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ScreenShot of "translucent", layered windows

Posted on 2002-05-17
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Last Modified: 2011-09-20
ScreenShot of "translucent", layered windows

How can i get a screenshot including "translucent", layered windows like you can create with alphablending ??

I need a picture of the screen, including also the "translucent", layered windows, but i don't want to change the clipboard contents.

But creating a DC and using BitBlt() or WM_PRINT, works only with normal windows.

If possible in any way, i need a short code example.

PS:
I use Delphi 6 Enterp. and it has to work with it

Thank you for any answer.
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Question by:Farderlorn
12 Comments
 
LVL 12

Expert Comment

by:Lee_Nover
ID: 7015945
interesting (listening :)
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LVL 9

Expert Comment

by:ginsonic
ID: 7018108
You don't wish to simulate the "PrintScreen"-key press ?
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Author Comment

by:Farderlorn
ID: 7019389
I need a picture of the screen, including also the "translucent", layered windows, but i don't want to change the clipboard contents.
0
 

Expert Comment

by:iddo_levin
ID: 7019798
I don't know how to do it, but you might save the clipboard content, simulate a PrintScreen key, and then reload the clipboard data saved earlier....

just a thaught
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Author Comment

by:Farderlorn
ID: 7020202
Yes, that's possible, i thaught about it, too.
But it could slow down the machine, if you have a bigger amount of data in the clipboard, and you always have, if you use 1 or 2 office - products or special software, like we do.
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LVL 1

Expert Comment

by:mgazza
ID: 7034610
heres a code to get a picture of the screen and it don't use the clipboard

procedure TForm1.createClick(Sender: TObject);
var
  DeskTopDC: HDc;
  DeskTopCanvas: TCanvas;
  DeskTopRect: TRect;
  Bitmap: TBitmap;
begin
  DeskTopDC := GetWindowDC(GetDeskTopWindow);
  DeskTopCanvas := TCanvas.Create;
  DeskTopCanvas.Handle := DeskTopDC;
  DeskTopRect := Rect(0,0,Screen.Width,Screen.Height);
  Bitmap := TBitmap.Create;
  with Bitmap do
  begin
    Width := Screen.Width;
    Height:= Screen.Height;
    PixelFormat := pfDevice;
  end;
  Bitmap.Canvas.CopyRect(DeskTopRect,DeskTopCanvas,DeskTopRect);
  image1.Picture.Bitmap:=bitmap;
  Bitmap.Free;
  DesktopCanvas.Free;
  ReleaseDC(GetDeskTopWindow,DeskTopDC);
 

end;
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Author Comment

by:Farderlorn
ID: 7035044
This is a usually way to get a screenshot, but it does not include the "translucent", layered windows like you can create with alphablending.

You will get a screenshot, only including not "translucent" windows.

It is not possible to solve this problem with functions, you have used the last years. I could do it with a DC, like you did and then use BitBlt() with the const. CAPTUREBLT. But CAPTUREBLT does not works on my Delphi 6 Enterp., it seems not to be defined. And if i define it my self with (DWORD)0x40000000 i only get a black picture, no screenshot.

This is a hard question, and I would give 1000 points to it, but i have only 114.
0
 

Author Comment

by:Farderlorn
ID: 7038677
I got the solution from <Serhiy Perevoznyk>:


procedure ScreenShot(x : integer; y : integer; Width : integer; Height :
integer; bm : TBitMap);
const
  CAPTUREBLT = $40000000;
var
  dc: HDC; lpPal : PLOGPALETTE;
begin
{test width and height}
  if ((Width = 0) OR (Height = 0)) then exit;
  bm.Width := Width;
  bm.Height := Height;
{get the screen dc}
  dc := GetDc(0);
  if (dc = 0) then exit;
{do we have a palette device?}
  if (GetDeviceCaps(dc, RASTERCAPS) AND
  RC_PALETTE = RC_PALETTE) then
  begin
  {allocate memory for a logical palette}
  GetMem(lpPal, sizeof(TLOGPALETTE) + (255 * sizeof(TPALETTEENTRY)));
  {zero it out to be neat}
  FillChar(lpPal^, sizeof(TLOGPALETTE) + (255 * sizeof(TPALETTEENTRY)), #0);
  {fill in the palette version}
  lpPal^.palVersion := $300;
  {grab the system palette entries}
  lpPal^.palNumEntries :=
  GetSystemPaletteEntries(dc,0,256,lpPal^.palPalEntry);
  if (lpPal^.PalNumEntries <> 0) then
  begin
  {create the palette}
  bm.Palette := CreatePalette(lpPal^);
  end;
  FreeMem(lpPal, sizeof(TLOGPALETTE) + (255 * sizeof(TPALETTEENTRY)));
  end;
{copy from the screen to the bitmap}
BitBlt(bm.Canvas.Handle,0,0,Width,Height,Dc,x,y,SRCCOPY OR CAPTUREBLT);
{release the screen dc}
ReleaseDc(0, dc);
end;
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LVL 3

Expert Comment

by:SteveWaite
ID: 7802436
it's 'SRCCOPY or CAPTUREBLT' that's important

DC := GetWindowDC(0);
try
  BitBlt(BackBuf.Canvas.Handle, 0, 0, BackBuf.Width, BackBuf.Height, DC, Cx, FCy, SRCCOPY or CAPTUREBLT);
finally
  ReleaseDC(0, DC);
end;


Regards,
Steve
0
 
LVL 3

Expert Comment

by:SteveWaite
ID: 7802447
as in:
const
  CAPTUREBLT = $40000000;

above
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by:pnh73
ID: 9005901
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

PAQ with refund

Please leave any comments here within the next seven days.
 
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!
 
Paul (pnh73)
EE Cleanup Volunteer
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