利用WPF制作一個(gè)背景燈光隨鼠標(biāo)閃動(dòng)效果

<Canvas x:Name="container" Width="400" Height="400"></Canvas>

/// <summary>
/// MainWindow.xaml 的交互邏輯
/// </summary>
 public partial class MainWindow : Window
 {
  private Point lastMousePosition = new Point(0, 0);//鼠標(biāo)位置
  private int triangleLength = 100;//三角形邊長(zhǎng)
 
  public MainWindow()
  {
   InitializeComponent();
   this.Loaded += MainWindow_Loaded;
   CompositionTarget.Rendering += UpdateTriangle;
   this.container.PreviewMouseMove += UpdateLastMousePosition;
  }
 
  private void MainWindow_Loaded(object sender, RoutedEventArgs e)
  {
   //將長(zhǎng)方形容易劃分成組合三角形
   int horizontalCount = (int)(this.container.ActualWidth / triangleLength);
   int verticalCount = (int)(this.container.ActualHeight / triangleLength);
   for (int i = 0; i < horizontalCount; i++)
   {
    for (int j = 0; j < verticalCount; j++)
    {
     Path trianglePath2 = new Path();
     var g1 = new StreamGeometry();
     using (StreamGeometryContext context = g1.Open())
     {
      context.BeginFigure(new Point(i * triangleLength, j * triangleLength), true, true);
      context.LineTo(new Point(i * triangleLength, (j + 1) * triangleLength), true, false);
      context.LineTo(new Point((i + 1) * triangleLength, (j + 1) * triangleLength), true, false);
     }
     trianglePath2.Data = g1;
     trianglePath2.Fill = new SolidColorBrush(Color.FromArgb(255, 247, 18, 65));
     this.container.Children.Add(trianglePath2);
 
     Path trianglePath3 = new Path();
     var g2 = new StreamGeometry();
     using (StreamGeometryContext context = g2.Open())
     {
      context.BeginFigure(new Point(i * triangleLength, j * triangleLength), true, true);
      context.LineTo(new Point((i + 1) * triangleLength, j * triangleLength), true, false);
      context.LineTo(new Point((i + 1) * triangleLength, (j + 1) * triangleLength), true, false);
     }
     trianglePath3.Data = g2;
     trianglePath3.Fill = new SolidColorBrush(Color.FromArgb(255, 247, 18, 65));
     this.container.Children.Add(trianglePath3);
    }
   }
  }
 
  private void UpdateTriangle(object sender, EventArgs e)
  {
   //獲取子控件
   List<Path> childList = GetChildObjects<Path>(this.container);
   for (int i = 0; i < childList.Count; i++)
   {
    for (int j = 1; j < childList.Count; j++)
    {
     string si = childList[i].Data.ToString();
     string si1 = MidStrEx(si, "M", "L");
     string si2 = MidStrEx(si, "L", " ");
     string si3 = MidStrEx(si, " ", "z");
     string sj = childList[j].Data.ToString();
     string sj1 = MidStrEx(sj, "M", "L");
     string sj2 = MidStrEx(sj, "L", " ");
     string sj3 = MidStrEx(sj, " ", "z");
     //左右三角形判斷
     if (si1 == sj1 && si3 == sj3)
     {
      double x = childList[i].Data.Bounds.X + (1 - Math.Pow(2, 0.5) / 2) * triangleLength - lastMousePosition.X;
      double y = childList[i].Data.Bounds.Y + (1 - Math.Pow(2, 0.5) / 2) * triangleLength - lastMousePosition.Y;
      double rRadio = 1 - Math.Pow(x * x + y * y, 0.5) / Math.Pow(this.container.ActualWidth * this.container.ActualWidth + this.container.ActualHeight * this.container.ActualHeight, 0.5);
      childList[j].Fill = new SolidColorBrush(Color.FromArgb((byte)(255 * rRadio), 247, 18, 65));
      x = childList[j].Data.Bounds.TopRight.X - (1 - Math.Pow(2, 0.5) / 2) * triangleLength - lastMousePosition.X;
      rRadio = 1 - Math.Pow(x * x + y * y, 0.5) / Math.Pow(this.container.ActualWidth * this.container.ActualWidth + this.container.ActualHeight * this.container.ActualHeight, 0.5);
      childList[i].Fill = new SolidColorBrush(Color.FromArgb((byte)(255 * rRadio), 247, 18, 65));
      break;
     }
    }
   }
  }
 
  private void UpdateLastMousePosition(object sender, MouseEventArgs e)
  {
   lastMousePosition = e.GetPosition(this.container);
  }
 
  /// <summary>
  /// 獲得所有子控件
  /// </summary>
  private List<T> GetChildObjects<T>(System.Windows.DependencyObject obj) where T : System.Windows.FrameworkElement
  {
   System.Windows.DependencyObject child = null;
   List<T> childList = new List<T>();
   for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
   {
    child = VisualTreeHelper.GetChild(obj, i);
    if (child is T)
    {
     childList.Add((T)child);
    }
    childList.AddRange(GetChildObjects<T>(child));
   }
   return childList;
  }
 
  /// <summary>
  /// 截取兩個(gè)指定字符中間的字符串
  /// </summary>
  public static string MidStrEx(string sourse, string startstr, string endstr)
  {
   string result = string.Empty;
   int startindex, endindex;
   try
   {
    startindex = sourse.IndexOf(startstr);
    if (startindex == -1)
     return result;
    string tmpstr = sourse.Substring(startindex + startstr.Length);
    endindex = tmpstr.IndexOf(endstr);
    if (endindex == -1)
     return result;
    result = tmpstr.Remove(endindex);
   }
   catch (Exception ex)
   {
   }
   return result;
  }
}