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Re: [csswg-drafts] [css-device-adapt] Terminology: define layout viewport and visual viewport

From: bokand via GitHub <sysbot+gh@w3.org>
Date: Wed, 19 Apr 2017 17:57:22 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-295367526-1492624641-sysbot+gh@w3.org>
I agree with Rick that "viewport" should default to what we colloquially call "layout viewport". "Layout viewport" is somewhat of a misnomer (in Chrome at least) as the ICB and "layout viewport" may differ in size under some scenarios. e.g. if the page has an element wider than the ICB, the layout viewport is expanded so that it covers the entire content width (to a limit). We do this since the layout viewport must always fully contain the visual viewport and we want to allow users to zoom out to fit the content width. It'd be more accurate to call it the "position: fixed viewport" or "minimally zoomed viewport".

I haven't seen how Safari iOS handles these cases yet, I'm looking into that now. IIRC Edge worked differently from Chrome here, I think their "layout viewport" really is the same size as the ICB regardless of the minimum-zoom/content width. In any case, I don't think we should enshrine "layout viewport" since it implies that it influences layout which reverses the relationship. IMHO, the fact that it often matches the size of the ICB is incidental to its purpose.

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Received on Wednesday, 19 April 2017 17:57:28 UTC

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