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Re: Constrained specification of Icon element

From: Ola Andersson <ola.andersson@ericsson.com>
Date: Tue, 10 Nov 2009 09:50:28 +0100
Message-ID: <53CCFDD6E346CB43994852666C210E9108E985DF@esealmw116.eemea.ericsson.se>
To: <marcosc@opera.com>
Cc: <public-webapps@w3.org>
I understand it might be too late to modify the spec now but I still think the spec isn't clear with regards to <icon> size and should be clarified, maybe in some future version at least. I'm also not fully convinced your description (bottom of this mail) about clipping an SVG icon is correct. This is because the Widget P&C spec states for the <icon> width/height attributes: "The width <http://dev.w3.org/2006/waf/widgets/#width0>  is only applicable to graphic formats that have no intrinsic width or height (e.g., SVG)." However, SVG do have intrinsic size when SVG width/height are specified [1] (except in the case when widht/height are %-values) so the widget spec might want to clarify this and your example below should, according to the <icon> definition, ignore the <icon> width/height and render the icon using the intrinsic 1000x1000px size.

To me this behavior is not what you want, rather I propose the following changes to the <icon> size:    

1. For the widget <icon> element's width and height attributes the spec should state that the width and height attribute values are to be seen as a guide to the UA in order for the widget provider to indicate the preferred size of the icon. The UA is allowed to ignore the width/height in order to change the size of the icon, exampels of when this might occur is if a UA is to display icons from different providers in a single GUI (and thus prefer to display them all at the same size). Or if a UA needs to enlarge icons in a GUI due to accessability requirements (vision impaired users...) 

2. icon width/height attributes should apply to all graphic formats, not just those without intrinsic size. Having this would make it possible to reuse the same icon resource for multiple resolutions. The following example (almost from the widget spec): 

<icon src="icons/big.png"/> 
<icon src="icons/medium.png"/> 
<icon src="icons/small.png"/> 

could then be rewritten as: 

<icon src="icons/big.png"/> 
<icon src="icons/big.png" width="128" height="128"/> 
<icon src="icons/big.png" width="64" height="64"/> 

Which would save the author the work of creating different pngs, and save bandwith. All UAs have features for raster scaling so no issue with that. 

Best regards
/ola andersson

[1] http://www.w3.org/TR/SVGTiny12/struct.html#SVGElementWidthAttribute

>>2009/11/2 Magnus Olsson <magnus.olsson@ericsson.com <mailto:magnus.olsson@ericsson.com?Subject=Re%3A%20Constrained%20specification%20of%20Icon%20element&In-Reply-To=%253Cb21a10670911060819t2ef5d143u54092e173ab1a549%40mail.gmail.com%253E&References=%253Cb21a10670911060819t2ef5d143u54092e173ab1a549%40mail.gmail.com%253E> >

>>  The icon element (*http://dev.w3.org/2006/waf/widgets/#icon0*<http://dev.w3.org/2006/waf/widgets/ <http://dev.w3.org/2006/waf/widgets/#icon0*%3Chttp://dev.w3.org/2006/waf/widgets/> >)
>> has width/height properties which only applies to SVG icons. To me the spec
>> isn't fully clear how to use them. Is it ok for a user agent to ignore the
>> width/height of an SVG icon? IMO it should be since it will be hard to do a
>> consistent "widget desktop manager" with widgets from multiple sources (and
>> therefore possibly with different width/height set) if the widget icons are
>> of different sizes. To me the width/height should just be a guide to the
>> user agent but the user agent should have the choice of scaling to the
>> appropriate size. This is of course also important for widgets intended to
>> run on multiple platforms with different screen sizes.
>Yes, the user agent can decide how best to treat icons based on the
>available size. Where the width and height help is to establish the viewport
>(the window in which the SVG will be rendered).  So, if an SVG declares
>itself to be 1000 by 1000px (<svg width="1000" height="1000" ...>), but the
>width and height of the icon both say 100 pixels, then the rendered
>representation of the SVG will simply get clipped because it won't fit in
>the 100 by 100 viewport.

>Marcos Caceres


Ola Andersson 
Senior System Manager 
Solution Area TV (SATV)
BU Multimedia Products (BMUM)

Mobile: +46 761 441320
Email: ola.andersson@ericsson.com

Ericsson AB
Tellusborgsvägen 83-87
SE-126 37, Stockholm, Sweden
Received on Tuesday, 10 November 2009 09:52:59 UTC

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