PC World 1998 June/PCWorld_1998-06_cd.bin/software/sharware/grafika/EROICA32/SAMPLE/IMGDEMO1.ZIP/DIALOG.ASC

Text File | 1997-12-23 | 23KB | 567 lines

    HOW TO USE THE BRIEF DIALOG MANAGER PACKAGE

WHAT IS THE DIALOG MANAGER?

The BRIEF dialog manager is a macro package containing tools for
generating pop-up menus and dialog boxes.  Menus allow a user to perform
complicated tasks by choosing from lists of possible actions.  Dialog
boxes allow a user to answer questions and fill in forms, while possibly
restricting the set of valid answers.

Many of BRIEF's standard macros (Help, for example) use the dialog
manager.  You can use the dialog manager in your own macros, too.

WHERE IS THE DIALOG MANAGER?

Source code for the package is located in the files dialog.m and
dialog.h; the compiled version is in dialog.cm.

WHY USE THE DIALOG MANAGER?

The BRIEF dialog manager provides a standard user interface for macros.
If you write a macro that uses this interface properly, it will have the
look and feel of the standard commands that are shipped with BRIEF, and
any BRIEF user will be able to use it with minimal effort.

Using the dialog manager conserves memory and avoids reinventing the
wheel.  Suppose you frequently use Help and three other macro packages
with separate user interfaces.  That's a lot of macros to load at once;
BRIEF may spend a fair amount of time re-reading the disk.  The macros
will take up far less memory if they reuse the same code.

WHAT CAPABILITIES ARE PROVIDED?

The dialog manager is essentially just two macro calls, one to create
and process a menu, and one to create and process a dialog box.
Although the dialog manager contains dozens of other macros (as well as
several global variables,) you should seldom need to deal with them.
(Consult the source code for more information.)

Menus are pop-up windows, within which one line ("button") is always
highlighted.  Pressing Enter ("picking") causes an action associated
with the highlighted button to be executed.  The up and down arrow keys
move the highlight up or down.  Windows scroll vertically as needed.

Menus offer a choice of several actions.  These actions may invoke other
menus or dialog boxes.  In Help, for example, picking some buttons
causes a window of help information on a particular topic to appear;
picking others causes another menu (more detailed) to appear.

Dialog boxes are the other half of the dialog manager.  Dialog boxes are
pop-up windows that contain descriptive text and any of several kinds of
input fields.  A user may move between fields and change the contents of
any field.  These changes can be saved or cancelled as a group.

The kinds of input fields are:
    Filenames
    Lists
    Integers
    Nonblank strings
    Strings

LISTS

Lists, like menus, are multiple-choice situations; however, lists are
choices of values, not actions, and the values are usually mutually
exclusive.  One very common list has two choices: Yes and No.

Lists appear on the screen on a single line, with items separated by
whitespace.  A highlight is used to mark the currently selected item
while the user's cursor is on the field; when he or she leaves, the
highlight changes to a pair of parentheses.

A list can be paired with a text string, which is usually a question:

    Do you want to save your changes?  (Yes)No
    Line drawing style:           Single(Double)Mixed None

FILENAMES, INTEGERS, NONBLANK STRINGS, AND STRINGS

The number of possible answers to a question is often so great that a
list is awkward or impossible.  In such situations, it's best to let the
user to type in his or her answer, then check it for validity.  The user
can be asked to re-enter an invalid answer.

Filenames, Integers, Nonblank strings, and Strings behave identically
except that they use different validation criteria.  Strings are not
checked at all.  Nonblank strings may not be blank.  Integer fields must
contain an integer value, and Filename fields must contain a
syntactically legal path name.

Fields are one line deep and may extend from their beginning to the
right edge of the window.  The entire field is highlighted when the
user's cursor enters it; the highlight disappears as soon as anything
happens.  When the user's cursor leaves, the field contents are
validated.

KEY ASSIGNMENTS

The key assignments for moving around and between menus and dialog boxes
are standardized.  You should not change these key assignments, although
you may add your own to the list.

