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Nitrox.Launcher/Models/Controls/BlurControl.cs

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+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Platform;
+using Avalonia.Rendering.SceneGraph;
+using Avalonia.Skia;
+using SkiaSharp;
+
+namespace Nitrox.Launcher.Models.Controls;
+
+/// <summary>
+///     Draws a blur filter over the already rendered content.
+/// </summary>
+/// <remarks>
+///     Based off of GrayscaleControl
+/// </remarks>
+public sealed class BlurControl : Decorator
+{
+    public static readonly StyledProperty<float> BlurStrengthProperty =
+        AvaloniaProperty.Register<BlurControl, float>(nameof(BlurStrength), 5);
+
+    /// <summary>
+    ///     Sets or gets how strong the blur should be. Defaults to 5.
+    /// </summary>
+    public float BlurStrength
+    {
+        get => GetValue(BlurStrengthProperty);
+        set => SetValue(BlurStrengthProperty, value);
+    }
+
+    static BlurControl()
+    {
+        ClipToBoundsProperty.OverrideDefaultValue<BlurControl>(true);
+        AffectsRender<BlurControl>(OpacityProperty);
+        AffectsRender<BlurControl>(BlurStrengthProperty);
+    }
+
+    public override void Render(DrawingContext context)
+    {
+        context.Custom(new BlurBehindRenderOperation((byte)Math.Round(byte.MaxValue * Opacity), BlurStrength, new Rect(default, Bounds.Size)));
+    }
+
+    private sealed record BlurBehindRenderOperation : ICustomDrawOperation
+    {
+        private readonly Rect bounds;
+        private readonly byte opacity;
+        private readonly float strength;
+
+        public Rect Bounds => bounds;
+
+        public BlurBehindRenderOperation(byte opacity, float strength, Rect bounds)
+        {
+            this.opacity = opacity;
+            this.strength = strength;
+            this.bounds = bounds;
+        }
+
+        public void Dispose()
+        {
+        }
+
+        public bool HitTest(Point p) => bounds.Contains(p);
+
+        public void Render(ImmediateDrawingContext context)
+        {
+            ISkiaSharpApiLeaseFeature leaseFeature = context.TryGetFeature<ISkiaSharpApiLeaseFeature>();
+            if (leaseFeature == null)
+            {
+                return;
+            }
+            using ISkiaSharpApiLease skia = leaseFeature.Lease();
+            if (!skia.SkCanvas.TotalMatrix.TryInvert(out SKMatrix currentInvertedTransform))
+            {
+                return;
+            }
+            if (skia.SkSurface == null)
+            {
+                return;
+            }
+
+            using SKImage backgroundSnapshot = skia.SkSurface.Snapshot();
+            using SKShader backdropShader = SKShader.CreateImage(backgroundSnapshot, SKShaderTileMode.Clamp, SKShaderTileMode.Clamp, currentInvertedTransform);
+            using SKImageFilter blurFilter = SKImageFilter.CreateBlur(strength, strength);
+            using SKPaint paint = new();
+            paint.Shader = backdropShader;
+            paint.ImageFilter = blurFilter;
+            paint.Color = new SKColor(0, 0, 0, opacity);
+            skia.SkCanvas.DrawRect(0, 0, (float)bounds.Width, (float)bounds.Height, paint);
+        }
+
+        public bool Equals(ICustomDrawOperation other) => Equals(other as BlurBehindRenderOperation);
+    }
+}