How to replace DrawClosedCurve / FillClosedCurve when moving from WinForms (GDI+) to WPF?

Question

I've got an array of points (X,Y) which constitute a convex hull (a simple, irregularly shaped contour). Rather than rendering a polygon with straight edges, I want to render them with an approximate "smoothly curved" contour that passes through all of these points.

In WinForms/GDI+, this could be accomplished with the Graphics.DrawClosedCurve or Graphics.FillClosedCurve methods. There does not appear to be an equivalent in WPF.

I've looked into drawing using things like Path and BezierSegment, but I'm not sure if (and how) these can be used to generate a continuous closed curve, given a set of points. It appears that to do this, I'd perhaps have to generate a set of control points based on my contour as an intermediate step?

I have tried using the GDI+ methods to render onto a System.Drawing.Bitmap and then displaying that in the WPF application. This works, but the performance (particularly the conversion from System.Drawing.Bitmap to BitmapSource) is poor and not sufficient for the application. This is why I'm looking for a pure WPF solution.

Has anyone been able to draw a closed curve based off a set of points in WPF?

Answer 1

Unfortunately, there is no single-method equivalent to DrawClosedCurve in WPF, even though it's been requested. So you are left with at least two options:

• Host a native window within your WPF window and perform all your drawing on it.
• Implement your own cardinal spline drawing. You are on the right track with Bezier segments. However, there are existing implementations of it you can look at out there.