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

From: Dave Crossland via GitHub <sysbot+gh@w3.org>
Date: Wed, 27 May 2020 20:43:39 +0000
To: public-css-archive@w3.org
Message-ID: <issue_comment.created-634928818-1590612218-sysbot+gh@w3.org>
> Rasterisation is a whole other topic. 

Sure, in the details. Perhaps I should say 'quantization' rather than 'rasterization' as the point is that the glyph outline design (what I just called the '1000 UPM grid') is resolved to a 'css px' grid, that has a varying "resolution", and that grid, not a physical size, is what MUST be targeted - because the actual physical size has been abstracted away, along with ppem raster sizes and real pixels.

And hey, I am not "proposing" CSS px as a unit for optical size design, I am **stating** the fact that it is now already that unit, and this is unlikely to ever change.

**The opsz scale HAS ALREADY been redefined to use 'px' as a unit.**

There is a difference between 9pt and 12pt, but it is constant; and on the same computer running macOS or running Windows 10x, there is the very same difference between the macOS 9px and the Windows 9px. But the macOS is the "oddity," and the general assumption is that there are 96 dips to a physical inch. 

Therefore, the point of the `font-optical-sizing: FLOAT` proposal is to allow CSS authors to account for that difference between 9px's, for the "oddity" casesl and to allow environments to differentiate their internal CSS px sizes from the px size used in the opsz scale, by documenting the font-optical-sizing ratio defined in the user agent stylesheet for `font-optical-sizing: auto;`.

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Received on Wednesday, 27 May 2020 20:43:40 UTC

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