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Re: Charter addition proposal: screen orientation lock

From: Mounir Lamouri <mounir@lamouri.fr>
Date: Mon, 30 Jan 2012 15:36:39 +0100
Message-ID: <4F26AAF7.3050706@lamouri.fr>
To: public-webapps@w3.org
On 01/30/2012 12:43 PM, Kenneth Rohde Christiansen wrote:
> Hi there,
> 
> Orientation lock is already part of the CSS Device Adaption spec as part
> of the viewport meta tag, though this is only going to be optional and
> should be ignored for normal web browsing due to the effect on usability
> (think about navigating session history). It is thus mostly useful for
> fullscreen applications and stand alone web apps.

Actually, I was thinking of asking this to be removed from CSS DA.
A JS API seems more useful than an CSS property. For example, CSS DA
doesn't seem to allow you to read screen orientation value. It also
doesn't allow you to know when the screen orientation changes. In
addition, doing dynamic changes to the current screen orientation is
pretty annoying (doable with CSSOM I believe).
In the other hand, a JS API would allow you to do all of that and
locking the orientation very easily. The only drawback is that you can't
declare the screen orientation of your application in the header of the
HTML file. However, at Mozilla we believe that could be set in the
application manifest (see the link to the conversion Robin gave for more
details).

Also, I do not think the specifications should restrain the conditions
in which the screen orientation lock can happen. At least not at the
beginning (so implementors can easily experiment) and that should not be
a hard requirement (not a MUST). If a UA wants to allow content to lock
the screen orientation in any situation, that should be doable. UA
should take care of their own user experiences. Some UA might require
fullscreen to be set before (that seems sensible), some might just allow
this for pre-installed content (without requiring fullscreen).

> On the other hand, I think it would be nice to have a hint to the
> fullscreen api requestFullscreen where you could define a preferred
> orientation (which it would then lock to), something like
> requestFullscreen(HORIZONTAL). It would even be nice if the UA could
> tell whether it was possible to enter horizontal fullscreen mode or not,
> so that there can be some kind of fallback. Having it this way, it would
> be possible to click/tap on some element and animate the transition
> (scale + rotation) into the final state.

Linking screen orientation and fullscreen like that seems a bad idea.
Basically, you can only lock and never reads. In addition, how do you
handle an iframe requesting fullscreen?

Cheers,
--
Mounir
Received on Monday, 30 January 2012 14:37:10 GMT

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