Programmer 7500/MAX_PROGRAMMERS.iso/VISUAL_B/BIBLIOTE/WINDOWS.TXT

Text File | 1992-09-16 | 29.1 KB | 813 lines

  WINDOW DEVICE COMMANDS
  ---------------------------------------------------------------------------------------

  In Liberty BASIC windows are treated like files, and we can refer
  to anything in this class as a BASIC 'Device'.  To open a window
  we use the OPEN statement, and to close the window we use the
  CLOSE statement.  To control the window we 'print' to it, just as
  we would print to a file.  The commands are sent as strings to the
  device.  As a simple example, here we will open a graphics window,
  center a pen (like a Logo turtle), and draw a simple spiral.  We
  will then pause by opening a simple dialog.  When you confirm the
  exit, we will close the window:

    button #graph, Exit, [exit], LR, 5, 5    'window will have a button
    open "Example" for graphics as #graph    'open graphics window
    print #graph, "up"                     'make sure pen is up
    print #graph, "home"                   'center the pen
    print #graph, "down"                   'make sure pen is down
    for index = 1 to 30                    'draw 30 spiral segments
      print #graph, "go "; index           'go foreward 'index' places
      print #graph, "turn 118"             'turn 118 degrees
    next index                             'loop back 30 times
    print #graph, "flush"                  'make the image 'stick'

  [inputLoop]
    input b$ : goto [inputLoop]            'wait for button press

  [exit]
    confirm "Close Window?"; answer$       'dialog to confirm exit
    if answer$ = "no" then [inputLoop]     'if answer$ = "no" loop back
    close #graph

  end



  WINDOW TYPES:
  ---------------------------------------------------------------------------------------

  Liberty BASIC provides ten different kinds of window types, to which you
  can add as many buttons and pull-down menus as needed.  Here is a list of
  the different kinds:

    graphics
        - open a graphic window
    graphics_fs
        - open a graphic window full screen (size of the screen)
    graphics_nsb
        - open a graphic window w/no scroll bars
    graphics_fs_nsb
        - open a graphic window full screen, w/no scroll bars

    text
        - open a text window
    text_fs
        - open a text window full screen
    text_nsb
        - open a text window w/no scroll bars
    text_nsb_ins
        - open a text window w/no scroll bars, with inset editor
          so that buttons can be placed around it
    text_fs_nsb
        - open a text window full screen, w/no scroll bars

    spreadsheet
        - open a spreadsheet window



  The way that you would specify what kind of window to open would be
  as follows:

    open "Window Title" for type   as #handle

  where type  would be one of the above ten descriptors



  CONTROLLING SIZE AND PLACEMENT OF WINDOWS
  --------------------------------------------------------------------------------------

  The size and placement of any window can be easily determined before
  it is opened in Liberty BASIC (except for any window type with a _fs in its
  descriptor).  If you do choose not to specify the size and placement of
  the windows that your programs open, Liberty BASIC will pick default sizes.
  However, for effect it is often best that you exercise control over this matter.

  There are four special variables that you can set to select the size and
  placement of your windows, whether they be text, graphics, or
  spreadsheet:

          UpperLeftX, UpperLeftY, WindowWidth, and WindowHeight

  Set UpperLeftX and UpperLeftY to the number of pixels from the
  upper-left corner of the screen to position the window.  Often determining
  the distance from the upper-left corner of the screen is not as important
  as determining the size of the window.

  Set  WindowWidth and WindowHeight to the number of pixels wide and
  high that you want the window to be when you open it.

  Once you have determined the size and placement of your window, then
  open it.  Here is an example:


  [openStatus]

      UpperLeftX = 32
      UpperLeftY = 32
      WindowWidth = 190
      WindowHeight = 160

      open "Status Window" for spreadsheet as #stats


  This will open a window 32 pixels from the corner of the screen, and with
  a width of 190 pixels, and a height of 160 pixels.



