getGlyph returns empty codePoints

[andreinitescu]

Any idea why getGlyph(gid) returns a Glyph with codePoints as an empty array?

I'm sure the gid I pass is correct.

[andreinitescu]

I'm trying to get the unicode for a glyph.

In the example below, I'm looking to get the F000 value for the glyph with index 66:

Per my understanding, in fontkit "unicode code point" refers to the "index" in the image above. How can I get the unicode (F000) value?

[guidoferreyra]

Having the same issue @andreinitescu did you find a workaround for this?

[Pomax]

@andreinitescu is there a specific public release for that font that you can link to, with some minimal code that does everything to reproduce the problem you had?

[guidoferreyra]

Here a reduced test case

test-Codepoints.zip

[andreinitescu]

@Pomax I cannot remember exactly which font was it, but I think it was Font Awesome (glass-martini glyph in the screenshot).

@guidoferreyra Sorry, I cannot remember, it's been a year.

[Pomax]

@guidoferreyra Interestingly, your test case uses a version of Roboto that has no official release. Turning that zip file into a post:

const fontkit = require('fontkit');

const font = fontkit.openSync('Roboto-Thin.ttf');

for (let i = 0; i < font.numGlyphs; i++) {
  const glyph = font.getGlyph(i);
  console.log(glyph.id, glyph.name, glyph.codePoints)
}

Does this also happen for v2.138? If so, can we turn that for loop into a specific single character for which this is known to go wrong, rather than a few tens of thousands of console logs? =)

[guidoferreyra]

I used Roboto just because was the first font that appeared on Google Fonts, but it’s happening with any font.

[guidoferreyra]

Just tested and this is happening with v2.138, v2.0 and v1.9

[Typogram]

I dig into the source code, the way getGlyph() is written is never meant to return codePoints, and it takes the second parameters and use that as codePoints, since the usage getGlyph(glyphId) omit the second parameter, it default the codePoints to an empty array [] and that is being used to construct the Glyph object and being returned.

When font.layout() internally called getGlyph(), the text string is converted to codePoints and pass into the getGlyph() as the second parameter and that get added to the Glyph object inside GlyphRun, so these Glyph has codePoints.

I find this API design confusing, making the Glyph object that get returned very unreliable.

Related source code snippets:

• getGlyph pass the params into this private function _getBaseGlyph

  
  _getBaseGlyph(glyph, characters = []) {
  if (!this._glyphs[glyph]) {
    if (this.directory.tables.glyf) {
      this._glyphs[glyph] = new TTFGlyph(glyph, characters, this);
  
    } else if (this.directory.tables['CFF '] || this.directory.tables.CFF2) {
      this._glyphs[glyph] = new CFFGlyph(glyph, characters, this);
    }
  }
  
  return this._glyphs[glyph] || null;
  }

• new TTFGlyph ( and other similar new Glyph for different format) all calls this constructor:

  export default class Glyph {
  constructor(id, codePoints, font) {
  /**
   * The glyph id in the font
   * @type {number}
   */
  this.id = id;
  
  /**
   * An array of unicode code points that are represented by this glyph.
   * There can be multiple code points in the case of ligatures and other glyphs
   * that represent multiple visual characters.
   * @type {number[]}
   */
  this.codePoints = codePoints;
  this._font = font;
  
  // TODO: get this info from GDEF if available
  this.isMark = this.codePoints.length > 0 && this.codePoints.every(isMark);
  this.isLigature = this.codePoints.length > 1;
  }
  ...

[guidoferreyra]

is it too nasty to use font._cmapProcessor.codePointsForGlyph(id); on the glyph constructor? It works for me.

export default class Glyph {
  constructor(id, codePoints, font) {
    /**
     * The glyph id in the font
     * @type {number}
     */
    this.id = id;

    /**
     * An array of unicode code points that are represented by this glyph.
     * There can be multiple code points in the case of ligatures and other glyphs
     * that represent multiple visual characters.
     * @type {number[]}
     */
    if (codePoints.length == 0) {
      this.codePoints = font._cmapProcessor.codePointsForGlyph(id);
    } else {
      this.codePoints = codePoints;
    }

    this._font = font;

    // TODO: get this info from GDEF if available
    this.isMark = this.codePoints.length > 0 && this.codePoints.every(isMark);
    this.isLigature = this.codePoints.length > 1;
  }