- From: Dominik Röttsches via GitHub <sysbot+gh@w3.org>
- Date: Tue, 07 Nov 2023 08:29:17 +0000
- To: public-css-archive@w3.org
From the font technology perspective, for OpenType fonts the maximum glyph extent and maximum per-glyph bounding box should be specified in the HEAD table in the xMin, xMax, yMin, yMax fields. [Compare here](https://learn.microsoft.com/en-us/typography/opentype/spec/head#:~:text=int16,Minimum%20x%20coordinate%20across%20all%20glyph%20bounding%20boxes.). This a per-font metrics, as opposed to a per-glyph metric. **But**: I am not sure if applications are practically limited by that or restricting glyph drawing to the extents of this top-level bounding box. The individual bounding box of a glyph can still be determined by calculating a bounding box of its glyph shape and thus, a drawing backing surface can be allocated for an individual glyph that's potentially larger than what the font specifies in the HEAD table. I haven't checked a set of fonts on whether they specify reasonable values in there. So what usually happens if relying on a font metrics that's not been used in a strict way before: We may find many existing fonts having incorrect values in these field and if they were used as a strict restriction, glyphs may be cut off. CC @bungeman @behdad -- GitHub Notification of comment by drott Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8649#issuecomment-1798028695 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Tuesday, 7 November 2023 08:29:19 UTC