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Peter Constable

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Peter Constable
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  • Re: [OTVar] Axes Proposals: variationsguide.typenetwork.com

    This might be just slightly off topic...

    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 one now. David says,
    The fifth registered axis is optical size. This is a treatment, because it does not change the script, class, family or style—just the appearance of a style at a particular size, or range of sizes.
    It seems to me that he considers optical-size variation to be a treatment rather than a style because a priori it is assumed that style cannot include optical-size variation. Is that a generally-held perspective?

    In the letterpress days, would a case of matrices had different drawers for different weights or widths and also different drawers for different sizes? If so, I suppose from that perspective optical-size variation was conflated with and not independent from text size. But in principle could flip things around by saying that optical-size variation was treated in a parallel manner to weight and width, and text-size was simply conflated with optical size. I guess the physical size is the more visible feature than the subtle changes in glyph design, though.

    But I still wonder: in what way is it useful to distinguish between style and treatment in the case of optical size? Earlier in the essay, he gave other examples of treatment, such as how a contour would be stroked or filled. Those involve changing the presentation with the contour staying constant. But with optical-size variation, the contour is changing.
  • Re: [OTVar] Axes Proposals: variationsguide.typenetwork.com

    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 interpreted as per-mille-of-em
    I can understand (at one level) what 0 "white" might mean. But it's not clear to me what negative values are supposed to mean.

    In the demo he provides, he points to the distance between stems of "H" as the xtra value. But it's not clear how that would relate to any other characters, such as "i" or "w" or "ই". Is the idea that the value would be based on glyphs for certain representative character or characters? If so, does it matter if this is done differently in different fonts?

    What's the interoperability need for such an axis?
  • Re: [OTVar] Axes Proposals: variationsguide.typenetwork.com

    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?
  • Re: [OTVAR] Exact definition of “bounding box” in a variable font.

    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 deltas that describe how the phantom points get translated for non-default instances, in the same way as it describes other points.

    Note: In the 'gvar' table, the number of glyph points is equal to the number of points in the glyph description in the 'glyf' table, plus the four phantom points (the last 4 points in 'gvar' point numbering).

    The hmtx/HVAR and vmtx/VVAR tables are expected to produce the same results as the rasterizer phantom points, modulo that the phantom points can potentially be adjusted by hints whereas hmtx/etc. values are not (just as in a non-variable font).

  • Re: OpenType 1.8.2 released

    @John Hudson: We've published an erratum for this in OT 1.8.2. Thanks for bringing it to my attention.