Hi Alex, I think this refactoring makes a lot of sense. This is very close to what I wanted to do with MathML four years ago so I'm very happy to hear that you're taking the initiative here.
- R. Niwa On Wed, Dec 9, 2015 at 3:35 AM, Alejandro Garcia Castro <a...@igalia.com> wrote: > > 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 > webkit-dev@lists.webkit.org > https://lists.webkit.org/mailman/listinfo/webkit-dev _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org https://lists.webkit.org/mailman/listinfo/webkit-dev