  BUTTONS
  ---------------------------------------------------------------------------------------

 Buttons are easily added to Liberty BASIC windows.  The format is simple:

    button #handle, "Label", [branchLabel], corner, distX, distY
    open "A Window!" for graphics as #handle

  By placing at least one button statement before  the open statement, we can
  add button(s) to the window.  Let's examine each part of the button statement:

    #handle - This needs to be the same as the handle of the window.

    "Label" - This is the text displayed on the button.  If only one word is used,
                          then the quotes are optional.

    [branchLabel] - This controls what the button does.  When the user clicks
                                  on the button, then program execution continues at
                                  [branchLabel] as if the program had encountered a
                                  goto [branchLabel] statement.

    corner, distX, distY - Corner is used to indicate which corner of the
                                   window to anchor the button to.  DistX and distY
                                   specify how far from that corner in x and y to place
                                   the button.  The following values are permitted for
                                   corner:

                      UL - Upper Left Corner
                      UR - Upper Right Corner
                      LL - Lower Left Corner
                      LR - Lower Right Corner

  Whenever a running program sits idle at an input statement, it is possible
  for a button-press to effect some action.  If any button is pressed while
  the program is busy doing something else, the button-press will be
  buffered and read later when an input statement is encountered.



  MENUS
  ---------------------------------------------------------------------------------------

  Menus are easily added to Liberty BASIC windows.  The format is simple:

    menu #handle, "Title", "Line1", [branchLabel1], "Line2", [branchLabel2], ...
    open "A Window!" for graphics as #handle

  By placing at least one menu statement before  the open statement, we can
  add menu(s) to the window.  Let's examine each part of the menu statement:

    #handle - This needs to be the same as the handle of the window.

    "Title" - This is the title displayed on the menu bar.  If only one word is used,
                 then the quotes are optional.  By including an ampersand & in
                 front of the character desired, you can turn that character
                 into a hot-key.  For example, if the title is "&Help", the
                 title will appear as Help.

    "Line1" and [branchLabel1] - This is a line item seen when the menu is
             pulled down.  [branchLabel1] is the place where execution continues
             if this menu item is selected.  Like "Title", "Line1"  requires quotes
             only if there is more than one word.  The ampersand & character is
             used to assign a hot-key to the label, as in "Title", above.

    "Line2" and [branchLabel2] - This is a second line item and branch
             label for the menu.  You can have as many is needed, going on
             with "Line3 . . . 4 . . .  5", etc.

  Adding seperators between menu items to group them is easy.  Simply add a
  bar | character between each group of items.  For example:

    . . . "&Red", [colorRed], |, "&Size", [changeSize] . . .

    adds a line seperator between the Red and Size menu items like so:

{Illustration was here}


  Whenever a running program sits idle at an input statement, it is possible
  for a menu selection to effect some action.  If any menu selection is made
  while the program is busy doing something else, the selection will be
  buffered and read later when an input statement is encountered.



  GRAPHICS
  ---------------------------------------------------------------------------------------

  Because graphics can involve many detailed drawing operations,
  Liberty BASIC does not force you to use just one print # statement
  for each drawing task.  If you want to perform several operations
  you can use a single line for each as such:

    print #handle, "cls"
    print #handle, "fill black"
    print #handle, "pen up"
    print #handle, "home"
    print #handle, "pen down"
    print #handle, "north"
    print #handle, "go 50"

  Or if you prefer:

    print #handle, "cls ; fill black ; pen up ; home ; pen down ; north ; go 50"

  will work just as well, and executes slightly faster.


  print #handle, "\text"

    Display text at the current pen position.  Each additional \ in the
    text will cause a carraige return and line feed.  Take for example,
    print #handle, "\text1\text2" will cause text1 to be printed at the
    pen position, and then text2 will be displayed directly under text1.


  print #handle, "cls"

    Clear the graphics window to white, erasing all drawn elements


  print #handle, "fill COLOR"

    Fill the window with COLOR.  For a list of accepted colors see
    the color command below.


  print #handle, "up"

    Lift the pen up.  All go or goto commands will now only move the
    pen to its new position without drawing.  Any other drawing
    commands will simply be ignored until the pen is put back down.


  print #handle, "down"

    Just the opposite of up.  This command reactivates the drawing
    process.


  print #handle, "color COLOR"

    Set the pen's color to be COLOR.

