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.

Answer 1

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);
        }