 TO 1)

    ' Check initialization and fonts:
    clClearError
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Set a global flag to indicate that this isn't a multiple-series chart:
    GP.MSeries = cNo

    ' Check for obvious parameter and ChartEnvironment errors:
    clChkForErrors Env, 4, 4, N%, 0, 0
    IF ChartErr > 100 THEN EXIT SUB

    ' Make a copy of the user's ChartEnvironment variable to the library's
    ' global environment variable:
    GE = Env

    ' Set the correct axis modes for the type of chart specified in the
    ' chart environment:
    clSetAxisModes

    ' Transfer the input data to the dynamic working data arrays (one
    ' for each axis):
    clFilter GE.XAxis, GP.XMode, ValX(), V1(), N
    clFilter GE.YAxis, GP.YMode, ValY(), V2(), N

    ' Analyze the data for scale-maximum and -minimum and set the scale-
    ' factor, etc. depending on the options set in the chart environment:
    clAnalyzeS N, Dum$(), 1, 1

    ' Copy the global chart environment back to the user's ChartEnvironment
    ' variable so that the settings that were calculated by the library are
    ' accessible.  Then, if this routine wasn't called by the library itself,
    ' in the course of drawing a scatter chart, deallocate the working
    ' data arrays:
    Env = GE
    IF GP.SysFlag = cNo THEN ERASE V1, V2

END SUB

'=== AnalyzeScatterMS - Analyzes multiple-series data for scale/window size
'
'  Arguments:
'     Env             - A ChartEnvironment variable
'
'     ValX(2)         - Two-dimensional array of values for X axis.  First
'                       dimension (rows) represents different values within
'                       a series.  Second dimension (columns) represents
'                       different series.
'
'     ValY(2)         - Two-dimensional array of values for Y axis.  Above
'                       comments apply
'
'     N%              - Number of values (beginning with 1) to chart per
'                       series
'
'     First%          - First series to analyze
'
'     Last%           - Last series to analyze
'
'     SeriesLabel$(1) - Labels for the different series
'
'  Return Values:
'     Various settings in the Env variable are altered in accordance with
'     the analysis.
'
'=================================================================
SUB AnalyzeScatterMS (Env AS ChartEnvironment, ValX() AS SINGLE, ValY() AS SINGLE, N AS INTEGER, First AS INTEGER, Last AS INTEGER, SeriesLabel$())

SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED V1(), V2()
REDIM V1(1 TO N, 1 TO Last - First + 1), V2(1 TO N, 1 TO Last - First + 1)
DIM Dum$(1 TO 1)

    ' Check initialization and fonts:
    clClearError
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Set a global flag to indicate that this is a multiple-series chart:
    GP.MSeries = cYes

    ' Check for obvious parameter and ChartEnvironment errors:
    clChkForErrors Env, 4, 4, N%, 0, 0
    IF ChartErr > 100 THEN EXIT SUB

    ' Make a copy of the user's ChartEnvironment variable to the library's
    ' global environment variable:
    GE = Env

    ' Set the correct axis modes for the type of chart specified in the
    ' chart environment:
    clSetAxisModes

    ' Transfer the input data to the dynamic working data arrays (one
    ' for each axis):
    clFilterMS GE.XAxis, GP.XMode, ValX(), V1(), N, First, Last
    clFilterMS GE.YAxis, GP.YMode, ValY(), V2(), N, First, Last

    ' Analyze the data for scale-maximum and -minimum and set the scale-
    ' factor, etc. depending on the options set in the chart environment:
    clAnalyzeS N, SeriesLabel$(), First%, Last%

    ' Copy the global chart environment back to the user's ChartEnvironment
    ' variable so that the settings that were calculated by the library are
    ' accessible.  Then, if this routine wasn't called by the library itself,
    ' in the course of drawing a scatter chart, deallocate the working
    ' data arrays:
    Env = GE
    IF GP.SysFlag = cNo THEN ERASE V1, V2

END SUB

'=== Chart - Draws a single-series category/value chart
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     Cat$(1)    - One-dimensional array of category labels
'
'     Value(1)   - One-dimensional array of values to plot
'
'     N          - The number of data values in data series
'
'  Return Values:
'     Some elements of the Env variable are altered by plotting routines
'
'  Remarks:
'     This routine takes all of the parameters set in the Env variable
'     and draws a single-series chart of type Bar, Column, or Line
'     depending on the chart type specified in the Env variable.
'
'=================================================================
SUB Chart (Env AS ChartEnvironment, Cat$(), value() AS SINGLE, N AS INTEGER)

SHARED V1()

    ' Analyze data for scale and window settings:
    clFlagSystem
    AnalyzeChart Env, Cat$(), value(), N
    clUnFlagSystem
    IF ChartErr < 100 THEN

        ' Draw the different elements of the chart:
        clDrawChartWindow
        clDrawTitles
        clDrawDataWindow
        clDrawAxes Cat$()

        ' Call appropriate Draw...Data routine for chart type:
        SELECT CASE Env.ChartType
            CASE 1: clDrawBarData
            CASE 2: clDrawColumnData
            CASE 3: clDrawLineData
        END SELECT

    END IF

    ' Deallocate the data array:
    ERASE V1

END SUB

'=== ChartMS - Draws a multiple-series category/value chart
'
'  Arguments:
'     Env               - A ChartEnvironment variable
'
'     Cat$(1)           - A one-dimensional array of category names for the
'                         different data values
'
'     Value(2)          - A two-dimensional array of values--one column for
'                         each series of data
'
'     N%                - The number of data points in each series of data
'
'     First%            - The first series to be plotted
'
'     Last%             - The last series to be plotted
'
'     SeriesLabel$(1)   - Labels used for each series in the legend
'
'  Return Values:
'     Some elements of the Env variable are altered by plotting routines
'
'  Remarks:
'     This routine takes all of the parameters set in the Env variable
'     and draws a multiple-series chart of type Bar, Column, or Line
'     depending on the chart type specified in the Env variable.
'
'=================================================================
SUB ChartMS (Env AS ChartEnvironment, Cat$(), value() AS SINGLE, N AS INTEGER, First AS INTEGER, Last AS INTEGER, SeriesLabel$())

SHARED V1()

    ' Analyze data for scale settings:
    clFlagSystem
    AnalyzeChartMS Env, Cat$(), value(), N, First, Last, SeriesLabel$()
    clUnFlagSystem
    IF ChartErr < 100 THEN

        ' Draw the different elements of the chart:
        clDrawChartWindow
        clDrawTitles
        clDrawDataWindow
        clDrawAxes Cat$()

        ' Call appropriate Draw...DataMS routine for chart type:
        SELECT CASE Env.ChartType
            CASE 1: clDrawBarData
            CASE 2: clDrawColumnData
            CASE 3: clDrawLineData
        END SELECT

        ' Lastly, add the legend:
        clDrawLegend SeriesLabel$(), First, Last

    END IF

    ' Deallocate the data array:
    ERASE V1

END SUB

'=== ChartPie - Draws a pie chart
'
'  Arguments:
'     Env      - A ChartEnvironment variable
'
'     Cat$()   - One-dimensional array of category names
'
'     Value()  - One-dimensional array of values to chart
'
'     Expl%()  - One-dimensional array of flags indicating whether slices
'                are to be "exploded" or not (0 means no, 1 means yes),
'                ignored if ChartStyle <> 1
'
'     N%       - The number of values to chart
'
'  Return Values:
'     No return values
'
'=================================================================
SUB ChartPie (Env AS ChartEnvironment, Cat$(), value() AS SINGLE, Expl() AS INTEGER, N AS INTEGER)
SHARED GP AS GlobalParams
    ' Set the global system flag to tell the AnalyzePie routine that it
    ' is being called by the system and not the user:
    clFlagSystem

    ' Calculate the size of the Data- and Legend-window:
    AnalyzePie Env, Cat$(), value(), Expl(), N

    ' Remove the system flag:
    clUnFlagSystem

    ' If there were no errors during analysis draw the chart:
    IF ChartErr < 100 THEN

        ' Draw the different chart elements:
        clDrawChartWindow
        clDrawTitles
        clDrawDataWindow
        clDrawPieData value(), Expl(), N
        IF ChartErr <> 0 THEN EXIT SUB
        clDrawLegend Cat$(), 1, N

    END IF

END SUB

'=== ChartScatter - Draws a single-series scatter chart
'
'  Arguments:
'     Env      - A ChartEnvironment variable
'
'     ValX(1)  - One-dimensional array of values for X axis
'
'     ValY(1)  - One-dimensional array of values for Y axis
'
'     N%       - The number of values to chart
'
'
'  Return Values:
'     Some elements of Env variable may be changed by drawing routines
'
'  Remarks:
'     ChartScatter should be called when a chart with two value axes is
'     desired
'
'=================================================================
SUB ChartScatter (Env AS ChartEnvironment, ValX() AS SINGLE, ValY() AS SINGLE, N AS INTEGER)
DIM Dum$(1 TO 1)
SHARED V1(), V2()

    ' Set the global system flag to tell the AnalyzeScatter routine that it
    ' is being called by the system and not the user:
    clFlagSystem

    ' Calculate the scale maximums and minimums and scale factor. Also
    ' calculate the sizes for the Data- and Legend-windows:
    AnalyzeScatter Env, ValX(), ValY(), N

    ' Remove the system flag:
    clUnFlagSystem

    ' If there were no errors during analysis draw the chart:
    IF ChartErr < 100 THEN

        ' Draw the different elements of the chart:
        clDrawChartWindow
        clDrawTitles
        clDrawDataWindow
        clDrawAxes Dum$()
        clDrawScatterData

    END IF

    ' Deallocate the dynamic working data arrays:
    ERASE V1, V2

END SUB

'=== ChartScatterMS - Draws a multiple-series scatter chart
'
'  Arguments:
'     Env            - A ChartEnvironment variable
'
'     ValX(2)        - Two-dimensional array of values for X axis
'
'     ValY(2)        - Two-dimensional array of values for Y axis
'
'     N%             - The number of values in each series
'
'     First%         - First series to chart (first column)
'
'     Last%          - Last series to chart (last column)
'
'     SeriesLabel$() - Label used for each series in legend
'
'
'  Return Values:
'     Some elements in Env variable may be changed by drawing routines
'
'  Remarks:
'     A scatter chart uses two value axes so it must have values for both
'     the X and Y axes (ValX(), ValY()).  The first dimension denotes
'     the different values within a series.  The second dimension specifies
'     different data series (e.g. ValX(4,3) would represent the fourth value
'     in the third series of data).
'
'=================================================================
SUB ChartScatterMS (Env AS ChartEnvironment, ValX() AS SINGLE, ValY() AS SINGLE, N AS INTEGER, First AS INTEGER, Last AS INTEGER, SeriesLabel$())
DIM Dum$(1 TO 1)
SHARED V1(), V2()

    ' Set the global system flag to tell the AnalyzeScatterMS routine that it
    ' is being called by the system and not the user:
    clFlagSystem

    ' Calculate the scale maximums and minimums and scale factor. Also
    ' calculate the sizes for the Data- and Legend-windows:
    AnalyzeScatterMS Env, ValX(), ValY(), N, First, Last, SeriesLabel$()

    ' Remove the system flag:
    clUnFlagSystem

    ' If there were no errors during analysis draw the chart:
    IF ChartErr < 100 THEN

        ' Draw the different elements of the chart:
        clDrawChartWindow
        clDrawTitles
        clDrawDataWindow
        clDrawAxes Dum$()
        clDrawScatterData
        clDrawLegend SeriesLabel$(), First, Last

    END IF

    ' Deallocate the dynamic working data arrays:
    ERASE V1, V2

END SUB

'=== ChartScreen - Sets the SCREEN mode and default palettes
'
'  Arguments:
'     N%    - A valid BASIC graphic mode, or mode 0
'
'  Return Values:
'     All palettes may be altered
'
'=================================================================
SUB ChartScreen (N AS INTEGER)
SHARED GP AS GlobalParams

    ' Check initialization and fonts:
    clClearError
    clChkInit

    ' Set up branch to error processor and attempt to set the specified
    ' screen mode and draw to it:
    ON ERROR GOTO ScreenErr
    SCREEN N
    IF N <> 0 THEN PRESET (0, 0)
    ON ERROR GOTO UnexpectedErr

    ' If the above PRESET failed, then the TestScreen error processor will
    ' have set the ChartErr error variable to a nonzero value.  If the last
    ' call to ChartScreen used the same mode, GP.PaletteScrn will equal N; and
    ' there is no need to rebuild palettes.  In either case there is no need
    ' to do anything else, so exit:
    IF ChartErr <> 0 OR (GP.PaletteScrn = N AND GP.PaletteSet) THEN EXIT SUB

    ' This is a new screen mode so use the SELECT CASE statement below
    ' to handle it.  It sets the number of bits per pixel for a screen
    ' mode so that the palettes can be built properly:
    SELECT CASE N

        ' Screen mode 0 is not a graphics mode and is included mainly for
        ' completeness.  The actual screen mode has been set above, so exit:
        CASE 0:
            EXIT SUB

        CASE 1:  Bits% = 2
        CASE 2:  Bits% = 1
        CASE 3:  Bits% = 1
        CASE 4:  Bits% = 1
        CASE 7:  Bits% = 4
        CASE 8:  Bits% = 4
        CASE 9:
                    ' For screen mode 9, assume a 256K EGA and try setting
                    ' a color to 63.  If that fails, assume it is a 64K EGA
                    ' (the number of bit planes is four for 256K and two for
                    ' 64K):
                    Bits% = 4
                    ON ERROR GOTO ScreenErr
                    clClearError
                    COLOR 15
                    IF ChartErr <> 0 THEN Bits% = 2
                    clClearError
                    ON ERROR GOTO UnexpectedErr

        CASE 10: Bits% = 2
        CASE 11: Bits% = 1
        CASE 12: Bits% = 4
        CASE 13: Bits% = 8

        ' If none of the above match then a valid screen mode was specified;
        ' however the mode is un-supported so set error and exit:
        CASE ELSE: clSetError cBadScreen
                      EXIT SUB
    END SELECT

    ' The screen aspect is 4/3 * MaxY/MaxX:
    VIEW
    WINDOW (0, 0)-(1, 1)
    GP.MaxXPix% = PMAP(1, 0) + 1
    GP.MaxYPix% = PMAP(0, 1) + 1
    GP.Aspect = 1.33333 * (GP.MaxYPix% - 1) / (GP.MaxXPix% - 1)
    WINDOW

    ' The number of colors available:
    GP.MaxColor = 2 ^ Bits% - 1

    ' Specify which color to use for white:
    SELECT CASE N
        CASE 13: GP.White = 15
        CASE ELSE: GP.White = GP.MaxColor
    END SELECT

    ' Build palette for this screen mode:
    clBuildPalette N, Bits%

END SUB

'=== clAdjustScale - Calculates scaling factor for an axis and adjusts max-min
'                  as appropriate for scale factor and log base if log axis:
'
'  Arguments:
'     Axis  -  AxisType variable describing axis to be scaled.
'
'  Return Values:
'     May set the ScaleFactor and ScaleTitle elements and alter
'     ScaleMin and ScaleMax elements of the Axis variable.
'
'=================================================================
SUB clAdjustScale (Axis AS AxisType)

    ' Don't try to scale a log axis:
    IF Axis.RangeType = cLog THEN

        Axis.ScaleFactor = 1
        Axis.ScaleTitle.Title = "Log" + STR$(Axis.LogBase)

    ' For a linear axis, choose a scale factor up to Trillions depending
    ' on the size of the axis limits:
    ELSE

        ' Choose the largest ABS from Max and Min for the axis:
        IF ABS(Axis.ScaleMax) > ABS(Axis.ScaleMin) THEN
            Max = ABS(Axis.ScaleMax)
        ELSE
            Max = ABS(Axis.ScaleMin)
        END IF

        ' Find out power of three by which to scale:
        Power% = INT((LOG(Max) / LOG(10)) / 3)

        ' And, choose the correct title to go with it:
        SELECT CASE Power%
            CASE -4:     Axis.ScaleTitle.Title = "Trillionths"
            CASE -3:     Axis.ScaleTitle.Title = "Billionths"
            CASE -2:     Axis.ScaleTitle.Title = "Millionths"
            CASE -1:     Axis.ScaleTitle.Title = "Thousandths"
            CASE 0:     Axis.ScaleTitle.Title = ""
            CASE 1:     Axis.ScaleTitle.Title = "Thousands"
            CASE 2:     Axis.ScaleTitle.Title = "Millions"
            CASE 3:     Axis.ScaleTitle.Title = "Billions"
            CASE 4:     Axis.ScaleTitle.Title = "Trillions"
            CASE ELSE:  Axis.ScaleTitle.Title = "10^" + LTRIM$(STR$(Power% * 3))
        END SELECT

        ' Calculate the actual scale factor:
        Axis.ScaleFactor = 10 ^ (3 * Power%)

        ' Finally, scale Max and Min by ScaleFactor:
        Axis.ScaleMin = Axis.ScaleMin / Axis.ScaleFactor
        Axis.ScaleMax = Axis.ScaleMax / Axis.ScaleFactor

    END IF

END SUB

'=== clAnalyzeC - Does analysis of category/value data
'
'  Arguments:
'     Cat$(1)     -  List of category names
'
'     N%          -  Number of data values per series
'
'     SLabels$    -  Labels for the different data series
'
'     First%      -  First series to chart
'
'     Last%       -  Last series to chart
'
'  Return Values:
'     Some values in GE are altered.
'
'=================================================================
SUB clAnalyzeC (Cat$(), N%, SLabels$(), First%, Last%)
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED TTitleLayout AS TitleLayout
SHARED XTitleLayout AS TitleLayout
SHARED YTitleLayout AS TitleLayout
SHARED V1()

