public class Particle
 {
  /// <summary>
  /// 形狀
  /// </summary>
  public Ellipse Shape;
  /// <summary>
  /// 坐標
  /// </summary>
  public Point Position;
}

/// <summary>
/// 粒子路徑
/// </summary>
private Geometry particleGeometry;
 
/// <summary>
/// 粒子個數(shù)
/// </summary>
private int particleCount = 100;
 
/// <summary>
/// 粒子最小尺寸
/// </summary>
private static int sizeMin = 10;
 
/// <summary>
/// 粒子最大尺寸
/// </summary>
private int sizeMax = 20;
 
/// <summary>
/// 隨機數(shù)
/// </summary>
private Random random;
 
/// <summary>
/// 粒子列表
/// </summary>
private List<Particle> particles;
 
/// <summary>
/// 粒子容器
/// </summary>
private Canvas containerParticles;
 
 
  public ParticleSystem(Geometry _path, int _maxRadius, int _particleCount, Canvas _containerParticles)
  {
   particleGeometry = _path;
   particleCount = _particleCount;
   sizeMax = _maxRadius;
   containerParticles = _containerParticles;
   random = new Random();
   particles = new List<Particle>();
   SpawnParticle();
  }
 
  /// <summary>
  /// 初始化粒子
  /// </summary>
  private void SpawnParticle()
  {
   //清空粒子隊列
   particles.Clear();
   containerParticles.Children.Clear();
 
   //生成粒子
   for (int i = 0; i < particleCount; i++)
   {
    double size = random.Next(sizeMin, sizeMax + 1);
    while(true)
    {
     Point po = new Point(random.Next((int)particleGeometry.Bounds.Left, (int)particleGeometry.Bounds.Right), random.Next((int)particleGeometry.Bounds.Top, (int)particleGeometry.Bounds.Bottom));
     if (particleGeometry.FillContains(po, 2, ToleranceType.Absolute))
     {
      Particle p = new Particle
      {
       Shape = new Ellipse
       {
        Width = size,
        Height = size,
        Stretch = System.Windows.Media.Stretch.Fill,
        Fill = GetRandomColorBursh(),
       },
       Position = po,
      };
      SetParticleSizeAnimation(p.Shape);
      particles.Add(p);
      Canvas.SetLeft(p.Shape, p.Position.X);
      Canvas.SetTop(p.Shape, p.Position.Y);
      containerParticles.Children.Add(p.Shape);
      break;
     }
    }
   }
  }
 
  /// <summary>
  /// 設置粒子大小動畫
  /// </summary>
  private void SetParticleSizeAnimation(Ellipse p)
  {
   Storyboard sb = new Storyboard();
   //動畫完成事件 再次設置此動畫
   sb.Completed += (S, E) =>
   {
    SetParticleSizeAnimation(p);
   };
   int size = random.Next(sizeMin, sizeMax + 1);
   int time = random.Next(100, 1000);
   DoubleAnimation daX = new DoubleAnimation(size, new Duration(TimeSpan.FromMilliseconds(time)));
   DoubleAnimation daY = new DoubleAnimation(size, new Duration(TimeSpan.FromMilliseconds(time)));
   Storyboard.SetTarget(daX, p);
   Storyboard.SetTarget(daY, p);
   Storyboard.SetTargetProperty(daX, new PropertyPath("Width"));
   Storyboard.SetTargetProperty(daY, new PropertyPath("Height"));
   sb.Children.Add(daX);
   sb.Children.Add(daY);
   sb.Begin();
  }
 
  /// <summary>
  /// 獲取隨機顏色畫刷
  /// </summary>
  private SolidColorBrush GetRandomColorBursh()
  {
   byte r = (byte)random.Next(128, 256);
   byte g = (byte)random.Next(128, 256);
   byte b = (byte)random.Next(128, 256);
   return new SolidColorBrush(Color.FromArgb(125, r, g, b));
}

private ParticleSystem ps;
 
public MainWindow()
  {
   InitializeComponent();
   this.Loaded += MainWindow_Loaded;
  }
 
  private void MainWindow_Loaded(object sender, RoutedEventArgs e)
  {
   Geometry g = CreateTextPath("H E L L O", new Point(this.cvs_particleContainer.Margin.Left, this.cvs_particleContainer.Margin.Top), new Typeface(new FontFamily("Arial"), FontStyles.Normal, FontWeights.Bold, FontStretches.Normal), 200);
   ps = new ParticleSystem(g, 25, 350, this.cvs_particleContainer);
  }
 
  /// <summary>
  /// 創(chuàng)建文本路徑
  /// </summary>
  /// <param name="word">文本字符串</param>
  /// <param name="point">顯示位置</param>
  /// <param name="typeface">字體信息</param>
  /// <param name="fontSize">字體大小</param>
  /// <returns></returns>
  private Geometry CreateTextPath(string word, Point point, Typeface typeface, int fontSize)
  {
   FormattedText text = new FormattedText(word, new System.Globalization.CultureInfo("en-US"), FlowDirection.LeftToRight, typeface, fontSize, Brushes.Black);
   Geometry g = text.BuildGeometry(point);
   PathGeometry path = g.GetFlattenedPathGeometry();
   return path;
}