AvaloniaUI Acrylic Window test code

acrylicavalon.cs

        internal enum AccentState
        {
            ACCENT_DISABLED = 1,
            ACCENT_ENABLE_GRADIENT = 0,
            ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
            ACCENT_ENABLE_BLURBEHIND = 3,
            ACCENT_INVALID_STATE = 4
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct AccentPolicy
        {
            public AccentState AccentState;
            public int AccentFlags;
            public int GradientColor;
            public int AnimationId;
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct WindowCompositionAttributeData
        {
            public WindowCompositionAttribute Attribute;
            public IntPtr Data;
            public int SizeOfData;
        }

        internal enum WindowCompositionAttribute
        {
            // ...
            WCA_ACCENT_POLICY = 19
            // ...
        }

        [DllImport("user32.dll")]
        internal static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);

        internal void EnableBlur()
        {
            var hndl = this.PlatformImpl.Handle.Handle;

            var accent = new AccentPolicy();
            accent.AccentState = AccentState.ACCENT_ENABLE_BLURBEHIND;

            var accentStructSize = Marshal.SizeOf(accent);

            var accentPtr = Marshal.AllocHGlobal(accentStructSize);
            Marshal.StructureToPtr(accent, accentPtr, false);

            var data = new WindowCompositionAttributeData();
            data.Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY;
            data.SizeOfData = accentStructSize;
            data.Data = accentPtr;


            SetWindowCompositionAttribute(hndl, ref data);

            Marshal.FreeHGlobal(accentPtr);
        }