win32下截屏代码

自己整理他人的截屏代码，方便以后使用BOOL Qos::SaveBitmapToFile(HBITMAP hBitmap, LPSTR szfilename)
{
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 = CreateDCA("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 = CreateFileA(szfilename, 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;

}

HBITMAP Qos::ScreenCapture(LPSTR filename, LPRECT lpRect)
{
HBITMAP hBitmap;
//显示器屏幕DC
HDC hScreenDC = CreateDCA("display", NULL, NULL, NULL);
HDC hmenDC = CreateCompatibleDC(hScreenDC);
//显示器屏幕的宽和高
int ScreenWidth = GetDeviceCaps(hScreenDC, HORZRES);
int ScreenHeight = GetDeviceCaps(hScreenDC, VERTRES);

HBITMAP hOldBM;
//保存位图数据
//截取获取的长度及起点
INT ixStart;
INT iyStart;
INT iX;
INT iY;

if (lpRect == NULL)
{
ixStart = iyStart = 0;
iX = ScreenWidth;
iY = ScreenHeight;
}
else
{
ixStart = lpRect->left;
iyStart = lpRect->top;
iX = lpRect->right - lpRect->left;
iY = lpRect->bottom - lpRect->top;
}
hBitmap = CreateCompatibleBitmap(hScreenDC, iX, iY);
hOldBM = (HBITMAP)SelectObject(hmenDC, hBitmap);
BitBlt(hmenDC, 0, 0, iX, iY, hScreenDC, ixStart, iyStart, SRCCOPY);
hBitmap = (HBITMAP)SelectObject(hmenDC, hOldBM);
if (filename == NULL)
{
DeleteDC(hScreenDC);
DeleteDC(hmenDC);
return hBitmap;
}

SaveBitmapToFile(hBitmap, filename);
ReleaseDC(0, hScreenDC);
DeleteDC(hmenDC);
return hBitmap;
}