Monday, 10 May 2010

Intersection of two WPF geometries

I needed to determine the intersection point of a Rectangle and a Bezier curve. I found the following code here.

I've included the code below in case the link is lost in the future.
public static Point[] GetIntersectionPoints(Geometry g1, Geometry g2)
{
Geometry og1 = g1.GetWidenedPathGeometry(new Pen(Brushes.Black, 1.0));
Geometry og2 = g2.GetWidenedPathGeometry(new Pen(Brushes.Black, 1.0));

CombinedGeometry cg = new CombinedGeometry(GeometryCombineMode.Intersect, og1, og2);
PathGeometry pg = cg.GetFlattenedPathGeometry();
Point[] result = new Point[pg.Figures.Count];

for (int i = 0; i < pg.Figures.Count; i++)
{
Rect fig = new PathGeometry(new PathFigure[] { pg.Figures[i] }).Bounds;
result[i] = new Point(fig.Left + fig.Width / 2.0, fig.Top + fig.Height / 2.0);
}
return result;
}

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