| commit | 2c87ebf6827eb57376d7cf2c314492b4051ef81f | [log] [tgz] |
|---|---|---|
| author | Jonah Williams <jonahwilliams@google.com> | Fri Oct 25 09:05:52 2024 -0700 |
| committer | GitHub <noreply@github.com> | Fri Oct 25 16:05:52 2024 +0000 |
| tree | d875e81e9c8bc0b3dce48648b08037e0991dfe14 | |
| parent | ecfdd290066a0fc3cd4cfaefe0b3b44b472946c0 [diff] |
[Impeller] Reland: hash less stuff per frame. (#55742) Reverted due to missing glyph when rolling into the framework. Problem was that we should be always using the unrounded rounded scale to compute subpixel position but we sometimes used the rounded scale. --- Currently we have multiple stages of hashing while font rendering, which is relatively expensive for the actualy required workload. First, we hash the contents of all text frames to compute the unique set of glyphs per frame. Then we diff this hash set against the hashmap of glyphs within the atlas. Finally we hash and lookup the final rendered bounds for each glyph. We can simplify this to 2. hash lookups for glyphs not yet in the atlas and 1. hash lookup for glyphs that are in the atlas. This is done by combing the step where we uniquely compute glyphs per frame with the diff against the current atlas. When this lookup is performed, we also store the glyph position (if found) in the text_frame itself - which allows text contents to skip the last hash, as long as the glyph has already been rendered. See https://github.com/flutter/engine/pull/55092
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