Re: Trim ellipse
A suggestion, but needs a little work. Assuming you have used an equation to calculate all of the points in your foreground ellipse and they are in pt and you are drawing in response to a Paint message and hence have the Graphics g.
Draw the foreground ellipse.
Create a GraphicsPath gp, using the points in pt.
Create a Region r passing gp in the constructor.
Do a g.ExcludeClip(r) to prevent painting in the Region r.
Draw the background ellipse.
I got it to work using the bounding Rectangle of the foreground ellipse to create the Region, but that is not exactly what you want.
Hope this helps.
Ohhhhh.... Old McDonald was dyslexic, E O I O EEEEEEEEEE.......