DrawTool画笔之纹理笔

先上图:

今天我们要实现的是DrawTool画笔集合中的一种纹理笔，很多人可能对纹理笔概念还比较生疏，其实如果你接触过类似一些教育行业交互式白板的话，对纹理笔并不会感到陌生，纹理笔我们可以简单的理解为是一种通过图片来呈现笔迹的方式.在继续下面的阅读前，你有必要先了解下以下知识:

• 1.WPF中笔迹线程处理模型
• 2.自定义呈现笔迹
• 3.截获触笔输入

通过上面的文章，我们知道DynamicRenderer为我们提供是呈现，而Stroke是最后我们生成笔迹，如果要实现纹理笔，我们需要重载DynamicRenderer的OnDraw和Stroke的DrawCore方法.

1. 自定义Stroke

public class TextureStroke : Stroke  {    private System.Windows.Media.ImageSource imageSource_;    //纹理图片    private string textureFile_;    public TextureStroke(StylusPointCollection stylusPoints, DrawingAttributes da , string file )      : base(stylusPoints, da)    {      this.textureFile_ = file;      this.imageSource_ = new System.Windows.Media.Imaging.BitmapImage(new Uri(this.textureFile_));    }    /// <summary>    /// 实现绘制    /// </summary>    /// <param name="drawingContext"></param>    /// <param name="drawingAttributes"></param>    protected override void DrawCore(DrawingContext drawingContext, DrawingAttributes drawingAttributes)    {      double width = drawingAttributes.Width * 2.0;      System.Windows.Media.StreamGeometry streamGeometry = new System.Windows.Media.StreamGeometry();      using (System.Windows.Media.StreamGeometryContext streamGeometryContext = streamGeometry.Open())      {        streamGeometryContext.BeginFigure((Point)base.StylusPoints[0], false, false);        foreach (System.Windows.Input.StylusPoint current in base.StylusPoints)        {          streamGeometryContext.LineTo((Point)current, true, true);        }        streamGeometryContext.Close();      }      DrawTexture(streamGeometry, this.imageSource_, drawingContext, width, this.textureFile_);    }    public static void DrawTexture(Geometry geometry, ImageSource imageSource, DrawingContext drawingContext, double width, string imagePath)    {      Rect rc = geometry.Bounds;      DrawingBrush drawingBrush = new DrawingBrush(new ImageDrawing      {        Rect = rc,        ImageSource = imageSource      });      drawingBrush.TileMode = TileMode.Tile;      Uri uriSource = new Uri(imagePath);      BitmapImage bitmapImage = new BitmapImage(uriSource);      drawingBrush.Viewport = new Rect(0.0, 0.0, (double)bitmapImage.PixelWidth, (double)bitmapImage.PixelHeight);      drawingBrush.ViewportUnits = BrushMappingMode.Absolute;      PathGeometry widenedPathGeometry = geometry.GetWidenedPathGeometry(new Pen(null, width)      {        StartLineCap = PenLineCap.Round,        EndLineCap = PenLineCap.Round      });      Pen pen = new Pen(drawingBrush, 80.0);      drawingContext.PushClip(widenedPathGeometry);      drawingContext.DrawRectangle(drawingBrush, pen, rc);      drawingContext.Pop();    }  }

2.实例应用

这里我们使用到上篇文章中介绍的多点触摸画板 ,修改其中_startStroke方法中stroke对象的生成，相应代码如下:

bool isTexturePen = true ; // 外部定义的私有变量private void _startStroke(object device, Point inputPosition){ // ... { some code } //==这里根据变量isTexturePen来判断使用默认的stroke还是自定义的stroke Stroke stroke = isTexturePen==true ? new TextureStroke( stylusPointCollection , this._inkCanvas.DefaultDrawingAttributes,"c:\\1.png") : new Stroke(stylusPointCollection);//end// .... { some code }}

3. 结束

  DrawTool系列文章中涉及的代码都是通过修改后的，仅仅适用于demo场景，如果需要商业请自行修改，包括性能上的调整.

原标题：DrawTool画笔之纹理笔

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