New issue
Advanced search Search tips

Issue 655143 link

Starred by 1 user
Status: Fixed
Owner:
sahel@chromium.org
Closed: Aug 2017
Cc:
dtapu...@chromium.org
tdres...@chromium.org
bokan@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: All
Pri: 3
Type: Bug



Sign in to add a comment

Main thread gets GSU and GSE without corresponding GSB

Project Member Reported by bokan@chromium.org, Oct 12 2016 
Repro:
1) In Blink, add Logging to the ScrollManager::handleGestureScrollBegin|Update|End methods (or print the event type in handleGestureScrollEvent.
2) Load the attached file
3) While the page is loading (before the scrollbar appears), wheel scroll on the page

Notice that Blink is receiving GestureScrollUpdate events and a GestureScrollEnd but it never receives the GestureScrollBegin. We should make sure that this situation can't occur. Additionally, we paper over this by doing a hit test in handleGestureScrollEvent even on GSU and GSE. We should only do hit testing while handling a GestureScrollBegin
dialog.html
1.0 KB View Download

Comment 1 by dtapu...@chromium.org, Apr 25 2017

Owner: sahel@chromium.org
Status: Assigned (was: Available)
I believe this is fixed by wheel latching. Currently the begin can be consumed by the compositor thread but then the update can be passed to the main thread. 

Latching will make the determination only in the begin so this situation can't happen anymore.

Comment 2 by sahel@chromium.org, Aug 10 2017

Status: Fixed (was: Assigned)
The following two cls fix the issue:
1) If the GSB is ignored (e.g. trying to scroll when the page is still loading) the
rest of the scroll sequence will get ignored as well.
https://codereview.chromium.org/2924953002

2) If in the middle of scrolling we need to switch to main thread a GSB will be sent before the first GSU:
https://codereview.chromium.org/2854683002
►

Sign in to add a comment