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主题:用DirectX实现屏幕截图txt
发信人: laical()
整理人: wenbobo(2002-12-06 23:15:09), 站内信件
                          用DirectX实现屏幕截图txt
在DirectDraw的非独占模式中,主表面即为当前屏幕。你可以直接Lock住主表面
,从而取得主表面图象数据。但如果你要对大量的数据进行直接的操作,最好还
是先在SystemRAM中建一个和主表面一样大小的后台表面。用BltFast把主表面Co
py一份到后台表面,然后锁住后台表面,再进行操作,这是因为CPU对显示RAM的
操作是什分慢的。
实现步骤如下:
1. 初始化DirectDraw
2. 得到图象数据的起始位置指针
3. 图象数据的转换

1. 初始化DirectDraw
你可以响应WM_CREATE消息,并在OnCreate中初始化DirectDraw
void CMainFrame::InitDirectX()
{
        //创建DirectDraw
        if (FAILED( DirectDrawCreate(NULL,&ddraw1,NULL)))
        {
                TRACE("Couldn't create DirectDraw object.\n");
        }
        if (FAILED( ddraw1->QueryInterface(IID_IDirectDraw2,(LPVOID *)
&ddraw2)))
        {
                TRACE("Couldn't query the interface.\n");
        }
        if (ddraw2)
        {
                ddraw2->SetCooperativeLevel(GetSafeHwnd(),DDSCL_NORMAL
);
        }
        if (ddraw1)
        {
                ddraw1->Release();
                ddraw1=NULL;
        }
        //创建主表面
        HRESULT r;
        DDSURFACEDESC desc;
        
        desc.dwSize = sizeof(desc);
        desc.dwFlags = DDSD_CAPS;
        desc.ddsCaps.dwCaps = DDSCAPS_PRIMARYSURFACE;
        r=ddraw2->CreateSurface(&desc, &primsurf, 0);
        if(r!=DD_OK)
        {
                AfxMessageBox("Create DirectX Surface failed\n ");
                PostMessage(WM_CLOSE);
        }
        r=ddraw2->CreateClipper(0, &clipper, 0);
        if(r!=DD_OK)
        {
                AfxMessageBox("CreateClipper() fialed\n ");
                PostMessage(WM_CLOSE);
        }
        r=clipper->SetHWnd(0,GetSafeHwnd());
        if(r!=DD_OK)
        {
                AfxMessageBox("SetHWnd() failed\n ");
                PostMessage(WM_CLOSE);
        }
        r=primsurf->SetClipper(clipper);
        if(r!=DD_OK)
        {
                AfxMessageBox("SetClipper() fialed\n ");
                PostMessage(WM_CLOSE);
        }
        //创建后台表面
        ZeroMemory(&desc,sizeof(desc));
        desc.dwSize=sizeof(desc);
        desc.dwFlags=DDSD_WIDTH|DDSD_HEIGHT|DDSD_CAPS;
        desc.dwWidth=::GetSystemMetrics(SM_CXSCREEN);
        desc.dwHeight=::GetSystemMetrics(SM_CYSCREEN);
        desc.ddsCaps.dwCaps = DDSCAPS_SYSTEMMEMORY | DDSCAPS_OFFSCREEN
PLAIN;

        r=ddraw2->CreateSurface(&desc,&backsurf,0);
        //收集图象参数
        DDSURFACEDESC ddsd;

        ZeroMemory(&ddsd, sizeof(ddsd));
        ddsd.dwSize=sizeof(ddsd);
        backsurf->GetSurfaceDesc(&ddsd);
        BitCount = ddsd.ddpfPixelFormat.dwRGBBitCount;
        lPitch = ddsd.lPitch;
        dwWidth = ddsd.dwWidth;
        dwHeight = ddsd.dwHeight;
        dwRBitMask = ddsd.ddpfPixelFormat.dwRBitMask;
        dwGBitMask = ddsd.ddpfPixelFormat.dwGBitMask;
        dwBBitMask = ddsd.ddpfPixelFormat.dwBBitMask;
        //确定16Bit色时的修正(16Bit色时有两种显示格式565和555)
        RMove = 8;//这里先假定为565格式
        GMove = 3;
        BMove = 3;
        if(BitCount==16)
        {
                  if(dwGBitMask==992)
                  {   //555格式
                           RMove = 7;
                           GMove = 2;
                  }
                  if(dwGBitMask==1984)//555格式
                           BMove = 2;
         }
}

