author Alexis Beingessner <>
Mon, 19 Jun 2017 10:58:28 -0400
changeset 424982 564959d26e8db243ded3d57380842620e60e89e7
parent 346136 3ec6380fca8207fa199693206a3ca24975bf9833
child 516934 625f71135038f79c075f758e316fbb00097c9a18
permissions -rw-r--r--
Bug 1357545 - handle text-shadows/decorations with webrender (layers-free) r=jrmuizel This replaces our DrawTargetCapture hack with a similar but more powerful TextDrawTarget hack. The old design had several limitations: * It couldn't handle shadows * It couldn't handle selections * It couldn't handle font/color changes in a single text-run * It couldn't handle decorations (underline, overline, line-through) Mostly this was a consequence of the fact that it only modified the start and end of the rendering algorithm, and therefore couldn't distinguish draw calls for different parts of the text. This new design is based on a similar principle as DrawTargetCapture, but also passes down the TextDrawTarget in the drawing arguments, so that the drawing algorithm can notify us of changes in phase (e.g. "now we're doing underlines"). This also lets us directly pass data to TextDrawTarget when possible (as is done for shadows and selections). In doing this, I also improved the logic copied from ContainsOnlyColoredGlyphs to handle changes in font/color mid-text-run (which can happen because of font fallback). The end result is: * We handle all shadows natively * We handle all selections natively * We handle all decorations natively * We handle font/color changes in a single text-run * Although we still hackily intercept draw calls * But we don't need to buffer commands, reducing total memcopies In addition, this change integrates webrender's PushTextShadow and PushLine APIs, which were designed for this use case. This is only done in the layerless path; WebrenderTextLayer continues to be semantically limited, as we aren't actively maintaining non-layers-free webrender anymore. This also doesn't modify TextLayers, to minimize churn. In theory they can be augmented to support the richer semantics that TextDrawTarget has, but there's little motivation since the API is largely unused with this change. MozReview-Commit-ID: 4IjTsSW335h

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