WPF InkCanvas 毛笔效果

 1  public class ChinesebrushRenderer : DynamicRenderer
 2     {
 3         private ImageSource imageSource;
 4         private readonly double width = 16;
 5 
 6         protected override void OnDrawingAttributesReplaced()
 7         {
 8             if (DesignerProperties.GetIsInDesignMode(this.Element))
 9                 return;
10 
11             base.OnDrawingAttributesReplaced();
12 
13             var dv = new DrawingVisual();
14             var size = 90;
15             using (var conext = dv.RenderOpen())
16             {
17                 //[关键]OpacityMask了解下？也许有童鞋想到的办法是，各种颜色的图片来一张？
18                 conext.PushOpacityMask(new ImageBrush(new BitmapImage(new Uri(AppDomain.CurrentDomain.BaseDirectory + "Images\\pen.png", UriKind.Absolute))));
19                 //用颜色生成画笔画一个矩形
20                 conext.DrawRectangle(new SolidColorBrush(this.DrawingAttributes.Color), null, new Rect(0, 0, size, size));
21                 conext.Close();
22             }
23             var rtb = new RenderTargetBitmap(size, size, 96d, 96d, PixelFormats.Pbgra32);
24             rtb.Render(dv);
25             imageSource = BitmapFrame.Create(rtb);
26             //[重要]此乃解决卡顿问题的关键！
27             imageSource.Freeze();
28         }
29 
30         protected override void OnDraw(DrawingContext drawingContext, StylusPointCollection stylusPoints, Geometry geometry, Brush fillBrush)
31         {
32             var p1 = new Point(double.NegativeInfinity, double.NegativeInfinity);
33             var p2 = new Point(0, 0);
34             var w1 = this.width + 20;
35 
36             for (int i = 0; i < stylusPoints.Count; i++)
37             {
38                 p2 = (Point)stylusPoints[i];
39 
40                 //两点相减得到一个向量[高中数学知识了解下？]
41                 var vector = p1 - p2;
42 
43                //得到 x、y的变化值
44                 var dx = (p2.X - p1.X) / vector.Length;
45                 var dy = (p2.Y - p1.Y) / vector.Length;
46 
47                 var w2 = this.width;
48                 if (w1 - vector.Length > this.width)
49                     w2 = w1 - vector.Length;
50 
51                 //为啥又来一个for？图像重叠，实现笔画的连续性，感兴趣的童鞋可以把for取消掉看看效果
52                 for (int j = 0; j < vector.Length; j++)
53                 {
54                     var x = p2.X;
55                     var y = p2.Y;
56 
57                     if (!double.IsInfinity(p1.X) && !double.IsInfinity(p1.Y))
58                     {
59                         x = p1.X + dx;
60                         y = p1.Y + dy;
61                     }
62 
63                     //画图，没啥可说的
64                     drawingContext.DrawImage(imageSource, new Rect(x - w2 / 2.0, y - w2 / 2.0, w2, w2));
65 
66                     //再把新的坐标赋值给p1，以序后来
67                     p1 = new Point(x, y);
68 
69                     if (double.IsInfinity(vector.Length))
70                         break;
71 
72                 }
73             }
74         }

 1 public class ChinesebrushStroke : Stroke
 2     {
 3 
 4         private ImageSource imageSource;
 5         private readonly double width = 16;
 6 
 7         public ChinesebrushStroke(StylusPointCollection stylusPointCollection, Color color) : base(stylusPointCollection)
 8         {
 9             if (DesignerProperties.GetIsInDesignMode(App.Current.MainWindow))
10                 return;
11             var dv = new DrawingVisual();
12             var size = 90;
13             using (var conext = dv.RenderOpen())
14             {
15                 conext.PushOpacityMask(new ImageBrush(new BitmapImage(new Uri(AppDomain.CurrentDomain.BaseDirectory + "Images\\pen.png", UriKind.Absolute))));
16                 conext.DrawRectangle(new SolidColorBrush(color), null, new Rect(0, 0, size, size));
17                 conext.Close();
18             }
19             var rtb = new RenderTargetBitmap(size, size, 96d, 96d, PixelFormats.Pbgra32);
20             rtb.Render(dv);
21             imageSource = BitmapFrame.Create(rtb);
22 
23             //Freezable 类提供特殊功能，以便在使用修改或复制开销很大的对象时帮助提高应用程序性能
24             //WPF中的Frozen（冻结）与线程及其他相关问题
25             imageSource.Freeze();
26         }
27 
28         //卡顿就是该函数造成，每写完一笔就会调用，当笔画过长，后果可想而知~
29         protected override void DrawCore(DrawingContext drawingContext, DrawingAttributes drawingAttributes)
30         {
31             if (this.StylusPoints?.Count < 1)
32                 return;
33 
34             var p1 = new Point(double.NegativeInfinity, double.NegativeInfinity);
35             var w1 = this.width + 20;
36            
37 
38             for (int i = 0; i < StylusPoints.Count; i++)
39             {
40                 var p2 = (Point)this.StylusPoints[i];
41                
42                 var vector = p1 - p2;
43 
44                 var dx = (p2.X - p1.X) / vector.Length;
45                 var dy = (p2.Y - p1.Y) / vector.Length;
46 
47                 var w2 = this.width;
48                 if (w1 - vector.Length > this.width)
49                     w2 = w1 - vector.Length;
50 
51                 for (int j = 0; j < vector.Length; j++)
52                 {
53                     var x = p2.X;
54                     var y = p2.Y;
55 
56                     if (!double.IsInfinity(p1.X) && !double.IsInfinity(p1.Y))
57                     {
58                         x = p1.X + dx;
59                         y = p1.Y + dy;
60                     }
61 
62                     drawingContext.DrawImage(imageSource, new Rect(x - w2 / 2.0, y - w2 / 2.0, w2, w2));
63 
64                     p1 = new Point(x, y);
65 
66                     if (double.IsInfinity(vector.Length))
67                         break;
68                 }
69             }
70         }
71     }

 1 public class ChinesebrushCanvas : InkCanvas
 2     {
 3         public ChinesebrushCanvas()
 4         {
 5             //当然要换上我们特地搞出来的ChinesebrushRenderer
 6             this.DynamicRenderer = new ChinesebrushRenderer();
 7         }
 8 
 9 
10         protected override void OnStrokeCollected(InkCanvasStrokeCollectedEventArgs e)
11         {
12             //感兴趣的童鞋，注释这一句看看？
13             this.Strokes.Remove(e.Stroke);
14             
15             this.Strokes.Add(new ChinesebrushStroke(e.Stroke.StylusPoints, this.DefaultDrawingAttributes.Color));
16         }
17     }