    Here is a list of valid colors (in alphabetical order):

      black, blue, brown, cyan, darkblue, darkcyan, darkgray,
      darkgreen, darkpink, darkred, green, lightgray, palegray,
      pink, red, white, yellow

  print #handle, "backcolor COLOR"

    This command sets the color used when drawn figures are filled with a
    color.  The same colors are available as with the color command above.

  print #handle, "goto X Y"

    Move the pen to position X Y.  Draw if the pen is down.


  print #handle, "place X Y"

    Position the pen at X Y.  Do not draw even if the pen is down.


  print #handle, "go D"

    Go foreward D distance from the current position, and going in the
    current direction.


  print #handle, "north"

    Set the current direction to 270 (north).  Zero degrees points to the
    right (east), 90 points down (south), and 180 points left (west).


  print #handle, "turn A"

    Turn from the current direction using angle A and adding it to the
    current direction.  A can be positive or negative.


  print #handle, "line X1 Y1 X2 Y2"

    Draw a line from point X1 Y1 to point X2 Y2.  If the pen is up, then
    no line will be drawn, but the pen will be positioned at X2 Y2.


  print #handle, "posxy"

    Return the position of the pen in x, y.  This command must be followed by:

      input #handle, xVar, yVar

    which will assign the pen's position to xVar & yVar


  print #handle, "size S"

    Set the size of the pen to S.  The default is 1.  This will affect the
    thickness of lines and figures plotted with most of the commands
    listed in this section.


  print #handle, "flush"

    This ensures that drawn graphics 'stick'.  Make sure to issue this
    command at the end of a drawing sequence to ensure that when the
    window is resized or overlapped and redrawn, its image will be
    retained.  To each group of drawn items that is terminated with flush,
    there is assigned a segment ID number.  See segment below.


  print #handle, "print"

    Send the plotted image to the Windows Print Manager for output.


  print #handle, "font facename width height"

    Set the pen's font to the specified face, width and height.  If an
    exact match cannot be found, then Liberty BASIC will try to find a
    close match, with size being of more prominance than face.


  print #handle, "circle r"

    Draw a circle with radius r at the current pen position.


  print #handle, "circlefilled r"

    Draw a circle with radius r, and filled with the color specified using
    the command backcolor (see above).


  print #handle, "box x y"

    Draw a box using the pen position as one corner, and x, y as the
    other corner.  print #handle, "boxfilled x y"

    Draw a box  using the pen position as one corner, and x, y as the other corner.
    Fill the box with the color specified using the command backcolor (see above).


  print #handle, "ellipse w h"

    Draw an ellipse at the pen position of width w and height h.


  print #handle, "ellipsefilled  w h"

    Draw an ellipse at the pen position of width w and height h.  Fill the ellipse
    with the color specified using the command backcolor (see above).


  print #handle, "pie w h angle1 angle2"

    Draw a pie slice inside of an ellipse of width w and height h.  Start the pie
    slice at angle1, and then sweep clockwise angle2 degrees if angle2 is
    positive, or sweep counter-clockwise angle2 degrees if angle2 is negative.


  print #handle, "piefilled w h angle1 angle2"

    Draw a pie slice inside of an ellipse of width w and height h.  Start the slice
    at angle1, and then sweep clockwise angle2 degrees if angle2 is positive,
    or sweep counter-clockwise angle2 degrees if angle2 is negative.  Fill the
    pie slice with the color specified using the command backcolor (see above).


  print #handle, "segment"

    This causes the window to return the segment ID of the most recently
    flushed drawing segment.  This segment ID can then be retrieved
    with an input #handle, varName and varName will contain the segment
    ID number.  Segment ID numbers are useful for manipulating different
    parts of a drawing.  For an example, see delsegment below.


  print #handle, "delsegment n"

