Botond Ballo [:botond] Reporter
	Description • 6 years ago

In https://webcompat.com/issues/18826, there is a webpage for which Firefox computes the layout viewport size based on the meta viewport tag differently from Chrome, and as a result the page is rendered differently.

The difference seems to be related to the "extend-to-zoom" semantics in the CSS Device Adaption spec (see [1]), which I believe Firefox does not implement.

[1] https://webcompat.com/issues/18826#issuecomment-423704698

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 1 • 6 years ago

Taking, I am going to fix this first.

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 4 • 6 years ago

https://treeherder.mozilla.org/#/jobs?repo=try&revision=0efb466c9237209a212cb90973924702ec50f537

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 5 • 6 years ago

In the previous try, I did forget to factor layoutDeviceScale into scale values, so the sites in question were correctly scaled in RDM with enabling touch and apz.allow_zooming but not on Android devices.

Here is a new try.
https://treeherder.mozilla.org/#/jobs?repo=try&revision=3a342af240a90e288a28f0bb1c17443bba994220

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 6 • 6 years ago

The relevant parts of the spec are:
 https://drafts.csswg.org/css-device-adapt/#resolve-extend-to-zoom
 https://drafts.csswg.org/css-device-adapt/#resolve-initial-width-height
 https://drafts.csswg.org/css-device-adapt/#resolve-width
 https://drafts.csswg.org/css-device-adapt/#resolve-height

This patch also introduces the parsing steps for width and height values in
viewport meta tag.
https://drafts.csswg.org/css-device-adapt/#width-and-height-properties

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 7 • 6 years ago

Depends on D8690

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 8 • 6 years ago

Moving a bunch of webcompat issue links in bug 1469747 into here.  Basically sites having 'initial-scale' but no 'width' in meta viewport will be fixed by extend-to-zoom.

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 10 • 6 years ago

A final try;
https://treeherder.mozilla.org/#/jobs?repo=try&revision=ac31f59bab4c49cfc6339a9f298ede436554e7d5

	Hiroyuki Ikezoe (:hiro) Assignee
	Comment 11 • 6 years ago

Never mind about the above try.  I thought all patches have gotten r+. :)

	Pulsebot
	Comment 12 • 6 years ago

Pushed by hikezoe@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/a7172b2e62e0
Introduce extend-to-zoom and resolve width and height using it. r=botond
https://hg.mozilla.org/integration/autoland/rev/d94fc104be3b
Test cases for viewport calculation. r=botond

	Daniel Varga [:dvarga]
	Comment 13 • 6 years ago
bugherder

https://hg.mozilla.org/mozilla-central/rev/a7172b2e62e0
https://hg.mozilla.org/mozilla-central/rev/d94fc104be3b