    ' Save the number of values and the number of series in the chart in
    ' the global parameter variables:
    GP.NVals = N%
    GP.NSeries = Last% - First% + 1

    ' Analyze data for scale-maximim and -minimum and scale-factor:
    clScaleAxis GE.XAxis, GP.XMode, V1()
    IF ChartErr > 100 THEN EXIT SUB

    clScaleAxis GE.YAxis, GP.YMode, V1()
    IF ChartErr > 100 THEN EXIT SUB

    ' Format tic labels (needed for sizing routines) and set global
    ' parameters (again used by sizing and other routines):
    clFormatTics GE.XAxis
    clFormatTics GE.YAxis
    clSetGlobalParams

    ' Layout Titles
    clLayoutTitle TTitleLayout, GE.MainTitle, GE.SubTitle
    clLayoutTitle YTitleLayout, GE.YAxis.AxisTitle, GE.YAxis.ScaleTitle
    clLayoutTitle XTitleLayout, GE.XAxis.AxisTitle, GE.XAxis.ScaleTitle

    ' If this is a multiple-series chart, calculate the legend size:
    IF GP.MSeries = cYes THEN clLayoutLegend SLabels$(), First%, Last%
    IF ChartErr > 100 THEN EXIT SUB

    ' Calculate the data-window size:
    clSizeDataWindow Cat$()
    IF ChartErr > 100 THEN EXIT SUB

    ' Finally, figure out the distance between tic marks:
    clSpaceTics

END SUB

'=== clAnalyzeS - Does actual analysis of scatter data
'
'  Arguments:
'     N%          -  Number of values per data series
'
'     SLabels$(1) -  Labels for the data series
'
'     First%      -  First series to analyze
'
'     Last%       -  Last series to analyze
'
'  Return Values:
'     Values in GE are altered.
'
'=================================================================
SUB clAnalyzeS (N%, SLabels$(), First%, Last%)
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED TTitleLayout AS TitleLayout
SHARED XTitleLayout AS TitleLayout
SHARED YTitleLayout AS TitleLayout
SHARED V1(), V2()
DIM Dum$(1 TO 1)

    ' Save the number of values and the number of series in the chart in
    ' the global parameter variables:
    GP.NVals = N%
    GP.NSeries = Last% - First% + 1

    ' Analyze data for scale-maximim and -minimum and scale-factor:
    clScaleAxis GE.XAxis, GP.XMode, V1()
    IF ChartErr > 100 THEN EXIT SUB

    clScaleAxis GE.YAxis, GP.YMode, V2()
    IF ChartErr > 100 THEN EXIT SUB

    ' Format tic labels (needed for sizing routines) and set global
    ' parameters (again used by sizing and other routines):
    clFormatTics GE.XAxis
    clFormatTics GE.YAxis
    clSetGlobalParams

    ' Layout Titles
    clLayoutTitle TTitleLayout, GE.MainTitle, GE.SubTitle
    clLayoutTitle YTitleLayout, GE.YAxis.AxisTitle, GE.YAxis.ScaleTitle
    clLayoutTitle XTitleLayout, GE.XAxis.AxisTitle, GE.XAxis.ScaleTitle

    ' If this is a multiple-series chart, calculate the legend size:
    IF GP.MSeries = cYes THEN clLayoutLegend SLabels$(), First%, Last%
    IF ChartErr > 100 THEN EXIT SUB

    ' Calculate the data window size:
    clSizeDataWindow Dum$()
    IF ChartErr > 100 THEN EXIT SUB

    ' Finally, figure out the distance between tic marks:
    clSpaceTics

END SUB

'=== clBuildBitP$ - Builds a pattern tile for a one bit-plane screen mode
'
'  Arguments:
'     Bits%    =  Number of bits per pixel in this screen mode
'
'     C%       =  The color used to make the pattern.
'
'     InP$     =  Reference pattern
'
'  Return Values:
'     Returns the specified pattern in specified color.
'
'  Remarks:
'     In screen modes where a pixel on the screen is represented by 1 or
'     more bits that are adjacent in memory, a byte of memory represents
'     one or more pixels depending on the number of bits per pixel the
'     mode uses (e.g. screen mode 1 uses 2 bits per pixel so each byte
'     contains 4 pixels).  To make a pattern tile in a specific color
'     you first decide which pixels should be on and which ones off.
'     Then, you set the corresponding two-bit pixels in the tile bytes
'     to the value of the color you want the pattern to be.  This routine
'     does this semi-automatically.  First it inputs a reference pattern that
'     contains the pattern defined in the highest color available for a
'     screen mode (all bits in a pixel set to one).  Then a color mask byte
'     is prepared with each pixel set to the color that was specified as
'     input to the routine.  When these two components (reference pattern
'     and color mask) are combined using a logical "AND" any pixel in the
'     reference pattern that was black (all zero) will remain black and any
'     pixel that was white will be of the input color.  The nice feature of
'     this scheme is that you can use one pattern set for any color
'     available for the screen mode.
'
'     Example: Screen mode 1; 2 bits per pixel; to build a pattern
'              with pixels alternating on and off in color 2:
'
'     Reference pattern:   11 00 11 00    (8 bits = 1 byte)
'     Color mask:          10 10 10 10    (each pixel set to color 2)
'                         -------------
'     Result of "AND"      10 00 10 00    (pattern in color 2)
'
'=================================================================
FUNCTION clBuildBitP$ (Bits%, c%, InP$)

    ' First get color mask to match this color and pixel size (bits per pixel):
    CMask% = clColorMaskL%(Bits%, c%)

    ' Initialize the output pattern to empty then combine the color
    ' mask with each byte in the input tile using a logical "AND":
    OutP$ = ""
    FOR i% = 1 TO LEN(InP$)
        NxtCH% = CMask% AND ASC(MID$(InP$, i%, 1))
        OutP$ = OutP$ + CHR$(NxtCH%)
    NEXT i%

    ' Return the completed pattern:
    clBuildBitP$ = OutP$

END FUNCTION

'=== clBuildPalette - Builds the five chart palettes
'
'  Arguments:
'     N           -  Screen mode for which to build palettes
'
'  Return Values:
'     Values in chart palettes set to standard ones for this mode
'
'  Remarks:
'     The following code sets up the palettes that are referenced when the
'     different chart elements are drawn.  See the charting library
'     documentation for a complete description of how these palettes are
'     used in drawing different portions of a chart.
'
'=================================================================
SUB clBuildPalette (ScrnMode AS INTEGER, Bits AS INTEGER)
SHARED PaletteC%(), PaletteS%(), PaletteP$(), PaletteCh%(), PaletteB%()
SHARED StdChars%()
SHARED GP AS GlobalParams

    ' Flag palette set and record the screen mode:
    GP.PaletteSet = cYes
    GP.PaletteScrn = ScrnMode
    GP.PaletteBits = Bits

    ' The first palettes to set are the character palette and the border
    ' style palette:
    PaletteCh%(0) = 0
    PaletteB%(0) = &HFFFF
    FOR i% = 1 TO cPalLen
        PaletteCh%(i%) = StdChars%(i%)
        PaletteB%(i%) = clGetStyle(i%)
    NEXT i%

    ' The next palette to set is the color palette, which is made up of
    ' a list of 10 (maybe repeating) colors.  Begin by setting the first
    ' two colors.  The first color (position 0) is always black and the
    ' second color is always white (or whatever the maximum color number
    ' is mapped to in the graphics-card palette).  Cycle through setting
    ' other colors.  They will be entered in order starting with color 1
    ' until the maximum number of colors is reached or the palette is filled
    ' (size governed by the cPalLen CONST).  If the maximum color is reached
    ' before the palette is filled then repeat the cycle again excluding
    ' color 0, and so on, until the color palette is filled:

    PaletteC%(0) = 0        ' Black
    PaletteC%(1) = GP.White ' White

    FOR i% = 2 TO cPalLen
        MappedI% = ((i% - 2) MOD GP.MaxColor) + 1
        PaletteC%(i%) = MappedI%
    NEXT i%

    ' Setting the line styles is almost the inverse of setting the colors
    ' in that each color within a cycle has the same line style.  When a
    ' new cycle of colors begins, though, the line style changes to
    ' differentiate the new cycle from previous ones.  The line style
    ' begins as &HFFFF or a solid line:

    ' The pattern component of the palette contains fill patterns for use in
    ' filling bars and pie slices.  Fill patterns are "bit" oriented whereas
    ' line styles are "pixel" oriented.  What this means is that a fill
    ' pattern of CHR$(&HFF) will be white regardless of what the current
    ' color is.  If you know that each pixel on the screen is represented by
    ' 2 bits in RAM and you want a solid fill with color 2, the corresponding
    ' definition would be CHR$(&HAA) (in binary 10 10 10 10 -- notice, four
    ' pixels of two bits each set to 2).  The following code automatically
    ' takes a fill pattern defined in terms of pixels, and by masking it
    ' with the current color generates the same fill pattern in the
    ' specified color.  Start with solid black (color 0):

    PaletteS%(0) = &HFFFF
    PaletteP$(0) = CHR$(0)

    FOR i% = 1 TO cPalLen

        ' The cycle number starts at one and is incremented each time
        ' the maximum number of colors for the current screen mode is reached:
        Cycle% = ((i% - 1) \ GP.MaxColor) + 1

        ' Set the style palette from the standard styles (which have
        ' previously been placed in the border palette):
        PaletteS%(i%) = PaletteB%(Cycle%)

        ' Get the default pattern and put it into the palette:
        SELECT CASE ScrnMode

            ' One bit plane modes:
            CASE 1, 2, 11, 13: RefPattern$ = GetPattern$(Bits, Cycle%)

            ' Multiple bit plane modes:
            CASE ELSE: RefPattern$ = GetPattern$(1, Cycle%)

        END SELECT
        PaletteP$(i%) = MakeChartPattern$(RefPattern$, PaletteC%(i%), 0)

    NEXT i%

END SUB

'=== clBuildPlaneP$ - Builds a pattern tile for multiple bit-plane screen modes
'
'  Arguments:
'     Bits%    =  Number of planes in this screen mode
'
'     C%       =  The color used to make the pattern
'
'     InP$     =  Reference pattern
'
'  Return Values:
'     Returns the specified pattern in specified color
'
'  Remarks:
'     PAINT tiles are different for screen modes that use 2 or more
'     bit-planes than for the modes that use only one (see remarks for
'     clBuildBitP$()).  When bit-planes are used each pixel requires only
'     one bit per byte, but, there needs to be one byte for each bit-
'     plane.  The process for building a pattern from a reference pattern
'     and color mask are logically the same as in the one bit-plane modes
'     the only difference is that a color mask requires several bytes
'     (one for each bit-plane) rather than one.
'
'  Example: Screen mode 9 with 2 bit planes; pattern with alternating
'           pixels on and off; color 2:
'
'           Reference pattern:   1 0 1 0 1 0 1 0
'           Color mask:          0 0 0 0 0 0 0 0   (plane 1)
'                                1 1 1 1 1 1 1 1   (plane 2)
'                               -----------------
'           Result of "AND"      0 0 0 0 0 0 0 0   (plane 1)
'                                1 0 1 0 1 0 1 0   (plane 2)
'
'
'=================================================================
FUNCTION clBuildPlaneP$ (Bits%, c%, InP$)
DIM CMask%(1 TO 4)

    ' First get color mask to match this color and pixel size (bits per pixel):
    clColorMaskH Bits%, c%, CMask%()

    ' Initialize the output pattern to empty then combine the color
    ' mask with each byte in the input tile using a logical "AND":
    OutP$ = ""
    FOR TileByte% = 1 TO LEN(InP$)
        RefTile% = ASC(MID$(InP$, TileByte%, 1))

        ' Combine each bit-plane in the color mask with the pattern byte:
        FOR Plane% = 1 TO Bits%
            OutP$ = OutP$ + CHR$(RefTile% AND CMask%(Plane%))
        NEXT Plane%
    NEXT TileByte%

    ' Return the completed pattern:
    clBuildPlaneP$ = OutP$

END FUNCTION

'=== clChkChartWindow - Makes sure the chart window is valid
'
'  Arguments:
'     Env   -  A ChartEnvironment variable
'
'  Return Values:
'     Changes global parameters for chart window
'
'  Remarks:
'     This routine forces the chart window to be valid.  If the input
'     values are invalid a full screen is chosen.  The valid chart window
'     is stored in the global parameter set and used by other charting
'     routines.  The last valid screen set by ChartScreen is used as
'     reference.
'
'=================================================================
SUB clChkChartWindow (Env AS ChartEnvironment)
SHARED GP AS GlobalParams

    ' Make sure X1 < X2:
    IF Env.ChartWindow.X1 < Env.ChartWindow.X2 THEN
        GP.CwX1 = Env.ChartWindow.X1
        GP.CwX2 = Env.ChartWindow.X2
    ELSE
        GP.CwX1 = Env.ChartWindow.X2
        GP.CwX2 = Env.ChartWindow.X1
    END IF

    ' Make sure Y1 < Y2:
    IF Env.ChartWindow.Y1 < Env.ChartWindow.Y2 THEN
        GP.CwY1 = Env.ChartWindow.Y1
        GP.CwY2 = Env.ChartWindow.Y2
    ELSE
        GP.CwY1 = Env.ChartWindow.Y2
        GP.CwY2 = Env.ChartWindow.Y1
    END IF

    ' If the X coordinates of the chart window are invalid,
    ' set them to full screen:
    IF GP.CwX1 < 0 OR GP.CwX2 >= GP.MaxXPix OR GP.CwX1 = GP.CwX2 THEN
        GP.CwX1 = 0
        GP.CwX2 = GP.MaxXPix - 1
    END IF

    ' If the Y coordinates of the chart window are invalid,
    ' set them to full screen:
    IF GP.CwY1 < 0 OR GP.CwY2 >= GP.MaxYPix OR GP.CwY1 = GP.CwY2 THEN
        GP.CwY1 = 0
        GP.CwY2 = GP.MaxYPix - 1
    END IF

    ' Set chart height and width for use later:
    GP.ChartWid = GP.CwX2 - GP.CwX1 + 1
    GP.ChartHgt = GP.CwY2 - GP.CwY1 + 1

    ' Put the valid coordinates in Env:
    Env.ChartWindow.X1 = GP.CwX1
    Env.ChartWindow.Y1 = GP.CwY1
    Env.ChartWindow.X2 = GP.CwX2
    Env.ChartWindow.Y2 = GP.CwY2

END SUB

'=== clChkFonts - Checks that there is at least one loaded font
'
'  Arguments:
'     none
'
'  Return Values:
'     Chart error set if no room for a font
'
'=================================================================
SUB clChkFonts ()

    ' See if a font is loaded:
    GetTotalFonts Reg%, LoadVar%

    ' If not then find out the maximum number of fonts allowed and if
    ' there's room, then load the default font:
    IF LoadVar% <= 0 THEN
        GetMaxFonts MReg%, MLoad%
        IF Reg% < MReg% AND LoadVar% < MLoad% THEN
            DefaultFont Segment%, Offset%
            FontNum% = RegisterMemFont(Segment%, Offset%)
            FontNum% = LoadFont("N" + STR$(LoadVar% + 1))

        ' If there's no room, then set an error:
        ELSE
            clSetError cNoFontSpace
        END IF
    END IF
END SUB

'=== CheckForErrors - Checks for and tries to fix a variety of errors
'
'  Arguments:
'     Env      -  ChartEnvironment variable
'
'     TypeMin% -  Minimum allowable ChartType
'
'     TypeMax% -  Maximum allowable ChartType
'
'     N%       -  Number of data values per series
'
'     First%   -  Column of data representing first series
'
'     Last%    -  Column of data representing last series
'
'  Return Values:
'     This routine is the main one that checks for errors of input in
'     the ChartEnvironment variable and routine parameters.
'
'=================================================================
SUB clChkForErrors (Env AS ChartEnvironment, TypeMin%, TypeMax%, N%, First%, Last%)

    ' Clear any previous error:
    clClearError

    ' Check for correct chart type:
    IF Env.ChartType < TypeMin% OR Env.ChartType > TypeMax% THEN
        clSetError cBadType
        EXIT SUB
    END IF

    ' Check for valid chart style:
    IF Env.ChartStyle < 1 OR Env.ChartStyle > 2 THEN
        clSetError cBadStyle
        Env.ChartStyle = 1
    END IF

    ' The following things are not relevant for pie charts:
    IF Env.ChartType <> cPie THEN

        ' Check LogBase for the X axis (default to 10):
        IF Env.XAxis.RangeType = cLog AND Env.XAxis.LogBase <= 0 THEN
            clSetError cBadLogBase
            Env.XAxis.LogBase = 10
        END IF

        ' Check LogBase for the Y axis (default to 10):
        IF Env.YAxis.RangeType = cLog AND Env.YAxis.LogBase <= 0 THEN
            clSetError cBadLogBase
            Env.YAxis.LogBase = 10
        END IF

        ' Check X axis ScaleFactor:
        IF Env.XAxis.AutoScale <> cYes AND Env.XAxis.ScaleFactor = 0 THEN
            clSetError cBadScaleFactor
            Env.XAxis.ScaleFactor = 1
        END IF

        ' Check Y axis ScaleFactor:
        IF Env.YAxis.AutoScale <> cYes AND Env.YAxis.ScaleFactor = 0 THEN
            clSetError cBadScaleFactor
            Env.YAxis.ScaleFactor = 1
        END IF
    END IF

    ' Make sure N > 0:
    IF N% <= 0 THEN
        clSetError cTooSmallN
        EXIT SUB
    END IF

    ' Check that First series <= Last one:
    IF First% > Last% THEN
        clSetError cTooFewSeries
        EXIT SUB
    END IF

