1340064 - [viewport] user-scalable, min-scale and max-scale will be ignored starting with iOS10

Status: RESOLVED INACTIVE

(Core :: Panning and Zooming, defect, P3)

Description

[Karl Dubost💡 :karlcow]

Filing this issue, for preemptively watch out any Web compatibility issues surfacing in the future. 

In https://webkit.org/blog/7367/new-interaction-behaviors-in-ios-10/

> Safari on iOS 10 allows the user to pinch zoom on every page. As a developer,
> you should be aware of this, and make sure your content works well when
> zoomed.
>  
> What changed? Prior to iOS 10, Safari allowed the content to block the
> user from zooming on a page by setting user-scalable=no in the
> viewport, or appropriate min-scale and max-scale values. This
> unfortunately enabled pages to pick a text size that was unreadable
> while giving the user no way to zoom. Also, there is now such a wide
> range of devices with different display dimensions, screen
> resolutions, pixel densities… it is very difficult to choose an
> appropriate text size in a design.
> 
> Now, we ignore the user-scalable, min-scale and max-scale settings. 
> If you have content that disabled zoom, please test it on iOS 10, 
> and understand that many users will be zooming now.

Comment 1

[Karl Dubost💡 :karlcow]

Created a test for user-scalable=no
http://la-grange.net/2016/12/01/viewport/viewport-test-0009.html

Firefox Android: NO zoom-in or zoom-out
Chrome Android: NO zoom-in or zoom-out
Safari 602.1 iOS 10: YES can zoom-in or zoom-out
Firefox 6.0 iOS 10 (Safari 602.4.1):  NO zoom-in or zoom-out (on the same device than Safari. It means the webview is not working the same.)

Comment 2

[Anthony Ricaud (:rik)]

That's also an accessibility issue, not only a webcompat one. Now that Safari is ignoring this, it seems safe to allow people to zoom in.

Comment 3

[Botond Ballo [:botond]]

Kats pointed out to me today that a user can already flip the pref "browser.ui.zoom.force-user-scalable" on Firefox for Android, and get what is effectively this behaviour.

So, from an implementation point of view, fixing this is as simple as flipping the default value of that pref.

Comment 4

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #3)
> Kats pointed out to me today that a user can already flip the pref
> "browser.ui.zoom.force-user-scalable" on Firefox for Android

And that, moreover, this is surfaced in the UI settings under Accessibility -> Always enable zoom.

Comment 5

[Firefox Bug Husbandry Bot]

Migrating Webcompat whiteboard priorities to project flags. See bug 1547409.

Comment 6

[Firefox Bug Husbandry Bot]

See bug 1547409. Migrating whiteboard priority tags to program flags.

Comment 7

[Dennis Schubert [:denschub][OOO, back Jan 12]]

We didn't see any WebCompat reports about this, and realistically, the only difference here would be that people can zoom on pages on Firefox for iOS, but they can't zoom in Firefox for Android. I don't think that's a very significant difference we should proactively track, so let's close this bug and if we ever see real-world breakage, we can dig into that.