1494422 - Implement "extend-to-zoom" semantics in meta viewport tags

Status: RESOLVED FIXED

(Core :: Layout: Scrolling and Overflow, enhancement, P3)

Description

[Botond Ballo [:botond]]

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

Comment 1

[Hiroyuki Ikezoe (:hiro)]

Taking, I am going to fix this first.

Comment 4

[Hiroyuki Ikezoe (:hiro)]

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

Comment 5

[Hiroyuki Ikezoe (:hiro)]

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

Comment 6

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1494422 - Introduce extend-to-zoom and resolve width and height using it. r=botond

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

Comment 7

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1494422 - Test cases for viewport calculation. r=botond

Depends on D8690

Comment 8

[Hiroyuki Ikezoe (:hiro)]

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.

Comment 10

[Hiroyuki Ikezoe (:hiro)]

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

Comment 11

[Hiroyuki Ikezoe (:hiro)]

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

Comment 12

[Pulsebot]

Pushed by [e-mail]:
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

Comment 13

[Daniel Varga [:dvarga]]

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