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Re: [manifest] screen sizes, Re: Review of Web Application Manifest Format and Management APIs

From: Scott Wilson <scott.bradley.wilson@gmail.com>
Date: Sun, 27 May 2012 20:46:27 +0100
Cc: Marcos Caceres <w3c@marcosc.com>, "SULLIVAN, BRYAN L" <bs3131@att.com>, "public-webapps@w3.org" <public-webapps@w3.org>
Message-Id: <D490BB01-7B74-4A52-9B14-6B8ACCB57184@gmail.com>
To: Anant Narayanan <anant@mozilla.com>
On 27 May 2012, at 17:45, Anant Narayanan wrote:

> On 05/27/2012 01:35 AM, Marcos Caceres wrote:
>> On 26 May 2012, at 18:32, Anant Narayanan<anant@mozilla.com>  wrote:
>>> The intent for the screen_size parameters is not to let the developer enforce a particular screen size or resolution, but rather specify the *minimum* width and height required by the app. This means that on a screen below the specified size, the app will not function at all.
>> 
>> To make this more clear, maybe call this min_screen_size.
> 
> Well, we haven't received this request from developers explicitly yet, but one can imagine a situation in which a developer makes an app only for mobile phones (Instagram?) and doesn't want users to use it on desktops. Even though it'll technically work, it might look ugly due to scaling. In this case, we'll need a max_screen_size.

However, it would work great on an interactive whiteboard for a purpose the original developer hadn't imagined... or could be used from a mobile phone projected into 3D space using a digital projector with pixel mapping... 

I think the intended functionality is something along the lines you see in Apple's App Store where you get a sense of which apps are designed for iphone/ipod and which are intended for the ipad, and which are fine with both. That works OK with a limited number of devices, but in a more heterogeneous world it breaks down quickly.

I don't know what the answer is, but fixating on screen sizes doesn't feel like quite right. Maybe its the best that can be done. 

(We already have some issues with what to do with the Widget width and height.... in Apache Rave we use it for min-width and min-height CSS attributes on the widget iFrame container. However on mobile we tend to ignore it and hope the widget includes a viewport tag)

>>> I will also note that it is upto the app store to interpret this field however they'd like. If they do not want to disallow installs on devices that don't meet the developer-specified criteria, that's fine. However, we should still convey this information from the developer to the store via the manifest.
>> 
>> At install time or when I am browsing apps, how does a server know my screen resolution? Or is this restriction imposed on by the user agent?
> 
> The same way an app would find out, by feature sniffing. The app store is also presumably a web page or a "native" store, in either case, it should be able to know the characteristics of the current device using standard techniques.
> 
>>> It is unrealistic to assume that all app developers will make a responsive design for all possible screen sizes. The tools aren't great and it costs time and money. We added this field after we received a request from the developer of a popular game that only worked on desktops, but not mobile phones (due to size). They wanted to make sure users weren't able to install them in places the app wasn't designed for and get a bad impression of the company. I think this is really important.
>> 
>> I think that's fine, but as Scott pointed pointed out, user agents have a history of allowing users to bypass these kinds of restrictions (or users hack around them). I think this field can only really serve as a warning that the app might not work as expected.
> 
> Serving as a warning is sufficient, I agree that we will always have some % of users ignore the warning and install it anyway.
> 
> -Anant
> 
> 
> 
Received on Sunday, 27 May 2012 19:47:02 GMT

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