These key assignments are uniform throughout the dialog manager:
Esc        Exit all levels        Keypad minus    Exit 1 level
Ctrl-Home    Top of window        Ctrl-End    End of window

Within menus, the additional assignments are:
Enter        Pick from menu
Up arrow    Previous item        Down arrow    Next item
Backspace    Previous item        Space        Next item
Home        First item        End        Last item
PgUp        Previous page        PgDn        Next page
Alphanumeric character sequence   Next item beginning with characters

Within any dialog box field, the following keys are defined:
Enter        Next field, or save if on last field (== Ctrl-m)
F10        Save dialog box and exit
Up arrow    Previous field        Down arrow    Next field
Shift-Tab    Previous field        Tab        Previous field

Within lists only, additional assignments are:
Left arrow    Previous item        Right arrow    Next item
Backspace    Previous item        Space        Next item
Home        First item        End        Last item
Alphanumeric character    Next item beginning with character

Within fields (excepting lists), additional key assignments are:
Left arrow    Left            Right arrow    Right
Backspace    Backspace        Space        Space
Home        Beginning of field    End        End of field
Del        Delete character    Alt-k        Delete to end
Ins, Alt-i    Toggle insert mode    Alt-d        Delete field

When a field is highlighted, typing causes the contents of the field to
be replaced by the new characters.

    MENUS

HOW TO CREATE A MENU

There are 3 steps involved in creating a menu.

1.  Create a data file containing the names of the menu buttons and the
actions you want the buttons to invoke.

2.  Write a macro that calls the dialog manager package.

3.  Write the action macros that will handle everything the user does in
the menu.

CREATING THE MENU DATA FILE

Menu data files are usually given a .mnu extension and kept in the same
directory as the help files (specified by BHELP).

A menu file contains one line for each line of the menu.  Each line
consists of a button name and optional additional information.  When
the menu is displayed, the additional information should be invisible
(just past the right edge of the window).  The menu button is normally
centered in the visible part of the line.

For fastest operation, each line is normally pre-formatted; in this
example (taken from help.mnu), spaces are used to center the buttons in
the visible part of the window, which is delimited by the semicolons.
Everything to the right of the semicolons is considered "additional
information":

   Help on Help    ;display_help "help"
  Quick Reference  ;display_help "keyboard layout"
 Key-Specific Help ;key_specific_help

You can also have the menu automatically formatted.  If you do, you
must use a semicolon as the delimiter, and leading/trailing whitespace
around the buttons will be ignored:

Help on Help;display_help "help"
Quick Reference;display_help "keyboard layout"
Key-Specific Help;key_specific_help

Action macros, described below, are free to do whatever they want with
the additional information.  In this case, the information is a macro
call (complete with a string parameter), and it is passed to
execute_macro.

CALLING UP THE MENU

The call to create and process a menu is as follows:

(_process_menu lx by rx ty title msg filename buf_id action fast
    picked_line picked_text)

Parameters 0 through 3 are integers, the coordinates of the left (lx),
bottom (by), right (rx), and top (ty) edges of the window.  These are
absolute screen coordinates; the top left corner of a 25x80 screen is
(0, 0) and the lower right is (24, 79).  If lx equals rx or ty equals
by, the menu is positioned at (lx, ty) and the size will be computed
automatically based on the number of lines on the menu and the column
position of the first semicolon.  (Be careful not to position menus
so close to the bottom and left edges of the screen so that there's
no room for automatic formatting.)

Parameter 4 is the title of the menu, a string to be displayed in the
top edge of the window.  It may be at most 12 characters long.

Parameter 5 is a string, a message to be displayed in the bottom edge of
the window.  Make sure it is shorter than the edge itself.

You should supply either, but not both, of parameters 6 and 7.  Supply
NULL in the place of whichever parameter you omit.  Parameter 6 is the
filename of a menu data file (in the BHELP directory), while parameter 7
is the identifier of a buffer containing a menu data file.  Use
parameter 7 if you have a .mnu file already in memory and want to keep
it there; otherwise, use parameter 6 and the dialog manager will delete
the buffer when you're done with it.  (If you use parameter 7, then the
title you passed in parameter 4 will be ignored, and the buffer name
already in existence will be used.)

