- From: John Daggett <jdaggett@mozilla.com>
- Date: Fri, 31 May 2013 18:03:04 -0700 (PDT)
- To: W3C Style <www-style@w3.org>
Glenn Adams wrote: > > The computed value is "as specified". You get out the same values > > you put in. > > Ah, thanks, I'd missed the Computed value line. I guess it was too > much to hope that it would be possible to indirectly discover the > font's supported features through getComputedStyle. Both the 'font-variant' and 'font-feature-settings' are basically "hints" to the layout system, unlike other CSS properties they don't require something to be altered in the layout and display of text [*]. They are simply inputs to the OpenType layout system. Whether glyph selection or positioning is altered by a given font feature is determined by a few factors. After all the default glyph for each character is selected from the character map of the font, for each glyph in a text run these things affect glyph selection and placement: 1. Is the feature defined for the given language/script? 2. Did other features already applied affect the glyph selection? 3. Do the lookups defined for a feature match the glyph? 4. If the lookups are conditional, do the adjacent glyphs match the conditions? So there isn't really a way to use the application of features as a way to determine just (1). Like many things in life, the answer is "it's complicated". ;) Cheers, John Daggett [*] Except where explicit fallback is defined for the 'font-variant-position' and 'font-variant-caps' properties.
Received on Saturday, 1 June 2013 01:03:32 UTC