    ' Force ChartWindow to be valid:
    clChkChartWindow Env

END SUB

'=== clChkInit - Check that chartlib has been initialized
'
'  Arguments:
'     none
'
'  Return Values:
'     none
'
'=================================================================
SUB clChkInit ()
SHARED GP AS GlobalParams

    IF NOT GP.Initialized THEN clInitChart

END SUB

'=== clChkPalettes - Makes sure that palettes are dimensioned correctly
'
'  Arguments:
'     C%()     -  Color palette array
'
'     S%()     -  Style palette array
'
'     P$()     -  Pattern palette array
'
'     Char%()  -  Plot character palette array
'
'     B%()     -  Border pattern palette array
'
'  Return Values:
'     Chart error may be set to cBadPalette
'
'=================================================================
SUB clChkPalettes (c() AS INTEGER, s() AS INTEGER, P$(), Char() AS INTEGER, B() AS INTEGER)

    ' Check each palette array to be sure it is dimensioned from 0
    ' to cPalLen:
    FOR i% = 1 TO 5
        SELECT CASE i%
            CASE 1:  L% = LBOUND(c, 1): U% = UBOUND(c, 1)
            CASE 2:  L% = LBOUND(s, 1): U% = UBOUND(s, 1)
            CASE 3:  L% = LBOUND(P$, 1): U% = UBOUND(P$, 1)
            CASE 4:  L% = LBOUND(Char, 1): U% = UBOUND(Char, 1)
            CASE 5:  L% = LBOUND(B, 1): U% = UBOUND(B, 1)
        END SELECT

        ' If incorrectly dimensioned then set error:
        IF (L% <> 0) OR (U% <> cPalLen) THEN
            clSetError cBadPalette
            EXIT SUB
        END IF
    NEXT i%

END SUB

'=== clClearError - Clears ChartErr, the ChartLib error variable
'
'  Arguments:
'     None
'
'  Return Values:
'     Sets ChartErr to 0
'
'=================================================================
SUB clClearError ()

    ChartErr = 0

END SUB

'=== clColorMaskH% - Function to generate a byte with each pixel set to
'                  some color - for high-res modes (7,8,9,10)
'
'  Arguments:
'     Bits%    -  Number of bits per pixel in current screen mode
'
'     Colr%    -  Color to make the mask
'
'     CMask%() -  One dimensional array to place mask values in
'
'  Return Values:
'     Screen modes 7, 8, 9 and 10 use bit planes.  Rather than using
'     adjacent bits in one byte to determine a color, they use bits
'     "stacked" on top of each other in different bytes.  This routine
'     generates one byte of a particular color by setting the different
'     levels of the stack to &H00 and &HFF to represent eight pixels
'     of a particular color.
'
'=================================================================
SUB clColorMaskH (Bits%, Colr%, CMask%())

    ' Copy the color to a local variable:
    RefColor% = Colr%

    ' Bits% is the number of bit planes, set a mask for each one:
    FOR i% = 1 TO Bits%

        ' Check rightmost bit in color, if it is set to 1 then this plane is
        ' "on" (it equals &HFF):
        IF RefColor% MOD 2 <> 0 THEN
            CMask%(i%) = &HFF

        ' If the bit is 0, the plane is off (it equals &H0):
        ELSE
            CMask%(i%) = &H0
        END IF

        ' Shift the reference color right by one bit:
        RefColor% = RefColor% \ 2
    NEXT i%

END SUB

'=== clColorMaskL% - Function to generate a byte with each pixel set to
'                 some color.
'
'  Arguments:
'     Bits%    -  Number of bits per pixel in current screen mode
'
'     Colr%    -  Color to make the mask
'
'  Return Values:
'     Returns integer with low byte that contains definitions for
'     pixels of specified color.
'
'=================================================================
FUNCTION clColorMaskL% (Bits%, Colr%)

    ' Initialize the mask to zero:
    M% = 0

    ' Multiplying a number by (2 ^ Bits%) will shift it left by "Bits%" bits:
    LShift% = 2 ^ Bits%

    ' Create a byte in which each pixel (of "Bits%" bits) is set to
    ' Colr%.  This is done by setting the mask to "Colr%" then shifting
    ' it left by "Bits%" and repeating until the byte is full:
    FOR i% = 0 TO 7 \ Bits%
        M% = M% * LShift% + Colr%
    NEXT i%

    ' Return the mask as the value of the function:
    clColorMaskL% = M% MOD 256

END FUNCTION

'=== clDrawAxes - Draws the axes for a chart
'
'  Arguments:
'     Cat$(1)  -  One-dimensional array or category names for use in
'                 labeling the category axis (ignored if category
'                 axis not used)
'
'  Return Values:
'     No return values
'
'=================================================================
SUB clDrawAxes (Cat$())
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED GFI AS FontInfo
SHARED PaletteC%(), PaletteB%()

    ' Use temporary variables to refer to axis limits:
    X1 = GE.XAxis.ScaleMin
    X2 = GE.XAxis.ScaleMax
    Y1 = GE.YAxis.ScaleMin
    Y2 = GE.YAxis.ScaleMax

    ' To draw the tic/grid lines it is necessary to know where the line
    ' starts and ends.  If tic marks are specified (by setting
    ' the "labeled" flag in the axis definition) then the
    ' tic lines start "ticwidth" below or to the left of the X and
    ' Y axis respectively.  If grid lines are specified then the
    ' tic/grid line ends at ScaleMax for the respective axis.  The
    ' case statements below calculate where the tic/grid lines start
    ' based on the above criteria.

    ' Check for tic marks first (X Axis):
    SELECT CASE GE.XAxis.Labeled
        CASE cNo:  XTicMinY = Y1
        CASE ELSE
            XTicMinY = Y1 - cTicSize * (Y2 - Y1)
            IF GP.XStagger = cYes THEN
                clSetChartFont GE.XAxis.TicFont
                XTicDropY = GFI.PixHeight * (Y2 - Y1) / (GE.DataWindow.Y2 - GE.DataWindow.Y1)
            ELSE
                XTicDropY = 0
            END IF
    END SELECT

    ' (Y Axis):
    SELECT CASE GE.YAxis.Labeled
        CASE cNo:  YTicMinX = X1
        CASE ELSE: YTicMinX = X1 - cTicSize * (X2 - X1)
    END SELECT

    ' Now for the other end of the tic/grid lines check for
    ' the grid flag (X axis):
    SELECT CASE GE.XAxis.grid
        CASE cNo:  XTicMaxY = Y1
        CASE ELSE: XTicMaxY = Y2
    END SELECT

    ' (Y Axis):
    SELECT CASE GE.YAxis.grid
        CASE cNo:  YTicMaxX = X1
        CASE ELSE: YTicMaxX = X2
    END SELECT

    ' Now that the beginning and end of the tic/grid lines has been
    ' calculated, it is necessary to figure out where they fall along the
    ' axes.  This depends on the type of axis: category or value.  On a
    ' category axis the tic/grid lines should fall in the middle of each
    ' bar set.  This is calculated by adding 1/2 of TicInterval to
    ' the beginning of the axis.  On a value axis the tic/grid line
    ' falls at the beginning of the axis.  It is also necessary to know
    ' the total number of tics per axis.  The following CASE statements
    ' calculate this.  Once the first tic/grid location on an axis is
    ' calculated the others can be calculated as they are drawn by adding
    ' TicInterval each time to the position of the previous tic mark:

    ' Location of the first (leftmost) tic/grid line on the X axis:
    TicTotX% = CINT((X2 - X1) / GE.XAxis.TicInterval)
    SELECT CASE GP.XMode
        CASE cCategory: TicX = X1 + GE.XAxis.TicInterval / 2
        CASE ELSE
            TicX = X1
            TicTotX% = TicTotX% + 1
    END SELECT

    ' Location of the first (top) tic/grid line on the Y axis:
    TicTotY% = CINT((Y2 - Y1) / GE.YAxis.TicInterval)
    SELECT CASE GP.YMode
        CASE cCategory: TicY = Y1 + GE.YAxis.TicInterval / 2
        CASE ELSE
            TicY = Y1
            TicTotY% = TicTotY% + 1
    END SELECT

    ' Now it's time to draw the axes; first the X then the Y axis.
    ' There's a small complexity that has to be dealt with first, though.
    ' The tic/grid lines are specified in "world" coordinates since that
    ' is easier to calculate but the current VIEW (the DataWindow) would
    ' clip them since tic marks (and also labels) lie outside of that
    ' region.  The solution is to extrapolate the DataWindow "world" to the
    ' ChartWindow region and set our VIEW to the ChartWindow.  This will
    ' clip labels if they are too long and try to go outside the Chart
    ' Window but still allow use of world coordinates for specifying
    ' locations.  To extrapolate the world coordinates to the ChartWindow,
    ' PMAP can be used.  This works since PMAP can take pixel coordinates
    ' outside of the current VIEW and map them to the appropriate world
    ' coordinates.  The DataWindow coordinates (calculated in the routine
    ' clSizeDataWindow) are expressed relative to the ChartWindow so
    ' it can be somewhat complicated trying to understand what to use with
    ' PMAP.  If you draw a picture of it things will appear more straight
    ' forward.

    ' To make sure that bars and columns aren't drawn over the axis lines
    ' temporarily move the left DataWindow border left by one and the bottom
    ' border down by one pixel:
    GE.DataWindow.X1 = GE.DataWindow.X1 - 1
    GE.DataWindow.Y2 = GE.DataWindow.Y2 + 1

    ' Select the DataWindow view and assign the "world" to it:
    clSelectRelWindow GE.DataWindow
    WINDOW (X1, Y1)-(X2, Y2)
    GTextWindow X1, Y1, X2, Y2, cFalse

    ' Next, use PMAP to extrapolate to ChartWindow:
    WorldX1 = PMAP(-GE.DataWindow.X1, 2)
    WorldX2 = PMAP(GP.ChartWid - 1 - GE.DataWindow.X1, 2)

    WorldY1 = PMAP(GP.ChartHgt - 1 - GE.DataWindow.Y1, 3)
    WorldY2 = PMAP(-GE.DataWindow.Y1, 3)

    ' Reset the DataWindow borders back to their original settings:
    GE.DataWindow.X1 = GE.DataWindow.X1 + 1
    GE.DataWindow.Y2 = GE.DataWindow.Y2 - 1

    ' Finally, select the ChartWindow VIEW and apply the extrapolated
    ' window to it:
    clSelectChartWindow
    WINDOW (WorldX1, WorldY1)-(WorldX2, WorldY2)
    GTextWindow WorldX1, WorldY1, WorldX2, WorldY2, cFalse

     ' Draw the X and Y axes (one pixel to left and bottom of window):
    CX% = PaletteC%(clMap2Pal%(GE.XAxis.AxisColor))  ' Color of X axis
    CY% = PaletteC%(clMap2Pal%(GE.YAxis.AxisColor))  ' Color of Y axis

    SX% = PaletteB%(clMap2Pal%(GE.XAxis.GridStyle)) ' Line styles; X grid
    SY% = PaletteB%(clMap2Pal%(GE.YAxis.GridStyle)) ' Line styles; Y grid

    LINE (X1, Y1)-(X2, Y1), CX%
    LINE (X1, Y1)-(X1, Y2), CY%

    ' X-Axis...Draw styled grid line then solid tic mark:
    TicLoc = TicX
    Stagger% = cFalse
    FOR i% = 1 TO TicTotX%
        LINE (TicLoc, Y1)-(TicLoc, XTicMaxY), CY%, , SX%
        IF Stagger% THEN
            LINE (TicLoc, XTicMinY - XTicDropY)-(TicLoc, Y1), CX%
            Stagger% = cFalse
        ELSE
            LINE (TicLoc, XTicMinY)-(TicLoc, Y1), CX%
            Stagger% = cTrue
        END IF
        TicLoc = TicLoc + GE.XAxis.TicInterval
    NEXT i%

    ' Y-Axis...Draw styled grid line then solid tic mark:
    TicLoc = TicY
    FOR i% = 1 TO TicTotY%
        LINE (X1, TicLoc)-(YTicMaxX, TicLoc), CX%, , SY%
        LINE (YTicMinX, TicLoc)-(X1, TicLoc), CY%
        TicLoc = TicLoc + GE.YAxis.TicInterval
    NEXT i%

    ' Label X tic marks and print titles:
    clLabelXTics GE.XAxis, Cat$(), TicX, TicTotX%, XTicMinY, YBoundry%
    clTitleXAxis GE.XAxis, GE.DataWindow.X1, GE.DataWindow.X2, YBoundry%

    ' Label Y tic marks and print titles:
    clLabelYTics GE.YAxis, Cat$(), YTicMinX, TicY, TicTotY%
    clTitleYAxis GE.YAxis, GE.DataWindow.Y1, GE.DataWindow.Y2

END SUB

'=== clDrawBarData - Draws data portion of multi-series bar chart
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clDrawBarData ()
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED PaletteC%()
SHARED V1()

    ' Set the VIEW to the DataWindow:
    clSelectRelWindow GE.DataWindow

    ' Set the WINDOW to match:
    WINDOW (GE.XAxis.ScaleMin, GE.YAxis.ScaleMin)-(GE.XAxis.ScaleMax, GE.YAxis.ScaleMax)
    GTextWindow GE.XAxis.ScaleMin, GE.YAxis.ScaleMin, GE.XAxis.ScaleMax, GE.YAxis.ScaleMax, cFalse

    ' If this is a linear axis then determine where the bars should grow from:
    IF GE.XAxis.RangeType = cLinear THEN

        ' If the scale minimum and maximum are on opposite sides of zero
        ' set the bar starting point to zero:
        IF GE.XAxis.ScaleMin < 0 AND GE.XAxis.ScaleMax > 0 THEN
            BarMin = 0

        ' If the axis range is all negative the the bars should grow from
        ' the right to the left so make the bar starting point the scale
        ' maximum:
        ELSEIF GE.XAxis.ScaleMin < 0 THEN
            BarMin = GE.XAxis.ScaleMax

        ' The axis range is all positive so the bar starting point is the
        ' scale minimum:
        ELSE
            BarMin = GE.XAxis.ScaleMin
        END IF

    ' The bar starting point for log axes should always be the scale minimum
    ' since only positive numbers are represented on a log axis (even though
    ' the log of small numbers is negative):
    ELSE
        BarMin = GE.XAxis.ScaleMin
    END IF

    ' Calculate the width of a bar.  Divide by the number of
    ' series if it's a plain (not stacked) chart:
    BarWid = GE.YAxis.TicInterval * cBarWid
    IF GE.ChartStyle = cPlain THEN BarWid = BarWid / GP.NSeries

    ' Calculate the beginning Y value of first bar then loop drawing
    ' all the bars:
    SpaceWid = GE.YAxis.TicInterval * (1 - cBarWid)
    StartLoc = GE.YAxis.ScaleMax - SpaceWid / 2

    FOR i% = 1 TO GP.NVals

        ' Reset sum variables for positive and negative stacked bars:
        RSumPos = 0
        RSumNeg = 0

        ' Reset the bar starting points:
        BarStartPos = BarMin
        BarStartNeg = BarMin

        ' Reset starting Y location of this bar set:
        BarLoc = StartLoc

        ' Now, chart the different series for this category:
        FOR J% = 1 TO GP.NSeries

            ' Get the value to chart from the data array:
            V = V1(i%, J%)

            ' If the value isn't a missing one then try to chart it:
            IF V <> cMissingValue THEN

                ' If the X-axis has the AutoScale flag set then divide
                ' the value by the axis' ScaleFactor variable:
                IF GE.XAxis.AutoScale = cYes THEN V = V / GE.XAxis.ScaleFactor

                ' If this is a plain chart then calculate the bar's location
                ' and draw it:
                IF GE.ChartStyle = cPlain THEN

                    BarLoc = StartLoc - (J% - 1) * BarWid
                    clRenderBar BarMin, BarLoc, V, BarLoc - BarWid, J%

                ' If the bars should be stacked then draw either a positive or
                ' negative portion of a bar depending on whether the data value
                ' is positive or negative:
                ELSE

                    ' If the value is positive:
                    IF V > 0 THEN

                        ' Add the value to the current sum for the bar and draw
                        ' the bar from the top of the last portion:
                        RSumPos = RSumPos + V
                        clRenderBar BarStartPos, BarLoc, RSumPos, BarLoc - BarWid, J%
                        BarStartPos = RSumPos

                    ' If the value is negative:
                    ELSE

                        ' Add the value to the current sum for the bar and draw
                        ' the bar from the bottom of the last portion:
                        RSumNeg = RSumNeg + V
                        clRenderBar BarStartNeg, BarLoc, RSumNeg, BarLoc - BarWid, J%
                        BarStartNeg = RSumNeg

                    END IF
                END IF
            END IF

        NEXT J%

        ' Update the bar cluster's starting location:
        StartLoc = StartLoc - GE.YAxis.TicInterval

    NEXT i%

    ' If BarMin isn't the axis minimum then draw a reference line:
    IF BarMin <> GE.XAxis.ScaleMin THEN
        LINE (BarMin, GE.YAxis.ScaleMin)-(BarMin, GE.YAxis.ScaleMax), PaletteC%(clMap2Pal%(GE.YAxis.AxisColor))
    END IF

END SUB

'=== clDrawChartWindow - Draws the Chart window
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine erases any previous viewport
'
'=================================================================
SUB clDrawChartWindow ()
SHARED GE AS ChartEnvironment

    ' Define viewport then render window:
    clSelectChartWindow
    clRenderWindow GE.ChartWindow

END SUB

'=== clDrawColumnData - Draws data portion of MS Column chart
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clDrawColumnData ()
SHARED GP AS GlobalParams, GE AS ChartEnvironment
SHARED PaletteC%(), V1()

