C#窗体透明

[DllImport("gdi32.dll")]

        public static extern IntPtr CreateCompatibleDC(IntPtr hDC);

        [DllImport("gdi32.dll")]

        public static extern Bool DeleteDC(IntPtr hdc);

        [DllImport("gdi32.dll")]

        public static extern Bool DeleteObject(IntPtr hObject);

        [DllImport("user32.dll")]

        public static extern IntPtr GetDC(IntPtr handle);

        [DllImport("user32.dll", ExactSpelling=true)]

        public static extern int ReleaseDC(IntPtr handle, IntPtr hDC);

        [DllImport("gdi32.dll")]

        public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);

        [DllImport("user32.dll")]

        public static extern Bool UpdateLayeredWindow(IntPtr handle, IntPtr hdcDst, ref Point pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, int crKey, ref BLENDFUNCTION pblend, int dwFlags);