vc++/mfc截图保存和显示

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## 1. 实现截图程序的api接口 ##

HBITMAP CaptureScreen(LPRECT lpRect)//lpRect为NULL时表示全屏幕截图
{HDC      hdc, hdcMem ;HBITMAP  hemfCopy ;HWND     hwndScr ;int      dstcx, dstcy ;if(lpRect){dstcx = lpRect->right - lpRect->left ;dstcy = lpRect->bottom - lpRect->top ;}else{dstcx = GetSystemMetrics(SM_CXSCREEN) ;dstcy = GetSystemMetrics(SM_CYSCREEN) ;}if (LockWindowUpdate(hwndScr = GetDesktopWindow ())){hdc  = GetDCEx (hwndScr, NULL, DCX_CACHE | DCX_LOCKWINDOWUPDATE) ;hdcMem = CreateCompatibleDC (hdc) ;if(NULL==hdcMem){ReleaseDC (hwndScr, hdc) ;LockWindowUpdate (NULL) ;return NULL;}hemfCopy = CreateCompatibleBitmap (hdc, abs(dstcx), abs(dstcy)) ;if(NULL==hemfCopy){DeleteDC (hdcMem) ;ReleaseDC (hwndScr, hdc) ;LockWindowUpdate (NULL) ;return NULL;}SelectObject (hdcMem, hemfCopy) ;if(lpRect)StretchBlt (hdcMem, 0, 0, abs(dstcx), abs(dstcy), hdc, lpRect->left, lpRect->top, dstcx, dstcy, SRCCOPY|CAPTUREBLT) ;elseBitBlt (hdcMem, 0, 0, dstcx, dstcy, hdc, 0, 0, SRCCOPY|CAPTUREBLT) ;DeleteDC (hdcMem) ;ReleaseDC (hwndScr, hdc) ;LockWindowUpdate (NULL) ;return hemfCopy;}return NULL;
}
``

2、保存图片

BOOL SaveBmp(HBITMAP hBitmap,CString FileName)         
{         HDC     hDC;         //当前分辨率下每象素所占字节数         int     iBits;         //位图中每象素所占字节数         WORD     wBitCount;         //定义调色板大小，     位图中像素字节大小     ，位图文件大小     ，     写入文件字节数             DWORD     dwPaletteSize=0,   dwBmBitsSize=0,   dwDIBSize=0,   dwWritten=0;             //位图属性结构             BITMAP     Bitmap;                 //位图文件头结构         BITMAPFILEHEADER     bmfHdr;                 //位图信息头结构             BITMAPINFOHEADER     bi;                 //指向位图信息头结构                 LPBITMAPINFOHEADER     lpbi;                 //定义文件，分配内存句柄，调色板句柄             HANDLE     fh,   hDib,   hPal,hOldPal=NULL;             //计算位图文件每个像素所占字节数             hDC  = CreateDC(TEXT("DISPLAY"),NULL,   NULL,   NULL);         iBits  = GetDeviceCaps(hDC,   BITSPIXEL)     *     GetDeviceCaps(hDC,   PLANES);             DeleteDC(hDC);             if(iBits <=  1)                                                   wBitCount = 1;             else  if(iBits <=  4)                               wBitCount  = 4;             else if(iBits <=  8)                               wBitCount  = 8;             else                                                                                                                               wBitCount  = 24;             GetObject(hBitmap,   sizeof(Bitmap),   (LPSTR)&Bitmap);         bi.biSize= sizeof(BITMAPINFOHEADER);         bi.biWidth = Bitmap.bmWidth;         bi.biHeight =  Bitmap.bmHeight;         bi.biPlanes =  1;         bi.biBitCount = wBitCount;         bi.biCompression= BI_RGB;         bi.biSizeImage=0;         bi.biXPelsPerMeter = 0;         bi.biYPelsPerMeter = 0;         bi.biClrImportant = 0;         bi.biClrUsed =  0;         dwBmBitsSize  = ((Bitmap.bmWidth *wBitCount+31) / 32)*4* Bitmap.bmHeight;         //为位图内容分配内存             hDib  = GlobalAlloc(GHND,dwBmBitsSize+dwPaletteSize+sizeof(BITMAPINFOHEADER));             lpbi  = (LPBITMAPINFOHEADER)GlobalLock(hDib);             *lpbi  = bi;             //     处理调色板                 hPal  = GetStockObject(DEFAULT_PALETTE);             if (hPal)             {             hDC  = ::GetDC(NULL);             hOldPal = ::SelectPalette(hDC,(HPALETTE)hPal, FALSE);             RealizePalette(hDC);             }         //     获取该调色板下新的像素值             GetDIBits(hDC,hBitmap, 0,(UINT)Bitmap.bmHeight,  (LPSTR)lpbi+ sizeof(BITMAPINFOHEADER)+dwPaletteSize,   (BITMAPINFO *)lpbi, DIB_RGB_COLORS);             //恢复调色板                 if (hOldPal)             {             ::SelectPalette(hDC,   (HPALETTE)hOldPal,   TRUE);             RealizePalette(hDC);             ::ReleaseDC(NULL,   hDC);             }             //创建位图文件                 fh  = CreateFile(FileName,   GENERIC_WRITE,0,   NULL,   CREATE_ALWAYS,           FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN,   NULL);             if (fh     ==  INVALID_HANDLE_VALUE)         return     FALSE;             //     设置位图文件头             bmfHdr.bfType  = 0x4D42;     //     "BM"             dwDIBSize  = sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+dwPaletteSize+dwBmBitsSize;                 bmfHdr.bfSize  = dwDIBSize;             bmfHdr.bfReserved1  = 0;             bmfHdr.bfReserved2  = 0;             bmfHdr.bfOffBits  = (DWORD)sizeof(BITMAPFILEHEADER)+(DWORD)sizeof(BITMAPINFOHEADER)+dwPaletteSize;             //     写入位图文件头             WriteFile(fh,   (LPSTR)&bmfHdr,   sizeof(BITMAPFILEHEADER),   &dwWritten,   NULL);             //     写入位图文件其余内容             WriteFile(fh,   (LPSTR)lpbi,   dwDIBSize,   &dwWritten,   NULL);             //清除                 GlobalUnlock(hDib);             GlobalFree(hDib);             CloseHandle(fh);             return     TRUE;         
}

3、在dialog中显示

在onPaint中显示，其中mfc设计到 BITMAP hbitmap和cbitmap之间的关系
在mfc程序中，使用cbitmap

        CPaintDC dc(this);CDC dcimage;CBitmap bkg;bkg.Attach(g_bitmap);BITMAP bkginfo;bkg.GetBitmap(&bkginfo);//获取位图信息dcimage.CreateCompatibleDC(&dc);dcimage.SelectObject(&bkg);//      dc.BitBlt(0,0,nWidth,nHeight,&dcimage,0,0,SRCCOPY);dc.StretchBlt(0,0,nWidth,nHeight,&dcimage,0,0,bkginfo.bmWidth,bkginfo.bmHeight,SRCCOPY);