Rendering performance improvement

Pixed.Application/Controls/ImageGrid.cs

@@ -1,11 +1,14 @@
-using Pixed.Application.Utils;
+using Avalonia;
+using Pixed.Application.Utils;
 using Pixed.Core;
 using SkiaSharp;
+using System;
 
 
 namespace Pixed.Application.Controls;
 internal class ImageGrid : OverlayControl
 {
+    public const int MinGridSize = 15;
     public ImageGrid()
     {
         ClipToBounds = false;
@@ -21,18 +24,44 @@
         {
             float stepX = GridWidth.ToFloat();
             float stepY = GridHeight.ToFloat();
-            float left = Bounds.Left.ToFloat();
-            float top = Bounds.Top.ToFloat();
-            float right = Bounds.Right.ToFloat() / Zoom.ToFloat();
-            float bottom = Bounds.Bottom.ToFloat() / Zoom.ToFloat();
+            float leftBounds = Bounds.Left.ToFloat() / Zoom.ToFloat();
+            float topBounds = Bounds.Top.ToFloat() / Zoom.ToFloat();
+            float rightBounds = Bounds.Right.ToFloat() / Zoom.ToFloat();
+            float bottomBounds = Bounds.Bottom.ToFloat() / Zoom.ToFloat();
+            float firstStepX = stepX;
+            float firstStepY = stepY;
+            float left = leftBounds;
+            float top = topBounds;
+            float right = rightBounds;
+            float bottom = bottomBounds;
 
-            for (float x = stepX; x < (int)right; x += stepX)
+            if (VisualToZoomMatrix.HasValue && ZoomBorder != null)
             {
-                canvas.DrawLine(new SKPoint(left + x, top), new SKPoint(left + x, bottom), new SKPaint() { Color = GridColor });
+                var inverted = VisualToZoomMatrix.Value.Invert();
+                var gridSize = new Point(GridWidth * Zoom, GridHeight * Zoom);
+
+                if(gridSize.X < MinGridSize | gridSize.Y < MinGridSize)
+                {
+                    return;
+                }
+                var firstTransform = inverted.Transform(new Point(0, 0));
+                var lastTransform = inverted.Transform(new Point(ZoomBorder.Bounds.Size.Width, ZoomBorder.Bounds.Size.Height));
+
+                left = Math.Max(left, Math.Round(firstTransform.X).ToFloat() - 1f);
+                top = Math.Max(top, Math.Round(firstTransform.Y).ToFloat() - 1f);
+                bottom = Math.Min(bottomBounds, Math.Round(lastTransform.Y).ToFloat() + 1f);
+                right = Math.Min(rightBounds, Math.Round(lastTransform.X).ToFloat() + 1f);
+                firstStepX = ((int)left / (int)stepX) * stepX;
+                firstStepY = ((int)top / (int)stepY) * stepY;
+            }
+
+            for (float x = firstStepX; x < (int)right; x += stepX)
+            {
+                canvas.DrawLine(new SKPoint(leftBounds + x, topBounds), new SKPoint(leftBounds + x, bottomBounds), new SKPaint() { Color = GridColor });
             }
-            for (float y = stepY; y < (int)bottom; y += stepY)
+            for (float y = firstStepY; y < MathF.Floor(bottom); y += stepY)
             {
-                canvas.DrawLine(new SKPoint(left, top + y), new SKPoint(right, top + y), new SKPaint() { Color = GridColor });
+                canvas.DrawLine(new SKPoint(leftBounds, topBounds + y), new SKPoint(rightBounds, topBounds + y), new SKPaint() { Color = GridColor });
             }
         }
     }

Pixed.Application/Controls/OverlayControl.cs

@@ -5,6 +5,7 @@
 using Avalonia.Rendering.SceneGraph;
 using Avalonia.Skia;
 using Avalonia.Threading;
+using Pixed.Application.Zoom;
 using SkiaSharp;
 
 namespace Pixed.Application.Controls;
@@ -42,10 +43,21 @@ public void Render(ImmediateDrawingContext context)
     }
 
     public virtual double Zoom { get; set; } = 1;
+    protected ZoomBorder? ZoomBorder { get; private set; }
+    protected Matrix? VisualToZoomMatrix { get; private set; }
+
+    public void AttachToZoomBorder(ZoomBorder zoomBorder)
+    {
+        ZoomBorder = zoomBorder;
+    }
 
     public override void Render(DrawingContext context)
     {
         context.Custom(new DrawOperation(new Rect(Bounds.X, Bounds.Y, Bounds.Width, Bounds.Height), this));
+        if(ZoomBorder != null)
+        {
+            VisualToZoomMatrix = this.TransformToVisual(ZoomBorder);
+        }
         Dispatcher.UIThread.InvokeAsync(InvalidateVisual, DispatcherPriority.Background);
     }
 

Pixed.Application/Controls/PaintCanvas.axaml

@@ -23,7 +23,7 @@
       <Border BorderBrush="{StaticResource Accent}" BorderThickness="0 2 0 0">
         <Border BorderBrush="{StaticResource ButtonBorder}" BorderThickness="2 0 2 2">
           <zoom:ZoomBorder Name="zoomBorder" ZoomSpeed="1.2" ClipToBounds="True" GestureZoomEnabled="{Binding GestureZoomEnabled, Mode=TwoWay}">
-            <Canvas
+            <zoom:ZoomCanvas
               Name="imageGrid"
               Width="{Binding GridWidth, Mode=TwoWay}"
               Height="{Binding GridHeight, Mode=TwoWay}"
@@ -37,7 +37,7 @@
               <controls:PaintCanvasImageControl Name="image" RenderOptions.BitmapInterpolationMode="None" Source="{Binding RenderModel}"/>
               <controls:ImageGrid Width="{Binding ScaledGridWidth}" Height="{Binding ScaledGridHeight}" Name="gridCanvas" IsHitTestVisible="False"/>
               <controls:SelectionOverlay Width="{Binding ScaledGridWidth}" Height="{Binding ScaledGridHeight}" Name="selectionOverlay" IsHitTestVisible="False"/>
-            </Canvas>
+            </zoom:ZoomCanvas>
           </zoom:ZoomBorder>
         </Border>
       </Border>

