Please help screenshot problums
lazarus / 39-Graphics

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BenJones · 2011-07-17 15:21

Hi all I been racking my head for over an hour with this bit of code,
I am trying to make a program to capture a screen shot of my desktop.
but my code seems to be produceing a black image., the only way it
works if I use text out and write some text on it then it saves ok but
i do not want to really do that can someone please have a look at my
code incase i done something wrong thanks.

Code: [Select]procedure TForm1.Button1Click(Sender: TObject);
var
  dc: HDC;
  img: TImage;
begin

  //Get desktop window dc
  dc := GetDc(GetDesktopWindow);
  //Create the image
  img := Timage.Create(self);
  //set image width and height
  img.Width := screen.Width;
  img.Height := screen.Height;
  //Hide form we do not want it included in our screeny
  Form1.Visible := False;
  sleep(500);
  //Take screen shot of desktop window
  BitBlt(img.Canvas.Handle, 0, 0, img.Width, img.Height, dc, 0, 0,
SRCCOPY);

  //img.Canvas.TextOut(90,0,'Screeny shot by ben');
  //save the image
  img.Picture.SaveToFile('c:\out\benny.bmp');

  //Show the main form
  Form1.Visible := True;

  //Clear up time
  ReleaseDc(GetDesktopWindow, dc);
  img.Free;

end;

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BlueIcaro · 2011-07-17 15:30

Did you tried this?:
http://wiki.lazarus.freepascal.org/Developing_with_Graphics#Taking_a_s
creenshot_of_the_screen

/BlueIcaro

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typo · 2011-07-17 15:49

Replace this:

Code: [Select]BitBlt(img.Canvas.Handle, 0, 0, img.Width, img.Height,
dc, 0, 0, SRCCOPY);
by this:

Code: [Select]img.Picture.Bitmap.LoadFromDevice(dc);

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BenJones · 2011-07-17 16:26

Thanks both it now working.