[RESOLVED] Opposite region

[madsun]

Hiya

Ive painted a circle inside a usercontrol, and derived graphicspath and a region from it. Now, i want the exact opposite of my current region. I want to use fillregion to fill whats outside the region. Ideas please?

Current code:

			Graphics gfx = this.CreateGraphics();
			gfx.Clear(this.BackColor);
			Pen myPen = new Pen(Color.Green);
			gfx.SmoothingMode=SmoothingMode.HighQuality;
			gfx.DrawEllipse(myPen,0,0,this.Width ,this.Height ); 

			//gfx.DrawLine(myPen,this.Width,this.Height/2,0,this.Height/4);

			GraphicsPath r = new GraphicsPath();
			r.AddEllipse(0,0,this.Width,this.Height);
			Region aa = new Region(r);
			
			SolidBrush myBrush = new SolidBrush(Color.Red);
 
			gfx.FillRegion(myBrush,aa);

[jmcilhinney]

Make use of the Region.Complement method. Create a Region for the entire area and a Region for the area you want to cut out, then pass the smaller Region to the larger Region's Complement method. The larger Region will then be the area of non-intersection of the two. This is all theoretical though, as I've never done it myself. I just went to the MSDN library and checked to see what members the Region class had and there it was.

[madsun]

Cool, works great!

Final code:

			
			Graphics gfx = this.CreateGraphics();
			gfx.Clear(this.BackColor);
			Pen myPen = new Pen(Color.Green);
			 gfx.DrawEllipse(myPen,0,0,this.Width ,this.Height ); 

			//gfx.DrawLine(myPen,this.Width,this.Height/2,0,this.Height/4);

			GraphicsPath r = new GraphicsPath();
			
			r.AddEllipse(0,0,this.Width,this.Height);
			Region aa = new Region(r);
			
			SolidBrush myBrush = new SolidBrush(Color.Red);
 
			gfx.DrawLine(myPen,this.Width,this.Height/2,0,this.Height/4);
			Region bb = new Region();
			 

			aa.Complement(bb);

			gfx.FillRegion(myBrush,aa);