An algorithm for inflating/deflating (offsetting, buffering) polygons

Question

How would I "inflate" a polygon? That is, I want to do something similar to this:

<

Answer 1

Big thanks to Angus Johnson for his clipper library. There are good code samples for doing the clipping stuff at the clipper homepage at http://www.angusj.com/delphi/clipper.php#code but I did not see an example for polygon offsetting. So I thought that maybe it is of use for someone if I post my code:

    public static List GetOffsetPolygon(List originalPath, double offset)
    {
        List resultOffsetPath = new List();

        List polygon = new List();
        foreach (var point in originalPath)
        {
            polygon.Add(new ClipperLib.IntPoint(point.X, point.Y));
        }

        ClipperLib.ClipperOffset co = new ClipperLib.ClipperOffset();
        co.AddPath(polygon, ClipperLib.JoinType.jtRound, ClipperLib.EndType.etClosedPolygon);

        List> solution = new List>();
        co.Execute(ref solution, offset);

        foreach (var offsetPath in solution)
        {
            foreach (var offsetPathPoint in offsetPath)
            {
                resultOffsetPath.Add(new Point(Convert.ToInt32(offsetPathPoint.X), Convert.ToInt32(offsetPathPoint.Y)));
            }
        }

        return resultOffsetPath;
    }