The code added in bug 1135907 prevented the displayport from expanding beyond the maximum texture size. However when doing so it calculated a "budget" and then spent as much of the budget as possible on the top/left margin, using the rest for the bottom/right margin. If this code is hit, it can result in the displayport being "skewed" towards the top/left of the visible area, and so checkerboarding occurs more easily when scrolling down/right. This happened in bug 1258051 for example.
Created attachment 8736700 [details] [diff] [review] Patch
Attachment #8736700 - Flags: review?(dvander)
Attachment #8736700 - Flags: review?(dvander) → review+
Created attachment 8736889 [details] [diff] [review] Patch for landing Update r= so patch is ready for landing, to go into landing queue.
Status: NEW → RESOLVED
Last Resolved: 3 years ago
status-firefox48: affected → fixed
Resolution: --- → FIXED
Target Milestone: --- → mozilla48
Comment on attachment 8736889 [details] [diff] [review] Patch for landing Approval Request Comment [Feature/regressing bug #]: APZ [User impact if declined]: bug 1258051 is one example - if the user's system has smaller max texture sizes they can run into checkerboarding more frequently. Not many users will run into this problem. [Describe test coverage new/current, TreeHerder]: tested by reporter of bug 1258051, no automated coverage for this particular bug [Risks and why]: low risk, the codepath in question is not hit very often. low-impact fix and low risk. [String/UUID change made/needed]: none
Attachment #8736889 - Flags: approval-mozilla-aurora?
Comment on attachment 8736889 [details] [diff] [review] Patch for landing Fix was verified in bug 1258051, Aurora47+
Attachment #8736889 - Flags: approval-mozilla-aurora? → approval-mozilla-aurora+
status-firefox47: affected → fixed
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