Title: How to Capture the Screen Shot of the Active Window from Delphi Code
Need to take a screen shoot from code? No problem ... here's how to capture the Windows desktop or the Active Window's image into a TBitmap object - and display it inside a TImage control.
Drop a TImage on a Form and use the following code:
procedure ScreenShot(activeWindow: bool; destBitmap : TBitmap) ;
var
w,h : integer;
DC : HDC;
hWin : Cardinal;
r : TRect;
begin
if activeWindow then
begin
hWin := GetForegroundWindow;
dc := GetWindowDC(hWin) ;
GetWindowRect(hWin,r) ;
w := r.Right - r.Left;
h := r.Bottom - r.Top;
end
else
begin
hWin := GetDesktopWindow;
dc := GetDC(hWin) ;
w := GetDeviceCaps (DC, HORZRES) ;
h := GetDeviceCaps (DC, VERTRES) ;
end;
try
destBitmap.Width := w;
destBitmap.Height := h;
BitBlt(destBitmap.Canvas.Handle,
0,
0,
destBitmap.Width,
destBitmap.Height,
DC,
0,
0,
SRCCOPY) ;
finally
ReleaseDC(hWin, DC) ;
end;
end;
Usage:
var
b:TBitmap;
begin
b := TBitmap.Create;
try
ScreenShot(TRUE, b) ;
Image1.Picture.Bitmap.Assign(b) ;
finally
b.FreeImage;
FreeAndNil(b) ;
end;
Note: the first parameter in the TakeShot is a bool value indicating whether to take a screen shot of the active window or to grab what's currently on the desktop window.
For an example application, download the source code.