hbitmap保存爲圖片

static BOOL SaveBitmapToFile(HBITMAP hBitmap, std::string szfilename)
{
HDC hDC;
//當前分辨率下每象素所佔字節數
int iBits;
//位圖中每象素所佔字節數
WORD wBitCount;
//定義調色板大小， 位圖中像素字節大小 ，位圖文件大小 ， 寫入文件字節數
DWORD dwPaletteSize = 0, dwBmBitsSize = 0, dwDIBSize = 0, dwWritten = 0;
//位圖屬性結構
BITMAP Bitmap;
//位圖文件頭結構
BITMAPFILEHEADER bmfHdr;
//位圖信息頭結構
BITMAPINFOHEADER bi;
//指向位圖信息頭結構
LPBITMAPINFOHEADER lpbi;
//定義文件，分配內存句柄，調色板句柄
HANDLE fh, hDib, hPal, hOldPal = NULL;

//計算位圖文件每個像素所佔字節數              
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
	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;

//爲位圖內容分配內存              
hDib = GlobalAlloc(GHND, dwBmBitsSize + dwPaletteSize + sizeof(BITMAPINFOHEADER));
lpbi = (LPBITMAPINFOHEADER)GlobalLock(hDib);
*lpbi = bi;

//     處理調色板                  
hPal = GetStockObject(DEFAULT_PALETTE);
if (hPal)
{
	hDC = ::GetDC(NULL);
	hOldPal = ::SelectPalette(hDC, (HPALETTE)hPal, FALSE);
	RealizePalette(hDC);
}

//     獲取該調色板下新的像素值              
GetDIBits(hDC, hBitmap, 0, (UINT)Bitmap.bmHeight,
	(LPSTR)lpbi + sizeof(BITMAPINFOHEADER) + dwPaletteSize,
	(BITMAPINFO *)lpbi, DIB_RGB_COLORS);

//恢復調色板                  
if (hOldPal)
{
	::SelectPalette(hDC, (HPALETTE)hOldPal, TRUE);
	RealizePalette(hDC);
	::ReleaseDC(NULL, hDC);
}

//創建位圖文件                  
fh = CreateFile(szfilename.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,
	FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL);

if (fh == INVALID_HANDLE_VALUE)         return     FALSE;

//     設置位圖文件頭              
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;
//     寫入位圖文件頭              
WriteFile(fh, (LPSTR)&bmfHdr, sizeof(BITMAPFILEHEADER), &dwWritten, NULL);
//     寫入位圖文件其餘內容              
WriteFile(fh, (LPSTR)lpbi, dwDIBSize, &dwWritten, NULL);
//清除                  
GlobalUnlock(hDib);
GlobalFree(hDib);
CloseHandle(fh);
return     TRUE;

}