Author: William Gerbert 

Screen capture into a BMP file

Answer:

This little routine grabs the whole screen, assigns it temporary to a bitmap and 
stores it into file "sample.bmp".

A potential problem:
If your system is set up to HiColor (32k colors = 15 bits per pixel), some programs 
will not be able to read the result since they are only capable to read 16 bits/ 
pixel.


1   procedure TForm1.Button1Click(Sender: TObject);
2   var
3     DeskTopDC: HDc;
4     DeskTopCanvas: TCanvas;
5     DeskTopRect: TRect;
6     Bitmap: TBitmap;
7   begin
8     DeskTopDC := GetWindowDC(GetDeskTopWindow);
9     DeskTopCanvas := TCanvas.Create;
10    DeskTopCanvas.Handle := DeskTopDC;
11    DeskTopRect := Rect(0, 0, Screen.Width, Screen.Height);
12    Bitmap := TBitmap.Create;
13    with Bitmap do
14    begin
15      Width := Screen.Width;
16      Height := Screen.Height;
17      PixelFormat := pfDevice;
18    end;
19    Bitmap.Canvas.CopyRect(DeskTopRect, DeskTopCanvas, DeskTopRect);
20    Bitmap.SaveToFile('c:\temp\sample.bmp');
21    Bitmap.Free;
22    DesktopCanvas.Free;
23    ReleaseDC(GetDeskTopWindow, DeskTopDC);
24  end;