- First of all you have to get the right window. As sharptooth already noted you should use
GetForegroundWindow
instead of GetDesktopWindow
. You have done it right in your improved version.
- But then you have to resize your bitmap to the actual size of the DC/Window. You haven't done this yet.
- And then make sure you don't capture some fullscreen window!
When I executed your code, my the Delphi IDE was captured and as it is on fullscreen by default, thus creating the illusion of a fullscreen screenshot. (Even though your code is mostly correct)
Considering the above steps, I was successfuly able to create a single-window screenshot with your code.
Just a hint: You can GetDC
instead of GetWindowDC
if you are only interested in the client area. (No window borders)
EDIT: Here's what I made with your code:
You should not use this code! Look at the improved version below.
procedure TForm1.Button1Click(Sender: TObject);
const
FullWindow = True; // Set to false if you only want the client area.
var
hWin: HWND;
dc: HDC;
bmp: TBitmap;
FileName: string;
r: TRect;
w: Integer;
h: Integer;
begin
form1.Hide;
sleep(500);
hWin := GetForegroundWindow;
if FullWindow then
begin
GetWindowRect(hWin,r);
dc := GetWindowDC(hWin) ;
end else
begin
Windows.GetClientRect(hWin, r);
dc := GetDC(hWin) ;
end;
w := r.Right - r.Left;
h := r.Bottom - r.Top;
bmp := TBitmap.Create;
bmp.Height := h;
bmp.Width := w;
BitBlt(bmp.Canvas.Handle, 0, 0, w, h, DC, 0, 0, SRCCOPY);
form1.Show ;
FileName := 'Screenshot_'+FormatDateTime('mm-dd-yyyy-hhnnss',now());
bmp.SaveToFile(Format('C:\Screenshots\%s.bmp', [FileName]));
ReleaseDC(hwin, DC);
bmp.Free;
end;
EDIT 2: As requested I'm adding a better version of the code, but I'm keeping the old one as a reference. You should seriously consider using this instead of your original code. It'll behave much nicer in case of errors. (Resources are cleaned up, your form will be visible again, ...)
procedure TForm1.Button1Click(Sender: TObject);
const
FullWindow = True; // Set to false if you only want the client area.
var
Win: HWND;
DC: HDC;
Bmp: TBitmap;
FileName: string;
WinRect: TRect;
Width: Integer;
Height: Integer;
begin
Form1.Hide;
try
Application.ProcessMessages; // Was Sleep(500);
Win := GetForegroundWindow;
if FullWindow then
begin
GetWindowRect(Win, WinRect);
DC := GetWindowDC(Win);
end else
begin
Windows.GetClientRect(Win, WinRect);
DC := GetDC(Win);
end;
try
Width := WinRect.Right - WinRect.Left;
Height := WinRect.Bottom - WinRect.Top;
Bmp := TBitmap.Create;
try
Bmp.Height := Height;
Bmp.Width := Width;
BitBlt(Bmp.Canvas.Handle, 0, 0, Width, Height, DC, 0, 0, SRCCOPY);
FileName := 'Screenshot_' +
FormatDateTime('mm-dd-yyyy-hhnnss', Now());
Bmp.SaveToFile(Format('C:\Screenshots\%s.bmp', [FileName]));
finally
Bmp.Free;
end;
finally
ReleaseDC(Win, DC);
end;
finally
Form1.Show;
end;
end;