Re: [css-device-adapt] Decoupling zoom and width/height

Just to point out that the device-width is always 320 on iPhone, and it
doesn't depend on orientation.

Kenneth

On Wed, Oct 31, 2012 at 11:56 AM, Kenneth Rohde Christiansen <
kenneth.r.christiansen@intel.com> wrote:

> Hi there,
>
> On Wed, Oct 31, 2012 at 8:58 AM, Rune Lillesveen <rune@opera.com> wrote:
>
>> The current constraining procedure has a coupling between zoom and auto
>> widths/heights (6-9) and extending widths/heights to fill the viewport for
>> a non-auto zoom (10-11).
>>
>> These stem from the Safari iOS meta viewport legacy.
>>
>> You can use a meta viewport tag with content="initial-scale=2" to get a
>> viewport which has a width/height that is 50% of the initial viewport
>> width/height. With an @viewport rule, you don't need to use zoom to achieve
>> that since you can have percentage lengths. For instance "@viewport {
>> width: 50%; height: auto; }".
>>
>> I would like to decouple the zoom from width/height by letting auto
>> width/height rely on non-auto width/height and initial viewport only. In
>> short, an auto width should get a width from the height and the initial
>> viewport aspect ratio. Vice versa for height. If both width and height are
>> auto, they will get initial viewport width and height respectively.
>>
>> I suspect the "extend width/height when both zoom and width is non-auto"
>> behavior is to handle the case content="width=320,initial-**scale=1"
>> which was used in Safari before device-width was available.
>
>
> I think this is because the viewport meta is always calculated given
> portrait mode. Ie. the iPhone has a device-height of 480 CSS units, so in
> landscape, width=320 and initial-scale=1 would not be possible. Thus the
> scale is respected first of all and then the width overflows and becomes
> 480. This makes it possible to use the same viewport meta tag for both
> orientations.
>
>
>> Extending the width/height to fill the initial viewport would make this
>> behave as width=device-width on different size displays like the iPad. I
>> don't see a use-case for this with @viewport apart from getting a backwards
>> compatible meta viewport implementation, which should be possible in the
>> property mapping.
>>
>
> Depends whether we intent people to use different @viewport's per
> orientation.
>
>
>>
>> Proposal, rule-wise:
>>
>> Replace step 6 and 7 with:
>>
>>   - If width and height are both ‘auto’, set width = initial-width
>>
>> and drop step 10 and 11.
>>
>> I have not worked out the details for the meta viewport to @viewport
>> mapping in chapter 11 to keep the same meta viewport behavior, but it looks
>> doable. I'll get back to that.
>>
>>
>> --
>> Rune Lillesveen
>>
>> --
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