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Re: Apple's Proposal for CSS Transformations

From: David Woolley <forums@david-woolley.me.uk>
Date: Wed, 07 Nov 2007 08:21:35 +0000
Message-ID: <4731758F.2040008@david-woolley.me.uk>
To: www-style@w3.org

David Hyatt wrote:

> This feature is generically applicable to all markup and works with both 
> HTML and SVG.  It allows for the creation of presentational effects 

I see it as further blurring the distinction between the different 
technologies.

>> The use of pixel measurements is generally discouraged.  In any case, 
>> there isn't a unique mapping between pixels and cm or pt.  In 
>> particular, could the examples be formulated using more appropriate 
>> units.
>>
> 
> I don't really understand this criticism.  The best way to think of the 
> resolved transformation matrix (CTM) is in terms of CSS pixels.  This 
> has nothing to do with what units might be used in the primitives 
> themselves (which do support em or pt or in or whatever).

Your perspective function is explicitly specified in pixels.

The problem with pixels is that, for typical visual browsers, they 
behave like absolute units, which is bad because it means that users 
cannot scale the text, in particular, to meet their eyesight needs. 
Moreover, even allowing for very high resolution media, they vary over 
more than about 2:1 in their angular range, so they are not well 
defined.  Generally, the use of pixels tends to be associated with 
designers who only design for their own display hardware configuration 
and want page description like rendering accuracy.

> 
> Yes, you can say transform: none !important; to kill all transforms if 
> desired.  Nothing stops transforms from making something unreadable, 
> just as nothing stops opacity from making something unreadable, or 
> relative positioning from shoving an object out of view to the top or 
> left of the viewport.

My concern is that accessibility has not been considered here and that 
people using this technology will not think about accessibility when 
they use it.


-- 
David Woolley
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Received on Wednesday, 7 November 2007 08:21:53 GMT

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