Note that parameter 6 is assumed to be the name of a file in the
BHELP directory unless an absolute path name is supplied.  The dialog
manager assumes that any name containing the characters /, \, or : is
an absolute path.

Parameter 8 is a string containing the name of your main action macro,
described below.

Parameter 9 may be omitted.  If it is passed and TRUE, your menu file
is not formatted in any way, saving oodles of time when it pops up.
If you use this parameter, make sure to pre-format your .mnu file.

Parameter 10 is an optional integer variable which will be set to the
number of the menu button that the user picks.  It is only valid when
the call to _process_menu returns TRUE.  If the user presses <Esc> or
<Keypad minus> to escape from a menu, this parameter will be zero.

Parameter 11 is an optional string variable which will be set to the
text of the menu button that the user picks.  It is only valud when
the call to _process_menu returns TRUE and parameter 10 is nonzero.

The dialog manager assumes the values you pass it are correct, so be
careful.

When the call to _process_menu is encountered, the menu will pop up and
processing of the user's keystrokes will begin immediately.  Processing
will stop when the user presses Esc (or the keypad minus key), and
control will return to your macro, just after the _process_menu call.
_process_menu returns TRUE if it was able to create and process a menu,
FALSE if an error occurred.

EVENTS

We have written the dialog manager to be as flexible as possible.
Hence, the system leaves a lot of decisions and a lot of work up to your
action macro.  The dialog manager is event-driven; it quietly goes about
its business until an "event" of significance occurs, at which point it
taps your macro on the shoulder, informs it of the situation, and waits
for a response before continuing.

Here's a list of all significant events, for both menus and dialog
boxes.  Matching #define statements are contained in the file
"dialog.h".  You should #include this file in any macro file you write
that calls the dialog manager, so that you can refer to the event types
by symbolic name rather than by number.

DIALOG_INIT        The dialog manager has just been invoked
DIALOG_TERM        The dialog manager is exiting
DIALOG_ENTER_FIELD    The cursor has just entered a non-list field
DIALOG_EXIT_FIELD    The cursor has just left a non-list field
DIALOG_ENTER_LIST    The cursor has just entered a list
DIALOG_EXIT_LIST    The cursor has just left a list
DIALOG_ALTER_LIST    The current item in a list has just been changed
DIALOG_ALTER_MENU    The current item in a menu has just been changed
DIALOG_MOVE_MENU    (Same as DIALOG_ALTER_MENU)
DIALOG_PICK_MENU    The user has just selected a menu button with Enter
DIALOG_ESCAPE        The user has just pressed Esc to exit all levels
DIALOG_F10        The user has just pressed F10 to save a dialog box
DIALOG_GREY_MINUS    The user has just pressed the keypad minus key
DIALOG_CREATE_MENU    A menu buffer has just been made current
DIALOG_CREATE_DBOX    A dialog box data buffer "

HOW TO WRITE THE MENU ACTION MACROS

When you're working with menus, only the invoke/exit events, the
Esc/keypad minus events, and the events for changing or selecting menu
items can happen.  Your job is to provide a single macro that responds
to these events; the name of this macro is parameter 8 in the call to
_process_menu, and the macro is called by _process_menu whenever one of
these events occurs.

Suppose you call your action macro "action".  When called, action will
be passed three parameters:

    (action event_type line text)

The first parameter is an integer matching one of the above #defines.
The second is the number of the current line in the menu (note that this
is also the number a user will see as Line: in the BRIEF message area).
The third is the text of the entire button, including the delimiter and
additional information (if any).

In the BRIEF macro language, parameters in the calling function are only
evaluated when the called function explicitly requests the parameter.
This means that, for best performance, your action macro should never
get a parameter it does not need.

The normal strategy for processing events within a menu action macro is
as follows:

1.  Get the event type parameter.

2.  If the event type is DIALOG_PICK_MENU, then get the line number or
text parameters and process them as desired.  Note that the dialog
manager does NOT execute an action associated with a button
automatically.  Your action macro must parse the button text and execute
the command.

