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Slight flicker in iOS Safari when cursor is placed past the first page of the document
Closed, DeclinedPublic

Assigned To
None
Authored By
ppelberg
May 24 2019, 10:20 PM
Referenced Files
F29603371: T224322.mp4
Jun 18 2019, 7:53 PM
F29603373: 97.png
Jun 18 2019, 7:53 PM
F29603375: 98.png
Jun 18 2019, 7:53 PM
F29603380: 99.png
Jun 18 2019, 7:53 PM
F29603387: 100.png
Jun 18 2019, 7:53 PM
F29603390: 101.png
Jun 18 2019, 7:53 PM
F29523539: ScreenRecording_06-13-2019 15-28-40.mp4
Jun 13 2019, 10:40 PM

Description

Expected behavior

There shouldn't be any flicker when you place cursor anywhere in the document.

Actual Behavior

There is still a slight flicker whenever the cursor is placed anywhere past the first page of the document.

Configuration

Browser:
Device:

Event Timeline

I have not yet been able to reproduce the issue first raised in T196839#5178009 and now represented by this ticket (T224322).

Attempt to reproduce iOS Safari flicker

YouTube: Mobile VE/iOS/Safari/Flicker: T224322

Configuration

Browser: Safari
Device: iPhone XS

There is also an issue with cursor hiding behind the keyboard which happens if you just open link inspector and close it. You will loose the previous cursor position since the page abruptly scrolls down and will have to scroll down to find that position. I am noting it down here, incase these are relevant. if not, I will open a new ticket. Here is a screen capture showing that behavior:

@Ryasmeen this looks like a separate issue--could you make a separate task for it? Thank you!

@ppelberg This happens very inconsistently for me, like 1 in 20 tries or even less often. I was able to capture it after trying for some time:

Still frames from the video:

97.png (1×640 px, 245 KB)
98.png (1×640 px, 244 KB)
99.png (1×640 px, 199 KB)
100.png (1×640 px, 237 KB)
101.png (1×640 px, 234 KB)

I am pretty sure that this weird flicker is caused by the code we added to fix T218414: Editing toolbar on mobile VE is not sticky (can scroll out of view) on iOS (where we essentially very quickly scroll down and then back up so that the toolbar position fixes itself). I noticed it back then, and noted it in a code comment in https://gerrit.wikimedia.org/r/c/mediawiki/extensions/VisualEditor/+/498256/3/modules/ve-mw/init/targets/ve.init.mw.MobileArticleTarget.js:

		// The scroll back up must be after a delay, otherwise no scrolling happens and the
		// viewports are not aligned. requestAnimationFrame() seems to minimize weird flashes
		// of white (although they still happen and I have no explanation for them).

As far as I can tell, there is no way to avoid this, as long as we require that workaround for the toolbar.

Aklapper added a subscriber: Ryasmeen.

Removing task assignee due to inactivity, as this open task has been assigned for more than two years (see emails sent to assignee on May26 and Jun17, and T270544). Please assign this task to yourself again if you still realistically [plan to] work on this task - it would be very welcome!

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