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

FYI, there's now discussion of this issue among the ad hoc OTvar stakeholder group, in response to a testing-the-waters proposal I wrote to change the opsz scale unit to 1/96 of a physical inch, as Dave suggests. I'm now leaning away from that option, because after a slow walk through of what Apple is doing, it seems to me that they're actually the ones getting it right, and the fault is in browsers that assume some unit equivalences that apply on the Apple platform can be applied elsewhere. So my current inclination is to update the spec to clarify the meaning of 'point' in the opsz context (as being 1/72 of a physical inch, as elsewhere in the OT spec), and to explicitly state that it is not appropriate to interpret the opsz scale as any other unit, such as CSS px. [I do like Nick's 3 arcminutes suggestion, but wonder if adding references to other units within the spec would confuse rather than clarify.]

This means, of course, that non-conformant browsers will need to be fixed, and hence an effort to log bugs, do a better job of communicating the correct way to implement opsz instance selection, and live with a period of increased variance in behaviour between browsers that get it right and those that don't. The good news is that fonts would not need to be updated, and the relatively small number of shipping fonts with opsz support can help make the case to browser makers that they can fix their current behaviour with minimal impact on websites.

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Received on Monday, 8 June 2020 17:29:51 UTC