Revisit the necessity of CSSSegmentedFontFace::m_approximateCharacterCount |
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Issue descriptionCSSSegmentedFontFace has a counter that accumulates number of characters styled with that font. This counter is used to calculate trace-based FirstMeaningfulPaint. However, this counting code is relying on the early font load trigger optimization, which we may want to remove (see Issue 542629). We should revisit and see if this trace value is really needed, or if we can replace it with something else.
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Mar 15 2017
Any updates on how this trace value is performing? Thanks.
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Mar 17 2017
This signal turned out to be very useful, so we would like to keep it in some form (doesn't have to be exactly the same as current one). Dominik, is your goal to replace willUseFontData(..., text) with willUseRange(..., rangeSet)? We may be able to use the size of range instead of the text length.
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Mar 17 2017
Okay, thanks for the update. Range from FontDataForRangeSet in this case refers to unicode ranges of web fonts, so it does not refer to the text content. I don't think that's what you need, right?
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Mar 17 2017
Ah that range comes from font, not text... Then it wouldn't be very useful information. We only use this information after layout, so we do not necessarily need to collect this in willUseFontData(). I'm not very familiar with current shaping code (sorry!), but would it be easy / good idea to add a counter to FontDataForRangeSet that represents how much text (approx. characters) has been shaped using that FontData?
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Mar 17 2017
I don't have the answer right now, but I'll keep this in mind: I am thinking how to improve lifecycle handling of our fonts, and such an information would be useful in this context.
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Aug 10 2017
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Aug 10 2017
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Comment 1 by drott@chromium.org
, May 20 2016