Commonly, a pick event will cause the action macro to pop up a window
of text (such as help) and enter a process under the user's control.
The window will remain visible until the user presses Esc or Keypad
minus to signal he's done.  If the user pressed Esc, the action macro
should push the Esc back into the keyboard buffer so that a DIALOG_ESC
event is generated as soon as the action macro returns.

3.  If the event type is DIALOG_CREATE_MENU, the unformatted menu
is the current buffer, and its name is the text parameter.  You can
use this event to add buttons to the menu.

(If the event type is anything else, you usually don't need to do any
more.  However, if you want to add key assignments to the normal menu
keymap, you can use DIALOG_INIT as a signal to add them, and DIALOG_TERM
as a signal to remove them.  And if you want to preclude the user from
moving to a particular line of the menu (for example, a heading) then
you can use DIALOG_MOVE_MENU.)

3.  Return TRUE.  The only time you should return FALSE is if the event
was DIALOG_MOVE_MENU, and the line number or text was such that you
don't want the cursor to be allowed to move to it (other lines will be
tried until EOF or until DIALOG_MOVE_MENU succeeds).

ACTION MACRO EXAMPLE

The following macro, when called by the dialog manager, will handle two
types of events.  First, the user will not be allowed to move to line 1
or line 4.  Second, when the user picks a button, this macro will use
the additional information present in the .mnu file to call another macro.

(macro action
   (
      (int      event_type
        line_no
        retval
      )
      (string   button_text)

      (get_parm 0 event_type)
      (= retval TRUE)

      (switch event_type

     DIALOG_MOVE_MENU
        (
           (get_parm 1 line_no)

           (if (|| (== line_no 1) (== line_no 4))
          (= retval FALSE)
           )
        )

     DIALOG_PICK_MENU
        (
           (get_parm 2 button_text)

           ;**   Trim the button name and treat the additional
           ;**   information as a command that can be executed.

           (execute_macro (substr button_text
           (+ (index button_text ";") 1)))
        )
      )
      (returns retval)
   )
)

    DIALOG BOXES

HOW TO CREATE A DIALOG BOX

As with menus, there are 3 steps to creating a dialog box: creating a
data file, writing a macro that calls the dialog manager, and writing
action macros.

DATA FILES FOR DIALOG BOXES

Dialog box data files must be kept in the BHELP directory.  Like menu
files, they contain one line for each item displayed.  Each line
contains the type of the input field, the row and column coordinates
(relative to the window's origin) at which the field should be placed,
and the field's initial contents.  The number of fields is unlimited
because dialog boxes, like menus, can scroll vertically.

The row and column coordinates must be surrounded by parentheses and
separated by a comma.  The initial contents must be surrounded by double
quotes.  Whitespace may go just about anywhere, and you can have
comments.  The following example shows a number of legal ways of
defining fields, and descriptive text, in a dialog box:

;**  Get the speed using a 3-item list.
Text at (1, 1) is "Speed:"
List ( 1, 8 ) = "(Slow)Medium Fast"

;**  Get the user's name.  Make sure they enter one.
text (3,1) "Name:"
    nonblank(3,9)  "Your name goes here"
;**  Prompt for user's age.  Make sure it's numeric.
T    (5, 1)   "Age:"
I(5,9)"24"

The first non-whitespace character on a line defines the type of the
field.  A 'T' means that this line is a descriptive text string that can
be displayed only.  The letters F, L, I, N, and S denote Filenames,
Lists, Integers, Nonblank strings, and Strings.

All fields, even lists and integers, are really strings.  Hence, you
should format the initial contents of every field as a quoted string, as
in the example above.

List strings have a special format.  Items must be separated by single
tab characters (since spaces are allowed in item names).  The item that
is to be initially highlighted should be surrounded by parentheses
instead of tabs.

Position lists as you would any other field.  If a list begins with
a (, the dialog manager will compensate for you.

If you omit the current item in a list, or if you supply a field that's
too wide for the window, the invalid field will not be displayed and an
error message will.

