public static Bitmap FromHbitmapWithAlpha(IntPtr hbm)
{
if (hbm == IntPtr.Zero)
{
throw new ArgumentException();
}
Microsoft.Win32.BITMAP lpObject = new Microsoft.Win32.BITMAP();
if (Windows.GetObjectBitmap(hbm, Marshal.SizeOf(lpObject), ref lpObject) != 0)
{
Bitmap bitmap2;
int bmWidth = lpObject.bmWidth;
int bmHeight = lpObject.bmHeight;
if ((lpObject.bmBits != IntPtr.Zero) && (lpObject.bmBitsPixel == 0x20))
{
bitmap2 = new Bitmap(bmWidth, bmHeight, PixelFormat.Format32bppArgb);
BitmapData bitmapdata = bitmap2.LockBits(new Rectangle(0, 0, bitmap2.Width, bitmap2.Height), ImageLockMode.WriteOnly, bitmap2.PixelFormat);
Debug.Assert(lpObject.bmWidthBytes == bitmapdata.Stride);
byte[] destination = new byte[bitmapdata.Stride];
IntPtr bmBits = lpObject.bmBits;
IntPtr ptr2 = bitmapdata.Scan0;
for (int i = 0; i < bmHeight; i++)
{
Marshal.Copy(bmBits, destination, 0, destination.Length);
Marshal.Copy(destination, 0, ptr2, destination.Length);
bmBits = bmBits.Offset(destination.Length);
ptr2 = ptr2.Offset(destination.Length);
}
bitmap2.UnlockBits(bitmapdata);
return bitmap2;
}
if (OS.IsWin2k)
{
bitmap2 = new Bitmap(bmWidth, bmHeight, PixelFormat.Format32bppPArgb);
using (Graphics graphics = Graphics.FromImage(bitmap2))
{
IntPtr hdc = graphics.GetHdc();
IntPtr ptr4 = Windows.CreateCompatibleDC(hdc);
IntPtr hgdiobj = Windows.SelectObject(ptr4, hbm);
BLENDFUNCTION blendFunction = new BLENDFUNCTION(0, 0, 0xff, 1);
Windows.AlphaBlend(hdc, 0, 0, bmWidth, bmHeight, ptr4, 0, 0, bmWidth, bmHeight, blendFunction);
Windows.SelectObject(ptr4, hgdiobj);
Windows.DeleteDC(ptr4);
graphics.ReleaseHdc(hdc);
}
return bitmap2;
}
}
return Image.FromHbitmap(hbm);
}
public static extern bool AlphaBlend(IntPtr hdcDest, int nXOriginDest, int nYOriginDest, int nWidthDest, int nHeightDest, IntPtr hdcSrc, int nXOriginSrc, int nYOriginSrc, int nWidthSrc, int nHeightSrc, BLENDFUNCTION blendFunction);