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Re: [mediaqueries4] pointer: coarse and pannable, zoomable viewports

From: Florian Rivoal <florian@rivoal.net>
Date: Sun, 30 Dec 2012 22:16:09 +0100
To: "Tab Atkins Jr." <jackalmage@gmail.com>, "Sylvain Galineau" <sylvaing@microsoft.com>
Cc: "www-style@w3.org" <www-style@w3.org>, "Edward O'Connor" <eoconnor@apple.com>
Message-ID: <op.wp5eo708f5de51@riboaru-nashiosamus-imac-2.local>
On Wed, 12 Dec 2012 21:38:56 +0100, Sylvain Galineau  
<sylvaing@microsoft.com> wrote:

>> > The UA picks the lowest resolution pointer available, right? A Surface
>> > with its type cover or a laptop with a touch screen have both coarse  
>> and
>> fine pointers.


> I really have no idea how the device would know which one to pick, and  
> that
> sounds disturbing to me: when the device's expectation changes then my  
> app
> layout would suddenly reflow?

I am a bit late to the conversation, but here is how I envisioned it when
I wrote it up.

First, let's quote what I wrote, it may not be very clear, but it is  
intended to provide some guidance over this:

"If a device has multiple input mechanisms, it is recommended that the UA
reports the characteristics of the least capable pointing device of the
primary input mechanisms."

So as you said, the UA picks the lowest resolution, but not necessarily of  
all input devices, just of the primary ones. By primary, I mean the normal  
way to interact with the device.

This media feature does not indicate that the user will never be able to  
click accurately, only that it is inconvenient for him to do so. If you  
require accurate clicks when the MQ said 'coarse', you may be forcing the  
user to zoom, or you may be forcing him to fetch his optional blue-tooth  
mouse from across the room.

Whether an input mechanism is primary or not is a subjective call from the  
UA vendors. In a bunch of cases, it should be obvious, and then of course,  
there is a grey area in the middle. My intention was to leave it up to  
vendors, as they know best how they know better than spec writers the UI  
paradigm of their device.

On an old fashioned tablet-pc (this kind:  
http://en.wikipedia.org/wiki/Microsoft_Tablet_PC), you may consider the  
touch screen to be a secondary input device when the laptop is open. As  
you are then faced with the good old mouse driven UI, the touch screen is  
not expected to be the normal way to use the device. If you fold it to  
tablet form, then the touch screen becomes the normal way to drive the  
device, and it would determine the media query.

On the other hand, on a Microsoft Surface, I would expect (I might be  
wrong, having never used one) that even when the cover is connected, touch  
is still intended to be a completely normal way of interacting with the  
device. In that case, both the touch screen and the trackpad on the cover  
would be considered primary input devices. In order not to force the user  
away from one of them, the MQ could report 'coarse'. Alternatively, if  
Microsoft thought that pluging the cover in indicates that we should  
switch to some kind of laptop mode, and makes various adjustments across  
the UI to be more suitable to the pad than to the touch screen, then  
switching to 'fine' could be more appropriate.

If you remove the mouse from a desktop computer (who needs a mouse when  
you know all the keyboard shortcuts), you'd switch from 'fine' to 'none'.

Plugging a game controller on a pc, however inaccurate, would not change  
the MQ, as the controller is not the normal way to interact with computer,  
just an extra thing.

I hope this clarifies what I had in mind. Does that sound reasonable?

  - Florian
Received on Sunday, 30 December 2012 21:16:34 UTC

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