    ' First, set the VIEW to DataWindow:
    clSelectRelWindow GE.DataWindow

    ' Set the WINDOW to match:
    WINDOW (GE.XAxis.ScaleMin, GE.YAxis.ScaleMin)-(GE.XAxis.ScaleMax, GE.YAxis.ScaleMax)
    GTextWindow GE.XAxis.ScaleMin, GE.YAxis.ScaleMin, GE.XAxis.ScaleMax, GE.YAxis.ScaleMax, cFalse

    ' If this is a linear axis then determine where the bars should grow from:
    IF GE.YAxis.RangeType = cLinear THEN

        ' Draw 0 reference line if the scale minimum and maximum are on
        ' opposite sides of zero.  Also set the bar starting point to zero
        ' so that bars grow from the zero line:
        IF GE.YAxis.ScaleMin < 0 AND GE.YAxis.ScaleMax > 0 THEN
            BarMin = 0

        ' If the axis range is all negative the the bars should grow from
        ' the right to the left so make the bar starting point the scale
        ' maximum:
        ELSEIF GE.YAxis.ScaleMin < 0 THEN
            BarMin = GE.YAxis.ScaleMax

        ' The axis range is all positive so the bar starting point is the
        ' scale minimum:
        ELSE
            BarMin = GE.YAxis.ScaleMin
        END IF

    ' The bar starting point for log axes should always be the scale minimum
    ' since only positive numbers are represented on a log axis (even though
    ' the log of small numbers is negative):
    ELSE
        BarMin = GE.YAxis.ScaleMin
    END IF

    ' Calculate the width of a bar.  Divide by the number of
    ' series if it's a plain (not stacked) chart:
    BarWid = GE.XAxis.TicInterval * cBarWid
    IF GE.ChartStyle = cPlain THEN BarWid = BarWid / GP.NSeries

    ' calculate the beginning X value of first bar and loop, drawing all
    ' the bars:
    SpaceWid = GE.XAxis.TicInterval * (1 - cBarWid)
    StartLoc = GE.XAxis.ScaleMin + SpaceWid / 2

    FOR i% = 1 TO GP.NVals

        ' Reset sum variables for positive and negative stacked bars:
        RSumPos = 0
        RSumNeg = 0

        BarStartPos = BarMin
        BarStartNeg = BarMin

        ' Reset starting Y location of this bar set:
        BarLoc = StartLoc

        ' Now, go across the rows charting the different series for
        ' this category:
        FOR J% = 1 TO GP.NSeries

            ' Get the value to chart from the data array:
            V = V1(i%, J%)

            ' If the value isn't a missing one then try to chart it:
            IF V <> cMissingValue THEN

                ' If the Y-axis has the AutoScale flag set then divide
                ' the value by the axis' ScaleFactor variable:
                IF GE.YAxis.AutoScale = cYes THEN V = V / GE.YAxis.ScaleFactor

                ' If this is a plain chart then calculate the bar's location
                ' and draw it:
                IF GE.ChartStyle = cPlain THEN

                    BarLoc = StartLoc + (J% - 1) * BarWid
                    clRenderBar BarLoc, BarMin, BarLoc + BarWid, V, J%

                ' If the bars should be stacked then draw either a positive or
                ' negative portion of a bar depending on whether the data value
                ' is positive or negative:
                ELSE

                    ' If the value is positive:
                    IF V > 0 THEN

                        ' Add the value to the current sum for the bar and draw
                        ' the bar from the top of the last portion:
                        RSumPos = RSumPos + V
                        clRenderBar BarLoc, BarStartPos, BarLoc + BarWid, RSumPos, J%
                        BarStartPos = RSumPos

                    ' If the value is negative:
                    ELSE

                        ' Add the value to the current sum for the bar and draw
                        ' the bar from the bottom of the last portion:
                        RSumNeg = RSumNeg + V
                        clRenderBar BarLoc, BarStartNeg, BarLoc + BarWid, RSumNeg, J%
                        BarStartNeg = RSumNeg

                    END IF
                END IF
            END IF

        NEXT J%

        ' Update the bar cluster's starting location:
        StartLoc = StartLoc + GE.XAxis.TicInterval

    NEXT i%

    ' If BarMin isn't the axis minimum then draw a reference line:
    IF BarMin <> GE.YAxis.ScaleMin THEN
        LINE (GE.XAxis.ScaleMin, BarMin)-(GE.XAxis.ScaleMax, BarMin), PaletteC%(clMap2Pal%(GE.XAxis.AxisColor))
    END IF

END SUB

'=== clDrawDataWindow - Draws the Data window
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine erases any previous viewport or window specification.
'
'=================================================================
SUB clDrawDataWindow ()
SHARED GE AS ChartEnvironment

    ' Define viewport then render window:
    clSelectRelWindow GE.DataWindow
    clRenderWindow GE.DataWindow

END SUB

'=== clDrawLegend - Draws a legend
'
'  Arguments:
'     SeriesLabel$(1)   - Array of labels for the legend
'
'     First%            - Label number corresponding to first series
'
'     Last%             - Label number corresponding to last series
'
'  Return Values:
'     None.
'
'=================================================================
SUB clDrawLegend (SeriesLabel$(), First AS INTEGER, Last AS INTEGER)

SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED PaletteC%(), PaletteP$(), PaletteCh%()
SHARED GFI AS FontInfo
SHARED LLayout AS LegendLayout

    ' If legend flag is No then exit:
    IF GE.Legend.Legend = cNo THEN EXIT SUB

    ' Select and render the legend window:
    clSelectRelWindow GE.Legend.LegendWindow
    clRenderWindow GE.Legend.LegendWindow
    WINDOW
    GTextWindow 0, 0, 0, 0, cFalse

    ' Start with the first label, set the Y position of the first line
    ' of labels and loop through all the rows in the legend:
    clSetChartFont GE.Legend.TextFont
    LabelNum% = First
    YPos% = LLayout.HorizBorder
    FOR i% = 1 TO LLayout.NumRow

        ' Set position of beginning of row:
        XPos% = LLayout.VertBorder

        FOR J% = 1 TO LLayout.NumCol

            ' Map the label number to a valid palette reference:
            MJ% = clMap2Pal%(LabelNum% - First + 1)

            ' Depending on ChartType draw either a filled box or the
            ' plot character used for plotting:
            XStep% = LLayout.SymbolSize / GP.Aspect
            SELECT CASE GE.ChartType

                CASE cBar, cColumn, cPie:
                    LINE (XPos%, YPos%)-STEP(XStep%, LLayout.SymbolSize), 0, BF
                    LINE (XPos%, YPos%)-STEP(XStep%, LLayout.SymbolSize), 1, B
                    PAINT (XPos% + 1, YPos% + 1), PaletteP$(MJ%), 1
                    LINE (XPos%, YPos%)-STEP(XStep%, LLayout.SymbolSize), PaletteC%(MJ%), B

                CASE cLine, cScatter:
                    clSetCharColor MJ%
                    PlotChr$ = CHR$(PaletteCh%(MJ%))
                    clHPrint XPos% + XStep% - GFI.AvgWidth, YPos% - GFI.Leading, PlotChr$

            END SELECT

            ' Print the label for this entry in the legend:
            clSetCharColor GE.Legend.TextColor
            clHPrint XPos% + LLayout.LabelOffset, YPos% - GFI.Leading, SeriesLabel$(LabelNum%)

            ' Increment the label count and check count has finished:
            LabelNum% = LabelNum% + 1
            IF LabelNum% > Last THEN EXIT SUB

            ' Move over to the next column:
            XPos% = XPos% + LLayout.ColSpacing

        NEXT J%

        ' Move position to the next row:
        YPos% = YPos% + LLayout.RowSpacing

    NEXT i%

END SUB

'=== clDrawLineData - Draws data portion line chart
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clDrawLineData ()
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED PaletteC%(), PaletteS%(), PaletteCh%()
SHARED GFI AS FontInfo
SHARED V1()

    ' First, set the appropriate font and make text horizontal:
    clSetChartFont GE.DataFont
    SetGTextDir 0

    ' Then, set the view to DataWindow:
    clSelectRelWindow GE.DataWindow

    ' Set the window to match:
    WINDOW (GE.XAxis.ScaleMin, GE.YAxis.ScaleMin)-(GE.XAxis.ScaleMax, GE.YAxis.ScaleMax)
    GTextWindow GE.XAxis.ScaleMin, GE.YAxis.ScaleMin, GE.XAxis.ScaleMax, GE.YAxis.ScaleMax, cFalse

    ' Loop through the series:
    FOR J% = 1 TO GP.NSeries

        ' Map the series number into a valid palette reference:
        MJ% = clMap2Pal%(J%)

        ' Calculate starting X location of first point and set
        ' last value to missing (since this is the first value in the
        ' series the last value wasn't there):
        StartLoc = GE.XAxis.ScaleMin + GE.XAxis.TicInterval / 2
        LastMissing% = cYes

        FOR i% = 1 TO GP.NVals

            ' Get a value from the data array:
            V = V1(i%, J%)

            ' If the value is missing, set the LastMissing flag to Yes and
            ' go to the next value:
            IF V = cMissingValue THEN
                LastMissing% = cYes

            ' If the value is not missing then try to chart it:
            ELSE

                ' Scale the value (and convert it to a log if this is a
                ' Log axis):
                IF GE.YAxis.AutoScale = cYes THEN V = V / GE.YAxis.ScaleFactor

                ' If the style dictates lines and the last point wasn't
                ' missing then draw a line between the last point and this one:
                IF GE.ChartStyle = cLines AND LastMissing% <> cYes THEN
                    LINE -(StartLoc, V), PaletteC%(MJ%), , PaletteS%(MJ%)
                END IF

                ' Position and print character:
                CX% = PMAP(StartLoc, 0) - GetGTextLen(CHR$(PaletteCh%(MJ%))) / 2
                CY% = PMAP(V, 1) - GFI.Ascent / 2
                clSetCharColor MJ%
                clHPrint CX%, CY%, CHR$(PaletteCh%(MJ%))

                PSET (StartLoc, V), POINT(StartLoc, V)

                LastMissing% = cNo
            END IF

            ' Move to next category position:
            StartLoc = StartLoc + GE.XAxis.TicInterval
        NEXT i%
    NEXT J%

END SUB

'=== clDrawPieData - Draws data part of a pie chart
'
'  Arguments:
'     Value(1)    -  One-dimensional array of data values
'
'     Expl(1)     -  One-dimensional array of explode flags (1=explode, 0=no)
'
'     N%          -  The number of data values to plot
'  Return Values:
'     None
'
'=================================================================
SUB clDrawPieData (value() AS SINGLE, Expl() AS INTEGER, N AS INTEGER)
SHARED GE AS ChartEnvironment
SHARED GP AS GlobalParams
SHARED GFI AS FontInfo
SHARED PaletteC%(), PaletteP$()

    ' Set the font to use for percent labels:
    clSetChartFont GE.DataFont

    ' Set up some reference variables:
    Pi2 = 2 * cPiVal                  ' 2*PI for radians conversions
    MinAngle = Pi2 / 120              ' Smallest wedge to try to paint
    A1 = -.0000001                    ' Starting and ending angle (set
    A2 = A1                           ' to very small negative to get
                                                 ' radius line for first wedge)

    ' Size the pie.
    ' Choose the point in the middle of the data window for the pie center:
    WINDOW (0, 0)-(1, 1)
    X = PMAP(.5, 0)                  ' Distance: left to center
    Y = PMAP(.5, 1)                  ' Distance: bottom to center
    WINDOW                           ' Now, use physical coordinates (pixels)
    GTextWindow 0, 0, 0, 0, cFalse

    ' Adjust radii for percent labels if required:
    clSetChartFont GE.DataFont
    IF GE.ChartStyle = cPercent THEN
        RadiusX = (X - 6 * GFI.AvgWidth) * GP.Aspect
        RadiusY = Y - 2 * GFI.PixHeight
    ELSE
        RadiusX = X * GP.Aspect
        RadiusY = Y
    END IF

    ' Pick the smallest radius (adjusted for screen aspect) then reduce
    ' it by 10% so the pie isn't too close to the window border:
    IF RadiusX < RadiusY THEN
        Radius = RadiusX
    ELSE
        Radius = RadiusY
    END IF
    Radius = (.9 * Radius) / GP.Aspect

    ' If radius is too small then error:
    IF Radius <= 0 THEN
        clSetError cBadDataWindow
        EXIT SUB
    END IF

    ' Find the sum of the data values (use double precision Sum variable to
    ' protect against overflow if summing large data values):
    Sum# = 0
    FOR i% = 1 TO GP.NSeries
        IF value(i%) > 0 THEN Sum# = Sum# + value(i%)
    NEXT i%

    ' Loop through drawing and painting the wedges:
    FOR i% = 1 TO N

        ' Map I% to a valid palette reference:
        MappedI% = clMap2Pal(i%)

        ' Draw wedges for positive values only:
        IF value(i%) > 0 THEN

            ' Calculate wedge percent and wedge ending angle:
            Percent = value(i%) / Sum#
            A2 = A1 - Percent * Pi2

            ' This locates the angle through the center of the pie wedge and
            ' calculates X and Y components of the vector headed in that
            ' direction:
            Bisect = (A1 + A2) / 2
            BisectX = Radius * COS(Bisect)
            BisectY = Radius * SIN(Bisect) * GP.Aspect

            ' If the piece is exploded then offset it 1/10th of a radius
            ' along the bisecting angle calculated above:
            IF Expl(i%) <> 0 THEN
                CX = X + .1 * BisectX
                CY = Y + .1 * BisectY
            ELSE
                CX = X
                CY = Y
            END IF

            ' If the angle is large enough, paint the wedge (if wedges of
            ' smaller angles are painted, the "paint" will sometimes spill out):
            IF (A1 - A2) > MinAngle THEN
                PX = CX + .8 * BisectX
                PY = CY + .8 * BisectY

                ' Outline the wedge in color 1 and paint it black.
                CIRCLE (CX, CY), Radius, 1, A1, A2, GP.Aspect
                PAINT (PX, PY), 0, 1
                ' Paint with the appropriate pattern:
                PAINT (PX, PY), PaletteP$(MappedI%), 1
            END IF
            ' draw the wedge in the correct color:
            CIRCLE (CX, CY), Radius, PaletteC%(MappedI%), A1, A2, GP.Aspect

            ' Label pie wedge with percent if appropriate:
            IF GE.ChartStyle = cPercent THEN
                Label$ = clVal2Str$(Percent * 100, 1, 1) + "%"
                LabelX% = CX + BisectX + (GFI.AvgWidth * COS(Bisect))
                LabelY% = CY + BisectY + (GFI.AvgWidth * SIN(Bisect)) * GP.Aspect

                ' Adjust label location for the quadrant:
                Quadrant% = FIX((ABS(Bisect / Pi2)) * 4)
                IF Quadrant% = 0 OR Quadrant% = 1 THEN
                    LabelY% = LabelY% - GFI.Ascent
                END IF
                IF Quadrant% = 1 OR Quadrant% = 2 THEN
                    LabelX% = LabelX% - GetGTextLen(Label$)
                END IF

                clSetCharColor GE.Legend.TextColor
                clHPrint LabelX%, LabelY%, Label$
            END IF
        END IF

        ' Set the beginning of next wedge to the end of this one:
        A1 = A2

    NEXT i%

END SUB

'=== clDrawScatterData - Draws data portion of Scatter chart
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clDrawScatterData ()
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED PaletteC%(), PaletteS%(), PaletteCh%()
SHARED GFI AS FontInfo
SHARED V1(), V2()

    ' Select the chart font and make text output horizontal:
    clSetChartFont GE.DataFont
    SetGTextDir 0

    ' Now, loop through all the points charting them:
    FOR Series% = 1 TO GP.NSeries

        ' Set LastMissing flag to Yes for first point in series:
        LastMissing% = cYes
        MS% = clMap2Pal%(Series%)

        ' Loop through all the points, charting them:
        FOR DataPoint% = 1 TO GP.NVals

            ' Get the X-value and Y-values from the data arrays:
            VX = V1(DataPoint%, Series%)
            VY = V2(DataPoint%, Series%)

            ' If either of the values to chart is missing set LastMissing
            ' flag to Yes to indicate a missing point and go to the next point:
            IF VX = cMissingValue OR VY = cMissingValue THEN
                LastMissing% = cYes

            ELSE

                ' Otherwise, scale the X and Y values if AutoScale is set for
                ' their respective axes:
                IF GE.XAxis.AutoScale = cYes THEN VX = VX / GE.XAxis.ScaleFactor
                IF GE.YAxis.AutoScale = cYes THEN VY = VY / GE.YAxis.ScaleFactor

                ' If this is a lined chart and the last point wasn't missing,
                ' then draw a line from last point to the current point:
                IF GE.ChartStyle = cLines AND LastMissing% <> cYes THEN
                    LINE -(VX, VY), PaletteC%(MS%), , PaletteS%(MS%)
                END IF

                ' In any case draw the plot character.  Start by getting the
                ' screen coordinates of the character relative to the point
                ' just charted:
                CX% = PMAP(VX, 0) - GetGTextLen(CHR$(PaletteCh%(MS%))) / 2
                CY% = PMAP(VY, 1) - GFI.Ascent / 2

                ' Now, set the character color and print it:
                clSetCharColor MS%
                clHPrint CX%, CY%, CHR$(PaletteCh%(MS%))

                ' Finally, reset the graphics cursor, since printing the
                ' character changed it:
                PSET (VX, VY), POINT(VX, VY)

                LastMissing% = cNo
            END IF

        NEXT DataPoint%
    NEXT Series%
END SUB

'=== clDrawTitles - Draws the main and subtitles on a chart
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clDrawTitles ()
SHARED GE AS ChartEnvironment
SHARED TTitleLayout AS TitleLayout

