Hans has been working on implementing Exclusions for WebKit and has been writing a series of blog posts that outline the rationale for the choices he made while implementing the features. This week he discusses the rationale for why Exclusion Shapes have their own internal co-ordinate system. WeKit has two kinds of co-ordinate systems – logical and physical.
Shapes used in Exclusions are specified in terms of the physical co-ordinate system, but the implementation itself requires a conversion to the Logical one and Hans describes in detail why he has instead opted to use an internal co-ordinate system that is private to ExclusionShape implementation to which both the co-ordinate systems are converted to.
Read more on Hans Muller’s blog