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[screen-orientation] Remove the ability to lock to multiple orientations?

From: Mounir Lamouri <mounir@lamouri.fr>
Date: Fri, 14 Mar 2014 05:21:42 +1100
Message-Id: <1394734902.16448.94151345.663B5F5E@webmail.messagingengine.com>
To: public-webapps@w3.org
Hi,

I would like to change the Screen Orientation API to make the locking
steps a bit simpler. Currently, the API tries to be flexible and allow
locking to any combination of values like "portrait", "landscape",
"portrait-primary" but also [ "portrait", "landscape-primary" ], [
"portrait-primary", "landscape-primary" ]. The three first orientations
are very common. The others are pretty odd and I doubt I ever saw that
in the wild.

Allowing to pass an array of orientation has a lot of impact on the
specification:
- given that the combinations are pretty exotic, we should assume that
some UA will not be able to lock because the system will not allow it
[1];
- we have the problem of whether all the items in the array should be
available or only one of them to work. The specifacation currently
answer the question of whether "portrait" <=> [ "portrait-primary",
"portrait-secondary" ] but what about [ "landscape-primary",
"portrait-primary" ].

Removing this feature will allow the specification to enforce that all
states are working because it is fair to assume that the system will not
block the UA to lock to those basic orientations. In addition, this
would be a future-compatible change in the sense that adding this later
will be smooth. I am really eager to make the specification a bit less
flexible because right now, implementing this specification without
being able to lock would be following the specification.

I am particularly interested to hear feedback from Microsoft and Mozilla
who have prefixed implementations. I know that Firefox Android only
allows the basic orientations but Firefox OS allows any orientation to
be passed I believed [2]. I unfortunately can't test IE11 on mobile.

[1] Very likely, any UA could simply re-write the mechanism that listen
for device orientation changes and do manual screen locking based on
that, though...
[2]
http://mxr.mozilla.org/mozilla-central/source/widget/gonk/OrientationObserver.cpp

-- Mounir
Received on Thursday, 13 March 2014 18:22:07 UTC

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