    ' Bottom of main title line is 1-1/2 character heights from the
    ' top of the chart window:
    YPos% = TTitleLayout.Top
    clPrintTitle GE.MainTitle, YPos%

    ' Add 1.5 * character height to y position for subtitle line position:
    YPos% = YPos% + TTitleLayout.TitleOne + TTitleLayout.Middle
    clPrintTitle GE.SubTitle, YPos%

END SUB

'=== clFilter - Filters input data into dynamic working data array
'
'  Arguments:
'     Axis     -  An AxisType variable
'
'     AxisMode%-  Mode for this axis
'
'     D1(1)    -  One-dimensional array of input data
'
'     D2(2)    -  Two-dimensional array for filtered data
'
'     N%       -  The number of values to transfer
'
'  Return Values:
'     Alters values in D2()
'
'=================================================================
SUB clFilter (Axis AS AxisType, AxisMode%, D1(), D2(), N%)

    ' If the axis is a category one then exit:
    IF AxisMode% = cCategory THEN EXIT SUB

    ' Transfer the data from the input data array to the working data
    ' array:
    FOR i% = 1 TO N%
        D2(i%, 1) = D1(i%)
    NEXT i%

    ' Call FilterMS to go through the data again scaling it and taking
    ' logs depending on the settings for this axis:
    clFilterMS Axis, AxisMode%, D2(), D2(), N%, 1, 1

END SUB

'=== clFilterMS - Filters two-dimensional input data into the dynamic working
'               data array
'
'  Arguments:
'     Axis     -  An AxisType variable
'
'     AxisMode%-  Axis mode for the axis
'
'     D1(2)    -  Two-dimensional array of input data
'
'     D2(2)    -  Two-dimensional array for filtered data
'
'     N%       -  The number of values to transfer
'
'     First%   -  First data series to filter
'
'     Last%    -  Last data series to filter
'
'  Return Values:
'     Alters values in D2()
'
'=================================================================
SUB clFilterMS (Axis AS AxisType, AxisMode%, D1(), D2(), N%, First%, Last%)

    ' If the axis is a category axis then exit:
    IF AxisMode% = cCategory THEN EXIT SUB

    ' If this isn't an autoscale axis, use the scale factor from the
    ' environment.  If it is an autoscale axis don't scale at all now
    ' it will be done when the data is drawn on the screen:
    IF Axis.AutoScale = cNo THEN
        ScaleFactor = Axis.ScaleFactor
    ELSE
        ScaleFactor = 1
    END IF

    ' If this a log axis calculate the log base:
    IF AxisMode% = cLog THEN LogRef = LOG(Axis.LogBase)

    ' Loop through the data series:
    FOR J% = First% TO Last%

        ' Loop through the values within the series:
        FOR i% = 1 TO N%

            ' Get a data value and if it isn't missing, then scale it:
            V = D1(i%, J%)
            IF V <> cMissingValue THEN V = V / ScaleFactor

            ' If the axis is a log axis, then if the value is greater than
            ' it is safe to take it's log.  Otherwise, set the data value to
            ' missing:
            IF Axis.RangeType = cLog THEN
                 IF V > 0 THEN
                    V = LOG(V) / LogRef
                ELSE
                    V = cMissingValue
                END IF
            END IF

            ' Place the value in the output data array:
            D2(i%, J% - First% + 1) = V

        NEXT i%

    NEXT J%

END SUB

'=== clFlagSystem - Sets GP.SysFlag to cYes
'
'  Arguments:
'     None
'
'  Return Values:
'     Alters the value of GP.SysFlag
'
'=================================================================
SUB clFlagSystem ()
SHARED GP AS GlobalParams

    GP.SysFlag = cYes

END SUB

'=== clFormatTics - Figures out tic label format and TicDecimals.
'
'  Arguments:
'     Axis     -  AxisType variable for which to format tics.
'
'  Return Values:
'     The TicFormat and Decimals elements may be changed for an axis
'     if AutoTic is cYes.
'
'=================================================================
SUB clFormatTics (Axis AS AxisType)

    ' If AutoScale isn't Yes then exit
    IF Axis.AutoScale <> cYes THEN EXIT SUB

    ' If the size of the largest value is bigger than seven decimal
    ' places then set TicFormat to exponential.  Otherwise, set it
    ' to normal:
    IF ABS(Axis.ScaleMin) >= 10 ^ 8 OR ABS(Axis.ScaleMax) >= 10 ^ 8 THEN
        Axis.TicFormat = cExpFormat
    ELSE
        Axis.TicFormat = cNormFormat
    END IF

    ' Pick the largest of the scale max and min (in absolute value) and
    ' use that to decide how many decimals to use when displaying the tic
    ' labels:
    Range = ABS(Axis.ScaleMax)
    IF ABS(Axis.ScaleMin) > Range THEN Range = ABS(Axis.ScaleMin)
    IF Range < 10 THEN
        TicResolution = -INT(-ABS(LOG(Range) / LOG(10!))) + 1
        IF TicResolution > 9 THEN TicResolution = 9
        Axis.TicDecimals = TicResolution
    ELSE
        Axis.TicDecimals = 0
    END IF

END SUB

'=== clGetStyle - Returns a predefined line-style definition
'
'  Arguments:
'     StyleNum%   -  A number identifying the entry to return
'
'  Return Values:
'     Returns the line-style for the specified style number
'
'=================================================================
FUNCTION clGetStyle% (StyleNum%)

    SELECT CASE StyleNum%
        CASE 1: Style% = &HFFFF
        CASE 2: Style% = &HF0F0
        CASE 3: Style% = &HF060
        CASE 4: Style% = &HCCCC
        CASE 5: Style% = &HC8C8
        CASE 6: Style% = &HEEEE
        CASE 7: Style% = &HEAEA
        CASE 8: Style% = &HF6DE
        CASE 9: Style% = &HF6F6
        CASE 10: Style% = &HF56A
        CASE 11: Style% = &HCECE
        CASE 12: Style% = &HA8A8
        CASE 13: Style% = &HAAAA
        CASE 14: Style% = &HE4E4
        CASE 15: Style% = &HC88C
    END SELECT
    clGetStyle% = Style%

END FUNCTION

'=== clHPrint - Prints text Horizontally on the screen
'
'  Arguments:
'     X     -  X position for the lower left of the first character to be
'              printed (in absolute screen coordinates)
'
'     Y     -  Y position for the lower left of the first character to be
'              printed (in absolute screen coordinates)
'
'     Txt$  -  Text to print
'
'  Return Values:
'     None
'
'=================================================================
SUB clHPrint (X%, Y%, Txt$)

    ' Map the input coordinates relative to the current viewport:
    X = PMAP(X%, 2)
    Y = PMAP(Y%, 3)

    ' Output the text horizontally:
    SetGTextDir 0
    TextLen% = OutGText(X, Y, Txt$)

END SUB

'=== clInitChart - Initializes the charting library.
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine initializes some default data structures and is
'     called automatically by charting routines if the variable
'     GP.Initialized is cNo (or zero).
'
'=================================================================
SUB clInitChart ()
SHARED StdChars%(), GP AS GlobalParams

    ' Clear any previous errors
    clClearError

    ON ERROR GOTO UnexpectedErr

    ' Initialize PaletteSet to no so palettes will be initialized properly
    ' when ChartScreen is called:
    GP.PaletteSet = cNo

    ' Set up the list of plotting characters:
    PlotChars$ = "*ox=+/:&#@%![$^"
    StdChars%(0) = 0
    FOR i% = 1 TO cPalLen
        StdChars%(i%) = ASC(MID$(PlotChars$, i%, 1))
    NEXT i%

    ' Initialize standard structures for title, axis, window and legend:
    clInitStdStruc

    GP.Initialized = cYes

END SUB

'=== clInitStdStruc - Initializes structures for standard titles, axes, etc.
'
'  Arguments:
'     None
'
'  Return Values:
'     None
'
'=================================================================
SUB clInitStdStruc ()
SHARED DAxis AS AxisType, DWindow AS RegionType
SHARED DLegend AS LegendType, DTitle AS TitleType

' Set up default components of the default chart
' environment; start with default title:

' Default title definition:
DTitle.Title = ""                ' Title text is blank
DTitle.TitleFont = 1             ' Title font is first one
DTitle.TitleColor = 1            ' Title color is white
DTitle.Justify = cCenter         ' Center justified

' Default axis definition:
DAxis.grid = cNo                 ' No grid
DAxis.GridStyle = 1              ' Solid lines for grid
DAxis.AxisTitle = DTitle         ' Use above to initialize axis title
DAxis.AxisColor = 1              ' Axis color is white
DAxis.Labeled = cYes             ' Label and tic axis
DAxis.RangeType = cLinear        ' Linear axis
DAxis.LogBase = 10               ' Logs to base 10
DAxis.AutoScale = cYes           ' Automatically scale numbers if needed
DAxis.ScaleTitle = DTitle        ' Scale title
DAxis.TicFont = 1                ' Tic font is first one
DAxis.TicDecimals = 0            ' No decimals

' Default window definition:
DWindow.Background = 0           ' Black background
DWindow.Border = cNo             ' Window will have no border
DWindow.BorderColor = 1          ' Make the borders white
DWindow.BorderStyle = 1          ' Solid-line borders

' Default legend definition:
DLegend.Legend = cYes            ' Draw a legend if multi-series chart
DLegend.Place = cRight           ' On the right side
DLegend.TextColor = 1            ' Legend text is white on black
DLegend.TextFont = 1             ' Legend text font is first one
DLegend.AutoSize = cYes          ' Figure out size automatically
DLegend.LegendWindow = DWindow   ' Use the default window specification

END SUB

'=== clLabelXTics - Labels tic marks for X axis
'
'  Arguments:
'     Axis     -  An AxisType variable containing axis specification
'
'     Cat$(1)  -  One-dimensional array of category labels.  Ignored
'                 if axis not category axis
'
'     TicX     -  X coordinate of first tic mark
'
'     TicY     -  Y coordinate of tic tip (portion away from axis)
'
'     YBoundry% -  Y coordinate of bottom of tic labels
'
'  Return Values:
'     None
'
'=================================================================
SUB clLabelXTics (Axis AS AxisType, Cat$(), TicX, TicTotX%, TicY, YBoundry%)
SHARED GFI AS FontInfo
SHARED GP AS GlobalParams
SHARED GE AS ChartEnvironment

    ' If this axis isn't supposed to be labeled then exit:
    IF Axis.Labeled <> cYes THEN EXIT SUB

    ' Set the appropriate color, font, and orientation for tic labels:
    clSetCharColor Axis.AxisColor
    clSetChartFont Axis.TicFont
    SetGTextDir 0

    ' The Y coordinate of the labels will be a constant .5 character
    ' heights below the end of the tic marks (TicY):
    Y% = PMAP(TicY, 1) + (GFI.Ascent - GFI.Leading) / 2
    IF GP.XStagger = cYes THEN
        YDrop% = (3 * GFI.Ascent - GFI.Leading) / 2
    ELSE
        YDrop% = 0
    END IF
    YBoundry% = Y% + YDrop% + GFI.PixHeight

    ' Loop through and write labels
    TX = TicX
    CatNum% = 1
    Stagger% = cFalse
    FOR i% = 1 TO TicTotX%

        ' The label depends on axis mode (category, value):
        SELECT CASE GP.XMode
            CASE cCategory: Txt$ = Cat$(CatNum%)
            CASE ELSE:      Txt$ = clVal2Str$(TX, Axis.TicDecimals, Axis.TicFormat)
        END SELECT
        TxtLen% = GetGTextLen(Txt$)
        IF GP.XMode = cCategory THEN
            MaxLen% = 2 * (GE.DataWindow.X2 - GE.DataWindow.X1) / GP.NVals - GFI.AvgWidth
            IF MaxLen% < 0 THEN MaxLen% = 0
            DO UNTIL TxtLen% <= MaxLen%
                Txt$ = LEFT$(Txt$, LEN(Txt$) - 1)
                TxtLen% = GetGTextLen(Txt$)
            LOOP
        END IF

        ' Center the label under the tic mark and print it:
        X% = PMAP(TX, 0) - (TxtLen%) / 2

        IF Stagger% THEN
            clHPrint X%, Y% + YDrop%, Txt$
            Stagger% = cFalse
        ELSE
            clHPrint X%, Y%, Txt$
            Stagger% = cTrue
        END IF

        ' Move to the next tic mark:
        TX = TX + Axis.TicInterval
        CatNum% = CatNum% + 1
    NEXT i%

END SUB

'=== clLabelYTics - Labels tic marks and draws Y axis title
'
'  Arguments:
'     Axis     -  An AxisType variable containing axis specification
'
'     Cat$(1)  -  One-dimensional array of category labels.  Ignored
'                 if axis not category axis
'
'     TicX     -  X coordinate of first tic's tip (away from axis)
'
'     TicY     -  Y coordinate of first tic
'
'  Return Values:
'     None
'
'=================================================================
SUB clLabelYTics (Axis AS AxisType, Cat$(), TicX, TicY, TicTotY%)
SHARED GFI AS FontInfo
SHARED GP AS GlobalParams

    ' If axis isn't supposed to be labeled then exit:
    IF Axis.Labeled <> cYes THEN EXIT SUB

    ' Set the appropriate color, font, and orientation for tic labels:
    clSetCharColor Axis.AxisColor
    clSetChartFont Axis.TicFont
    SetGTextDir 0

    ' Loop through and write labels
    TY = TicY
    CatNum% = 1
    FOR i% = 1 TO TicTotY%

        ' The label depends on axis mode (category, value):
        SELECT CASE GP.YMode
            CASE cCategory: Txt$ = Cat$(GP.NVals - CatNum% + 1)
            CASE ELSE:      Txt$ = clVal2Str$(TY, Axis.TicDecimals, Axis.TicFormat)
        END SELECT
        TxtLen% = GetGTextLen(Txt$)

        ' Space the label 1/2 character width to the left of the tic
        ' mark and center it vertically on the tic mark (round vertical
        ' location to the next highest integer):
        X% = PMAP(TicX, 0) - TxtLen% - (.5 * GFI.MaxWidth)
        Y% = -INT(-(PMAP(TY, 1) - (GFI.Ascent + GFI.Leading) / 2))

        ' Print the label:
        clHPrint X%, Y%, Txt$

        ' Go to the next tic mark:
        TY = TY + Axis.TicInterval
        CatNum% = CatNum% + 1
    NEXT i%

END SUB

'=== clLayoutLegend - Calculates size of the legend
'
'  Arguments:
'     SeriesLabel$(1) - The labels used in the legend
'
'     First%   - The first series (label) to process
'
'     Last%    - The last series (label) to process
'
'  Return Values:
'     The coordinates in the legend window portion of Env are altered
'
'  Remarks:
'     Sizing the legend window requires finding out where it goes (right
'     or bottom) and determining how big the labels are and how big
'     the legend needs to be to hold them.
'
'=================================================================
SUB clLayoutLegend (SeriesLabel$(), First%, Last%)
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED GFI AS FontInfo
SHARED LLayout AS LegendLayout
SHARED TTitleLayout AS TitleLayout
DIM W AS RegionType

    ' If "no legend" is specified, then exit:
    IF GE.Legend.Legend = cNo THEN EXIT SUB

    ' This may be an auto legend or not, but, in either case we're
    ' going to need the following information:
    clSetChartFont GE.Legend.TextFont

    LLayout.SymbolSize = GFI.Ascent - GFI.Leading - 1
    LLayout.HorizBorder = GFI.Ascent
    LLayout.VertBorder = GFI.AvgWidth
    LLayout.RowSpacing = 1.75 * (LLayout.SymbolSize + 1)
    LLayout.LabelOffset = LLayout.SymbolSize / GP.Aspect + GFI.AvgWidth

    'RowLeading% = LLayout.RowSpacing - LLayout.SymbolSize
    RowLeading% = .75 * LLayout.SymbolSize + 1.75

    ColWid% = clMaxStrLen(SeriesLabel$(), First%, Last%) + LLayout.LabelOffset
    LLayout.ColSpacing = ColWid% + GFI.AvgWidth

    ' If this isn't an autosize legend:
    IF GE.Legend.AutoSize = cNo THEN

        ' Check the legend coordinates supplied by the user to make
        ' sure that they are valid.  If they are, exit:
        W = GE.Legend.LegendWindow
        LWid% = W.X2 - W.X1
        LHgt% = W.Y2 - W.Y1
        IF LWid% > 0 AND LHgt% > 0 THEN

            ' Calculate the number of columns and rows of labels that will
            ' fit in the legend:
            NumCol% = INT((LWid% - LLayout.VertBorder) / (LLayout.ColSpacing))
            IF NumCol% <= 0 THEN NumCol% = 1
            IF NumCol% > GP.NSeries THEN NumCol% = GP.NSeries
            NumRow% = -INT(-GP.NSeries / NumCol%)
            LLayout.NumRow = NumRow%
            LLayout.NumCol = NumCol%

            ' Re-calculate the column and row spacing:
            LLayout.ColSpacing = INT((LWid% - LLayout.VertBorder) / NumCol%)
            LLayout.RowSpacing = INT((LHgt% - 2 * LLayout.HorizBorder + RowLeading%) / NumRow%)

            EXIT SUB

        ' If invalid legend coordinates are discovered set an error and
        ' go on to calculate new ones:
        ELSE

          clSetError cBadLegendWindow

        END IF
    END IF

    ' Do remaining calculations according to the legend placement specified
    ' (right, bottom, overlay):
    SELECT CASE GE.Legend.Place

        CASE cRight, cOverlay:

