How to draw a collection of points as separate circles? - wpf

Question

My view model has a PointCollection property like this:
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)));
}
}
}
This is usually shown as a polyline:
<Polyline Points="{Binding Points}" Stroke="Black" StrokeThickness="2"/>
How would I efficiently show it as a collection of separate circles?
It may well be done by an ItemsControl with e.g. a Path element with an EllipseGeometry in its ItemTemplate, however that would involve a large number of UI elements, which may not perform well for a large number of Points in the PointsCollection.

Answer 1

A Binding Converter like shown below could convert an IEnumerable<Point> into a StreamGeometry that consists of a set of zero-length lines.
These could be drawn as circles by a Path with StrokeStartLineCap and StrokeEndLineCap set to 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();
}
}
The Path would look like this:
<Path Data="{Binding Points, Converter={StaticResource LinePointsConverter}}"
Stroke="Black" StrokeThickness="5"
StrokeStartLineCap="Round" StrokeEndLineCap="Round"/>