Load a bitmap and palette from a resource file

Problem/Question/Abstract:

Load a bitmap and palette from a resource file

Answer:

This routine loads a bitmap from a resource file and gets its palette and bitmap handle:


procedure LoadBitmapPalette(szTitle: PChar; var hPal: HPalette;
  var hBitmap: HBitmap);
type
  TMLogPalette = record
    palVersion: Word;
    palNumEntries: Word;
    palPalEntry: array[0..255] of TPaletteEntry;
  end;
var
  hOldPal: HPALETTE;
  pPal: TMLogPalette;
  dc: hDC; { device context for palette }
  hRes: THandle; { resource handle for bitmap }
  pBits: PBITMAPINFOHEADER; { pointer to bitmapinfoheader
  in resource }
  pRgb: ^TRGBQUAD; { Zeiger auf DIB-Palettendaten }
  i: integer;
  Data: PChar;
begin
  hRes := FindResource(hInstance, szTitle, RT_BITMAP);
  if hRes <> 0 then
    hRes := LoadResource(hInstance, hRes);

  if hRes <> 0 then
  begin
    pBits := PBITMAPINFOHEADER(LockResource(hRes));

    { so: having 16 colors, we do not need a palette
      (LoadBitmap is allright)
      > 256 colors: no palette is needed ("hi-/direct/true color")  }

    if (pBits^.biBitCount <= 8) and { only for <= 256 color bitmaps }
    (pBits^.biSize =
      sizeof(TBITMAPINFOHEADER)) { only Windows-bitmaps, not OS/2 } then
    begin
      pRgb := pointer(pBits);
      inc(PChar(pRgb), pBits^.biSize);

      pPal.palNumEntries := 1 shl pBits^.biBitCount;
      pPal.palVersion := $300;

      for i := 0 to pPal.palNumEntries - 1 do
      begin
        pPal.palPalEntry[i].peRed := pRgb^.rgbRed;
        pPal.palPalEntry[i].peGreen := pRgb^.rgbGreen;
        pPal.palPalEntry[i].peBlue := pRgb^.rgbBlue;
        pPal.palPalEntry[i].peFlags := 0 {PC_NOCOLLAPSE};
        inc(PChar(pRgb), 4);
      end;

      hPal := CreatePalette(PLogPalette(@pPal)^);

      DC := GetDC(0);

      hOldPal := SelectPalette(DC, hPal, false);
      RealizePalette(DC);

      with pBits^ do
      begin
        biClrImportant := 0;
        biClrUsed := 0;
      end;

      Data := pointer(pBits);
      inc(Data, pBits^.biSize + pPal.palNumEntries * sizeof(TRGBQUAD));
      hBitmap := CreateDIBitmap(DC, pBits^, CBM_INIT,
        Data, PBitmapInfo(pBits)^,
        dib_RGB_Colors);

      SelectPalette(DC, hOldPal, FALSE);

      ReleaseDC(0, DC);
    end;

    UnlockResource(hRes);
  end
  else
    hBitmap := LoadBitmap(hInstance, szTitle);
end;