1503798 - Text flickering several times during page loading.

Status: RESOLVED INCOMPLETE

(Core :: Graphics: Text, defect, P3)

Description

[Alice0775 White]

Attachment: screencast

The problem happens not only first load but also reload(F5).
On Edge, no flickering.
On Chrome, flickering but only once.

Reproducible: always

Steps To Reproduce:
1. Open https://this.kiji.is/430568820663403617?c=44341039600582657
   (not a permanent link)

Actual Results:
Text flickering several times during page loading

Expected Results:
no flickering as Edge

Comment 1

[Alice0775 White]

Attachment: screencast

Comment 2

[Alice0775 White]

Setting gfx.downloadable_fonts.fallback_delay to 0 fixes the flickering.

Comment 3

[Alice0775 White]

Regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=4c2e56373aab1b1a556f46f94642d4fd69957ae2&tochange=ad43c7344bdb41ecca4cd6a2c157c8a9267bec64

Triggered by: ad43c7344bdb	Frédéric Wang — Bug 1242904 - Update Brotli to latest upstream revision ; now at 33aa40220b96cf95ad2b9ba61dc8d7fd2f964f2c. r=mcmanus


Indeed, setting "network.http.accept-encoding.secure" = "gzip, deflate" instead "gzip, deflate, br" fixes the flicker on Nightly65.0a1 as well as

Comment 4

[Alice0775 White]

s/as well as/and the bad build as well./

Comment 5

[Jonathan Kew [:jfkthame]]

This seems to be caused because the site is using the Noto Sans JP font as a webfont, and https://fonts.googleapis.com/earlyaccess/notosansjp.css has "sharded" the font across dozens of resources, each providing a subset of the characters. So the rendering of the title "日航副操縦士が英国で拘束", for example, actually uses 10 separate @font-face resources. It looks like we may be repainting the page repeatedly as each of those resources becomes available, whereas Chrome blocks the rendering until all the downloads have completed.

Comment 6

[Jonathan Kew [:jfkthame]]

BTW, on macOS I can reproduce flickering even with br removed from network.http.accept-encoding.secure, though it does seem to be worse with that option present. I suspect that may affect timing in such a way that the problem tends to show up more, but isn't really the root cause.

Comment 7

[Alice0775 White]

okey, remove dependency.

Comment 8

[Alice0775 White]

The website no longer exists.