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InkCanvasForClass/Helpers/InkStrokesOverlay.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Drawing;
+using System.Runtime.Remoting.Contexts;
+using System.Windows;
+using System.Windows.Ink;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows.Media.Animation;
+using Pen = System.Windows.Media.Pen;
+
+namespace Ink_Canvas.Helpers
+{
+    
+    public class InkStrokesOverlay : FrameworkElement
+    {
+        private VisualCollection _children;
+        private ImprovedDrawingVisual _layer = new ImprovedDrawingVisual();
+        private StrokeCollection cachedStrokeCollection = new StrokeCollection();
+        private DrawingGroup cachedDrawingGroup = new DrawingGroup();
+        private bool isCached = false;
+        private DrawingContext context;
+
+        public class ImprovedDrawingVisual: DrawingVisual {
+            public ImprovedDrawingVisual() {
+                CacheMode = new BitmapCache() {
+                    EnableClearType = false,
+                    RenderAtScale = 1,
+                    SnapsToDevicePixels = false
+                };
+            }
+        }
+
+        public InkStrokesOverlay()
+        {
+            _children = new VisualCollection(this) {
+                _layer // 初始化DrawingVisual
+            };
+        }
+
+        protected override int VisualChildrenCount => _children.Count;
+
+        protected override Visual GetVisualChild(int index)
+        {
+            if (index < 0 || index >= _children.Count) throw new ArgumentOutOfRangeException();
+            return _children[index];
+        }
+
+        public DrawingContext Open() {
+            context = _layer.RenderOpen();
+            return context;
+        }
+
+        public void Close() {
+            context.Close();
+        }
+
+        public void DrawStrokes(StrokeCollection strokes, Matrix? matrixTransform, bool isOneTimeDrawing = true) {
+            if (isOneTimeDrawing) {
+                context = _layer.RenderOpen();
+            }
+
+            if (matrixTransform != null) context.PushTransform(new MatrixTransform((Matrix)matrixTransform));
+
+            if (strokes.Count != 0) {
+                if (!isCached || (isCached && !strokes.Equals(cachedStrokeCollection))) {
+                    cachedStrokeCollection = strokes;
+                    cachedDrawingGroup = new DrawingGroup();
+                    var gp_context = cachedDrawingGroup.Open();
+                    var stks_cloned = strokes.Clone();
+                    foreach (var stroke in stks_cloned) {
+                        stroke.DrawingAttributes.Width += 2;
+                        stroke.DrawingAttributes.Height += 2;
+                    }
+                    stks_cloned.Draw(gp_context);
+                    foreach (var ori_stk in strokes) {
+                        var geo = ori_stk.GetGeometry();
+                        gp_context.DrawGeometry(new SolidColorBrush(Colors.White),null,geo);
+
+                    }
+                    gp_context.Close();
+                }
+            }
+
+            context.DrawDrawing(cachedDrawingGroup);
+
+            if (matrixTransform != null) context.Pop();
+
+            if (isOneTimeDrawing) {
+                context.Close();
+            }
+        }
+    }
+}