Don't attempt to draw transparent text

RESOLVED FIXED in mozilla25

Status

()

Core
Graphics: Text
RESOLVED FIXED
5 years ago
5 years ago

People

(Reporter: mstange, Assigned: mstange)

Tracking

({perf})

Trunk
mozilla25
Points:
---

Firefox Tracking Flags

(Not tracked)

Details

Attachments

(1 attachment)

(Assignee)

Description

5 years ago
Created attachment 777160 [details] [diff] [review]
patch

PDF.js creates a layer of transparent text on top of its canvas for selection and copying. During scrolling, sometimes the whole page is invalidated and all the text on it is "repainted". For pages with a lot of text, the gfxTextRun::Draw part of this repaint takes long enough to cause noticeable jank on its own.
Attachment #777160 - Flags: review?(roc)
Hmm wait. Does this create a timing channel attack against link-visited, by using CSS rules that make text invisible if a link is visited? I think it might :-(.

Maybe we can block this at a higher level where we can check for that?
Oh, no, it's not a problem, because we require that color changes due to visited rules don't change alpha values. Never mind.
https://hg.mozilla.org/mozilla-central/rev/ba041d0f69b3
Status: ASSIGNED → RESOLVED
Last Resolved: 5 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla25
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