Subject: Graphics programming primer

71. *****
 Q: How do I get started with graphics programming?

 A:
  (* This simple test shows the rudiments of getting started with Turbo
     Pascal graphics programming *)
  uses Crt, Graph;
  var grDriver : integer;
      grMode   : integer;
      ErrCode  : integer;
      i, j     : integer;
      xm, ym   : integer;
  const CharSize : integer = 3;
  begin
    { Request graphics driver autodetection }
    grDriver := Detect;
    { Initialize graphics system and put hardware into graphics mode }
    { The relevant .bgi driver is needed in the current directory
      for example egavga.bgi }
    InitGraph (grDriver, grMode, ' ');
    { Return an error code for the previous graphic operation }
    ErrCode := GraphResult;
    { Test for initialialization success }
    if ErrCode <> grOk then begin
      Writeln ('Graphics error:', GraphErrorMsg(ErrCode)); halt; end;
    { Clear the output device and home the current pointer }
    ClearDevice;
    {}
    { Use your own coordinates }
    xm := Round (GetMaxX / 100.0);
    ym := Round (GetMaxY / 100.0);
    {}
    { Set the current line width and style, optional }
    SetLineStyle (SolidLn, 0, ThickWidth);
    { Set the drawing color }
    SetColor (Yellow);
    { Draw a line }
    Line (70*xm, 50*ym, 90*xm, 80*ym);
    {}
    { Drawing bars }
    { Set the fill pattern and color }
    SetFillStyle (SolidFill, Red);
    Bar (0, 0, 25*xm, 25*ym);
    {}
    SetColor (Magenta);
    SetFillStyle (SolidFill, Blue);
    Bar3D (30*xm, 20*ym, 50*xm, 60*ym, 8*xm, TopOn);
    {}
    { Writing text in the graphics mode }
    { Set the drawing color }
    SetColor (LightCyan);
    { Set the current background color }
    SetBkColor (Black);
    { Set style for text output in graphics mode }
    SetTextStyle(DefaultFont, HorizDir, CharSize);
    OutTextXY (0, 80*ym, 'Press any key');
    {}
    repeat until KeyPressed;
    {}
    { Restore the original screen mode before graphics was initialized }
    RestoreCrtMode;
    writeln ('That''s all folks');
    { Shut down the graphics system }
    CloseGraph;
  end.
For an example what you can do with graphics, see
 111673 Oct 8 1993 ftp://garbo.uwasa.fi/pc/ts/tsdemo16.zip
 tsdemo16.zip Assorted graphics demonstrations of functions etc
(or whatever is the current version).
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