opacity on text with overlapping letters should not show darker areas (ex: RTL Arabic)
Categories
(Core :: Graphics: Text, defect)
Tracking
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Webcompat Priority | P3 |
Tracking | Status | |
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firefox82 | --- | fix-optional |
People
(Reporter: karlcow, Unassigned, NeedInfo)
Details
(Keywords: regression)
Attachments
(2 files)
Test Case:
data:text/html,<!doctype html><html><meta charset='utf-8'><div style='font-size:100px; opacity:0.5'>فطيرة الجبن بالتوت البري</div></html>
The overlapping letter should not exhibit darker areas.
- Gecko: FAIL
- Blink: PASS
- WebKit: PASS
Reporter | ||
Comment 1•4 years ago
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Reporter | ||
Comment 2•4 years ago
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See the specification https://w3c.github.io/alreq/#h_joining_and_transparency
3.4.7.2 Transparency
Arabic fonts achieve joining by overlapping letters. A left-joining letter extends out of its bounding box from the left side and a right-joining letter extends out of its bounding box from the right side. Making each letter transparent can expose these overlapping joinings, which should be avoided. Joining the paths of the joined letter into a single shape can remove the overlappings and create the good results.
Comment 3•4 years ago
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I cannot reproduce the issue when compositing is Direct3D 11 (Advanced Layers).
And I can reproduce when compositing is Basic and WebRender.
Comment 4•4 years ago
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Regression window under Basic compositor:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=717d85fc2046149b2a3443ffcc7aff04e119b0f7&tochange=729307f6ac594f76d1de7d7697ca5c3880135de3
Reporter | ||
Comment 5•4 years ago
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Ah if there are platform differences then I should note that I was using
macos 10.15.6 (19G2021) and nightly 82.0a1 (2020-08-29) (64-bit)
about: support shows WebRender
Intel Inc. -- Intel(R) Iris(TM) Plus Graphics OpenGL Engine
4.1 INTEL-14.7.8
Updated•4 years ago
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Comment 6•4 years ago
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(In reply to Karl Dubost💡 :karlcow from comment #5)
Ah if there are platform differences then I should note that I was using
macos 10.15.6 (19G2021) and nightly 82.0a1 (2020-08-29) (64-bit)about: support shows WebRender
Intel Inc. -- Intel(R) Iris(TM) Plus Graphics OpenGL Engine
4.1 INTEL-14.7.8
Okay
Comment 8•3 years ago
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Jonathan, this looks like something that might need to be dealt with at a higher level up in thebes itself? Or would this already be dealt with via ligatures?
Updated•3 years ago
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Updated•2 years ago
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Description
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