            ' Leave room at top for chart titles:
            Top% = TTitleLayout.TotalSize

            ' Figure out the maximum number of legend rows that will
            ' fit in the amount of space you have left for the legend
            ' height.  Then, see how many columns are needed.  Once
            ' the number of columns is set refigure how many rows are
            ' required:
            NumRow% = INT((GP.ChartHgt - Top% - 2 * LLayout.HorizBorder) / LLayout.RowSpacing)
            IF NumRow% > GP.NSeries THEN NumRow% = GP.NSeries
            NumCol% = -INT(-GP.NSeries / NumRow%)
            NumRow% = -INT(-GP.NSeries / NumCol%)

            ' Set the width and height:
            LWid% = NumCol% * LLayout.ColSpacing - GFI.AvgWidth + 2 * LLayout.VertBorder
            LHgt% = (NumRow% * LLayout.RowSpacing - RowLeading% + 2 * LLayout.HorizBorder)

            ' Place the legend one character width from right and even with
            ' what will be the top of the data window:
            LLft% = GP.ChartWid - 1 - LWid% - GFI.AvgWidth
            LTop% = Top%

        CASE cBottom:

            ' The number of label columns that will fit (using the same
            ' procedure as above except figure columns first):
            NumCol% = INT((GP.ChartWid - 2 * LLayout.HorizBorder) / LLayout.ColSpacing)
            IF NumCol% > GP.NSeries THEN NumCol% = GP.NSeries
            NumRow% = -INT(-GP.NSeries / NumCol%)
            NumCol% = -INT(-GP.NSeries / NumRow%)

            ' Set the width and height:
            LWid% = NumCol% * LLayout.ColSpacing - GFI.AvgWidth + 2 * LLayout.VertBorder
            LHgt% = (NumRow% * LLayout.RowSpacing - RowLeading% + 2 * LLayout.HorizBorder)

            ' Center the legend horizontally one character from the bottom:
            LLft% = (GP.ChartWid - 1 - LWid%) / 2
            LTop% = GP.ChartHgt - 1 - LHgt% - GFI.Ascent

    END SELECT

    ' Record legend columns and rows:
    LLayout.NumRow = NumRow%
    LLayout.NumCol = NumCol%

    ' Finally, place the legend coordinates in GE:
    GE.Legend.LegendWindow.X1 = LLft%
    GE.Legend.LegendWindow.Y1 = LTop%
    GE.Legend.LegendWindow.X2 = LLft% + LWid%
    GE.Legend.LegendWindow.Y2 = LTop% + LHgt%

    ' If, after all this, the legend window is invalid, set error:
    IF LLft% < 0 OR LTop% < 0 OR LWid% <= 0 OR LHgt% <= 0 THEN
        clSetError cBadLegendWindow
    END IF

END SUB

'=== clLayoutTitle - Figures out title layouts for Top, X-axis and
'                      Y-axis titles
'
'  Arguments:
'     TL    -  Layout variable into which to place titles
'
'     T1    -  First title
'
'     T2    -  Second Title
'
'  Return Values:
'     none
'
'=================================================================
SUB clLayoutTitle (TL AS TitleLayout, T1 AS TitleType, T2 AS TitleType)
SHARED GFI AS FontInfo

    ' Set the title heights initially to 0:
    TL.TitleOne = 0
    TL.TitleTwo = 0

    ' If the first title is set then get its height:
    Total% = 0
    IF LTRIM$(T1.Title) <> "" THEN
        clSetChartFont T1.TitleFont
        TL.TitleOne = GFI.PixHeight
        Total% = Total% + 1
    END IF

    ' If the second title is set then get it's height:
    IF LTRIM$(T2.Title) <> "" THEN
        clSetChartFont T2.TitleFont
        TL.TitleTwo = GFI.PixHeight
        Lead2% = GFI.Leading
        Total% = Total% + 1
    END IF

    ' Set the "leading" values for label spacing depending on how many
    ' of the titles were non-blank:
    TotalHeight% = TL.TitleOne + TL.TitleTwo
    SELECT CASE Total%
        CASE 0:
            TL.Top = 8
            TL.Middle = 0
            TL.Bottom = 4

        CASE 1:
            TL.Top = 8 + TotalHeight% / 8
            TL.Middle = 0
            TL.Bottom = TL.Top

        CASE 2:
            TL.Top = 8 + TotalHeight% / 8
            TL.Middle = 0: IF Lead2% = 0 THEN TL.Middle = TL.TitleOne / 2
            TL.Bottom = TL.Top
    END SELECT

    TL.TotalSize = TL.Top + TL.TitleOne + TL.Middle + TL.TitleTwo + TL.Bottom

END SUB

'=== clMap2Attrib% - Maps an integer to a screen attribute for current
'                    screen mode
'
'  Arguments:
'     N% - The number to map
'
'  Return Values:
'     The function returns:
'        0 is mapped to 0, all other numbers are mapped to the range
'        1 to GP.MaxColor
'
'=================================================================
FUNCTION clMap2Attrib% (N%)
SHARED GP AS GlobalParams

    AbsN% = ABS(N%)
    IF AbsN% = 0 THEN
        clMap2Attrib% = AbsN%
    ELSE
        clMap2Attrib% = (AbsN% - 1) MOD GP.MaxColor + 1
    END IF

END FUNCTION

'=== clMap2Pal% - Maps an integer into a palette reference
'
'  Arguments:
'     N% - The number to map
'
'  Return Values:
'     The function returns (N%-1) MOD cPalLen + 1
'
'  Remarks:
'     This FUNCTION is used in almost every reference to a palette to ensure
'     that an invalid number doesn't cause a reference outside of a palette
'     array (and thus crash the library).  This FUNCTION maps the first
'     cPalLen values to themselves. Numbers above cPalLen are mapped to
'     the values 2..cPalLen.
'
'=================================================================
FUNCTION clMap2Pal% (N%)

    AbsN% = ABS(N%)
    IF AbsN% > cPalLen THEN
        clMap2Pal% = (AbsN% - 2) MOD (cPalLen - 1) + 2
    ELSE
        clMap2Pal% = AbsN%
    END IF

END FUNCTION

'=== clMaxStrLen% - Finds the length of the longest string in a list
'
'  Arguments:
'     Txt$(1)  -  One-dimensional array of strings to search
'
'     First%   -  First string to consider
'
'     Last%    -  Last string to consider
'
'  Return Values:
'     This FUNCTION returns the length of the longest string
'
'=================================================================
FUNCTION clMaxStrLen% (Txt$(), First%, Last%)

    ' Set Max to 0 then loop through each label updating Max if the
    ' label is longer:
    Max% = 0
    FOR Row% = First% TO Last%
        L% = GetGTextLen(Txt$(Row%))
        IF L% > Max% THEN Max% = L%
    NEXT Row%

    ' Return Max as the value of the FUNCTION:
    clMaxStrLen% = Max%

END FUNCTION

'=== clMaxVal - Returns the maximum of two numbers
'
'  Arguments:
'     A  -  The first number
'
'     B  -  The second number
'
'  Return Values:
'     The function returns the maximum of the two values
'
'=================================================================
FUNCTION clMaxVal (A, B)

    IF A > B THEN clMaxVal = A ELSE clMaxVal = B

END FUNCTION

'=== clPrintTitle - Prints title correctly justified and colored
'
'  Arguments:
'     TitleVar - A TitleType variable containing specifications for the
'                title to be printed
'
'     Y%       - Vertical position in window for bottom of line
'
'  Return Values:
'     None
'
'=================================================================
SUB clPrintTitle (TitleVar AS TitleType, Y%)
SHARED GFI AS FontInfo, GP AS GlobalParams

    ' Calculate width of the title text:
    clSetChartFont TitleVar.TitleFont

    Txt$ = RTRIM$(TitleVar.Title)
    TxtLen% = GetGTextLen(Txt$)
    IF TxtLen% = 0 THEN EXIT SUB

    ' Calculate horizontal position depending on justification style
    SELECT CASE TitleVar.Justify

        CASE cCenter: X% = (GP.ChartWid - 1 - (TxtLen%)) / 2
        CASE cRight:  X% = GP.ChartWid - 1 - TxtLen% - GFI.AvgWidth
        CASE ELSE:    X% = GFI.AvgWidth

    END SELECT

    ' Set color of text and print it:
    clSetCharColor TitleVar.TitleColor
    clHPrint X%, Y%, Txt$

END SUB

'=== clRenderBar - Renders a bar for a bar or column chart
'
'  Arguments:
'     X1    -  Left side of bar (in data world coordinates)
'
'     Y1    -  Top of bar (in data world coordinates)
'
'     X2    -  Right side of bar (in data world coordinates)
'
'     Y2    -  Bottom of bar (in data world coordinates)
'
'     C%    -  Palette entry number to use for border color and fill pattern
'
'  Return Values:
'     None
'
'=================================================================
SUB clRenderBar (X1, Y1, X2, Y2, c%)
SHARED PaletteC%(), PaletteP$()

    ' First clear out space for the bar by drawing a bar in black:
    LINE (X1, Y1)-(X2, Y2), 0, BF

    ' Put a border around the bar and fill with pattern:
    MC% = clMap2Pal%(c%)

    LINE (X1, Y1)-(X2, Y2), 1, B
    PAINT ((X1 + X2) / 2, (Y1 + Y2) / 2), PaletteP$(MC%), 1
    LINE (X1, Y1)-(X2, Y2), PaletteC%(MC%), B

END SUB

'=== clRenderWindow - Renders a window on the screen
'
'  Arguments:
'     W - A RegionType variable
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine assumes that the viewport is set to the borders of
'     the window to be rendered
'
'=================================================================
SUB clRenderWindow (W AS RegionType)
SHARED PaletteC%(), PaletteB%()

    ' Set window since the size of the viewport is unknown and draw
    ' a filled box of the background color specified by the window
    ' definition:
    WINDOW (0, 0)-(1, 1)
    LINE (0, 0)-(1, 1), PaletteC%(clMap2Pal%(W.Background)), BF

    ' Draw a border if specified:
    IF W.Border = cYes THEN
        LINE (0, 0)-(1, 1), PaletteC%(clMap2Pal%(W.BorderColor)), B, PaletteB%(clMap2Pal%(W.BorderStyle))
    END IF

END SUB

'=== clScaleAxis - Calculates minimum, maximum and scale factor for an axis
'
'  Arguments:
'     A        - An AxisType variable
'
'     AxisMode%- cCategory or cValue
'
'     D1(2)    - Two-dimensional array of values to be scaled
'
'  Return Values:
'     ScaleMin, ScaleMax, ScaleFactor, and ScaleTitle elements in
'     axis variable will be altered if it is a category axis or
'     AutoScale is Yes.
'
'=================================================================
SUB clScaleAxis (Axis AS AxisType, AxisMode%, D1())
SHARED GE AS ChartEnvironment, GP AS GlobalParams

    ' If this is a category axis then ignore all the flags and force
    ' scale parameters to those needed by charting routines:
    IF AxisMode% = cCategory THEN
        Axis.ScaleMin = 0
        Axis.ScaleMax = 1
        Axis.ScaleFactor = 1
        Axis.ScaleTitle.Title = ""
        EXIT SUB
    END IF

    ' If AutoScale isn't Yes then exit:
    IF Axis.AutoScale <> cYes THEN EXIT SUB

    ' AutoScale was specified, calculate the different scale variables
    ' Set maximum and minimum to defaults.

    ' Initialize the value- and row-minimum and maximum values to zero:
    VMin = 0
    VMax = 0

    RMin = 0
    RMax = 0

    ' Compare data values for minimum and maximum:
    FOR Row% = 1 TO GP.NVals

        ' Initialize positive and negative sum variables:
        RSumPos = 0
        RSumNeg = 0

        ' Evaluate the value from this row in each series:
        FOR Column% = 1 TO GP.NSeries

            ' Get the value from the data array:
            V = D1(Row%, Column%)

            ' Process values that aren't missing only:
            IF V <> cMissingValue THEN

                ' Add positive values to positive sum and negative ones to
                ' negative sum:
                IF V > 0 THEN RSumPos = RSumPos + V
                IF V < 0 THEN RSumNeg = RSumNeg + V

                ' Compare the value against current maximum and minimum and
                ' replace them if appropriate:
                IF V < VMin THEN VMin = V
                IF V > VMax THEN VMax = V

            END IF

        NEXT Column%

        ' Compare the positive and negative sums for this row with the
        ' current row maximum and minimum and replace them if appropriate:
        IF RSumNeg < RMin THEN RMin = RSumNeg
        IF RSumPos > RMax THEN RMax = RSumPos

    NEXT Row%

    ' If the chart style is one, meaning that the data isn't stacked for
    ' bar and column charts, or it is a line or scatter chart then the scale
    ' minimum and maximum are the minimum and maximum values found.
    ' Each value is adjusted so the data is not drawn on or beyond the
    ' border of the data window:
    IF GE.ChartStyle = 1 OR GE.ChartType = cLine OR GE.ChartType = cScatter THEN
        IF VMin < 0 THEN
            Axis.ScaleMin = VMin - .01 * (VMax - VMin)
        END IF
        IF VMax > 0 THEN
            Axis.ScaleMax = VMax + .01 * (VMax - VMin)
        END IF

    ' Otherwise, the scale minimum and maximum are the minimum and maximum
    ' sums of the data for each row:
    ELSE
        IF RMin < 0 THEN
            Axis.ScaleMin = RMin - .01 * (RMax - RMin)
        END IF
        IF RMax > 0 THEN
            Axis.ScaleMax = RMax + .01 * (RMax - RMin)
        END IF
    END IF

    ' If no data then force range to be non-zero:
    IF Axis.ScaleMin = Axis.ScaleMax THEN Axis.ScaleMax = 1

    ' Adjust the scale limits by ScaleFactor if required:
    clAdjustScale Axis

END SUB

'=== clSelectChartFont - Selects a font to use and gets info about it
'
'  Arguments:
'     N%    -  Font number to use
'
'  Return Values:
'     none
'
'=================================================================
SUB clSelectChartFont (N%)
SHARED GFI AS FontInfo

    ' Select the font and get information about it:
    SelectFont N%
    GetFontInfo GFI
END SUB

'=== clSelectChartWindow - Sets viewport to chart window
'
'  Arguments:
'     Env         - A ChartEnvironment variable
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine erases any previous viewport
'
'=================================================================
SUB clSelectChartWindow ()
SHARED GP AS GlobalParams

    ' Set viewport to chart window:
    VIEW (GP.CwX1, GP.CwY1)-(GP.CwX2, GP.CwY2)

END SUB

'=== clSelectRelWindow - Sets viewport to window relative to chart window
'
'  Arguments:
'     Env   - A ChartEnvironment variable
'
'     W     - RegionType variable of window to set
'
'  Return Values:
'     None
'
'  Remarks:
'     This routine erases any previous viewport
'
'=================================================================
SUB clSelectRelWindow (W AS RegionType)
SHARED GP AS GlobalParams

    ' New viewport is defined relative to the current one:
    VIEW (GP.CwX1 + W.X1, GP.CwY1 + W.Y1)-(GP.CwX1 + W.X2, GP.CwY1 + W.Y2)

END SUB

'=== clSetAxisModes - Sets axis modes for X- and Y-axis according to
'                   ChartType
'
'  Arguments:
'     None
'
'  Return Values:
'     Alters XAxis and YAxis axis modes
'
'=================================================================
SUB clSetAxisModes ()
SHARED GE AS ChartEnvironment
SHARED GP AS GlobalParams

    SELECT CASE GE.ChartType

        CASE cBar:
            GP.XMode = cValue
            GP.YMode = cCategory

        CASE cColumn, cLine:
            GP.XMode = cCategory
            GP.YMode = cValue

        CASE cScatter:
            GP.XMode = cValue
            GP.YMode = cValue

        CASE cPie:
            GP.XMode = cCategory
            GP.YMode = cCategory

    END SELECT

END SUB

'=== clSetCharColor - Sets color for DRAW characters
'
'  Arguments:
'     N%    -  Color number
'
'  Return Values:
'     None
'
'=================================================================
SUB clSetCharColor (N%)
SHARED PaletteC%()

    ' Check for valid color number then set color if correct:
    SetGTextColor PaletteC%(clMap2Pal%(N%))

END SUB

'=== clSetChartFont - Selects the specified font
'
'  Arguments:
'     N%    -  Number of loaded font to select
'
'  Return Values:
'     none
'
'=================================================================
SUB clSetChartFont (N AS INTEGER)
SHARED GFI AS FontInfo

    ' Select font and get information on it:
    SelectFont N%
    GetFontInfo GFI

END SUB

'=== clSetError - Sets the ChartLib error variable
'
'  Arguments:
'     ErrNo    - The error number to set
'
'  Return Values:
'     Sets ChartErr to ErrNo
'
'=================================================================
SUB clSetError (ErrNo AS INTEGER)

    ChartErr = ErrNo

END SUB

'=== clSetGlobalParams - Sets some global parameters that other routines use
'
'  Arguments:
'     None
'
'  Return Values:
'     GP.ValLenX and GP.ValLenY are altered
'
'=================================================================
SUB clSetGlobalParams ()
SHARED GP AS GlobalParams, GE AS ChartEnvironment

    ' Figure out longest label on X axis:
    clSetChartFont GE.XAxis.TicFont
    SF = GE.XAxis.ScaleMin
    Len1 = GetGTextLen(clVal2Str$(SF, GE.XAxis.TicDecimals, GE.XAxis.TicFormat))
    SF = GE.XAxis.ScaleMax
    Len2 = GetGTextLen(clVal2Str$(SF, GE.XAxis.TicDecimals, GE.XAxis.TicFormat))
    GP.ValLenX = clMaxVal(Len1, Len2)