Pixed.Application/Controls/TransparentBackground.cs

@@ -1,35 +1,47 @@
-using Pixed.Application.Utils;
+using Avalonia.Interactivity;
+using Pixed.Application.Utils;
 using Pixed.Core;
 using SkiaSharp;
-using System;
 
 namespace Pixed.Application.Controls;
 internal class TransparentBackground : OverlayControl
 {
+    private readonly SKBitmap _transparentBackground;
+    private readonly SKShader _shader;
+    private readonly SKPaint _paint;
     public TransparentBackground()
     {
         ClipToBounds = true;
+        _transparentBackground = CreateTransparentBackground();
+        _shader = SKShader.CreateBitmap(_transparentBackground, SKShaderTileMode.Repeat, SKShaderTileMode.Repeat);
+        _paint = new SKPaint()
+        {
+            Shader = _shader,
+        };
     }
-    public override void Render(SKCanvas canvas)
+
+    protected override void OnUnloaded(RoutedEventArgs e)
     {
-        SKPaint paint1 = new() { Color = new UniColor(76, 76, 76), Style = SKPaintStyle.Fill };
-        SKPaint paint2 = new() { Color = new UniColor(85, 85, 85), Style = SKPaintStyle.Fill };
+        base.OnUnloaded(e);
+        _transparentBackground.Dispose();
+        _shader.Dispose();
+        _paint.Dispose();
+    }
 
-        float right = Bounds.Right.ToFloat();
-        float bottom = Bounds.Bottom.ToFloat();
-        int xCount = ((int)right / 32)+1;
-        int yCount = ((int)bottom / 32)+1;
-        float size = 32f / Zoom.ToFloat();
+    public override void Render(SKCanvas canvas)
+    {
+        canvas.DrawRect(SKRect.Create(Bounds.Width.ToFloat() / Zoom.ToFloat(), Bounds.Height.ToFloat() / Zoom.ToFloat()), _paint);
+    }
 
-        for(int x = 0; x < xCount; x++)
-        {
-            for(int y = 0; y < yCount; y++)
-            {
-                int c = (x + y) % 2;
-                float cellRight = (x.ToFloat() * size) + size;
-                float cellBottom = (y.ToFloat() * size) + size;
-                canvas.DrawRect(new SKRect(x.ToFloat() * size, y.ToFloat() * size, MathF.Min(cellRight, right / Zoom.ToFloat()), MathF.Min(cellBottom, bottom / Zoom.ToFloat())), c == 0 ? paint1 : paint2);
-            }
-        }
+    private static SKBitmap CreateTransparentBackground()
+    {
+        UniColor color1 = new(76, 76, 76);
+        UniColor color2 = new(85, 85, 85);
+        SKBitmap bitmap = new(2, 2);
+        bitmap.SetPixel(0, 0, color1);
+        bitmap.SetPixel(1, 0, color2);
+        bitmap.SetPixel(1, 1, color1);
+        bitmap.SetPixel(0, 1, color2);
+        return bitmap;
     }
 }

Pixed.Application/Zoom/ZoomBorder.cs

@@ -6,6 +6,8 @@
 using Avalonia.Media;
 using Avalonia.Media.Transformation;
 using Avalonia.Reactive;
+using Avalonia.VisualTree;
+using Pixed.Application.Controls;
 using System;
 using System.Linq;
 
@@ -205,6 +207,16 @@ private void ChildChanged(Control? element)
         if (element != null && element != _element)
         {
             AttachElement(element);
+
+            var children = element.GetVisualChildren();
+
+            foreach( var child in children )
+            {
+                if(child is OverlayControl control)
+                {
+                    control.AttachToZoomBorder(this);
+                }
+            }
         }
     }
 

Pixed.Application/Zoom/ZoomCanvas.cs

@@ -0,0 +1,23 @@
+using Avalonia.Controls;
+using Pixed.Application.Controls;
+using System.Collections.Specialized;
+
+namespace Pixed.Application.Zoom;
+internal class ZoomCanvas : Canvas
+{
+    protected override void ChildrenChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if(Parent is ZoomBorder zoomBorder)
+        {
+            foreach (var child in Children)
+            {
+                if (child is OverlayControl control)
+                {
+                    control.AttachToZoomBorder(zoomBorder);
+                }
+            }
+        }
+
+        base.ChildrenChanged(sender, e);
+    }
+}

Pixed.Core/Utils/SkiaUtils.cs

@@ -99,7 +99,7 @@
         canvas.DrawLine(p0, p1, paint);
     }
 
-    public static void DrawPatternLine(this SKCanvas canvas, SKPoint p0, SKPoint p1, float[] pattern, UniColor color)
+    public static void DrawPatternLine(this SKCanvas canvas, SKPoint p0, SKPoint p1, float[] pattern, UniColor color, float lineWidth = 1f)
     {
         SKPath path = new();
         path.MoveTo(p0.X, p0.Y);
@@ -111,7 +111,8 @@
         {
             Color = color,
             PathEffect = effect,
-            Style = SKPaintStyle.Stroke
+            Style = SKPaintStyle.Stroke,
+            StrokeWidth = lineWidth
         };
 
         canvas.DrawPath(path, paint);