[whatwg] <img> element comments

[Henri Sivonen]

On Nov 4, 2006, at 08:37, Ian Hickson wrote:

> I'm thinking of only allowing integer values, and requiring them to be
> equal to the dimensions of the image, if present (and requiring  
> both to
> be present if either is present). Would people be ok with that?

Suppose there are desktop systems in the near future that double the  
pixel density of the display compared to what is common today.  
Considering the handheld displays Nokia ships, I guess it is only a  
matter of time for similarly small pixels to appear in desktop-sized  
panels at affordable prices. Apple already seems to be preparing for  
this.

To render legacy pages, browsers will probably have to define 1 CCS  
px to be equal to two device pixels and render each image pixel of  
legacy bitmaps as 2 by 2 device pixels. Now if an author wants to  
deliver more precision to such new systems while being compatible  
with legacy systems, the reasonable thing to do is leaving the width  
and height attributes to values that would make sense for legacy  
systems and to quadruple the number of samples in the bitmap by  
doubling its pixel height and width.

So I think width and height should not have conformance requirements  
tied to pixel dimensions of the references image file. They are  
presentational, but they are such a useful presentational  
optimization that I think it doesn't make sense to try the get rid of  
that presentationalism just to comply with a principle.

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/