    ' Figure out longest label on Y axis:
    clSetChartFont GE.YAxis.TicFont
    SF = GE.YAxis.ScaleMin
    Len1 = GetGTextLen(clVal2Str$(SF, GE.YAxis.TicDecimals, GE.YAxis.TicFormat))
    SF = GE.YAxis.ScaleMax
    Len2 = GetGTextLen(clVal2Str$(SF, GE.YAxis.TicDecimals, GE.YAxis.TicFormat))
    GP.ValLenY = clMaxVal(Len1, Len2)

END SUB

'=== clSizeDataWindow - Calculates general data window size
'
'  Arguments:
'     Cat$(1)  - One-dimensional array of category labels (only
'                used if one of the axes is a category one)
'
'  Return Values:
'     The X1, Y1, X2, Y2 elements of the GE variable will be
'     set to the data window coordinates
'
'=================================================================
SUB clSizeDataWindow (Cat$())
SHARED GE AS ChartEnvironment
SHARED GP AS GlobalParams
SHARED GFI AS FontInfo
SHARED TTitleLayout AS TitleLayout
SHARED XTitleLayout AS TitleLayout
SHARED YTitleLayout AS TitleLayout

    ' *** TOP
    ' Adjust the top of the data window:
    DTop% = TTitleLayout.TotalSize

    ' *** LEFT
    ' Do left side:
    DLeft% = YTitleLayout.TotalSize

    ' Add room for axis labels if the axis is labeled and not a pie chart:
    IF GE.ChartType <> cPie THEN
        IF GE.YAxis.Labeled = cYes THEN

            ' Get the correct font:
            clSetChartFont GE.YAxis.TicFont

            ' If it is a category axis then add longest category label:
            IF GP.YMode = cCategory THEN
                DLeft% = DLeft% + clMaxStrLen%(Cat$(), 1, GP.NVals) + .5 * GFI.MaxWidth

            ' If it a value axis just add characters for label (plus 1/2 for
            ' spacing):
            ELSE
                DLeft% = DLeft% + GP.ValLenY + (.5 * GFI.MaxWidth)
            END IF

        ELSEIF GP.XMode = cValue AND GE.XAxis.Labeled = cYes THEN

            ' Then space over 1/2 of the leftmost label on the X Axis if it's
            ' a value axis; if it's a category axis assume the label will be
            ' correct:
            DLeft% = DLeft% + GP.ValLenX \ 2
        END IF
    END IF

    ' *** RIGHT
    ' For the right, space over 8 pixels from the right:
    DRight% = 12

    ' Then space over 1/2 of the rightmost label on the X Axis if it's
    ' a value axis; if it's a category axis assume the label will be
    ' correct:
    IF GP.XMode = cValue AND GE.XAxis.Labeled = cYes THEN
        DRight% = DRight% + (GP.ValLenX) \ 2
    END IF

    DRight% = GP.ChartWid - DRight%

    ' *** YTIC MARKS
    ' Finally, adjust the window coordinates for tic marks (if it's not a
    ' pie chart):
    IF GE.ChartType <> cPie THEN
        IF GE.YAxis.Labeled = cYes THEN
            DLeft% = DRight% - (DRight% - DLeft%) / (1 + cTicSize)
        END IF
    END IF

    ' *** LEGEND
    ' Account for the legend if its on the right:
    IF GE.Legend.Legend = cYes AND GP.MSeries = cYes THEN
        IF GE.Legend.Place = cRight THEN
            A% = GE.Legend.LegendWindow.X1
            DRight% = DRight% - ABS(GP.ChartWid - A%)
        END IF
    END IF

    ' Now we have DLeft%, DRight% we can check if the labels fit on the
    ' X axis or if we need to put them on two rows:
    GP.XStagger = cFalse
    IF GP.XMode = cCategory AND GE.ChartType <> cPie THEN
        clSetChartFont GE.XAxis.TicFont
        TicInterval% = (DRight% - DLeft%) \ GP.NVals
        IF clMaxStrLen%(Cat$(), 1, GP.NVals) + .5 * GFI.MaxWidth > TicInterval% THEN
            GP.XStagger = cTrue
        END IF
    END IF

    ' If we do have to stagger, check if there is enough space to the
    ' left and right for long categories.  Make adjustments as necessary:
    IF GP.XStagger THEN
        LenLeft% = GetGTextLen%(Cat$(1)) + GFI.AvgWidth
        LenRight% = GetGTextLen%(Cat$(GP.NVals)) + GFI.AvgWidth
        SizeRight% = cTrue
        SizeLeft% = cTrue
        OldRight% = DRight%
        OldLeft% = DLeft%
        DO WHILE SizeRight% OR SizeLeft%
            IF LenRight% - TicInterval% > 2 * (GP.ChartWid - DRight%) AND 2 * (GP.ChartWid - DRight%) < TicInterval% THEN
                SizeRight% = cTrue
            ELSE
                SizeRight% = cFalse
            END IF
            IF SizeRight% THEN
                TicInterval% = (2 * (GP.ChartWid - DLeft%) - LenRight%) \ (2 * GP.NVals - 1)
                IF LenRight% > 2 * TicInterval% THEN
                    TicInterval% = (GP.ChartWid - DLeft%) / (GP.NVals + .5)
                END IF
                DRight% = DLeft% + GP.NVals * TicInterval%
            END IF
            IF LenLeft% - TicInterval% > 2 * DLeft% AND 2 * DLeft% < TicInterval% THEN
                SizeLeft% = cTrue
            ELSE
                SizeLeft% = cFalse
            END IF
            IF SizeLeft% THEN
                TicInterval% = (2 * DRight% - LenLeft%) \ (2 * GP.NVals - 1)
                IF LenLeft% > 2 * TicInterval% THEN
                    TicInterval% = DRight% / (GP.NVals + .5)
                END IF
                DLeft% = DRight% - GP.NVals * TicInterval%
            END IF

            ' Make sure we haven't gone too far on either side:
            IF DRight% > OldRight% THEN
                DRight% = OldRight%
            END IF
            IF DLeft% < OldLeft% THEN
                DLeft% = OldLeft%
            END IF

            ' Check if there has been a change, if not, we are done:
            IF ABS(ChangeRight% - DRight%) + ABS(ChangeLeft% - DLeft%) > 0 THEN
                EXIT DO
            ELSE
                ChangeRight% = DRight%
                ChangeLeft% = DLeft%
            END IF
        LOOP
    END IF

    ' *** BOTTOM
    DBot% = XTitleLayout.TotalSize

    ' If axis is labeled (and not a pie chart), add row for tic
    ' labels + 1/2 row spacing:
    IF GE.XAxis.Labeled = cYes AND GE.ChartType <> cPie THEN
        IF GP.XStagger = cTrue THEN
            DBot% = DBot% + 3 * GFI.PixHeight
        ELSE
            DBot% = DBot% + 1.5 * GFI.PixHeight
        END IF
    END IF

    ' Make the setting relative to the chart window:
    DBot% = GP.ChartHgt - 1 - DBot%


    ' *** XTIC MARKS
    ' Finally, adjust the window coordinates for tic marks (if it's not a
    ' pie chart):
    IF GE.ChartType <> cPie THEN
        IF GE.XAxis.Labeled = cYes THEN
            DBot% = DTop% + (DBot% - DTop%) / (1 + cTicSize)
        END IF

    END IF

    ' *** LEGEND
    ' Account for the legend if its on the bottom:
    IF GE.Legend.Legend = cYes AND GP.MSeries = cYes THEN
        IF GE.Legend.Place = cBottom THEN
            A% = GE.Legend.LegendWindow.Y1
            DBot% = DBot% - ABS(GP.ChartHgt - A%)
        END IF
    END IF

    ' Install values in the DataWindow definition:
    GE.DataWindow.X1 = DLeft%
    GE.DataWindow.X2 = DRight%
    GE.DataWindow.Y1 = DTop%
    GE.DataWindow.Y2 = DBot%

    ' If the window is invalid then set error:
    IF DLeft% >= DRight% OR DTop% >= DBot% THEN
        clSetError cBadDataWindow
    END IF

END SUB

'=== clSpaceTics - Calculates TicInterval
'
'  Arguments:
'     None
'
'  Return Values:
'     The TicInterval will be altered
'
'  Remarks:
'     The TicInterval is the distance between tic marks in WORLD
'     coordinates (i.e. the coordinates your data are in)
'
'=================================================================
SUB clSpaceTics ()
SHARED GE AS ChartEnvironment, GP AS GlobalParams
SHARED GFI AS FontInfo

    ' X-Axis:
    ' Calculate the length of the axis and of the longest tic label.  Then,
    ' use that information to calculate the number of tics that will fit:
    clSetChartFont GE.XAxis.TicFont
    AxisLen% = GE.DataWindow.X2 - GE.DataWindow.X1 + 1
    TicWid% = GP.ValLenX + GFI.MaxWidth
    clSpaceTicsA GE.XAxis, GP.XMode, AxisLen%, TicWid%

    ' Y-Axis:
    ' Same procedure as above:
    clSetChartFont GE.YAxis.TicFont
    AxisLen% = GE.DataWindow.Y2 - GE.DataWindow.Y1 + 1
    TicWid% = 2 * GFI.Ascent
    clSpaceTicsA GE.YAxis, GP.YMode, AxisLen%, TicWid%

END SUB

'=== clSpaceTicsA - Figures out TicInterval for an axis
'
'  Arguments:
'     Axis     -  An AxisType variable to space tics for
'
'     AxisMode%-  cCategory or cValue
'
'     AxisLen% -  Length of the axis in pixels
'
'  Return Values:
'     The TicInterval value may be changed for an axis
'
'  Remarks:
'     The TicInterval is the distance between tic marks in adjusted world
'     coordinates (i.e. the coordinates your data are in scaled by
'     ScaleFactor and adjusted by LogBase if it is a log axis).
'
'=================================================================
SUB clSpaceTicsA (Axis AS AxisType, AxisMode%, AxisLen%, TicWid%)
SHARED GP AS GlobalParams

    ' If this is a category axis the tic interval is 1
    ' divided by the number-of-categories:
    IF AxisMode% = cCategory THEN
        Axis.TicInterval = 1 / GP.NVals
        EXIT SUB
    END IF

    ' Otherwise, if we're supposed to scale this axis then the tic interval
    ' depends on how many will fit and some aesthetic considerations:
    IF Axis.AutoScale = cYes THEN

        ' Figure which is bigger in absolute value between scale maximum
        ' and minimum:
        MaxRange = ABS(Axis.ScaleMax)
        IF ABS(Axis.ScaleMin) > MaxRange THEN MaxRange = ABS(Axis.ScaleMin)

        ' Calculate the maximum number of tic marks that will fit:
        MaxTics% = INT(AxisLen% / TicWid%)

        ' If the maximum number of tics is one or less set the tic
        ' interval to the axis range and the number of tics to one:
        IF MaxTics% <= 1 THEN
            NumTics% = 1
            TicInterval = Axis.ScaleMax - Axis.ScaleMin

        ELSE
            ' Guess that the tic interval is equal to 1/10th of the order
            ' of magnitude of the largest of the scale max or min:
            TicInterval = .1 * 10 ^ INT(LOG(MaxRange) / LOG(10!))

            ' If this doesn't result in too many tic marks then OK. Otherwise
            ' multiply the tic interval by 2 and 5 alternatively until the
            ' number of tic marks falls into the acceptable range.
            NextStep% = 2
            ScaleRange = Axis.ScaleMax - Axis.ScaleMin
            DO
                NumTics% = -INT(-ScaleRange / TicInterval)
                IF (NumTics% <= MaxTics%) THEN EXIT DO
                TicInterval = TicInterval * NextStep%
                NextStep% = 7 - NextStep%
            LOOP UNTIL NumTics% <= MaxTics%
        END IF

        ' Set Axis.TicInterval and adjust scale maximum and minimum:
        Axis.TicInterval = TicInterval
        IF ABS(TicInterval) < 1 THEN
            Axis.TicDecimals = -INT(-ABS(LOG(1.1 * TicInterval) / LOG(10!)))
        END IF

        Axis.ScaleMax = -INT(-Axis.ScaleMax / TicInterval) * TicInterval
        Axis.ScaleMin = INT(Axis.ScaleMin / TicInterval) * TicInterval
    END IF

END SUB

'=== clTitleXAxis - Draws titles on X axis (AxisTitle and ScaleTitle)
'
'  Arguments:
'     Axis  -  AxisType variable describing axis
'
'     X1%   -  Left of DataWindow
'
'     X2%   -  Right of DataWindow
'
'     YBoundry%   -  Top boundry of title block
'
'=================================================================
SUB clTitleXAxis (Axis AS AxisType, X1%, X2%, YBoundry%)
SHARED GFI AS FontInfo
SHARED XTitleLayout AS TitleLayout

    CH% = GFI.PixHeight
    CW% = GFI.MaxWidth

    ' Set position of first title:
    Y% = YBoundry% + XTitleLayout.Top

    ' Loop through the two titles (AxisTitle and ScaleTitle), printing
    ' them if they aren't blank:
    FOR i% = 1 TO 2

        ' Get the test, color, and justification for the title to be printed:
        SELECT CASE i%

            CASE 1:  ' AxisTitle
                Txt$ = Axis.AxisTitle.Title
                c% = Axis.AxisTitle.TitleColor
                J% = Axis.AxisTitle.Justify
                F% = Axis.AxisTitle.TitleFont
                Lead% = XTitleLayout.Middle

            CASE 2:  ' ScaleTitle
                Txt$ = Axis.ScaleTitle.Title
                c% = Axis.ScaleTitle.TitleColor
                J% = Axis.ScaleTitle.Justify
                F% = Axis.ScaleTitle.TitleFont
                Lead% = XTitleLayout.Bottom

        END SELECT
        clSetChartFont F%
        Txt$ = RTRIM$(Txt$)
        TxtLen% = GetGTextLen(Txt$)

        ' If the title isn't all blank:
        IF TxtLen% <> 0 THEN

            ' Set the title's color:
            clSetCharColor c%

            ' Calculate x position of title's first character depending on
            ' the justification flag:
            SELECT CASE J%
                CASE cLeft:   X% = X1%
                CASE cCenter: X% = ((X1% + X2%) - TxtLen%) / 2
                CASE ELSE:    X% = X2% - TxtLen%
            END SELECT

            ' Write out the text:
            clHPrint X%, Y%, Txt$

            ' Move down to the next title position:
            Y% = Y% + GFI.PixHeight + XTitleLayout.Middle

        END IF

    NEXT i%

END SUB

'=== clTitleYAxis - Draws titles on Y axis (AxisTitle and ScaleTitle)
'
'  Arguments:
'     Axis  -  AxisType variable describing axis
'
'     Y1%   -  Top of DataWindow
'
'     Y2%   -  Bottom of DataWindow
'
'  Return Values:
'
'=================================================================
STATIC SUB clTitleYAxis (Axis AS AxisType, Y1%, Y2%)
SHARED GFI AS FontInfo
SHARED YTitleLayout AS TitleLayout


    ' Set position for first title:
    X% = YTitleLayout.Top

    ' Loop through the two titles (AxisTitle and ScaleTitle), printing
    ' them if they aren't blank:
    FOR i% = 1 TO 2

        ' Get the test, color, and justification for the title to be printed:
        SELECT CASE i%

            CASE 1:  ' AxisTitle
                Txt$ = Axis.AxisTitle.Title
                c% = Axis.AxisTitle.TitleColor
                J% = Axis.AxisTitle.Justify
                F% = Axis.AxisTitle.TitleFont
                Lead% = YTitleLayout.TitleOne + YTitleLayout.Middle

            CASE 2:  ' ScaleTitle
                Txt$ = Axis.ScaleTitle.Title
                c% = Axis.ScaleTitle.TitleColor
                J% = Axis.ScaleTitle.Justify
                F% = Axis.ScaleTitle.TitleFont
                Lead% = 0

        END SELECT
        clSetChartFont F%
        Txt$ = RTRIM$(Txt$)
        TxtLen% = GetGTextLen(Txt$)

        IF TxtLen% <> 0 THEN

            ' Set title's color:
            clSetCharColor c%

            ' Calculate y position of title's first character depending on
            ' the justification flag:
            SELECT CASE J%
                CASE cLeft:   Y% = Y2%
                CASE cCenter: Y% = ((Y1% + Y2%) + TxtLen%) / 2
                CASE ELSE:    Y% = Y1% + (TxtLen% - 1)
            END SELECT

            ' Write out the text:
            clVPrint X%, Y%, Txt$

            ' Move to next title position:
            X% = X% + Lead%

        END IF

    NEXT i%

END SUB

'=== clUnFlagSystem - Sets GP.SysFlag to cNo
'
'  Arguments:
'     None
'
'  Return Values:
'     Alters the value of GP.SysFlag
'
'=================================================================
SUB clUnFlagSystem ()
SHARED GP AS GlobalParams

    GP.SysFlag = cNo

END SUB

'=== clVal2Str$ - Converts a single precision value to a string
'
'  Arguments:
'     X        -  The value to convert
'
'     Places%  -  The number of places after the decimal to produce
'
'     Format%  -  1 For normal, other than 1 for exponential
'
'  Return Values:
'     Returns a string representation of the input number
'
'=================================================================
FUNCTION clVal2Str$ (X, Places%, Format%)

    ' Make a local copy of the value:
    XX = ABS(X)

    ' Force format to exponential if that is specified or number is
    ' bigger than a long integer will hold (2^31-1):
    IF Format% <> cNormFormat OR XX >= 2 ^ 31 THEN

        ' For exponential format calculate the exponent that will make
        ' one decimal to left of decimal place.  This is done by truncating
        ' the log (base 10) of XX:
        IF XX = 0 THEN ExpX = 0 ELSE ExpX = INT(LOG(XX) / LOG(10))
        XX = XX / (10 ^ ExpX)