    This causes the drawn segment identified as n to be removed from the
    window's list of drawn items.  Then when the window is redrawn the
    deleted segment will not be included in the redraw.


  print #handle, "redraw"

    This will cause the window to redraw all flushed drawn segments.  Any
    deleted segments will not be redrawn (see delsegment above).  Any items
    drawn since the last flush will not be redrawn either, and will be lost.


  print #handle, "discard"

    This causes all drawn items since the last flush to be discarded, but does not
    not force an immediate redraw, so the items that have been discarded will
    still be displayed until a redraw (see above).


print #handle, "trapclose branchLabel"

    This will tell Liberty BASIC to continue execution of the program at
    branchLabel if the user double clicks on the system menu box
    or pulls down the system menu and selects close (see buttons1.bas
    example below).


{Illustration was here}


  The trapclose code in buttons1.bas looks like this:

    open "This is a turtle graphics window!" for graphics_nsb as #1
    print #1, "trapclose [quit]"

[loop]    ' stop and wait for buttons to be pressed
    input a$
    goto [loop]


  And then the code that is executed when the window is closed looks like this:

[quit]
    confirm "Do you want to quit Buttons?"; quit$
    if quit$ = "no" then [loop]
    close #1
    end


  Since this only works when the program is halted at an input statement, the
  special variable TrapClose permits detection of the window close when you
  are running a continuous loop that doesn't stop to get user input.  As long as
  TrapClose <> "true", then the window has not been closed.  Once it has been
  determined that TrapClose = "true", then it must be reset to "false" via the
  BASIC LET statement.  See clock.bas for an example.

  print #handle, "when event branchLabel"

    This tells the window to process mouse events.  These events occur
    when someone clicks, double-clicks, drags, or just moves the mouse
    inside of the graphics window.  This provides a really simple mechanism
    for controlling flow of a program which uses the graphics window.  For
    an example, see the program draw1.bas.

    Sending print #handle, "when leftButtonDown [startDraw]" to any
    graphics window will tell that window to force a goto [startDraw] when
    the mouse points inside of that window and someone press the left mouse
    button down.

    Whenever a mouse event does occur, Liberty BASIC places the x and y
    position of the mouse in the variables MouseX, and MouseY.  The
    values will represent the number of pixels in x and y the mouse was from
    the upper left corner of the graphic window display pane.

    If the expression print #handle, "when event" is used, then trapping
    for that event is discontinued.  It can however be reinstated at any time.

    Events that can be trapped:

      leftButtonDown - the left mouse button is now down
      leftButton Up - the left  mouse button has been released
      leftButtonMove - the mouse moved while the left button is down
      leftButtonDouble - the left button has been double-clicked
      rightButtonDown - the right mouse button is now down
      rightButton Up - the right  mouse button has been released
      rightButtonMove - the mouse moved while the right button is down
      rightButtonDouble - the right button has been double-clicked
      mouseMove - the mouse moved when no button was down



  SPREADSHEET
  ---------------------------------------------------------------------------------------

  The spreadsheet used in Liberty BASIC is composed of 35 rows of 26
  columns labeled from A to Z.  The upper-left-most cell is A1 and the
   lower-right-most cell is Z35.  Each cell can contain one of three types
   of data:  string, number, or formula.  To enter one of these three types into
   any cell, simply move the selector over the cell on the spreadsheet
   and begin typing.  When done entering that cell's   contents, press 'Return'.

   A string is entered by preceding it with an apostrophe '.  Each cell
   is 11 characters wide so if the string is longer than 11 characters
   it will run into the next cell to its right.

   A number is entered by entering its value, either an integer or a
   floating point number.

   A formula is a simple arithmatic expression, using numbers (see above) or
   cell references.  The result of the formula is displayed  in the cell's position.
   Any arithmatic precedence is ignored, so any formula is always evaluated
   from left to right and parenthesis are not permitted (They aren't needed).

     A formula to compute the average of 3 cells might be:     a1 + a2 + a3 / 3

  The spreadsheet is a very special widget.  Alone it is a very simple
  but complete spreadsheet.  But being able to send it commands and data
  and to be able to read back data from it via Liberty BASIC makes it
  a very powerful tool.  For examples, see grapher.bas and customer.bas.

