wpf - 如何将一组点绘制为单独的圆圈？

Question

我的 View 模型有一个 PointCollection 属性，如下所示:

public class ViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private PointCollection points;
    public PointCollection Points
    {
        get { return points; }
        set
        {
            points = value;
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Points)));
        }
    }
}

这通常显示为折线:

<Polyline Points="{Binding Points}" Stroke="Black" StrokeThickness="2"/>

我如何有效地将其显示为单独圆圈的集合？

它可以通过 ItemsControl 来完成，例如在其 ItemTemplate 中具有 EllipseGeometry 的 Path 元素，但是这将涉及大量 UI 元素，这对于 PointsCollection 中的大量点可能效果不佳。

Answer 1

如下所示的绑定(bind)转换器可以转换 IEnumerable<Point>变成 StreamGeometry它由一组长度为零的线组成。

这些可以通过带有 StrokeStartLineCap 的路径绘制为圆形。和 StrokeEndLineCap设置为 Round .

public class LinePointsConverter : IValueConverter
{
    public object Convert(
        object value, Type targetType, object parameter, CultureInfo culture)
    {
        var geometry = new StreamGeometry();
        var points = value as IEnumerable<Point>;

        if (points != null && points.Any())
        {
            using (var sgc = geometry.Open())
            {
                foreach (var point in points)
                {
                    sgc.BeginFigure(point, false, false);
                    sgc.LineTo(point, true, false);
                }
            }
        }

        return geometry;
    }

    public object ConvertBack(
        object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

路径看起来像这样:

<Path Data="{Binding Points, Converter={StaticResource LinePointsConverter}}"
      Stroke="Black" StrokeThickness="5"
      StrokeStartLineCap="Round" StrokeEndLineCap="Round"/>