C# 如何定期向画布添加随机线？

我需要一张画布，用彩色线条填充，长度随机选择，

Stroke

，

StrokeThickness

和

Opacity

。最好采用MVVM方法，并根据父窗口的

宽度

和

高度

的变化进行调整

主窗口

ViewModelLine _viewModel;
private List<Brush> _brushes;
Random _rand;
public MainWindow()
{
    this.InitializeComponent();
    _viewModel = new ViewModelLine();
    this.DataContext = _viewModel;
    _rand = new Random();
    _brushes = new List<Brush>();
    var props = typeof(Brushes).GetProperties(BindingFlags.Public | BindingFlags.Static);
    foreach (var propInfo in props)
        _brushes.Add((Brush)propInfo.GetValue(null, null));
    int interval = 10;
    Task.Factory.StartNew(() =>
    {
        while (true)
        {
             System.Threading.Thread.Sleep(interval);
             Dispatcher.Invoke(new Action(() => AddNew()));
        }
     });
}

void AddNew()
{
    int w = (int)ActualWidth;
    int h = (int)ActualHeight;
    _viewModel.Models.Add(new ModelLine() {
         X1 = _rand.Next(1, w),
         X2 = _rand.Next(1, w),
         Y1 = _rand.Next(1, h),
         Y2 = _rand.Next(1, h),
         Thickness = _rand.Next(1, 4),
          Opacity = _rand.NextDouble(),
          Brush = _brushes[_rand.Next(_brushes.Count)]
    });
}

<Grid> 
    <ItemsControl DockPanel.Dock="Bottom" DataContext="{Binding}" ItemsSource="{Binding Models}">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Line X1="{Binding X1}" X2="{Binding X2}" Y1="{Binding Y1}" Y2="{Binding Y2}" 
                  Stroke="{Binding Brush}" StrokeThickness="{Binding Thickness}" Opacity="{Binding Opacity}"/>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
        <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
                <Canvas />
            </ItemsPanelTemplate>
        </ItemsControl.ItemsPanel>
    </ItemsControl>
</Grid>

public class ViewModelLine
{
    public ViewModelLine()
    {
        _models = new ObservableCollection<ModelLine>();
    }
    ObservableCollection<ModelLine> _models;
    public ObservableCollection<ModelLine> Models { get { return _models; } set { _models = value; } }

}

public class ModelLine : INotifyPropertyChanged
{
    int _x1;
    public int X1 { get { return _x1; } set { _x1 = value; RaisePropertyChanged("X1"); } }

    int _x2;
    public int X2 { get { return _x2; } set { _x2 = value; RaisePropertyChanged("X2"); } }

    int _y1;
    public int Y1 { get { return _y1; } set { _y1 = value; RaisePropertyChanged("Y1"); } }

    int _y2;
    public int Y2 { get { return _y2; } set { _y2 = value; RaisePropertyChanged("Y2"); } }

    double _opacity;
    public double Opacity { get { return _opacity; } set { _opacity = value; RaisePropertyChanged("Opacity"); } }

    Brush _brush;
    public Brush Brush { get { return _brush; } set { _brush = value; RaisePropertyChanged("Brush"); } }

    double _thickness;
    public double Thickness { get { return _thickness; } set { _thickness = value; RaisePropertyChanged("Thickness"); } }

    public event PropertyChangedEventHandler PropertyChanged;
    void RaisePropertyChanged(string propname)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propname));
    }
}