Hacker News Reader

Does anyone know why there are two different font paths and how WebCore chooses which one to use? I assume the difference between fast and complex would be very platform dependent.

View on HN

The fast path is for most languages where the text glyphs are placed in order. The complex path is for languages where the shape and size of a glyph depends on the characters around it. For example, Arabic text or Thai text would go through the complex code path. There are some other cases where the complex text path is used (I think "text-rendering: optimizeLegibility" forces the complex text path).

In Safari and most of the time on Chromium Mac, the complex code path is handled by CoreText. In other Chromium ports and on Blackberry, complex text is handled by Harfbuzz-NG, which is also used by Firefox.

The fast path is much faster and handles the common case. The complex path is, well, complex, but it's the "all sing, all dance" path that handles all the difficult cases.

Reply on news.ycombinator.com