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

@jfkthame 

> Text styled as font-size:24pt might be rendered mere millimeters high, thanks to transform: scale(...), for example, or might be rendered several times larger as the user zooms the page, but it remains stylistically 24-point text and the optical size appropriate to this should be used. Zooming, transforms, OS resolution changes.... they're all simple linear scalings that should not result in a different rendering.

This is how the current draft revision to the opsz axis description discusses text scaling (using a distinction suggested by @PeterCon):

> In applications that automatically select an Optical size variant, this should normally be done based on the text size with a default or “100%” zoom level, not on a combination of text size and zoom level. Types of zoom that do not trigger re-layout of text should not change Optical size variant selection, while content enlarging or diminishing operations that change re-layout of text should make a new Optical size variant selection based on the new displayed sized.

So yes, linear scaling should not result in reselection of automatic opsz instance, but forms of scaling that involve re-layout, e.g. enlarging text such that lines reflow, would.

I'd also suggest that if an override mechanism has been used to explicitly specify a 24pt opsz instance, rather than automatic opsz selection, that explicit setting should be preserved even when text scaling involves re-layout. That is, explicit opsz selection should be understood as text styling, akin to setting an explicit weight, witdth or slant, as distinct from opsz selection as text automation.

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Received on Wednesday, 23 September 2020 16:47:37 UTC