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Re: [csswg-drafts] [css-fonts] Proposal to extend CSS font-optical-sizing (#4430)

From: John Hudson via GitHub <sysbot+gh@w3.org>
Date: Mon, 22 Jun 2020 18:30:20 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-647699321-1592850619-sysbot+gh@w3.org>
> But I would find it surprising (and unwelcome) for this to affect the choice of font faces (or used values of opsz), and perhaps erase the intended design difference between the elements.

That presumes that the opsz variation is a form of stylistic differentiation between text elements, like bold or italic style, that one expects to be retained when layout changes. I think that is an error, because _optical_ size-specific design is about making adjustments appropriate to the size of text that the reader is seeing, not styling the text in a particular way.

So if text is being enlarged — as distinct from zoomed — such that a new layout with differently sized text is presented to the reader, then it absolutely makes sense that a new opsz instance is selected, even if that meant that some text elements that were previously dfferent opsz variants are now clamped to the same opsz variant. [In practice, I think few opsz variable fonts would have so narrow a range of opsz variation as 9–18.]

As noted in the draft rewording of the opsz axis definition, it is recommended that software provide means to override automatic Optical size variant selection, as may be appropriate for particular platforms, intended use, known viewing distance, or accessibility. That could include, I suppose, overriding behaviour in text resizing situations.

> Another surprising result would be that line breaks within a fixed-width block on the page (e.g. a sidebar that has an absolute width set in CSS pixels (or em units, or whatever) will change when the page is zoomed, if this results in an opsz change. I believe that is unexpected and unwanted.

If I understand you correctly, this suggests that in a page content enlarging operation some text elements may need to allow reflow of layout and some may not, or, to put it another way, some may be enlarged and others zoomed. That seems to me something that CSS would need to be able to address.

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Received on Monday, 22 June 2020 18:30:26 UTC

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