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Re: Screen Orientation Feedback

From: Jonas Sicking <jonas@sicking.cc>
Date: Mon, 11 Aug 2014 14:33:52 -0700
Message-ID: <CA+c2ei-tOcAAFcsyoLK0vtZAJ6dho7bs=iTkeKjz6mjKe6AHLg@mail.gmail.com>
To: Mounir Lamouri <mounir@lamouri.fr>
Cc: Webapps WG <public-webapps@w3.org>, Rich Tibbett <richt@opera.com>, Tim Volodine <timvolodine@google.com>
On Fri, Aug 8, 2014 at 6:44 AM, Mounir Lamouri <mounir@lamouri.fr> wrote:
> Maybe this feedback should be more for DeviceOrientation than Screen
> Orientation. There has been a few discussions there
> (public-geolocation).

This is the type of procedural issues that I'd really rather not get
caught in. I think it's fine to defer to the DeviceOrientation spec,
but only if we think there's any chance of it getting added there
anytime soon. Given that no drafts, to my knowledge, has been
published for a DeviceOrientation v2, that does not seem to be the

> Anyway. I am not convinced that adding new properties will really fix
> how developers handle this. I asked around and it seems that native
> platforms do not expose Device Orientation relative to the screen. I am
> not sure why we should expose something different on the Web platform.

I don't think the fact that other platforms do not supply screen
relative orientation events is a strong technical argument for why we

I'm definitely in favor of looking at what other platforms do, but not
with the mindset that what other platforms do is the right thing to
do, but rather to see if they have good solutions that we could learn
from. Surely other platforms will make design mistakes, just like we

> I think we should work on providing developers the right tools in order
> for them to do the right thing.

I totally agree with this. For all the use cases that I can think of
for getting the coordinates relative to the screen is more important
than relative to the device. This includes:

* A navigation page which shows a map as well as how the device is
oriented relative to the map.
* A navigation page which shows a map orientated so that the on-screen
map matches real world.
* A game where an in-game character is controlled by tilting the
device left and right to make the character walk left vs. right.

I'm sure there are use cases where you need to know the orientation
relative to the device rather than relative to the screen, they just
seem to be less common to me.

Given that, the right tool seems to be to provide the
DeviceOrientation events relative to the screen and allow them to be
compensated to be relative to the device if needed.

Sadly it's too late for that. Authors already have the wrong tool as a
default since the DeviceOrientation spec is written and implemented
the way it is.

However we can at least give authors the right tool as well, by
introducing screeAlpha etc.

> For example, without the Screen
> Orientation API, they do not know the relative angle between the device
> natural orientation and the screen. This API is not yet widely
> available. Some version of it ships in Firefox and IE but is prefixed.
> It should be in Chrome Beta soon.

I don't think "the right tool to do the right thing" in this case
means "give them coordinates in a coordinate system that they don't
want, and then give them enough information to transform the
coordinate into the coordinate system that they do want".

I'm not arguing that we remove the relative angle that's in the spec
right now. I'm arguing that for device orientation events, we should
provide coordinates relative to the screen as well.

/ Jonas
Received on Monday, 11 August 2014 21:34:49 UTC

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