The dialog manager does not check to see if any fields overlap.  Hence,
only one input field is allowed per line.  Text can be placed anywhere
except to the right of an input field.

HOW TO CALL UP A DIALOG BOX

The call to create and process a dialog box is nearly identical to the
call to create a menu, except that the macro name is _process_dialog_box:

(_process_dialog_box lx by rx ty title msg filename buf_id action)

All parameters have the same meaning as for _process_menu, except:

1.  There is no automatic sizing for dialog boxes, so lx must not equal
rx, and by must not equal ty.

2.  Parameter 4, the title, is always used, even when a buffer ID is passed
for parameter 7.

3.  There are no parameters 9, 10, or 11.

This call may return when the user presses F10, Esc, or the keypad minus
key.  _process_dialog_box returns TRUE if it was successful, FALSE if an
error occurred.

HOW TO WRITE THE ACTION MACROS

The first two parameters passed to your action function are the event
type and line number.  The third parameter is either (for lists) the
text of the current list item, not counting separator characters, or
(for other field types) the full text of the field, not counting the
newline at the end.

Any event may occur in a dialog box except DIALOG_ALTER_MENU or
DIALOG_PICK_MENU.  However, the only events you normally have to worry
about are DIALOG_EXIT_FIELD, DIALOG_EXIT_LIST, and DIALOG_F10.

You can perform additional validation on the contents of a field when
the user wants to move to another field (DIALOG_EXIT_FIELD).  After the
dialog manager has performed its built-in type checking on the field,
your action macro will be called.  If your action macro returns FALSE
for any reason, the user will not be allowed to leave the field.  You
can use a String field coupled with your own validation function to
check for almost any value.  Lists are not validated, since all the
possible answers are known in advance.

When the user leaves a field or a list (DIALOG_EXIT_FIELD or
DIALOG_EXIT_LIST), keep track of the value of that input field.  There
is no way to determine the value of an input field at any other time.
We recommend you use a separate buffer, where each line represents the
contents of one input field, for dialog boxes containing more than three
or four input fields; otherwise, use string variables to store the
current values.

Treat DIALOG_F10 as a signal that the user is satisfied with his or her
changes and wishes to save them.  The current list or field will be
exited before DIALOG_F10 occurs.  When it does, process the values you
have saved in your macro.  (DIALOG_ESC and DIALOG_GREY_MINUS should just
ignore the saved values.)

EXAMPLE

This data file ("example") defines a dialog box containing two lists.

Text (1, 3)  = "Do you want case-sensitive search?"
List (1, 38) = "(Yes)No"
Text (3, 3)  = "Do you want regular expressions?"
List (3, 38) = "(Yes)No"

This macro puts up a dialog box containing the above information, and
defines two string variables which are used by the action macro.  Both
variables are set to Yes, since the data file's defaults are Yes.

(macro put_up_box
   (
      (string   case_sens
        reg_exp
      )
      (global  case_sens
           reg_exp
      )

      (= case_sens "Yes")
      (= reg_exp "Yes")
      (_process_dialog_box 10 15 60 10 "Search" "Set search parameters"
        "example" NULL "action")
   )
)

The following macro will process the dialog box, and save the current
values when F10 is pressed:

(macro action
   (
      (int    event_type
          line_no
      )
      (string  button_text)

      (get_parm 0 event_type)

      (switch event_type
     DIALOG_EXIT_LIST
        (
           (get_parm 1 line_no)
           (get_parm 2 button_text)

           (if (== line_no 1)
          (= case_sens button_text)
           ;else
          (= reg_exp button_text)
           )
        )
     DIALOG_F10
        (
           (search_case (if (== case_sens "Yes") 0 1))
           (toggle_re (if (== reg_exp "Yes") 1 0))
        )
      )
      (returns TRUE)
   )
)

A more sophisticated macro could keep the data file in a buffer and
continuously alter it to make sure the correct values of case
sensitivity and regular expressions were always displayed.

That's all you need to know to design menus and dialog boxes in the
BRIEF macro language.  Enjoy.