27690 2014-12-24 09:57:22 +0000 Problematic definition of TextMetrics.emHeightDescent 2014-12-24 09:57:22 +0000 1 1 1 Unclassified HTML WG HTML Canvas 2D Context unspecified All All NEW P2 normal --- 1 motiz88 jaymunro mike public-html-admin public-html-wg-issue-tracking public-html-bugzilla oldest_to_newest 116673 0 motiz88 2014-12-24 09:57:22 +0000 Quoting the current spec and adding my own comments inline: > emHeightDescent attribute ... > positive numbers indicating that the given baseline is below the bottom of that em square This breaks the following convention otherwise followed by all Ascent/Descent attribute pairs: Ascent = positive numbers indicating a distance going up Descent = positive numbers indicating a distance going down (Thus Ascent+Descent = Height in a sense) I propose that emHeightDescent be brought in line with this convention. > (Zero if the given baseline is the top of that em square.) This was probably meant to say "bottom". To give some context - I am the author of https://github.com/motiz88/canvas-text-metrics-polyfill and actively working on bringing conforming measureText implementations to Chrome and Firefox (Chrome Canary has it, behind a flag and with some issues).