ClashWidget/Helpers/NativeMethods.cs

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;

namespace ClashWidget.Helpers;

internal static class NativeMethods
{
    [DllImport("user32.dll")]
    private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter,
        int X, int Y, int cx, int cy, uint uFlags);

    [DllImport("dwmapi.dll")]
    private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr,
        ref int attrValue, int attrSize);

    [DllImport("dwmapi.dll")]
    private static extern int DwmExtendFrameIntoClientArea(IntPtr hwnd,
        ref MARGINS margins);

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

    [DllImport("user32.dll")]
    private static extern int GetWindowLong(IntPtr hWnd, int nIndex);

    [DllImport("user32.dll")]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);

    private static readonly IntPtr HWND_TOPMOST = new(-1);
    private const uint SWP_NOMOVE = 0x0002;
    private const uint SWP_NOSIZE = 0x0001;
    private const uint SWP_NOACTIVATE = 0x0010;
    private const uint SWP_SHOWWINDOW = 0x0040;
    private const int GWL_EXSTYLE = -20;
    private const int WS_EX_TOOLWINDOW = 0x00000080;
    private const int WS_EX_APPWINDOW = 0x00040000;
    private const int DWMWA_SYSTEMBACKDROP_TYPE = 38;

    [StructLayout(LayoutKind.Sequential)]
    private struct MARGINS { public int Left, Right, Top, Bottom; }

    private enum AccentState { ACCENT_DISABLED = 0, ACCENT_ENABLE_ACRYLICBLURBEHIND = 4 }

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

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

    private enum WindowCompositionAttribute { WCA_ACCENT_POLICY = 19 }

    public static void ApplyAcrylic(Window window)
    {
        var hwnd = new WindowInteropHelper(window).EnsureHandle();

        // Extend DWM frame into entire client area
        var margins = new MARGINS { Left = -1, Right = -1, Top = -1, Bottom = -1 };
        DwmExtendFrameIntoClientArea(hwnd, ref margins);

        // Try Win11 modern API first
        int backdrop = 3; // DWMSBT_TRANSIENTWINDOW = Acrylic
        int hr = DwmSetWindowAttribute(hwnd, DWMWA_SYSTEMBACKDROP_TYPE, ref backdrop, sizeof(int));

        if (hr != 0)
        {
            // Fallback: Win10 acrylic
            try
            {
                var accent = new AccentPolicy
                {
                    AccentState = AccentState.ACCENT_ENABLE_ACRYLICBLURBEHIND,
                    AccentFlags = 2,
                    GradientColor = 0x01FFFFFF
                };
                var data = new WindowCompositionAttributeData
                {
                    Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY,
                    SizeOfData = Marshal.SizeOf<AccentPolicy>(),
                    Data = Marshal.AllocHGlobal(Marshal.SizeOf<AccentPolicy>())
                };
                Marshal.StructureToPtr(accent, data.Data, false);
                SetWindowCompositionAttribute(hwnd, ref data);
                Marshal.FreeHGlobal(data.Data);
            }
            catch { }
        }
    }

    public static void SetTopmost(Window window)
    {
        try
        {
            var hwnd = new WindowInteropHelper(window).EnsureHandle();
            SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, 0,
                SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE | SWP_SHOWWINDOW);
        }
        catch { }
    }

    public static void HideFromTaskbar(Window window)
    {
        try
        {
            var hwnd = new WindowInteropHelper(window).EnsureHandle();
            int exStyle = GetWindowLong(hwnd, GWL_EXSTYLE);
            exStyle |= WS_EX_TOOLWINDOW;
            exStyle &= ~WS_EX_APPWINDOW;
            SetWindowLong(hwnd, GWL_EXSTYLE, exStyle);
        }
        catch { }
    }
}