Capture screen

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3 total messages Started by FrankW Wed, 07 May 2003 06:30

#16557

Author: FrankW
Date: Wed, 07 May 2003 06:30

75 lines
2635 bytes

Hi,

  Can anybody offer tips on how to capture a screen image? I came across a
Delphi code 'ScreenShot', but have problem converting it to C++, anybody can
help?

Thanks,


procedure ScreenShot(hWindow: HWND; bm: TBitmap);
var
  Left, Top, Width, Height: Word;
  R: TRect;
  dc: HDC;
  lpPal: PLOGPALETTE;
begin
  {Check if valid window handle}
  if not IsWindow(hWindow) then Exit;
  {Retrieves the rectangular coordinates of the specified window}
  GetWindowRect(hWindow, R);
  Left := R.Left;
  Top := R.Top;
  Width := R.Right - R.Left;
  Height := R.Bottom - R.Top;

  bm.Width := Width;
  bm.Height := Height;
  {get the screen dc}
  dc := GetDc(0);
  if (dc = 0) then
  begin
    Exit;
  end;
  {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,
    Left,
    Top,
    SRCCOPY);
  {release the screen dc}
  ReleaseDc(0, dc);
end;

Re: Capture screen

#16558

Author: Remy Lebeau (TeamB)
Date: Wed, 07 May 2003 06:57

68 lines
2820 bytes

"FrankW" <nospam@nospam.com> wrote in message
news:3eb8a7f7@newsgroups.borland.com...

> I came across a Delphi code 'ScreenShot', but have
> problem converting it to C++

It would help if you would specify the actual problems you are having with
it.

Here is a translation for you:

    void __fastcall ScreenShot(HWND hWindow, Graphics:::TBitmap *bm)
    {
        LONG Left, Top, Width, Height;
        RECT R;
        HDC dc;
        PLOGPALETTE lpPal;

        // Check if valid window handle
        if( !IsWindow(hWindow) ) return;

        // Retrieves the rectangular coordinates of the specified window
        GetWindowRect(hWindow, &R);
        Left = R.left;
        Top = R.top;
        Width = (R.right - R.left);
        Height = (R.bottom - R.top);

        bm->Width = Width;
        bm->Height = Height;

        // get the screen dc
        dc = GetDC(0);
        if( dc == NULL ) return;

        // do we have a palette device?
        if( (::GetDeviceCaps(dc, RASTERCAPS) & RC_PALETTE) == RC_PALETTE )
        {
            // allocate memory for a logical palette
            lpPal = (PLOGPALETTE) ::GlobalAlloc(GPTR, sizeof(LOGPALETTE) +
(255 * sizeof(PALETTEENTRY)));

            // fill in the palette version
            lpPal->palVersion = 0x300;

            // grab the system palette entries
            lpPal->palNumEntries = ::GetSystemPaletteEntries(dc, 0, 256,
lpPal->palPalEntry);
            if( lpPal->palNumEntries != 0 )
            {
                // create the palette
                bm->Palette = ::CreatePalette(lpPal);
            }

            ::GlobalFree((HGLOBAL)lpPal);
        }

        // copy from the screen to the bitmap
        ::BitBlt(bm->Canvas->Handle, 0, 0, Width, Height, dc, Left, Top,
SRCCOPY);

        // release the screen dc
        ReleaseDC(0, dc);
    }


Gambit

Re: Capture screen

#16574

Author: FrankW
Date: Wed, 07 May 2003 15:31

19 lines
1471 bytes

Hi,

Thanks for the excellent translation, it works !

Frank

"Remy Lebeau (TeamB)" <gambit47@yahoo.com> wrote in message
news:3eb8adfe$1@newsgroups.borland.com...
>
> "FrankW" <nospam@nospam.com> wrote in message
> news:3eb8a7f7@newsgroups.borland.com...
>
> > I came across a Delphi code 'ScreenShot', but have
> > problem converting it to C++
>
> It would help if you would specify the actual problems you are having with
> it.
>
> Here is a translation for you:

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