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Peter Constable

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Peter Constable
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  • John Hudson said: [A bit meta: We have no formal process in place for registering new axes in the new OT Design-Variation Axis Tag Registry. ... The goal you describe, of avoiding dead, redundant or inconsistently-implemented axes, is a g…
  • David: I had wondered if negative xtra values meant that the counter has flipped. But if you want to do that in the x-direction, why not also for ytra?
  • I'm digesting David's proposed axes. Here's the first one: Tag: xtra Name: x transparent Description: assigns a “white” per mille value to each instance of the design space Valid numeric range: -1000 to 2000 Scale interpretation: values can be inter…
  • This might be just slightly off topic... Dave Crossland said: Last week week, Type Network published 3 long-form essays on Variable Fonts by David Berlow, which provide context to David’s vision of variable fonts... I'm reading the third on…
  • The bounding box computed by the rasterizer -- the "phantom" points -- is derived (in a TT-flavoured font) solely using the 'glyf' and 'gvar' tables: the 'glyf' table provides phantom points for the default instance, and the 'gvar' table provides de…
  • Christian Thalmann said: From the Glyphs tutorial: ... In recent discussions, the ‘UPM dogma’ (the spec requirement that typoAscender and typoDescender add up to the UPM) ... There is no OpenType spec requirement that typoAscend…
  • @John Hudson: We've published an erratum for this in OT 1.8.2. Thanks for bringing it to my attention.
  • @John Hudson, I wasn't aware of that statement at the bottom of the script registry page. Theunis has located the relevant change. We'll need to revise the script registry page at some point.
  • OpenType lookups cannot be sensitive to line or paragraph boundaries since there are no glyphs that correspond to these. At best, lookups can recognize the ends of runs (by the absence of any glyph), though note that runs can be affected by several …
  • Old typo; I wasn't checking for such. Thanks.
  • See the information in the last section on this page for details: https://www.microsoft.com/typography/otspec/TTOCHAP1.htm
  • Sure: "Function: To minimize the number of glyph alternates, it is sometimes desirable to decompose the default glyph for a character into two or more glyphs. Additionally, it may be preferable to compose default glyphs for two or more characters …
  • Booo! Unicode supplementary-plane characters have been around since Unicode 3.1 -- published over 16 years ago!
  • I'll revise the 'ccmp' feature description as follows (changed text shown as bold): "Function: To minimize the number of glyph alternates, it is sometimes desired to decompose the default glyph for a character into two glyphs. Additionally, it may…
  • John and Khaled have been providing the right answers here. The 'ccmp' feature can map glyphs into other glyphs, and should be processed in all shaping engines (certainly will be on Windows); but the application of 'init'/'medi'/'fina' features for …
  • @John Hudson Thanks for that reminder. I recall now Rob mentioning you had brought this up, though I'm not sure I ever got around to reading that email. (I may have been relying on Rob to inform me of what mattered.) Great to have made history toge…
  • @John Hudson : Interestingly, I don't think I ever saw your proposal. I wasn't working in the text/font space at the time, though. For a bit more history... In the spring of 2014, we had finished Windows 8.1 and were starting Windows 10 planning, …
  • Oops! I certainly meant to include the link. Thanks, Bianca!
  • What I'm concerned about is that I know in the future there will be a desire for some differentiated treatment of variation axes in user interfaces. As soon as we create new APIs exposing variation axes, there will be font-picker/text-formatting use…
  • Dave, what's the difference between "show in expert modes" and "show to developers and people who really care to see everything"?
  • We just posted two new errata: 1. The gvar chapter had an incomplete specification of how to calculated inferred deltas when a contour point doesn't have explicit deltas. 2. The CFF2 chapter inadvertently had a maxstack operator introduced, but it'…
  • Re more detailed metadata, I think it's way to early to be guessing at what the best future UI affordances for axes may be. As John indicates, there is always some assumption to be made when no flags are set. If we don't explicitly say what should …
  • D. Epar ted said: ... It sounds like you want a three-way distinction: * Axis can always be exposed in UI. * Axis should only be exposed in "advanced" UI. * Axis should never be exposed in UI. I don't think we'd need three flag bits define…
  • How high a UPM do you want? (OpenType allows up to 16384.)
  • But do some (lots of?) people futz with spacing anyway? Or are tracking / character spacing features in apps simply an artefact that designs tailored to optical size went away in the phototypesetting era and didn't immediately return in the DTP era…
  • I'll need to investigate this. I think this may be relevant -- from the head table: "Note that, in a variable font with TrueType outlines, the left side bearing for each glyph must equal xMin, and bit 1 in the flags field must be set." For that re…
  • From the 'hmtx' chapter of the OpenType spec: "The horizontal metrics table provides horizontal metrics for each glyph — advance widths and left side bearings... In a font with TrueType outline data, these values can be computed from the 'glyf' tab…
  • I'm not sure about CFF2-flavoured fonts, but for variable fonts with TrueType outlines, that would not be a reliable thing to do. The reason is that the HVAR table is used to modify hmtx values, which you can think of as cached values. Ultimately, t…
  • Georg Seifert said: I just found a typo in https://www.microsoft.com/typography/otspec/otff.htm TAG ttcTag Font Collection ID string: 'ttcf' (used for used for fonts with CFF or CFF2 outlines as well as TrueType outlines) Ack (already …
  • The Typo LABS conference was great! Interesting presentations, and good discussions. I'm curious to know what others thought: Most interesting topic wrt variable fonts? Most interesting topic not related to variable fonts? Most significant take-awa…