        ' If no decimals are specified then a number of 9.5x will be
        ' rounded up to 10 leaving two places to left of decimal so check
        ' for that and if that occurs divide number by 10 and add 1 to exponent:
        IF Places% <= 0 AND CLNG(XX) > 9 THEN
            XX = XX / 10
            ExpX = ExpX + 1
        END IF

    END IF

    ' If no decimal places are specified then generate a rounded integer:
    IF Places% <= 0 THEN
        ValStr$ = LTRIM$(STR$(CLNG(XX)))

    ' If decimal places are called for, round number to requisite number of
    ' decimals and generate string:
    ELSE

        ' Limit places after decimal to six:
        DP% = Places%
        IF DP% > 6 THEN DP% = 6
        RF% = 10 ^ DP%

        ' Figure out integer portion:
        IntX = FIX(XX)

        ' Round the fractional part to correct number of decimals.  If
        ' the fraction carries to the 1's place in the rounding
        ' adjust IntX by adding 1:
        FracX = CLNG((1 + XX - IntX) * RF%)
        IF FracX >= 2 * RF% THEN
            IntX = IntX + 1
        END IF

        'Finally, generate the output string:
        ValStr$ = LTRIM$(STR$(IntX)) + "." + MID$(STR$(FracX), 3)

    END IF

    ' Add exponent ending if format is exponent:
    IF Format% <> cNormFormat OR ABS(X) > 2 ^ 31 THEN
        ValStr$ = ValStr$ + "E"
        IF ExpX >= 0 THEN ValStr$ = ValStr$ + "+"
        ValStr$ = ValStr$ + LTRIM$(STR$(ExpX))
    END IF

    ' Add minus sign if appropriate:
    IF X < 0 AND VAL(ValStr$) <> 0 THEN ValStr$ = "-" + ValStr$
    clVal2Str$ = ValStr$

END FUNCTION

'=== clVPrint - Prints text vertically on the screen
'
'  Arguments:
'     X     -  X position of lower left of first char (in absolute screen
'              coordinates)
'
'     Y     -  Y position of lower left of first char (in absolute screen
'              coordinates)
'
'     Txt$  -  Text to print
'
'  Return Values:
'     None
'
'=================================================================
SUB clVPrint (X%, Y%, Txt$)

    ' Map the input coordinates relative to the current viewport:
    X = PMAP(X%, 2)
    Y = PMAP(Y%, 3)

    ' Print text out vertically:
    SetGTextDir 1
    TextLen% = OutGText(X, Y, Txt$)
    SetGTextDir 0

END SUB

'=== DefaultChart - Sets up the ChartEnvironment variable to generate a
'                   default chart of the type and style specified
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     ChartType  - The chart type desired: 1=Bar, 2=Column, 3=Line,
'                  4=Scatter, 5=Pie
'
'     ChartStyle - The chart style (depends on type, see README file)
'
'
'  Return Values:
'     Elements of Env variable are set to default values
'
'  Remarks:
'     This subprogram should be called to initialize the ChartEnvironment
'     variable before a charting routine is called.
'
'=================================================================
SUB DefaultChart (Env AS ChartEnvironment, ChartType AS INTEGER, ChartStyle AS INTEGER)

SHARED DTitle AS TitleType, DWindow AS RegionType
SHARED DAxis AS AxisType, DLegend AS LegendType

    ' Clear any previous chart errors:
    clClearError

    ' Check initialization:
    clChkInit

  ' Put type in environment:
    IF ChartType < 1 OR ChartType > 5 THEN
        clSetError cBadType
        EXIT SUB
    END IF
    Env.ChartType = ChartType

    ' Put chart style in environment:
    IF ChartStyle < 1 OR ChartStyle > 2 THEN
        clSetError cBadStyle
        ChartStyle = 1
    END IF
    Env.ChartStyle = ChartStyle

    ' Set elements of chart to default:
    Env.DataFont = 1

    Env.MainTitle = DTitle
    Env.SubTitle = DTitle

    Env.ChartWindow = DWindow           ' Chart window is default window
    Env.ChartWindow.Border = cYes       ' with a border.

    Env.DataWindow = DWindow

    Env.XAxis = DAxis
    Env.YAxis = DAxis

    Env.Legend = DLegend

END SUB

'=== GetPaletteDef - Changes an entry in the internal palette
'
'  Arguments:
'     C%()     -  Color palette array
'
'     S%()     -  Style palette array
'
'     P$()     -  Pattern palette array
'
'     Char%()  -  Plot character palette array
'
'     B%()     -  Border style palette array
'
'  Return Values:
'     Chart error may be set
'
'=================================================================
SUB GetPaletteDef (c() AS INTEGER, s() AS INTEGER, P$(), Char() AS INTEGER, B() AS INTEGER)
SHARED GP AS GlobalParams
SHARED PaletteC%(), PaletteS%(), PaletteP$(), PaletteCh%(), PaletteB%()

    ' Reset any outstanding errors:
    clClearError

    ' Make sure palettes have been initialized:
    IF NOT GP.PaletteSet THEN
        clSetError cPalettesNotSet
        EXIT SUB
    END IF

    ' Make sure the user's palettes are the correct size:
    clChkPalettes c(), s(), P$(), Char(), B()
    IF (ChartErr <> 0) THEN EXIT SUB

    ' Replace the palette values with input variables (making sure that
    ' the color and character numbers are in range):
    FOR N% = 0 TO cPalLen
        c(N%) = PaletteC%(N%)
        s(N%) = PaletteS%(N%)
        P$(N%) = PaletteP$(N%)
        Char(N%) = PaletteCh%(N%)
        B(N%) = PaletteB%(N%)
    NEXT N%

END SUB

'=== GetPattern - Returns a pattern from among 3 pattern palettes
'
'  Arguments:
'     Bits%       -  The number of bits per pixel for the pattern
'
'     PatternNum% -  The pattern number to return
'
'  Return Values:
'     Returns a pattern tile from the list below.
'
'  Remarks:
'     Below are three pattern sets.  There is a set of patterns for one, two
'     and eight bit-per-pixel screens.
'
'=================================================================
FUNCTION GetPattern$ (Bits%, PatternNum%)

    SELECT CASE Bits%

        ' One bit-per-pixel patterns:
        CASE 1:
            SELECT CASE PatternNum%
                CASE 1: P$ = CHR$(&HFF)
                CASE 2: P$ = CHR$(&H55) + CHR$(&HAA)
                CASE 3: P$ = CHR$(&H33) + CHR$(&HCC)
                CASE 4: P$ = CHR$(&H0) + CHR$(&HE7)
                CASE 5: P$ = CHR$(&H7F) + CHR$(&HBF) + CHR$(&HDF) + CHR$(&HEF) + CHR$(&HF7) + CHR$(&HFB) + CHR$(&HFD) + CHR$(&HFE)
                CASE 6: P$ = CHR$(&H7E) + CHR$(&HBD) + CHR$(&HDB) + CHR$(&HE7) + CHR$(&HE7) + CHR$(&HDB) + CHR$(&HBD) + CHR$(&H7E)
                CASE 7: P$ = CHR$(&HFE) + CHR$(&HFD) + CHR$(&HFB) + CHR$(&HF7) + CHR$(&HEF) + CHR$(&HDF) + CHR$(&HBF) + CHR$(&H7F)
                CASE 8: P$ = CHR$(&H33) + CHR$(&HCC) + CHR$(&HCC) + CHR$(&H33)
                CASE 9: P$ = CHR$(&H0) + CHR$(&HFD) + CHR$(&H0) + CHR$(&HF7) + CHR$(&H0) + CHR$(&HDF) + CHR$(&H0) + CHR$(&H7F)
                CASE 10: P$ = CHR$(&HF) + CHR$(&H87) + CHR$(&HC3) + CHR$(&HE1) + CHR$(&HF0) + CHR$(&H78) + CHR$(&H3C) + CHR$(&H1E)
                CASE 11: P$ = CHR$(&HA8) + CHR$(&H51) + CHR$(&HA2) + CHR$(&H45) + CHR$(&H8A) + CHR$(&H15) + CHR$(&H2A) + CHR$(&H54)
                CASE 12: P$ = CHR$(&HAA) + CHR$(&H55) + CHR$(&H0) + CHR$(&H0) + CHR$(&HAA) + CHR$(&H55) + CHR$(&H0) + CHR$(&H0)
                CASE 13: P$ = CHR$(&H2A) + CHR$(&H15) + CHR$(&H8A) + CHR$(&H45) + CHR$(&HA2) + CHR$(&H51) + CHR$(&HA8) + CHR$(&H54)
                CASE 14: P$ = CHR$(&H88) + CHR$(&H0) + CHR$(&H22) + CHR$(&H0) + CHR$(&H88) + CHR$(&H0) + CHR$(&H22) + CHR$(&H0)
                CASE 15: P$ = CHR$(&HFF) + CHR$(&H0) + CHR$(&HFF) + CHR$(&H0) + CHR$(&HFF) + CHR$(&H0) + CHR$(&HFF) + CHR$(&H0)
            END SELECT

        ' Two bit-per-pixel patterns:
        CASE 2:
            SELECT CASE PatternNum%
                CASE 1: P$ = CHR$(&HFF)
                CASE 2: P$ = CHR$(&HCC) + CHR$(&H33)
                CASE 3: P$ = CHR$(&HF0) + CHR$(&H3C) + CHR$(&HF) + CHR$(&HC3)
                CASE 4: P$ = CHR$(&HF0) + CHR$(&HF)
                CASE 5: P$ = CHR$(&H3) + CHR$(&HC) + CHR$(&H30) + CHR$(&HC0)
                CASE 6: P$ = CHR$(&HFF) + CHR$(&HC)
                CASE 7: P$ = CHR$(&HF0) + CHR$(&HF0) + CHR$(&HF) + CHR$(&HF)
                CASE 8: P$ = CHR$(&HFF) + CHR$(&HC) + CHR$(&H30) + CHR$(&HC0)
                CASE 9: P$ = CHR$(&HC0) + CHR$(&H30) + CHR$(&HC) + CHR$(&H3)
                CASE 10: P$ = CHR$(&HC0) + CHR$(&HC)
                CASE 11: P$ = CHR$(&HCC) + CHR$(&HCC) + CHR$(&H33) + CHR$(&H33)
                CASE 12: P$ = CHR$(&HCC) + CHR$(&HCC) + CHR$(&H0) + CHR$(&H0)
                CASE 13: P$ = CHR$(&HFF) + CHR$(&H33) + CHR$(&H33)
                CASE 14: P$ = CHR$(&HFF) + CHR$(&H0)
                CASE 15: P$ = CHR$(&HCC) + CHR$(&H30) + CHR$(&H0)
            END SELECT

        ' Eight bit-per-pixel patterns:
        CASE 8:
            P$ = CHR$(&HFF)

    END SELECT

    ' Return the pattern as the value of the function:
    GetPattern$ = P$

END FUNCTION

'=== LabelChartH - Prints horizontal text on a chart
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     X          - Horizontal position of text relative to the left of
'                  the Chart window (in pixels)
'
'     Y          - Vertical position of text relative to the top of
'                  the Chart window (in pixels)
'
'     Font%      - Font number to use for the text
'
'     TxtColor   - Color number (in internal color palette) for text
'
'     TxtString$ - String variable containing text to print
'
'  Return Values:
'     None
'
'=================================================================
SUB LabelChartH (Env AS ChartEnvironment, X AS INTEGER, Y AS INTEGER, font AS INTEGER, TxtColor AS INTEGER, TxtString$)

    ' Reset any outstanding errors:
    clClearError

    ' Check initialization and fonts:
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Select ChartWindow as reference viewport:
    clSelectChartWindow

    ' Select font and set color:
    SelectFont font
    clSetCharColor TxtColor

    ' Call internal print routine to print text:
    clHPrint X, Y, TxtString$

END SUB

'=== LabelChartV - Prints vertical text on a chart
'
'  Arguments:
'     Env        - A ChartEnvironment variable
'
'     X          - Horizontal position of text relative to the left of
'                  the Chart window (in pixels)
'
'     Y          - Vertical position of text relative to the top of
'                  the Chart window (in pixels)
'
'     Font%      - Font number to use for the text
'
'     TxtColor   - Color number (in internal color palette) for text
'
'     TxtString$ - String variable containing text to print
'
'  Return Values:
'     None
'
'=================================================================
SUB LabelChartV (Env AS ChartEnvironment, X AS INTEGER, Y AS INTEGER, font AS INTEGER, TxtColor AS INTEGER, TxtString$)

    ' Reset any outstanding errors:
    clClearError

    ' Check initialization and fonts:
    clChkInit
    clChkFonts
    IF ChartErr >= 100 THEN EXIT SUB

    ' Select ChartWindow as reference viewport:
    clSelectChartWindow

    ' Select font and set color:
    SelectFont font%
    clSetCharColor TxtColor

    ' Call internal print routine to print text:
    clVPrint X, Y, TxtString$

END SUB

'=== MakeChartPattern$ - Makes a pattern given reference pattern and
'                        foreground and background colors
'
'  Arguments:
'     RefPattern$ -  Reference pattern
'
'     FG%         -  Foreground color
'
'     BG%         -  Background color
'
'  Return Values:
'     Returns a pattern in standard PAINT format
'     Sets error cBadScreen if ChartScreen hasn't been called
'
'=================================================================
FUNCTION MakeChartPattern$ (RefPattern$, FG AS INTEGER, BG AS INTEGER)
SHARED GP AS GlobalParams

    ' Reset any outstanding errors:
    clClearError

    ' Check initialization:
    clChkInit
    IF ChartErr >= 100 THEN EXIT FUNCTION
    IF NOT GP.PaletteSet THEN
        clSetError cBadScreen
        EXIT FUNCTION
    END IF

    FGColor% = clMap2Attrib%(FG%)
    BGColor% = clMap2Attrib%(BG%)

    ' Screens 1, 2, 11 and 13 are 1 bit plane modes and require one method
    ' of generating pattern tiles.  The other modes supported are multiple
    ' bit plane modes and require another method of generating pattern
    ' tiles.  Select the appropriate method for this screen mode:
    SELECT CASE GP.PaletteScrn

        ' One bit plane modes:
        CASE 1, 2, 11, 13: SinglePlane% = cTrue
        CASE ELSE: SinglePlane% = cFalse

    END SELECT

    ' Do foreground part of pattern:
    IF SinglePlane% THEN
            FGPattern$ = clBuildBitP$(GP.PaletteBits, FGColor%, RefPattern$)
    ELSE
            FGPattern$ = clBuildPlaneP$(GP.PaletteBits, FGColor%, RefPattern$)
    END IF

    ' Do background part of pattern (if background color is black then
    ' the pattern is just the foreground pattern):
    IF BGColor% = 0 THEN
        Pattern$ = FGPattern$

    ELSE
        ' Background reference pattern is inverted foreground pattern:
        BGPattern$ = ""
        FOR i% = 1 TO LEN(RefPattern$)
            BGPattern$ = BGPattern$ + CHR$(ASC(MID$(RefPattern$, i%, 1)) XOR &HFF)
        NEXT i%

        ' Build the corresponding PAINT style pattern:
        IF SinglePlane% THEN
                BGPattern$ = clBuildBitP$(GP.PaletteBits, BGColor%, BGPattern$)
        ELSE
                BGPattern$ = clBuildPlaneP$(GP.PaletteBits, BGColor%, BGPattern$)
        END IF

        ' Put foreground and background patterns back together:
        Pattern$ = ""
        FOR i% = 1 TO LEN(FGPattern$)
            Pattern$ = Pattern$ + CHR$(ASC(MID$(FGPattern$, i%, 1)) OR ASC(MID$(BGPattern$, i%, 1)))
        NEXT i%

    END IF

    MakeChartPattern$ = Pattern$

END FUNCTION

'=== ResetPaletteDef - Resets charting palettes for last screen
'                      mode set with ChartScreen.
'
'=================================================================
SUB ResetPaletteDef ()
SHARED GP AS GlobalParams

    ' Clear outstanding errors:
    clClearError

    ' Check initialization:
    clChkInit

    ' Make sure that ChartScreen has been called at least once:
    IF NOT GP.PaletteSet THEN
        clSetError cBadScreen
        EXIT SUB
    END IF

    ' Now rebuild the palette with the last set screen mode:
    clBuildPalette GP.PaletteScrn, GP.PaletteBits

END SUB

'=== SetPaletteDef - Changes an entry in the internal palette
'
'  Arguments:
'     C%()     -  Color palette array
'
'     S%()     -  Style palette array
'
'     P$()     -  Pattern palette array
'
'     Char%()  -  Plot character palette array
'
'     B%()     -  Border style palette array
'
'  Return Values:
'     Internal chart palettes may be modified or ChartErr set
'
'=================================================================
SUB SetPaletteDef (c() AS INTEGER, s() AS INTEGER, P$(), Char() AS INTEGER, B() AS INTEGER)
SHARED PaletteC%(), PaletteS%(), PaletteP$(), PaletteCh%(), PaletteB%()

    ' Reset any outstanding errors and check that palettes are dimesioned
    ' correctly:
    clClearError
    clChkPalettes c(), s(), P$(), Char(), B()
    IF (ChartErr <> 0) THEN EXIT SUB

    ' Check initialization:
    clChkInit

    ' Replace the palette values with input variables (making sure that
    ' the color and character numbers are in range):
    FOR N% = 0 TO cPalLen
        PaletteC%(N%) = clMap2Attrib%(c%(N%))
        PaletteS%(N%) = s(N%)
        PaletteP$(N%) = P$(N%)
        PaletteCh%(N%) = ABS(Char(N%)) MOD (cMaxChars + 1)
        PaletteB%(N%) = B(N%)
    NEXT N%

END SUB