Ejemplo n.º 1
0
        public void SelectBitmap(Bitmap bitmap, int opacity = 255)
        {
            if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
            {
                throw new ApplicationException("The bitmap must be 32bpp with alpha-channel.");
            }

            IntPtr screenDc = NativeMethods.GetDC(IntPtr.Zero);
            IntPtr memDc = NativeMethods.CreateCompatibleDC(screenDc);
            IntPtr hBitmap = IntPtr.Zero;
            IntPtr hOldBitmap = IntPtr.Zero;

            try
            {
                hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
                hOldBitmap = NativeMethods.SelectObject(memDc, hBitmap);

                SIZE newSize = new SIZE(bitmap.Width, bitmap.Height);
                POINT sourceLocation = new POINT(0, 0);
                POINT newLocation = new POINT(Left, Top);
                BLENDFUNCTION blend = new BLENDFUNCTION();
                blend.BlendOp = NativeMethods.AC_SRC_OVER;
                blend.BlendFlags = 0;
                blend.SourceConstantAlpha = (byte)opacity;
                blend.AlphaFormat = NativeMethods.AC_SRC_ALPHA;

                NativeMethods.UpdateLayeredWindow(Handle, screenDc, ref newLocation, ref newSize, memDc, ref sourceLocation, 0, ref blend, NativeMethods.ULW_ALPHA);
            }
            finally
            {
                NativeMethods.ReleaseDC(IntPtr.Zero, screenDc);
                if (hBitmap != IntPtr.Zero)
                {
                    NativeMethods.SelectObject(memDc, hOldBitmap);
                    NativeMethods.DeleteObject(hBitmap);
                }
                NativeMethods.DeleteDC(memDc);
            }
        }