可分为两个步骤:
一 将屏幕保存为位图句柄
HBITMAP CopyScreenToBitmap(LPRECT lpRect)
{
HDC hScrDC,hMemDC;
HBITMAP hBitmap,hOldBitmap;
int nX1,nX2,nY1,nY2;
int nWidth,nHeight;
if (IsRectEmpty(lpRect))
{
return FALSE;
}
//为屏幕创建设备描述表
hScrDC = CreateDC("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
nX1 = lpRect->left;
nY1 = lpRect->top;
nX2 = lpRect->right;
nY2 = lpRect->bottom;
//确保选定区域是可见的
if (nX1 < 0)
nX1 = 0;
if (nY1 < 0)
nY1 = 0;
if (nX2 > m_xScreen)
nX2 = m_xScreen;
if (nY2 > m_yScreen)
nY2 = m_yScreen;
nWidth = nX2 - nX1;
nHeight = nY2 - nY1;
// 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,nX1,nY1,SRCCOPY);
//得到屏幕位图的句柄
hBitmap = (HBITMAP)SelectObject(hMemDC,hOldBitmap);
//清除
DeleteDC(hScrDC);
DeleteDC(hMemDC);
return hBitmap;
}
二 将位图句柄另存为bmp图片
int SaveBitmapToFile(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("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=(1<<wBitCount)*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1
biWidth *= 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(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; // "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, sizeof(BITMAPINFOHEADER)+dwPaletteSize+dwBmBitsSize , &dwWritten, NULL);
//清除
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);
return TRUE;
}
在程序中可以通过下列调用即可:
HBITMAP g_screenBmp=NULL;
//获取x方向屏幕像素()
int m_xScreen = GetSystemMetrics(SM_CXSCREEN);
//获取y方向屏幕像素()
int m_yScreen = GetSystemMetrics(SM_CYSCREEN);
RECT g_qq_DlgRt;
g_qq_DlgRt.left = 0;
g_qq_DlgRt.top = 0;
g_qq_DlgRt.right = m_xScreen;
g_qq_DlgRt.bottom = m_yScreen;
g_screenBmp = CopyScreenToBitmap(&g_qq_DlgRt);
SaveBitmapToFile(g_screenBmp,"e://025.bmp");最后的结果25.bmp):