DrawRectangle in DrawingGroup's DrawingContext does not support rounded corners

[jroessel]

Describe the bug

var drawing = new DrawingGroup();
using(var ctx = drawing.Open()) {
  ctx.DrawRectangle(Brushes.Green, Pens.Red, new RoundedRect(new Rect(0, 0, 100, 50), 25));
}

results in

This is because DrawingGroup's context implementation simply creates a rectangle geometry without any radii in

Avalonia/src/Avalonia.Base/Media/DrawingGroup.cs

Lines 224 to 231 in 1bce702

	protected override void DrawRectangleCore(IBrush? brush, IPen? pen, RoundedRect rrect, BoxShadows boxShadows = default)
	{
	// Instantiate the geometry
	var geometry = _platformRenderInterface.CreateRectangleGeometry(rrect.Rect);
	// Add Drawing to the Drawing graph
	AddNewGeometryDrawing(brush, pen, new PlatformGeometry(geometry));
	}

As a workaround, DrawGeometry with a RectangleGeometry can be used.

To Reproduce

Create a DrawingGroup, call DrawingGroup.Open to obtain a DrawingContext and call DrawRectangle with a RoundedRect (or one of the other overloads that allows to specify corner radii).

Expected behavior

The specified corner radii should be honored.

Avalonia version

11.3.10

OS

Windows

Additional context

No response