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Re: Behavior of device-pixel-ratio under zoom

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 13 Nov 2012 11:47:43 -0800
Message-ID: <CAAWBYDDZttQqc30Ho7J+JTwN54LECSBMWFRW-gJtD1p5YugBEQ@mail.gmail.com>
To: "Robert O'Callahan" <robert@ocallahan.org>
Cc: Simon Fraser <smfr@me.com>, "L. David Baron" <dbaron@dbaron.org>, www-style <www-style@w3.org>
On Mon, Nov 12, 2012 at 1:15 AM, Robert O'Callahan <robert@ocallahan.org> wrote:
> On Sun, Nov 11, 2012 at 7:13 PM, Simon Fraser <smfr@me.com> wrote:
>> We (Apple) feel quite strongly that device-pixel-ratio, like
>> window.devicePixelRatio,
>> should not change under zoom. It's answering a question about the device
>> hardware,
>> not the current zoom state of the page.
>>
>> I think in general authors should not be able to directly affect the
>> layout of the page
>> under different zoom levels. Zooming should shouldn't have unsurprising
>> side effects
>> for the user.
>
> For years Firefox has supported a zoom mode that does relayout the page (by
> changing the viewport size in CSS pixels). I believe Safari has supported
> something similar.
>
> I'm asking whether *that* kind of zoom should affect devicePixelRatio and
> device-pixel-ratio.

Like others, I feel strongly that *that* kind of zoom should affect
dPR and d-p-r.  (Perhaps we should call it "rescale", to separate it
from the related-only-thematically "zoom" operation that mobile
devices do?)

I suspect that Simon's statements are about "zoom", not "rescale", and
that he (and Apple in general) are fine with rescaling affecting dPR.

In any case, it appears that FF and IE both change dPR when you
"rescale", so that's the behavior we should go with.

~TJ
Received on Tuesday, 13 November 2012 19:48:31 GMT

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