  Modes:
  The spreadsheet has two modes, manual and indirect.  Manual mode means that
  that the operator can freely move about from cell to cell with the arrow keys.
  He/she can also insert formulas in manual mode.  Using  indirect mode, the user
  can only move to cells predefined by the controlling application, which also
  decides what type of data is contained by each cell, either string or number.


  Here are the commands:


  print #handle, "manual"

    The manual mode is the default setting.  This mode permits the
    user to move the cell selector wherever he/she wants and to
    enter any of three data types into any cell: number, string, formula


  print #handle, "format COLUMN right|fixed|none"

    This command lets the application control formatting for an individual
    column (COLUMN can be any letter A .. Z).

    right - right justify column
    fixed - assume 2 decimal places for numbers, and right justify also
    none - left justify, default



  print #handle, "indirect"

    The indirect mode is the most useful when using a spreadsheet for
    data entry.  It enables the application to control which cells the
    user has access to, and what kind of information they can contain.


  print #handle, "cell ADDRESS CONTENTS"

    Place CONTENTS into the cell at ADDRESS.  ADDRESS can be any cell
    address from A1 to Z35.  The letter A to Z must be in uppercase.
    CONTENTS can be any valid string, number or formula (see above).


  print #handle, "user ADDRESS string|number"

    Set aside the cell at ADDRESS (same rules apply as for ADDRESS in
    command cell, above) as a user cell and specify the data it
    contains to be either a string or a number (data entered will be
    automatically converted to correct type).  This command is only
    effective when indirect mode is in effect (see above).


  print #handle, "select ADDRESS"

    Place the selector over the cell at ADDRESS (again, same rules).
    It is important to place the selector over the first cell that
    the user will edit.


  print #handle, "result? ADDRESS"

    Answer the result or value of the cell at ADDRESS (again, same
    rules).  If ADDRESS is not a valid cell address, then an empty
    string will be returned.  This command must be followed by:

    input #handle, var$  (or  input #handle, var  if number expected)

    which will leave the desired cell's contents in var$  (or var)


  print #handle, "formula? ADDRESS"

    Answer the formula of the cell at ADDRESS (again, same rules).
    This command must also be followed with:

    input #handle, var$  (should always be a string returned)

    which will leave the desired cell's formula in var$


  print #handle, "flush"

    This commands forces the spreadsheet to display its most up to
    date results.


  print #handle, "load pathFileName"

    This causes a Liberty BASIC spreadsheet file (which always have
    an .abc extension) named pathFileName to be loaded, replacing
    the current data set.


  print #handle, "save pathFileName"

    This causes spreadsheet data set (which will always have
    an .abc extension) to be saved to disk at pathFileName.


  print #handle, "modified?"

    This returns a string (either "true" or "false") that indicates whether any
    data in the spreadsheet has been modified.  This is useful for checking
    to see whether to save the contents of the window before closing it.

    To read the result, an input #handle, varName$, must be performed
    after.


  print #handle, "nolabels"

    This turns off the row and column labels.


  print #handle, "labels"

    This turns on the row and column labels.


  print #handle, "trapclose branchLabel"

    This will tell Liberty BASIC to continue execution of the program at
    branchLabel if the user double clicks on the system menu box
    or pulls down the system menu and selects close (see rolodex1.bas).

    See the text for trapclose in the above graphic window section for a
    more complete explanation.


  TEXT WINDOW
  ---------------------------------------------------------------------------------------

  The text window works a little differently.  Whatever you print to a
  text window is displayed exactly as sent.  The way to send commands to
  a text window is to make the ! character the first character in the string.
  It is also important to add a semicolon to the end of command line (a
  print #handle line with text window commands) as in the example below.
  If you don't, the print statement will force a carraige return into the text
  window each time you print a command to the window if you don't.

