1416849 - Incomplete page rendering, page cut off at bottom (iOS 11?)

Status: RESOLVED FIXED

(Firefox for iOS :: Browser, defect, P1)

Description

[:garvan]

Attachment: IMG_0016.MP4

Reported on iPad Pro 12.9 inch 2017

See screencap. The page is not fully rendered and is cut off towards the bottom of the page. The content size of the page is correct and the cut off area is whitespace.

Restarting the app fixes the behaviour.

Comment 1

[:garvan]

*If* this correlates with device CPU/memory starvation:
hiding/showing the toolbar triggers re-rendering of the page (once for each frame of the hide/show animation). This is CPU and memory intensive. Hide/show toolbars *requires* updating the page content insets so header/footer divs get placed correctly.

Alternatively, instead of updating the content insets for each animation frame, we could move the UIView for the web view up/down in-sync with the hide/show animation (which would avoid updating the header inset), and only update the footer inset when the animation is complete. (A theoretical approach only, this is big refactor to even try this behaviour, and we have no repro steps yet).

Comment 3

[:garvan]

I had this happen on 10 release build on iPad 9.7 current gen. 
The cutoff point is ~150% of the screen height.
Until I closed all tabs, any tab I created was cut off.
I was using the app for about an hour and had 4 tabs open when it stated happening.

Comment 4

[:garvan]

Filed to webkit: https://bugs.webkit.org/show_bug.cgi?id=179885

Comment 5

[Richard Newman [:rnewman]]

Also happens on 9.x release, and on master, on an iOS 11 device. It seems roughly correlated to usage (e.g., large peak number of tabs) for me, but that's not even close to scientific.

Comment 7

[Farhan Patel [:farhan]]

https://bugs.chromium.org/p/chromium/issues/detail?id=774452

Comment 8

[Justin D'Arcangelo [:justindarc]]

Will update this bug with a link to a GitHub repo for a small proof-of-concept app to repro this issue when ready.

Comment 9

[Justin D'Arcangelo [:justindarc]]

Marking this as resolved per conversation in WebKit bug:

https://bugs.webkit.org/show_bug.cgi?id=179885

tl;dr -- This issue is fixed in iOS 11.3b2