Drawing polygon with more than one hole?

Question

I'm trying to draw a polygon with more than one holes. I tried the following code and it does not work correctly. Please advise.

    PointF[] mypoly = new PointF[6 + 5 + 5];

    mypoly[0] = new PointF(0, 0);
    mypoly[1] = new PointF(100, 0);
    mypoly[2] = new PointF(100, 100);
    mypoly[3] = new PointF(0, 100);
    mypoly[4] = new PointF(10, 80);
    mypoly[5] = new PointF(0, 0);

    mypoly[6] = new PointF(10, 10);
    mypoly[7] = new PointF(10, 20);
    mypoly[8] = new PointF(20, 20);
    mypoly[9] = new PointF(20, 10);
    mypoly[10] = new PointF(10, 10);

    mypoly[11] = new PointF(40, 10);
    mypoly[12] = new PointF(40, 20);
    mypoly[13] = new PointF(60, 20);
    mypoly[14] = new PointF(60, 10);
    mypoly[15] = new PointF(40, 10);

    g.FillPolygon(new SolidBrush(Color.Red), mypoly, FillMode.Winding);

The first part is the outer polygon. The second and the third parts are the two holes inside the polygon.

What did you get? Is there any reason this can't be 3 separate poly's? — Andrew Cooper, Oct 26 '10 at 06:04
What have you tried for FillMode? That controls how intersections are rendered. — , Oct 26 '10 at 06:28
Why not draw outer polygon in one color and inner one in 'background' color? — Daniel Mošmondor, Oct 27 '10 at 10:02

score 11 · Accepted Answer · edited Sep 29 '15 at 11:28

Use a GraphicsPath instead. You can draw it with Graphics.FillPath, like this:

using System.Drawing.Drawing2D;
...
    using (var gp = new GraphicsPath()) {
        PointF[] outer = new PointF[] { new PointF(0, 0), new PointF(100, 0), 
            new PointF(100, 100), new PointF(0, 100), new PointF(10, 80),new PointF(0, 0) };
        gp.AddPolygon(outer);  
        PointF[] inner1 = new PointF[] { new PointF(10, 10), new PointF(10, 20), 
            new PointF(20, 20), new PointF(20, 10), new PointF(10, 10) };
        gp.AddPolygon(inner1);
        PointF[] inner2 = new PointF[] { new PointF(40, 10), new PointF(40, 20), 
            new PointF(60, 20), new PointF(60, 10), new PointF(40, 10) };
        gp.AddPolygon(inner2);
        e.Graphics.FillPath(Brushes.Black, gp);
    }

I had found a solution before reading your answer. It's right on the FillPath reference page of the Microsoft website. They had the same answer as yours. — Mark Attwood, Oct 27 '10 at 22:42

Drawing polygon with more than one hole?

1 Answers1

Linked