  For example:

  open "Example" for text as #1        'open a text window
    print #1, "Hello World"            'print Hello World in the window
    print #1, "!font helv 16 37" ;       'change the text window's font
    print #1, "!line 1" ;               'read line 1
    input #1, string$
    print "The first line of our text window is:"
    print string$
    input "Press 'Return'"; r$
  close #1                             'close the window


  Here are the text window commands:


  print #handle, "!cls" ;

    Clears the text window of all text.


  print #handle, "!font faceName width height" ;

    Sets the font of the text window to the specified face of width and
    height.  If an exact match cannot be found, then Liberty BASIC will
    try to match as closely as possible, with size figuring more
    prominently than face in the match.


  print #handle, "!line #" ;

    Returns the text at line #.  If # is less than 1 or greater than the
    number of lines the text window contains, then "" (an empty string)
    is returned.  After this command is issued, it must be followed by:

    input #handle, string$

    which will assign the line's text to string$


  print #handle, "!lines" ;

    Returns the number of lines in the text window.  After this command
    is issued, it must be followed by:

    input #handle, countVar

    which will assign the line count to countVar



  print #handle, "!modified?" ;

    This returns a string (either "true" or "false") that indicates whether any
    data in the text window has been modified.  This is useful for checking
    to see whether to save the contents of the window before closing it.

    To read the result, an input #handle, varName$, must be performed
    after.


  print #handle, "!selection?" ;

    This returns the highlighted text from the window.  To read the result
    an input #handle, varName$ must be performed after.


  print #handle, "!selectall" ;

    This causes everything in the text window to be selected.


  print #handle, "!copy" ;

    This causes the currently selected text to be copied to the
    WINDOWS clipboard.


  print #handle, "!cut" ;

    This causes the currently selected text to be cut out of the
    text window and copied to the WINDOWS clipboard.


  print #handle, "!paste" ;

    This causes the text in the WINDOWS clipboard (if there is any) to be
    pasted into the text window at the current cursor position.


  print #handle, "!origin?" ;

    This causes the current text window origin to be returned.  When a text
    window is first opened, the result would be row 1, column 1.  To read the
    result an input #handle, rowVar, columnVar must be performed after.


  print #handle, "!origin row column" ;

    This forces the origin of the window to be row and column.


  print #handle, "!trapclose branchLabel" ;

    This will tell Liberty BASIC to continue execution of the program at
    branchLabel if the user double clicks on the system menu box
    or pulls down the system menu and selects close (see rolodex1.bas).

    See the text for trapclose in the above graphic window section for a
    more complete explanation.



  TIPS
  ------------------------------------------------------------------------

  - Once its techniques are mastered, the spreadsheet becomes a much better
  mechanism for data entry than do plain INPUT statements in a BASIC
  program's main window.  This is especially true when many items need to
  be entered.  In this case, making the spreadsheet the control center
  for your application might be a good idea.  Just add buttons to the
  spreadsheet to perform needed functions after data is entered.

  - Remember, any window can have buttons (except for the main window,
  which is for some applications best kept minimized).  Take advantage of this.

  - Many applications do not need the main window at all, and in these cases,
  you can simply include the NOMAINWIN command in your programs, which
  causes the main window to be omitted from your running program.

  - Don't forget to take advantage of the PROMPT, CONFIRM, and NOTICE
  statements, which borrow the syntax from the INPUT statement, but do their
  thing in Windows dialogs.  These simple statements can help make your programs
  more Windows-like.

  - When running grapher.bas, try pulling down the command menu and
  selecting Open.  Two *.abc files will be offered.  Load one of these
  and click on the Graph button.

  - If you want to edit more than one *.bas file at once, after you select a file
  to edit, pull down the Files menu and select BASIC Editor.  A seperate
  editor window will open containing the file you select.  NOTE:  The file that
  is displayed will be the last saved  version, so if you have made changes and
  have not saved them, they will not appear in the newly opened window.

  - When drawing graphic figures, you can create a three dimensional effect
  by first drawing each figure in gray or black, and with a slight offset, and then
  drawing the figures on top in some other color.  This creates a shadow effect.