Open Bug 1662057 Opened 4 years ago Updated 2 years ago

opacity on text with overlapping letters should not show darker areas (ex: RTL Arabic)

Categories

(Core :: Graphics: Text, defect)

defect

Tracking

()

Webcompat Priority P3
Tracking Status
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

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.

I cannot reproduce the issue when compositing is Direct3D 11 (Advanced Layers).
And I can reproduce when compositing is Basic and WebRender.

Component: Layout: Text and Fonts → Graphics: Text

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

(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

No longer regressed by: skia-windows

Font related issue for triage.

Flags: needinfo?(lsalzman)

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?

Flags: needinfo?(lsalzman) → needinfo?(jfkthame)
Severity: -- → S3
Webcompat Priority: ? → P3
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