checking whether a point is within a polygon should also not be too difficult to implement in an efficient way
A path region is not always a polygon.[^p] For example, it may have a bézier curve along the path.
a point is within a polygon should also not be too difficult to implement in an efficient way
Right, this is useful for implementing GdipIsVisibleRegionPoint *specifically*, but that's not the point of this MR.[^1] This patchset intends to introduce a generic bounding box calculation mechanism so that plenty of other HRgn-computing functions can benefit in the future. GdipIsVisibleRegionPoint is merely an example.[^e]
[^p]: Yes, technically everything is a polygon after rasterization, but this is not very useful here. [^1]: From paragraph 3-4 of the MR description: "The rasterization should be limited to a specific integer rectangle, which in the case of GdipIsVisibleRegionPoint can be 1x1 pixel. We should then be able to eliminate all internal uses of GdipGetRegionHRgn, except when we have to return an HRGN to the application. This would also be useful for implementing anti-aliasing, as we could keep the memory usage down by only rasterizing the part we need for each scanline at a time." [^e]: For 1x1 case only.