Rectangle/Path Intersection

[G-Man]

Is there a quick way if supplied with a System.Drawing.Rectangle or RectangleF and a closed System.Drawing.Drawing2d.GraphicsPath (comprised only of lines), to derive the path (or paths) that an intersection of the two would create?

If you look at the attached file, Path.Jpg you see a closed path. Looking at the file Clipping.jpg shows that path being intersected by a rectangle and Result.Jpg shows the resulting paths created by the intersection.

So, if the function declaration looked like:

Private Function CropPath(ByVal SrcPath As GraphicsPath, ByVal Rect As RectangleF) As PathIntersection

...and the returned structure looked like:

Public Structure PathIntersection

​

Public PathCount As Integer
Public Paths() As System.Drawing.Drawing2D.GraphicsPath
​

End Structure

Is there a quick way to impliment this?

 

[vis781]

Yea, you need to create a region from the path and use the Region.Complement method (mmm I think, thing is there's a couple of different methods in the region class and one of them does what you want. I'm sure it's the Complement method.

 

[G-Man]

Don't those region methods return regions and not paths? ...Or is there some way to convert regions back to paths?

 

[JohnH]

The Region methods don't return anything, they are sub methods that modifies the existing region (self) with the used method and input data. I don't think there is a way back from Region to GraphicsPath, but you can set the Graphics.Clip to the Region.

 

[vis781]

There may be a way back with the GetRegionData Function. Cheers JohnH i was a bit unsure about the exact usage but i knew i was heading the the right direction. It's been a while since i played around with the region class.