Working with Mica

I know Mica is not supported yet. However, with the help of some PInvoke functions, Mica is activated on WPF apps

so I tried to do the same in WinUI3 preview 3

[DllImport("dwmapi.dll")]
        public static extern int DwmSetWindowAttribute(IntPtr hwnd, DwmWindowAttribute dwAttribute, ref int pvAttribute, int cbAttribute);

        [Flags]
        public enum DwmWindowAttribute : uint
        {
            DWMWA_USE_IMMERSIVE_DARK_MODE = 20,
            DWMWA_MICA_EFFECT = 1029
        }
        public static void EnableMica(IntPtr source, bool darkThemeEnabled)
        {
            int trueValue = 0x01;
            int falseValue = 0x00;

            // Set dark mode before applying the material, otherwise you'll get an ugly flash when displaying the window.
            if (darkThemeEnabled)
                DwmSetWindowAttribute(source, DwmWindowAttribute.DWMWA_USE_IMMERSIVE_DARK_MODE, ref trueValue, Marshal.SizeOf(typeof(int)));
            else
                DwmSetWindowAttribute(source, DwmWindowAttribute.DWMWA_USE_IMMERSIVE_DARK_MODE, ref falseValue, Marshal.SizeOf(typeof(int)));

            DwmSetWindowAttribute(source, DwmWindowAttribute.DWMWA_MICA_EFFECT, ref trueValue, Marshal.SizeOf(typeof(int)));
        }

public MainWindow()
        {
            this.InitializeComponent();
            IntPtr hwnd = WinRT.Interop.WindowNative.GetWindowHandle(this);
            EnableMica(hwnd, true);
        }

TitleBar activates Mica well, but not Windows content

Is there a solution?😁

[IcySnex]

You need to set the background of your application to transparent.

You can do this via Win32 API calls. I have created a sample project here: https://github.com/IcySnex/WinUI3-Transparent-Mica-Acrylic-Blurred. You can also look at a video here: https://www.youtube.com/watch?v=mfS8PT9Z3u8. But be aware that you need to have at least the WindowsAppSDK version 1.1 - preview 1.

[dongle-the-gadget]

That method depends on a private API that has been removed since 22494+ (in 22523 and later it’s replaced. The proper way is to use Windows.UI.Composition.Compositor, however this approach requires either a swapchain or a HwndHost (or some other way idk), the latter causes the airspace problem.