VC将指定区域保存为图片.doc

1.HBITMAP CopyScreenToBitmap(LPRECT lpRect);/将屏幕指定区域存成图片HBITMAP CopyScreenToBitmap(LPRECT lpRect) /lpRect 代表选定区域HDC hScrDC, hMemDC; / 屏幕和内存设备描述表HBITMAP hBitmap,hOldBitmap; / 位图句柄int nX, nY, nX2, nY2; / 选定区域坐标int nWidth, nHeight; / 位图宽度和高度int xScrn, yScrn; / 屏幕分辨率/ 确保选定区域不为空矩形if (IsRectEmpty(lpRect)return NULL;/为屏幕创建设备描述表hScrDC = CreateDC(_T(DISPLAY), NULL, NULL, NULL);/为屏幕设备描述表创建兼容的内存设备描述表hMemDC = CreateCompatibleDC(hScrDC);/ 获得选定区域坐标nX = lpRect-left;nY = lpRect-top;nX2 = lpRect-right;nY2 = lpRect-bottom;/ 获得屏幕分辨率xScrn = GetDeviceCaps(hScrDC, HORZRES);yScrn = GetDeviceCaps(hScrDC, VERTRES);/确保选定区域是可见的if (nX 0) nX = 0;if (nY xScrn) nX2 = xScrn;if (nY2 yScrn) nY2 = yScrn;nWidth = nX2 - nX;nHeight = nY2 - nY;/ 创建一个与屏幕设备描述表兼容的位图hBitmap=CreateCompatibleBitmap(hScrDC,nWidth,nHeight);/ 把新位图选到内存设备描述表中hOldBitmap=(HBITMAP)SelectObject(hMemDC,hBitmap);/ 把屏幕设备描述表拷贝到内存设备描述表中BitBlt(hMemDC,0,0, nWidth,nHeight,hScrDC, nX, nY, SRCCOPY);/得到屏幕位图的句柄hBitmap=(HBITMAP)SelectObject(hMemDC,hOldBitmap);/清除 DeleteDC(hScrDC);DeleteDC(hMemDC);/ 返回位图句柄return hBitmap;2.HBITMAP GetSrcBit(HDC hDC,LPRECT rEct)/设置一个成员变量m_hBitmap ，在OnDraw 或者 OnPaint中调用，从内存中首先获得它，而不像第一个函数那样，临时去截屏幕，因为如果突然在截图的瞬间最小化了窗口，那么函数1截取的范围就不是我们所需要的了。HBITMAP GetSrcBit(HDC hDC,LPRECT rEct)HDC hBufDC;HBITMAP hBitmap, hBitTemp;/创建设备上下文(HDC)hBufDC = CreateCompatibleDC(hDC);/创建HBITMAPhBitmap = CreateCompatibleBitmap(hDC, abs(rEct-right - rEct-left), abs(rEct-bottom - rEct-top);hBitTemp = (HBITMAP) SelectObject(hBufDC, hBitmap);/得到位图缓冲区StretchBlt(hBufDC, 0, 0, abs(rEct-right - rEct-left), abs(rEct-bottom - rEct-top),hDC, rEct-left, rEct-top, abs(rEct-right - rEct-left), abs(rEct-bottom - rEct-top), SRCCOPY);/得到最终的位图信息hBitmap = (HBITMAP) SelectObject(hBufDC, hBitTemp);/释放内存DeleteObject(hBitTemp);:DeleteDC(hBufDC);return hBitmap;3.bool SaveBMPToFile(HBITMAP hBitmap, LPSTR lpFileName);/将图片存成bmp文件bool SaveBMPToFile(HBITMAP hBitmap, LPSTR lpFileName) /hBitmap 为刚才的屏幕位图句柄,lpFileName 为位图文件名HDC hDC; /设备描述表int iBits; /当前显示分辨率下每个像素所占字节数WORD wBitCount; /位图中每个像素所占字节数/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,dwDIBSize, dwWritten;BITMAP Bitmap; /位图属性结构BITMAPFILEHEADER bmfHdr; /位图文件头结构BITMAPINFOHEADER bi; /位图信息头结构 LPBITMAPINFOHEADER lpbi; /指向位图信息头结构HANDLE fh, hDib, hPal;HPALETTE hOldPal=NULL; /定义文件，分配内存句柄，调色板句柄/计算位图文件每个像素所占字节数hDC = CreateDC(_T(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 if (iBits = 24) wBitCount = 24;else wBitCount = 32;/计算调色板大小if (wBitCount = 8) dwPaletteSize = (1wBitCount) * sizeof(RGBQUAD);/设置位图信息头结构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.biClrUsed = 0;bi.biClrImportant = 0;dwBmBitsSize = (Bitmap.bmWidth*wBitCount+31)/32)*4*Bitmap.bmHeight; /为位图内容分配内存/*xxxxxxxx计算位图大小分解一下(解释一下上面的语句)xxxxxxxxxxxxxxxxxxxx /每个扫描行所占的字节数应该为4的整数倍，具体算法为:int biWidth = (Bitmap.bmWidth*wBitCount) / 32;if(Bitmap.bmWidth*wBitCount) % 32)biWidth+; /不是整数倍的加1biWidth *= 4;/到这里，计算得到的为每个扫描行的字节数。dwBmBitsSize = biWidth * Bitmap.bmHeight;/得到大小xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/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, hOldPal, TRUE);RealizePalette(hDC);:ReleaseDC(NULL, hDC);/创建位图文件 fh=CreateFile(LPCWSTR)lpFileName, 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; / BMdwDIBSize = 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, sizeof(BITMAPINFOHEADER)+dwPaletteSize+dwBmBitsSize , &dwWritten, NULL); /清除 GlobalUnlock(hDib);GlobalFree(hDib);CloseHandle(fh);return true;4.bool SaveBitmapToFile(HBITMAP hBitmap, LPSTR lpFileName)/该方法更为简单，代码量少，但是使用前必须使用命名空间：using namespace ATL;否则“CImage”: 未声明的标识符。该方法在存图片时，根据传入的文件名决定保存格式，例如，（m_hBitmap由函数2取得，或者自行处理取得）SaveBitmapToFile(m_hBitmap,(LPSTR)_T(C:temp.bmp);/保存为bmpSaveBitmapToFile(m_