Question

I have a GraphicsPath that represents a letter. I want to check whether it intersects with a RectangleF but it is too slow to use Region.Intersect
I’m willing to sacrifice accuracy for speed so I thought if I could split the letter into a certain number of rectangle (say for example 2, which cover most of the letter e.g. split a P into 2 rectangles one for the stem and one for the head) and then compare against these. As I will be doing 1000s of compares it will be quicker. What would be the best way to chop up a graphics path into a number of rectangles that best cover the occupied space (i.e. for a p it would be a wider one for the head and a longer thiner one for the tail).

Edit: I guess you could also think about it in reverse, i.e. how can I get the e.g. 2 biggest rectangles that are within the bounds of a graphics path but do not overlap with it.

Answer 1

The intermediate steps are the Region(GraphicsPath) constructor and the Region.GetRegionScans() method. That ought to be faster by decomposing the Region to rectangles just once, testing against the returned RectangleF[] thousands of time. You can reduce the number of rectangles by passing a matrix that scales the region down.