Unit GLWinMessages

Description

Various dialog boxes (asking user for confirmation, question, simple text input etc.) drawn by OpenGL inside TGLWindow window.

Features:

• MessageInputXxx ask user to enter some text.

• The dialog boxes have vertical scroll bar, displayed when needed. So don't worry about displaying long text. Scroll bar can be operated with keys (up/down, ctrl+up/down, page up/down, home/end) and mouse (drag the scroll bar, or click below/above it).

• Long text lines are automatically broken, so don't worry about displaying text with long lines.

  We will try to break text only at whitespace. Note that our "line breaking" works correctly for all fonts (see TGLWinMessagesTheme.Font), even if font is not fixed-character-width font.

  If you pass a text as a single string parameter, then our "line breaking" works correctly even for text that already contains newline characters (they are correctly recognized as forcing line break).

  If you pass a text as an "array of string" or TStringList, it's expected that strings inside don't contain newline characters anymore. It's undefined what will happen (i.e. whether they will be correctly broken) otherwise. Of course, TStringList contents used to pass text to MessageXxx will never be modified in any way.

• User is allowed to resize the window while MessageXxx works. (As long as TGLWindow.ResizeAllowed = raAllowed, of course.) Long lines are automatically broken taking into account current window width.

• You can configure dialog boxes look using GLWinMessagesTheme variable. For example, you can make the dialog box background partially transparent (by real transparency or by OpenGL stipple pattern).

Call MessageXxx functions only when glwin.Closed = false. Note that MessageXxx will do glwin.MakeCurrent (probably more than once). Calling MessageXxx requires one free place on OpenGL attrib stack.

Notes about implementation:

• It's implemented using GLWinModes approach. Which means that when you call some MessageXxx procedure, it temporarily switches all TGLWindow callbacks (OnDraw, OnKeyDown, OnMouseDown, OnIdle etc.) for it's own. So you can be sure that e.g. no glwin callbacks that you registered in your own programs/units will be called while MessageXxx works. When message box ends (e.g. for simple MessageOk, this happens when user will accept it by Enter key or clicking OK), original callbacks are restored.

  This way you can call MessageXxx procedures in virtually any place of your program, and things will magically work — inside MessageXxx we wait until user answers the dialog box.

  This also means that this units is only able to work when GLWindow unit implements Glwm.ProcessMessage routine. For now this means that GLWindow unit must not work on top of glut (GLWINDOW_GLUT must not be defined while compiling GLWindow), other GLWindow implementations are OK.

• Be careful if you use Glwm callbacks, OnIdle / OnTimer. They are tied to GL window manager, Glwn, not to any particular window, and so they continue to work even while we're inside MessageXxx procedure.

  While this can be useful, you should be careful when implementing these Glwm callbacks. When they access some TGLWindow instance, it may be currently inside MessageXxx call.

• The whole MessageXxx is supposed to start and end on an open TGLWindow instance, so no Init or Close methods of TGLWindow will be called during MessageXxx.

  OnCloseQuery during MessageXxx calls prevents user from exiting the program, actually OnCloseQuery callback is simple no-op. Which means, among other things, that you can safely use MessageXxx inside your own OnCloseQuery, for example you can implement you OnCloseQuery like

    if MessageYesNo('Are you sure ?') then
      Glwin.Close;
  

uses

• Classes
• GLWindow
• KambiGLUtils
• GL
• GLU
• GLExt
• KambiUtils
• OpenGLFonts
• KambiStringUtils
• VectorMath

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