新建一个MFC基于对话框的应用程序，在界面上放一个Button，为其实现点击事件，代码如下：

void CScreenShotDlg::OnBtnScreenshot()
{RECT rect = {0, 0, 1900, 1000};HBITMAP hbmp = CopyScreenToBitmap(&rect);SaveBitmapToFile(hbmp, "a.bmp");MessageBox("Save bmp file Successful");
}

被调用的这两个函数实现如下：

HBITMAP CopyScreenToBitmap(LPRECT lpRect)
{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if (IsRectEmpty(lpRect))return NULL;hScrDC = CreateDC("DISPLAY", NULL, NULL, NULL);		// 为屏幕创建设备描述表hMemDC = CreateCompatibleDC(hScrDC);				// 为屏幕设备描述表创建兼容的内存设备描述表nX = lpRect->left;nY = lpRect->top;nX2 = lpRect->right;nY2 = lpRect->bottom;xScrn = GetDeviceCaps(hScrDC, HORZRES);	// 获得屏幕水平分辨率yScrn = GetDeviceCaps(hScrDC, VERTRES);if (nX < 0)nX = 0;if (nY < 0)nY = 0;if (nX2 > xScrn)nX2 = xScrn;if (nY2 > yScrn)nY2 = yScrn;nWidth = nX2 - nX;nHeight = nY2 - nY;hBitmap = CreateCompatibleBitmap(hScrDC, nWidth, nHeight);		// 创建一个与屏幕设备描述表兼容的位图hOldBitmap = (HBITMAP)SelectObject(hMemDC, hBitmap);			// 把新位图选到内存设备描述表中BitBlt(hMemDC, 0, 0, nWidth, nHeight, hScrDC, nX, nY, SRCCOPY);	// 把屏幕设备描述表拷贝到内存设备描述表中hBitmap = (HBITMAP)SelectObject(hMemDC, hOldBitmap);			// 得到屏幕位图的句柄DeleteDC(hScrDC);DeleteDC(hMemDC);return hBitmap;
}/*lpFileName: 位图文件名
*/
BOOL SaveBitmapToFile(HBITMAP hBitmap, LPSTR lpFileName)
{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DWORD dwPaletteSize = 0, dwBmBitsSize, dwDIBSize, dwWritten;	// 调色板大小，位图数据大小，位图文件大小，写入文件字节数BITMAP Bitmap;					//位图属性结构BITMAPFILEHEADER bmfHdr;		// 位图文件头BITMAPINFOHEADER bi;			// 位图信息头LPBITMAPINFOHEADER lpbi;		// 指向位图信息头结构HANDLE fh, hDib;				// 定义文件，分配内存句柄HPALETTE hPal, hOldPal=NULL;	// 调色板句柄// 计算位图文件每个像素所占字节数hDC = CreateDC("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;elsewBitCount = 32;if (wBitCount <= 8)dwPaletteSize = (1 << wBitCount) * sizeof(RGBQUAD);		// 计算调色板大小// 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;hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER));	// 为位图内容分配内存lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);*lpbi = bi;// 处理调色板hPal = (HPALETTE)GetStockObject(DEFAULT_PALETTE);if (hPal){hDC = GetDC(NULL);hOldPal = SelectPalette(hDC, 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);if (hOldPal)				// 恢复调色板{SelectPalette(hDC, hOldPal, TRUE);RealizePalette(hDC);ReleaseDC(NULL, hDC);}// 创建位图文件 fh = CreateFile(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;		// 文件类型: "BM"dwDIBSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + dwPaletteSize + dwBmBitsSize; bmfHdr.bfSize = dwDIBSize;	// 位图文件大小bmfHdr.bfReserved1 = 0;bmfHdr.bfReserved2 = 0;bmfHdr.bfOffBits = (DWORD)sizeof(BITMAPFILEHEADER) + (DWORD)sizeof(BITMAPINFOHEADER) + dwPaletteSize;WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);	// 写入位图文件头WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);					// 写入位图文件其余内容GlobalUnlock(hDib);GlobalFree(hDib);CloseHandle(fh);return TRUE;
}