WPF faster DrawingVisuals initialization.

[Polykar]

Hello, We are planning to migrate to WPF. For a few use cases, drawingspeed is an issue. Drawing 10'000 mostly static lines on a zoomable/panable canvas is about as much as I need. Using DrawingVisuals, the performance is not acceptable, because the initialization takes around 10 seconds (which is ridiculous). After the initalization, the paning/zooming works fine. Please have a look at my sample code and tell me which part is terribly wrong...

        Pen pen = new Pen(Brushes.Red, 5);
        Random random = new Random();

        DrawingVisual visual = new DrawingVisual();
        using (DrawingContext dc = visual.RenderOpen())
        {
            for (int i = 0; i < 10000; i++)
            {
                Point p1 = new Point(random.Next(0, 5000), random.Next(0, 5000));
                Point p2 = new Point(random.Next(0, 100), random.Next(0, 100));
                dc.DrawLine(pen, p1, new Point(p1.X - p2.X, p1.Y - p2.Y));
            }
            dc.Close();
        }            
        MyCanvas.AddVisual(visual);

where MyCanvas is an overload of Canvas

using System.Collections.Generic;
using System.Windows.Controls;
using System.Windows.Media;

namespace WpfApplication1
{
public class DrawingCanvas : Canvas
{
private List _visuals = new List();

    protected override int VisualChildrenCount
    {
        get
        {
            return \_visuals.Count;
        }
    }

    protected override Visual GetVisualChild(int index)
    {
        return \_visuals\[index\];
    }

    public void AddVisual(Visual visual)
    {
        \_visuals.Add(visual);
        base.AddVisualChild(visual);
        base.AddLogicalChild(visual);
    }
}

}

thanks a lot. regards. mike.

[lneir]

This is an old discussion but might be helpful for you: drawingcontext very slow many geometries

[Polykar]

Thanks a lot. Freezing the Pen did the Trick.