- From: fantasai via GitHub <sysbot+gh@w3.org>
- Date: Thu, 13 Aug 2020 02:18:27 +0000
- To: public-css-archive@w3.org
> Currently IIUC Ascent and Descent Metrics is used only for Canvas TextMetrics No, they are used in CSS layout also, e.g. for line height calculation. em-top/em-bottom are only used for Canvas, though. > When text-orientation: mixed, glyphs may be rendered upright or rotated sideways. Should Ascent and Descent Metrics use horizontal metrics for rotated sideways glyphs, or vertical metrics for upright glyphs? @kojiishi oh, that's tricky question. In general we [use the appropriate metrics per run based on orientation](https://www.w3.org/TR/css-writing-modes-3/#vertical-font-features). But you're right that for getting the metrics of a box, we have to decide whether `mixed` should be considered upright or sideways. I think I'm leaning towards using vertical metrics, unless they're missing, then use rotated horizontal metrics. I think that will work best for CJK, but I'm unsure about Mongolian--I think internally it's treated as rotated even though such characters are "upright" for the reader? That used to be the case in the past, I think; I'm unsure about current practices. -- GitHub Notification of comment by fantasai Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5381#issuecomment-673208925 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Thursday, 13 August 2020 02:18:29 UTC