Thanks for this addon, may be Forefox includes the callbacks in its renderer to allow tracking this info. Still Chrome does not allow this (this is hidden in the OpenType support library, which is also OS-dependant ; there's no standard DOM extension to inspect the rendering of a single text-element).
I've also asked to Chrome/Chromium developers to add an ainterface to inspect the contents of any plain-text string. I.e. enumerating the characters encoded in any string value, code point by code point (or may be only by 16-bit code unit, as this is the way Strings are perceived in Javascript) directly from the DOM inspector interface, including for all DOM and CSS properties, or in javascript text sources, or in the debugging console (such extension should not require any modification of the tricky text rendering OpenType support functions, it's just an addition to the UI layer of this debugging console). As these are internally exposed as "String" objects, the methods in the String class are usable for this. 2012/7/11 Khaled Hosny <khaledho...@eglug.org>: > On Wed, Jul 11, 2012 at 03:39:23AM +0200, Philippe Verdy wrote: >> (Unfortunately it's still almost impossible to determine how browsers >> are selecting fonts and which fonts get finally used to render text in >> their tricky code, > > Firefox has an addon for that: > https://addons.mozilla.org/en-US/firefox/addon/fontinfo/ > > Regards, > Khaled