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

From: Peter Beverloo <beverloo@google.com>
Date: Fri, 21 Oct 2011 12:36:01 +0100
Message-ID: <CALt3x6nhgmQNYpJWiDPUSe1zN0BS+D6GLmvarCAYnKKWTnPZqQ@mail.gmail.com>
To: Kenneth Rohde Christiansen <kenneth.christiansen@gmail.com>
Cc: Rune Lillesveen <rune@opera.com>, www-style@w3.org
On Fri, Oct 21, 2011 at 11:48 AM, Kenneth Rohde Christiansen
<kenneth.christiansen@gmail.com> wrote:
> 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.

While I'm aware of this, the Android Browser has supported this long
enough to create a wide-spread adoption among authors. As a result of
this, there are compatibility issues created by the -now- lack of
support for the separator, which is why I proposed the spec change.

Peter

> 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 11:36:27 GMT

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