- From: Levantovsky, Vladimir <Vladimir.Levantovsky@monotype.com>
- Date: Wed, 23 Sep 2015 15:59:38 +0000
- To: Jonathan Kew <jfkthame@gmail.com>, "w3c-webfonts-wg (public-webfonts-wg@w3.org)" <public-webfonts-wg@w3.org>
Hi Jonathan, On Wednesday, September 23, 2015 11:46 AM Jonathan Kew wrote: > As currently written, ISTM that the draft spec REQUIRES the encoder > to check the LSBs against the 'glyf' table xMin values, and use transform > v.1 if they match. > I was assuming the use of this transform would be optional; the encoder > would always be allowed to use v.0 (i.e. the null transform), even if the > LSBs are such that one or both of the lsb/leftSideBearing streams could > be omitted. What the rationale would be to make it optional? In order to improve the compression gains we made the transforms for other two tables (glyf and loca) mandatory - what do we gain by not transforming the hmtx even if the data suggests certain things can be omitted? I would understand that the existing woff2 font files do not have this transform applied but the requirement to check and apply the transform is for the AT, not FF so by introducing this new option we do not invalidate any existing files. I understand that from the UA point of view having to support the transform when the flags indicate it was applied would be a necessity (unless it's an unlikely case when an old UA hasn't been updated yet) - but why define this as an option for the encoder? I'm not sure I see the benefit, or the use case, that would justify this (as you know I have a tendency to avoid options in the spec whenever we can). Thank you, Vlad
Received on Wednesday, 23 September 2015 16:10:35 UTC