RE: WOFF 2.0: Known Table Tags Proposal

I agree, for WOFF 2.0 encoding we should compile a list of popular / frequently used tables, and any one-of-a-kind table that is rarely seen can simply be treated as an arbitrary tag. As far as table tags in general are concerned, the SFNT /TrueType / OpenType common structures presume that all original TrueType tags are spelled in lowercase letters, and all other tags should be all caps only. The mix of caps / lowercase characters in the same tag is not permitted.

Thank you,
Vlad


From: Behdad Esfahbod [mailto:behdad@google.com]
Sent: Friday, April 11, 2014 6:57 PM
To: David Kuettel
Cc: public-webfonts-wg@w3.org
Subject: Re: WOFF 2.0: Known Table Tags Proposal

At the end of the day, this doesn't matter much, we are talking saving, say, 20 bytes, for a rare font.  I think you should just fix a set and move on.

On Fri, Apr 11, 2014 at 3:51 PM, David Kuettel <kuettel@google.com<mailto:kuettel@google.com>> wrote:
On Fri, Apr 11, 2014 at 2:41 PM, Behdad Esfahbod <behdad@google.com<mailto:behdad@google.com>> wrote:
Thanks David.  Your code may be buggy with tags that have space in them.  It doesn't make sense that you didn't find any "cvt " or "CFF ".  Other than that, I suggest dropping EPAR as well as anything that shouldn't be in a final shipped product (VTT, etc).

Great points Behdad, I should have elaborated in my earlier emails.

The tool that I used was 'showttf' on Linux, which did segfault on some of the files.  A better tool would have been fonttools, esp. due to the worldclass support from you. :)

The collection of fonts (while good sized) did not contain PostScript/CFF fonts.  I need a bigger test set.

Really, lets just keep this to the union of OpenType spec, Apple TrueType, Graphite, and color fonts.

Regarding the Apple TrueType font tables, given that so few are likely still in use today, would it make since to whittle down the list a bit?  Or perhaps again, my test collection was too limited.

Cheers,
behdad

On Fri, Apr 11, 2014 at 2:05 PM, David Kuettel <kuettel@google.com<mailto:kuettel@google.com>> wrote:
To sanity check the initial list, I dumped the tables over a moderate sized collection of fonts, and then color coded the entries in the spreadsheet to reflect real-world usage (for this collection).

https://docs.google.com/a/google.com/spreadsheets/d/111MT0l7LOVqotAnMXD4PMOm36jTPSznUigJPfxUYY_0/edit#gid=0


The color coding ranges from dark green, to represent the most commonly used tables (e.g. name, glyph), to light green, to represent the least commonly used tables (e.g. JSTF, mort, Silf, etc).

The red entries represent tables that were not found with this collection (e.g. acnt, fmtx, TeX, etc).

The white (no color) entries represent tables that likely would have been present in a larger collection (e.g. CFF, cvt, sbix, COLR, etc).


Interestingly enough, the more tables that I look for, the more I find.  For example, FontLab's Glossary page documents a ton of optional font tables: http://blog.fontlab.com/info/  e.g. TSI1..TSIV and many more.

Thus, I am wondering if we should revisit the goal of trying to capture all known / used table tags.  Perhaps, esp. in light of this data, it would be better to just capture the most commonly used tables today, while ensuring that the rarely used ones would simply be passed through the WOFF 2.0 encode/decode process...

Thoughts?