Hi, In the last months we have been working on refactoring the MathML layout code to make it more maintainable, because in the current point fixing issues or adding new features has been too complex.
We have reached the point where we think we have to discuss whether this work makes sense and whether it is interesting for the WebKit community. If so, we will start pushing the initial patches from our branch to upstream. The idea behind the refactor is to remove FlexBox dependency and create its own layout MathML methods. The main reasons to do this are: - Reduce code complexity: Adapting FlexBox layout (which is already complex) in order to create the MahtML layout made the code too complex, a big technical debt that made the improvement of MathML more difficult every day. - Avoid just another FlexBox dependent code: When we had to add general layout alignment support we had a lot of problems trying to solve some the MathML issues because it was not clear how it worked with the FlexBox. - Improve performance: We do not need all the features FlexBox layout adds for most of the MathML blocks but we are executing all that code. We also can simplify the render tree structures that were created to make the FlexBox layout work. - Make easier to improve the MathML implementation: Using independent renderer classes gives more flexibility to get exact positioning and spacing required to get high-quality math rendering based on TeX rules and the OpenType MATH table. (cf http://www.mathml-association.org/MathMLinHTML5/) We have a working prototype that basically passes the current MathML tests and removes the FlexBox dependency in: https://github.com/alexgcastro/webkit/tree/MathMLLayout We have basically one commit per MathML renderer that we had to replace. This is still initial code and we need more work and add more tests to make sure we are improving the situation. We want to do it incrementally with 2 steps: 1. Remove FlexBox dependency but do not break the tests, this means keep the RenderTree structure. This is basically done, and we just need review and try to push them. 2. Refactor the RenderTree structure, removing the anonymous nodes created to make FlexBox work and all the code that it was required. We already have the Fractions and Underover implemented and the code is much clearer. This will break the tests relying on a PNG image or a render tree reference. Hence we will do it also per renderer and rebasing the tests after each commit. The main con of the change that the code could be bigger in some parts of the renderers, but more direct and simple, so it should be actually good regarding maintenance. If you have any question, proposal or comment just send it, it would be great to hear some more feedback, and check if we should proceed with this effort. Greetings, Alex _______________________________________________ webkit-dev mailing list email@example.com https://lists.webkit.org/mailman/listinfo/webkit-dev