[whatwg] question on @width and @height attributes on <video>

Simon Pieters simonp at opera.com
Mon Nov 8 06:55:18 PST 2010

On Mon, 08 Nov 2010 15:36:38 +0100, Silvia Pfeiffer  
<silviapfeiffer1 at gmail.com> wrote:

> On Tue, Nov 9, 2010 at 12:16 AM, Simon Pieters <simonp at opera.com> wrote:
>> On Mon, 08 Nov 2010 08:27:30 +0100, Silvia Pfeiffer
>> <silviapfeiffer1 at gmail.com> wrote:
>>> Hi all,
>>> I am staring at the @width and @height attributes of the <video>
>>> element, because I have just noticed that the implementation of IE9
>>> doesn't respect percentage values in there. I remembered Hixie saying
>>> that if you gave them a value that included "px", that's strictly
>>> speaking not valid, since the value is a unsigned long but a browser
>>> will just drop the "px" and interpret it correctly.
>> That it's unsigned long is only relevant for getting and setting the  
>> .width
>> and .height IDL attributes, it's not relevant for how the content
>> attribute's value is interpreted.
>>> I am now wondering if a percentage value is correct,
>> Following the link for <video width> I come to
>> http://www.whatwg.org/specs/web-apps/current-work/complete/the-map-element.html#attr-dim-width
>> which says
>> "Author requirements: The width and height attributes [...] if  
>> specified,
>> must have values that are valid non-negative integers."
>> and
>> "A string is a valid non-negative integer if it consists of one or more
>> characters in the range U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9)."
>> So that makes it clear that percentage values are invalid as far as  
>> document
>> conformance goes.
>> But the UA requirements gives:
>> http://www.whatwg.org/specs/web-apps/current-work/complete/rendering.html#dimRendering
>> http://www.whatwg.org/specs/web-apps/current-work/complete/rendering.html#maps-to-the-dimension-property
>> http://www.whatwg.org/specs/web-apps/current-work/complete/common-microsyntaxes.html#rules-for-parsing-dimension-values
>> ...which supports percentage values.
> So, now I am even more confused: are they invalid or supported? How do
> you reconcile these two seemingly opposing positions?

They are invalid *and* supported. :-) Defined error handling if you will.  
It's all over the place in HTML5. See this section:


Simon Pieters
Opera Software

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