RE: [mediaqueries4]Differentiating touchscreen+mouse from touchscreen only scenarios

Thanks François, for the explanation.
This helps clarify the intention.

“this behavior is therefore left to the user agent’s own discretion”
I guess I see the amount of discretion to the UA a potential for interoperability issues.
It would be strange if Firefox, Opera, Chrome and IE all reported different primary interaction modes on the same machine providing different experiences.

I CCed Rick as UAs probably want to align to avoid the above.


From: François REMY []
Sent: Friday, April 25, 2014 9:30 AM
To: Oren Freiberg; CSS WG
Subject: Re: [mediaqueries4]Differentiating touchscreen+mouse from touchscreen only scenarios

My understanding of the spec is that the paragraph about the exact values being matched is not normative (no “should”, no “must”), and this behavior is therefore left to the user agent’s own discretion. That being said, there’s a notion of “primary” input device -- you do not have to report a value for all input modes, only the ones that are considered primary.

For instance, a laptop that has both a touch screen and a trackpad may report a different value in function of the way it’s currently being used. I own a Lenovo Yoga, and I expect “fine” to be returned in laptop mode and “coarse” in theater or tablet mode -- the fact I can interact using touch in laptop mode is irrelevant because this is not the primary interaction mode (which does not mean I may not use it, just that this is secondary to trackpad in most cases); but maybe this is not the case for someone else using the same device in a different way.

In the same way, a Surface Pro tablet may probably want to return “coarse” irrespective of the fact it supports a pen input device which can feature “fine” pointing, because touch is the most likely input pattern, but again some designers may have different habits.

At the end of the day, the goal of this media query is to allow websites to provide the best UI to the user, and it’s the responsibility of the user agent to report the hints that will enable web authors to have the most accurate represention of the user pointing habits. I’m not sure we can specify this in a formal way.

Note that if your goal is to align with Chrome and that you want more input from Rick, you should maybe CC him then.

De : Oren Freiberg<>
Envoyé : ‎vendredi‎ ‎25‎ ‎avril‎ ‎2014 ‎15‎:‎27
À : CSS WG<>

Hey everyone,

I have been reading the media queries 4<> a bit and I am confused and I am trying to see if my thoughts are aligned with the intention of the spec.

For hybrid devices (touch and mouse - laptop or desktop) it is seems matching the least accurate will cause web developer to provide mobile content or mobile optimized content to none mobile devices. Matching both ‘fine’ and ‘coarse’ seems like the best way to provide data to web developers to avoid providing mobile content under these conditions.

For non-hybrid devices (touch only or mouse only) matching the least accurate makes sense as there is only one choice.

My end interpretation is split. On a hybrid device where mouse is the primary input but has added touch as a bonus (desktop with a touch monitor) the UA should either report ‘fine’ as the touch monitor might not be consider primary source of input or should report both ‘fine’ and ‘coarse’..

“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; if there are multiple reasonable "primary" input mechanisms with different characteristics, UAs may make the feature match multiple values.”

It seems Rick felt we should match both but it looks like Chrome never implemented it. Rick do you still feel the same way and plan on implementing a solution that supports matching both fine and coarse on a hybrid device?


Received on Friday, 25 April 2014 17:42:18 UTC