Viewing Targa Bitmap File Format in Delphi (256-colors)

Problem/Question/Abstract:

How to view Bitmap in Targa File Format (*.tga) using Delphi ?

Answer:

This is quite simple way to answer above question: viewing Targa file format using Delphi (not compress and limited only 256 colors).

Here is the example code:

const
  FERRORMSG2 = 'Sorry, Unsupported Compressed(RLE) File Format';
  FERRORMSG3 = 'Sorry, Unsupported More Than 256 Colours File Format';

type
  TArrBuff = array[1..512] of Byte;
  TPalette_Cell = record
    b2, g2, r2: byte;
  end;
  TPal = array[0..255] of TPalette_Cell;
  TPPal = ^TPal;
  TTGA_Header = record // Targa(TGA) HEADER //
    IDLength, ColorMap, ImageType: byte;
    ClrMapSpes: array[1..5] of byte;
    XAwal, YAwal, Width, Height: SmallInt;
    BpPixel, ImageDescription: byte;
  end;

var
  pal: TPPal;
  pFile: file;
  buffer: TArrBuff;
  FTgaHeader: TTGA_Header;

procedure THPTGA.ReadImageData2Bitmap;
var
  i, j, idx: integer;
begin
  Seek(pFile, sizeof(FtgaHeader) + FtgaHeader.IDLength + 768);
  for i := FtgaHeader.Height - 1 downto FtgaHeader.YAwal do
  begin
    BlockRead(pFile, buffer, FtgaHeader.Width);
    for j := FtgaHeader.XAwal to FtgaHeader.Width - 1 do
    begin
      idx := j - FtgaHeader.XAwal + 1;
      SetPixel(Bitmap.Canvas.Handle, j, i, rgb(pal^[buffer[idx]].r2,
        pal^[buffer[idx]].g2, pal^[buffer[idx]].b2));
    end;
  end;
end;

procedure THPTGA.LoadFromFile(const FileName: string);
begin
  AssignFile(pFile, FileName);
{$I-}Reset(pFile, 1);
{$I+}
  if (IOResult = 0) then
  begin
    try
      BlockRead(pFile, FtgaHeader, SizeOf(FtgaHeader));
      // checking unsupported features here
      if (FtgaHeader.ImageType > 3) then
      begin
        MessageBox(Application.Handle, FERRORMSG2, 'TGA Viewer Error', MB_ICONHAND);
        exit;
      end;
      if (FtgaHeader.BpPixel > 8) then
      begin
        MessageBox(Application.Handle, FERRORMSG3, 'TGA Viewer Error', MB_ICONHAND);
        exit;
      end;
      GetMem(pal, 768);
      try
        Bitmap.Width := FtgaHeader.Width;
        Bitmap.Height := FtgaHeader.Height;
        // if use Color-Map and Uncompressed then read it
        if (FtgaHeader.ImageType = 1) then
          BlockRead(pFile, pal^, 768);
        ReadImageData2Bitmap;
      finally
        FreeMem(pal);
      end;
    finally
      CloseFile(pFile);
    end;
  end
  else
    MessageBox(Application.Handle, 'Error Opening File', 'TGA Viewer Error',
      MB_ICONHAND);
end;

How to try this code ?? Just call the "LoadFromFile" procedure above in your application (probably with little modification offcourse, especially about the name of mainForm that I used here [THPTGA]).

Hopefully It can help you.

For full source code and simple application that use this, you can look and download from my website: www.geocities.com/h4ryp/delphi.html.

Note: At http://www.delphi-gems.com/Graphics.php you can download the freeware Delphi unit GraphicEx.pas which makes a bunch of graphics formats available to Delphi programs, among them PCX, TIFF, TGA, etc. The formats are embedded into Delphi in the same way as Borland's jpeg unit.