[Gtk-sharp-list] Strange Behaviour with Graphics.Clear and Graphics.DrawImage

Aaron Radich aaron at radich.com
Fri Jul 30 13:34:20 EDT 2010

I'm seeing some strange behavior when debugging Graphics.Clear() and
Graphics.DrawImage() method calls in my Render() method code below.  The
first time Render is called it works fine.  The 2nd time the call to
Graphics.Clear caused the debugger to jump down X lines to the
"         g.DrawImage(rightImage, xr, yr);" line.  When
Graphics.DrawImage is called, the application is then killed without an
exception being raised.  Any idea what might be going on? 
"buffer" is defined as a
void Render()
   if (buffer.GdkWindow == null)

   // Init the placement values
   if (x == -1)

      x = (sceneWidth / 2) - (centerImage.Width / 2);
      y = sceneHeight / 10;
      yl = y;
      yr = y;

   using (Graphics g =
Gtk.DotNet.Graphics.FromDrawable(buffer.GdkWindow, true)) 
      // the next statement works the first time Render() is called, but
the 2nd time it forces the debugger to
      // jump down do
'g.DrawImage(rightImage, xr, yr);', where that statment then kills the
      // no exception is raised
      // first draw the center image
g.DrawImage(centerImage, x, y - centerGrowRate);

(leftImage != null) 
         // next we do the left
         xl = x - objectSeparation - leftImage.Width;
         g.DrawImage(leftImage, xl, yl);

if (rightImage != null) 
         // finally the right
         xr = x + objectSeparation +
         // the next line kills the application
on the 2nd call to Render()
         g.DrawImage(rightImage, xr,
   } // using Graphics

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