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Re: [css-device-adapt] Accepting semi-colons as a separator for meta-viewport

From: Kenneth Rohde Christiansen <kenneth.christiansen@gmail.com>
Date: Fri, 21 Oct 2011 12:48:43 +0200
Message-ID: <CAEC208v-PJDXJ5pfrc0XONy+K_NEFCFr9NUCJnDOs2b6FtKeuQ@mail.gmail.com>
To: Peter Beverloo <beverloo@google.com>
Cc: Rune Lillesveen <rune@opera.com>, www-style@w3.org
The ; was basically widespread by Android but I have been told that to
follow Safari, they removed their support for it, which let us to do
the same for our N9 browser.

Kenneth

On Fri, Oct 21, 2011 at 12:35 PM, Peter Beverloo <beverloo@google.com> wrote:
> On Fri, Oct 21, 2011 at 10:14 AM, Rune Lillesveen <rune@opera.com> wrote:
>> On Thu, 20 Oct 2011 19:12:01 +0200, Peter Beverloo <beverloo@google.com>
>> wrote:
>>
>>> The CSS Device Adapt specification defines a parsing algorithm[1] for
>>> the meta-element viewport content, which has been based on WebKit's
>>> implementation that shipped with iOS4. This algorithm only accepts
>>> commas as separators between properties.
>>
>> First, it's in a non-normative section, and we want UAs to move towards an
>> @viewport implementation. That being said, it's there to suggest a mapping
>> between viewport meta and @viewport in a transition phase.
>>
>>> In reality, web authors are using both commas as semi-colons. A wide
>>> range of websites, including CNN[2], Flickr[3] and Reddit[4] depend on
>>> this behavior, which has led at least Mozilla and Microsoft to
>>> implement it and, in case of the latter, write about it[5].
>>
>> Yes, and they have to add some combination of scale properties to compensate
>> for the fact that "width=device-width;" is the same as "width=0" in Safari
>> and Opera (see comments for the mentioned sites below).
>
> The fact that the numeric properties' values are being recognized are
> purely a work-around, which, in case of WebKit-based browsers, depends
> on disregarding trailing garbage for numeric values to parse these
> correctly (warnings for which are being shown in Web Inspector).
>
>>> I think the specification should adapt to reflect what authors are
>>> doing. While it's unfortunate that the divergence between commas and
>>> semi-colons happened, it's important for compatibility among mobile
>>> browsers.
>>
>> Two alternative proposed changes:
>>
>> 1. Keep the algorithm as it is and mention that some implementations accept
>> ';' as a separator in addition to ','.
>>
>> 2. Modify the algorithm to include ';' as a separator and say that it's
>> based on the Safari implementation with the ';' added as a recognized
>> separator.
>
> Your second alternative proposal describes the change I'm proposing,
> with the addition of a note saying that it differs there from Safari's
> implementation.
>
>>> [1] http://dev.w3.org/csswg/css-device-adapt/#parsing-algorithm
>>> [2] http://m.cnn.com
>>
>> Does not give me a viewport meta in Opera.
>
> I verified that they do give a viewport meta in WebKit, so they
> probably are sniffing for the browser. For reference:
>
> <meta xmlns="http://www.w3.org/1999/xhtml"
>      name="viewport"
>      content="initial-scale=1.0; maximum-scale=1.0; user-scalable=0;" />
>
>>> [3] http://m.flickr.com
>>
>> "width=device-width; initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"
>>
>> Works in Safari because the over-constraining scale values cause the width
>> to end up at device-width anyway. This would not have worked in Safari or
>> Opera: "width=device-width; user-scalable=0;".
>
> As said, this is because strtod() accepts trailing garbage, which
> applies to the numeric values. I don't expect authors to know about
> this difference.
>
> Peter
>
>>> [4] http://www.reddit.com/.compact (or http://m.reddit.com/)
>>
>> Same as for m.flickr.com.
>>
>>> [5]
>>> http://blogs.msdn.com/b/iemobile/archive/2010/11/22/the-ie-mobile-viewport-on-windows-phone-7.aspx
>>
>> --
>> Rune Lillesveen
>> Layout Group Manager
>> Core Technology Department
>> Opera Software ASA
>>
>
>
>
> --
> Peter Beverloo | Software Engineer | beverloo@google.com | +31-6-41000722
>
>



-- 
Kenneth Rohde Christiansen
Senior Engineer
Application and Service Frameworks, Nokia Danmark A/S
Phone  +45 4093 0598 / E-mail kenneth.christiansen at gmail.com

http://codeposts.blogspot.com ﹆﹆﹆
Received on Friday, 21 October 2011 10:49:40 GMT

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