2. 得到图象数据的起始位置指针
         DDSURFACEDESC ddsd;

         ZeroMemory(&ddsd,sizeof(ddsd));
         ddsd.dwSize=sizeof(ddsd);

         if FAILED(backsurf->Lock(NULL, &ddsd, DDLOCK_WAIT , NULL))
                 TRACE("backsurf->lock failed\n");
// ddsd.lpSurface即为图象数据的指针

3. 图象数据的转换
DirectX是不支持图象格式转换的(DirectX7.0就不知到了,135MB要Download实
在太恐怖了),如果你想得到的是24Bit的图象,而现在的显示模式为16Bit色,
你就要自己动手了。(看过下面的代码后你可能会发现,经转换后图象是倒置的
,这是我为了方便对数进行压缩而进行的,你可以改变其for循环语句把图象换过
来。)
void CMainFrame:: Conversion()
{
         int x,y;
         DDSURFACEDESC ddsd;

         ZeroMemory(&ddsd,sizeof(ddsd));
         ddsd.dwSize=sizeof(ddsd);

         if FAILED(backsurf->Lock(NULL, &ddsd, DDLOCK_WAIT , NULL))
                   TRACE("backsurf->lock failed\n");

         BYTE *scr=new BYTE[3*ddsd.dwHeight*ddsd.dwWidth];
         BYTE *scrt=scr;

         //Surface to RGB
         switch(BitCount)
         {
                   case 8:
                   {
                   //TRACE("8 Bit\n");
                   BYTE *tem=(BYTE *)ddsd.lpSurface;
                   PALETTEENTRY entry[256];

                   HDC hScrDC=CreateDC("DISPLAY", NULL, NULL, NULL);
                   ::GetSystemPaletteEntries(hScrDC,0,256, entry);

                            for(y=(int)dwHeight-1;y>=0;y--)
                            {
                                      for(x=0;x<(int)dwWidth;x++)
{
*scrt++=entry[tem[x+lP
itch*y]].peRed;
*scrt++=entry[tem[x+lP
itch*y]].peGreen;
*scrt++=entry[tem[x+lP
itch*y]].peBlue;
}
}
break;
}
case 16:
{
//TRACE("16 Bit\n");
WORD *tem=(WORD *)ddsd.lpSurface;
WORD color;
for(y=(int)dwHeight-1;y>=0;y--)
                           {
                                   for(x=0;x<(int)lPitch/2;x++)
{
color=tem[x+lPitch/2*y];
*scrt++=(BYTE)((color&dwRBi
tMask)>>RMove);
                                           *scrt++=(BYTE)((color&dwGBi
tMask)>>GMove);
                                           *scrt++=(BYTE)(((color&dwBB
itMask))<<BMove);
}
}
break;
}
case 24:
{
//TRACE("24 Bit\n");
BYTE *tem=(BYTE *)ddsd.lpSurface;
for(y=(int)dwHeight-1;y>=0;y--)
                            {
                                     for(x=0;x<(int)dwWidth*3;x+=3)
{
*scrt++=tem[x+2+y*lPitch];

*scrt++=tem[x+1+y*lPitch];

*scrt++=tem[x+y*lPitch];
}
}
break;
}
case 32:
{
AfxMessageBox("目前还不支持32Bit色\n请调整为
24Bit色或16Bit色");
backsurf->Unlock(NULL);
                           delete scr;
                           PostMessage(WM_CLOSE);
                           break;
                   }
         }
         backsurf->Unlock(NULL);
//在里进行你的数据处理

         delete scr;//数据处理完毕释放内存
}
请保留以下内容
E-mail: [email protected]
Home page:  http://laical.year.net or http://www.gz168.com/~laical
1999年10月12日


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