FromHBITMAP 这个函数会丢失透明信息。

在用 FromHBITMAP 你会发现出来的图是带有黑边的，这是因为这个函数有个 bug，解决的办法是用下列的函数进行转换，大体意思就是自己 memcpy 不要用 FromHBITMAP 函数。

 Bitmap* CreateBitmapFromHBITMAP(IN HBITMAP hBitmap)
    {
        BITMAP bmp = { 0 };
        if ( 0 == GetObject(hBitmap, sizeof(BITMAP), (LPVOID)&bmp) )
        {
            return FALSE;
        }

        BYTE *piexlsSrc = NULL;
        LONG cbSize = bmp.bmWidthBytes * bmp.bmHeight;
        piexlsSrc = new BYTE[cbSize];

        BITMAPINFO bmpInfo = { 0 };
        bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
        bmpInfo.bmiHeader.biWidth = bmp.bmWidth;
        bmpInfo.bmiHeader.biHeight = bmp.bmHeight; 
        bmpInfo.bmiHeader.biPlanes = bmp.bmPlanes;
        bmpInfo.bmiHeader.biBitCount = bmp.bmBitsPixel;
        bmpInfo.bmiHeader.biCompression = BI_RGB;

        HDC hdcScreen = CreateDC(L"DISPLAY", NULL, NULL,NULL);
        LONG cbCopied = GetDIBits(hdcScreen, hBitmap, 0, 
            bmp.bmHeight, piexlsSrc, &bmpInfo, DIB_RGB_COLORS);
        DeleteDC(hdcScreen);
        if ( 0 == cbCopied )
        {
            delete [] piexlsSrc;
            return FALSE;
        }

        Bitmap *pBitmap = new Bitmap(bmp.bmWidth, bmp.bmHeight, PixelFormat32bppPARGB);

        BitmapData bitmapData;
        Rect rect(0, 0, bmp.bmWidth, bmp.bmHeight);
        if ( Ok != pBitmap->LockBits(&rect, ImageLockModeRead, 
            PixelFormat32bppPARGB, &bitmapData) )
        {
            SAFE_DELETE(pBitmap);
            return NULL;
        }

        BYTE *pixelsDest = (BYTE*)bitmapData.Scan0;
        int nLinesize = bmp.bmWidth * sizeof(UINT);
        int nHeight = bmp.bmHeight;


        for ( int y = 0; y < nHeight; y++ )
        {
            memcpy_s( (pixelsDest + y * nLinesize), nLinesize, 
                (piexlsSrc + (nHeight - y - 1) * nLinesize), nLinesize);
        }

        if ( Ok != pBitmap->UnlockBits(&bitmapData) )
        {
            delete pBitmap;
        }

        delete [] piexlsSrc;
        return pBitmap;
    }

　　

参考信息：http://blog.sina.com.cn/s/blog_5f8817250100g1dj.html 

　　　　　https://groups.google.com/forum/#!topic/microsoft.public.win32.programmer.gdi/stjG06_EPfM