Open Bug 1554795 Opened 3 years ago Updated 1 month ago

Support desktop scrollbar thumb sizing logic in APZ


(Core :: Panning and Zooming, defect, P2)




Tracking Status
firefox69 --- affected


(Reporter: botond, Unassigned, Mentored)


(Blocks 2 open bugs)


(Whiteboard: [lang=c++])

When pinch-zooming, scrollbar thumbs are scaled asynchronously to approximate what they will look like when we repaint at the new resolution.

Our current scaling logic works on Android, where the scroll thumb length is basically scaled proportionally to the page length. On desktop, however, scroll thumbs appear to have a minimum length, making the scaling logic not exactly proportional.

The resulting inaccuracy is not super noticeable, but we do need to resolve it to get these reftests to pass (or else significantly up the fuzz factor on them).

I'm going to make this an Outreachy intermediate task. Please note that this is one of the more challenging ones; before taking this on, please (1) complete another C++ intermediate task first; and (2) double-check in the #apz channel that there's enough time left in the application period to have a good chance of completing this.

Mentor: botond
Whiteboard: [apz-outreachy]
Mentor: kats
Whiteboard: [apz-outreachy] → [apz-outreachy][lang=c++]
Assignee: nobody → tnikkel
Priority: P3 → P2
Whiteboard: [apz-outreachy][lang=c++] → [lang=c++]
Assignee: tnikkel → nobody
Mentor: kats
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