Painting on PDFViewWPF

[David]

I try to paint in my WPF PDF viewer.

If no PDF is loaded, this works. 

When i opened a file, the painted things are not longer visible.

I would like that my red rectangle drawn (and displayed), even if a file is opened.

That's my OnRender Method, what i'm doing wrong?

public class PDFView : PDFViewWPF

{

// ...

#region Drawing

protected override void OnRender(DrawingContext drawingContext)

{

  Trace.WriteLine("PDFView: OnRender");

  base.OnRender(drawingContext);

  drawingContext.DrawRectangle(Brushes.Red, new Pen(Brushes.Black, 0), new System.Windows.Rect(150, 150, 100, 100));

}

#endregion Drawing

// ...

 }

[Support]

 

The answer is given by Chales Petzold here. His answer is 'don't know why', however a comment correctly suggests that setting the window's Background to transparent fixes the bug. It is possible that Grid generates this problem. Default Window contains a Grid element.

[Support]

 

Also,

see http://social.msdn.microsoft.com/forums/en-US/wpf/thread/750e91c2-c370-4f0a-b18e-892afd99bd9b