delphi 屏幕截图完美解决方案


可以截取layered窗口(包括透明窗口)的代码:

procedure CaptureScreen(AFileName: string);
const
 CAPTUREBLT = $40000000;
var
 hdcScreen: HDC;
 hdcCompatible: HDC;
 bmp: TBitmap;
 hbmScreen: HBITMAP;
begin
 hdcScreen := CreateDC('DISPLAY', nil, nil, nil);
 hdcCompatible := CreateCompatibleDC(hdcScreen);
 hbmScreen := CreateCompatibleBitmap(hdcScreen,
 GetDeviceCaps(hdcScreen, HORZRES),
 GetDeviceCaps(hdcScreen, VERTRES));
 SelectObject(hdcCompatible, hbmScreen);
 bmp := TBitmap.Create;
 bmp.Handle := hbmScreen;
 BitBlt(hdcCompatible,
 0, 0,
 bmp.Width, bmp.Height,
 hdcScreen,
 0, 0,
 SRCCOPY or CAPTUREBLT);

 bmp.SaveToFile(AFileName);
 bmp.Free;
 DeleteDC(hdcScreen);
 DeleteDC(hdcCompatible);
end;


DX Primary Surface截图代码!包含DX8与DX9两个版本

...
interface

{$DEFINE D3D9}

uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls, Buttons,
{$IFDEF D3D9}
 // D3DX9, // use D3D to save surface
 Direct3D9
{$ELSE}
 // D3DX8, // use D3D to save surface
 Direct3D8
{$ENDIF};
...
procedure TForm1.BitBtn1Click(Sender: TObject);
// Capture screen through D3D.
var
 BitsPerPixel: Byte;
 {$IFDEF D3D9}
 pD3D: IDirect3D9;
 pSurface: IDirect3DSurface9;
 g_pD3DDevice: IDirect3DDevice9;
 {$ELSE}
 pD3D: IDirect3D8;
 pSurface: IDirect3DSurface8;
 g_pD3DDevice: IDirect3DDevice8;
 {$ENDIF}
 D3DPP: TD3DPresentParameters;
 ARect: TRect;
 LockedRect: TD3DLockedRect;
 BMP: TBitmap;
 i, p: Integer;
begin
 BitsPerPixel := GetDeviceCaps(Canvas.Handle, BITSPIXEL);
 FillChar(d3dpp, SizeOf(d3dpp), 0);
 D3DPP.Windowed := True;
 D3DPP.Flags := D3DPRESENTFLAG_LOCKABLE_BACKBUFFER;
 D3DPP.SwapEffect := D3DSWAPEFFECT_DISCARD;
 D3DPP.BackBufferWidth := Screen.Width;
 D3DPP.BackBufferHeight := Screen.Height;
 D3DPP.BackBufferFormat := D3DFMT_X8R8G8B8;
 {$IFDEF D3D9}
 pD3D := Direct3DCreate9(D3D_SDK_VERSION);
 pD3D.CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, GetDesktopWindow,
 D3DCreate_SOFTWARE_VERTEXPROCESSING, @D3DPP, g_pD3DDevice);
 g_pD3DDevice.CreateOffscreenPlainSurface(Screen.Width, Screen.Height, D3DFMT_A8R8G8B8, D3DPOOL_SCRATCH, pSurface, nil);
 g_pD3DDevice.GetFrontBufferData(0, pSurface);
 {$ELSE}
 pD3D := Direct3DCreate8(D3D_SDK_VERSION);
 pD3D.CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_REF, GetDesktopWindow,
 D3DCreate_SOFTWARE_VERTEXPROCESSING, D3DPP, g_pD3DDevice);
 g_pD3DDevice.CreateImageSurface(Screen.Width, Screen.Height, D3DFMT_A8R8G8B8, pSurface);
 g_pD3DDevice.GetFrontBuffer(pSurface);
 {$ENDIF}
 // use D3D to save surface. Notes: D3DX%ab.dll is required!
//  D3DXSaveSurfaceToFile('Desktop.bmp', D3DXIFF_BMP, pSurface, nil,  nil);
 // use Bitmap to save surface
 ARect := Screen.DesktopRect;
 pSurface.LockRect(LockedRect, @ARect, D3DLOCK_NO_DIRTY_Update or D3DLOCK_NOSYSLOCK or D3DLOCK_READONLY);
 BMP := TBitmap.Create;
 BMP.Width := Screen.Width;
 BMP.Height := Screen.Height;
 BMP.PixelFormat := pf32bit;
 p := Cardinal(LockedRect.pBits);
 for i := 0 to Screen.Height - 1 do
 begin
 CopyMemory(BMP.ScanLine[i], Ptr(p), Screen.Width * BitsPerPixel div 8);
 p := p + LockedRect.Pitch;
 end;
 BMP.SaveToFile('Desktop.bmp');
 BMP.Free;
 pSurface.UnlockRect;
end;

以上DX截图代码,不需要额外的DLL支持,有DirectX 9.0即可

采用上面的2个方案以外,还有些视频播放器的图像不能截取吧,呵呵

怎么解决呢?

它们使用的,是称为"覆盖表面"的技术,截取覆盖表面,需要Hook的手段才行

思路是:
通过Hook DDraw的DirectDrawCreate(RealOne用)同DirectDrawCreateEx(WMP用)
获得IDirectDraw(7)
再COM Hook CreateSurface,注意RealOne使用的是通过QueryInterface获得IDirectDraw2
WMP则是IDirectDraw7

Hook了CreateSurface后,就能获得OverlaySurface

所以必须在软件使用前,启动全局Hook,才有效


在需要截图的时候
Lock Overlay Surface,读取数据,马上Unlock,以免损失性能

解码读出来的数据,即可,但是由于获得的数据是显卡硬件VRAM的数据,一般是YUY2,YV12等格式,需要转换为RGB格式

例如,在我的GF6600上,RealOne(RMVB)用的是YUY2,而WMP(AVI)用的是YV12,还与当前播放的文件格式有关


提供主表面截图源码和覆盖表面截图的测试程序
现在支持YV12,NV12,YUY2,UUVY 4个格式

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