PrivacyGlass/PrivacyGlass/Native.cs

using System;
using System.Runtime.InteropServices;

namespace PrivacyGlass
{
    internal static class Native
    {
        [Flags]
        private enum DwmBlurBehindFlags : uint
        {
            DWM_BB_ENABLE = 0x00000001,
            DWM_BB_BLURREGION = 0x00000002,
            DWM_BB_TRANSITIONONMAXIMIZED = 0x00000004
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct DWM_BLURBEHIND
        {
            public DwmBlurBehindFlags dwFlags;
            public bool fEnable;
            public IntPtr hRgnBlur;
            public bool fTransitionOnMaximized;
        }

        [DllImport("dwmapi.dll")]
        private static extern int DwmEnableBlurBehindWindow(
            IntPtr hWnd,
            ref DWM_BLURBEHIND pBlurBehind);


        // Window styles
        public const int WS_CHILD = 0x40000000;
        public const int WS_VISIBLE = 0x10000000;

        // Extended styles
        public const int WS_EX_TOPMOST = 0x00000008;
        public const int WS_EX_LAYERED = 0x00080000;
        public const int WS_EX_TRANSPARENT = 0x00000020;

        public const int GWL_EXSTYLE = -20;

        // ----- Magnification API -----

        [DllImport("Magnification.dll", SetLastError = true)]
        internal static extern bool MagInitialize();

        [DllImport("Magnification.dll", SetLastError = true)]
        internal static extern bool MagUninitialize();

        [DllImport("Magnification.dll", SetLastError = true)]
        internal static extern bool MagSetWindowSource(IntPtr hwnd, RECT rect);

        [DllImport("Magnification.dll", SetLastError = true)]
        internal static extern bool MagSetColorEffect(IntPtr hwnd, ref MAGCOLOREFFECT effect);

        // ----- User32 stuff -----

        [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        internal static extern IntPtr CreateWindowEx(
            int dwExStyle,
            string lpClassName,
            string lpWindowName,
            int dwStyle,
            int x, int y,
            int nWidth, int nHeight,
            IntPtr hWndParent,
            IntPtr hMenu,
            IntPtr hInstance,
            IntPtr lpParam);

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

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

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

        // structures

        [StructLayout(LayoutKind.Sequential)]
        internal struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }

        [StructLayout(LayoutKind.Sequential)]
        internal struct MAGCOLOREFFECT
        {
            // 5x5 color matrix (row-major)
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 25)]
            public float[] transform;
        }

        /// <summary>
        /// Strong privacy colour effect: desaturated + darkened.
        /// Not a geometric blur, but kills readability hard.
        /// </summary>
        internal static MAGCOLOREFFECT CreatePrivacyEffect()
        {
            var fx = new MAGCOLOREFFECT
            {
                transform = new float[25]
            };

            // We’ll map R,G,B all to the same gray value and darken it.
            // Gray = (R+G+B)/3 * factor
            float factor = 0.25f;       // 0..1, lower = darker
            float g = factor / 3f;

            // Row 0: R'
            fx.transform[0] = g;  // R
            fx.transform[1] = g;  // G
            fx.transform[2] = g;  // B

            // Row 1: G'
            fx.transform[5] = g;
            fx.transform[6] = g;
            fx.transform[7] = g;

            // Row 2: B'
            fx.transform[10] = g;
            fx.transform[11] = g;
            fx.transform[12] = g;

            // Row 3: A' = A
            fx.transform[18] = 1.0f;

            // Row 4: w' (bias) – leave as identity
            fx.transform[24] = 1.0f;

            return fx;
        }
        [DllImport("Magnification.dll", SetLastError = true)]
        internal static extern bool MagSetWindowTransform(
    IntPtr hwnd,
    ref MAGTRANSFORM pTransform);

        [StructLayout(LayoutKind.Sequential)]
        internal struct MAGTRANSFORM
        {
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 9)]
            public float[] v; // 3x3 matrix
        }

    }


}