is_rectilinear

Checks if all corners of this are right angles and the rectangle covers all of its bounds.

This information can be used to decide if [ctor@Gsk.ClipNode.new] or [ctor@Gsk.RoundedClipNode.new] should be called.

Parameters:

this	the `GskRoundedRect` to check

Returns:

true if the rectangle is rectilinear