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