What a font knows about its own letters

Four samples set twice each, once plain and once with a single setting turned on: joined letters, small capitals, figures that hang below the line, and pairs moved closer together.

JSON write_typography.json 421 lines

This one is not a program. It is the request the document server is sent: the same page, asked for over the network by an application that writes no PDF code at all.

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{
  "font_variants": [
    {
      "name": "serif_ligatures",
      "from": "serif",
      "ligatures": true
    },
    {
      "name": "serif_small_capitals",
      "from": "serif",
      "small_capitals": true
    },
    {
      "name": "serif_oldstyle_figures",
      "from": "serif",
      "oldstyle_figures": true
    },
    {
      "name": "serif_kerning",
      "from": "serif",
      "kerning": true
    }
  ],
  "items": [
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 756.0,
        "urx": 535.0,
        "ury": 780.0
      },
      "content": [
        "Four things a font knows about its own letters"
      ],
      "font": "serif",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 672.0,
        "urx": 535.0,
        "ury": 748.0
      },
      "content": [
        "A font file carries more than one glyph per character. It says which letters are drawn joined, which figures hang below the line, which letters have a small capital of their own, and how far apart each pair of glyphs should stand.\nNone of it is used unless it is asked for, so a document written before these settings existed comes out byte for byte as it did. Each sample below is set twice, and only the setting differs."
      ],
      "font": "serif",
      "font_size": 10.0,
      "leading": 14.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 624.0,
        "urx": 535.0,
        "ury": 640.0
      },
      "content": [
        "Ligatures"
      ],
      "font": "serif",
      "font_size": 12.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 612.0,
        "urx": 535.0,
        "ury": 624.0
      },
      "content": [
        "Letters that meet are drawn as one glyph the font designer cut for them."
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 586.0,
        "urx": 535.0,
        "ury": 598.0
      },
      "content": [
        "off"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 574.0,
        "urx": 581.0,
        "ury": 598.0
      },
      "content": [
        "office filing affidavit"
      ],
      "font": "serif",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 560.0,
        "urx": 535.0,
        "ury": 572.0
      },
      "content": [
        "on"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 548.0,
        "urx": 581.0,
        "ury": 572.0
      },
      "content": [
        "office filing affidavit"
      ],
      "font": "serif_ligatures",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 499.0,
        "urx": 535.0,
        "ury": 515.0
      },
      "content": [
        "Small capitals"
      ],
      "font": "serif",
      "font_size": 12.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 487.0,
        "urx": 535.0,
        "ury": 499.0
      },
      "content": [
        "Lowercase letters drawn as capitals no taller than an x."
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 461.0,
        "urx": 535.0,
        "ury": 473.0
      },
      "content": [
        "off"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 449.0,
        "urx": 581.0,
        "ury": 473.0
      },
      "content": [
        "reprinted quarterly"
      ],
      "font": "serif",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 435.0,
        "urx": 535.0,
        "ury": 447.0
      },
      "content": [
        "on"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 423.0,
        "urx": 581.0,
        "ury": 447.0
      },
      "content": [
        "reprinted quarterly"
      ],
      "font": "serif_small_capitals",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 374.0,
        "urx": 535.0,
        "ury": 390.0
      },
      "content": [
        "Old-style figures"
      ],
      "font": "serif",
      "font_size": 12.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 362.0,
        "urx": 535.0,
        "ury": 374.0
      },
      "content": [
        "Figures that rise and fall around the x-height instead of standing at cap height."
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 336.0,
        "urx": 535.0,
        "ury": 348.0
      },
      "content": [
        "off"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 324.0,
        "urx": 581.0,
        "ury": 348.0
      },
      "content": [
        "1 234 567 890"
      ],
      "font": "serif",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 310.0,
        "urx": 535.0,
        "ury": 322.0
      },
      "content": [
        "on"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 298.0,
        "urx": 581.0,
        "ury": 322.0
      },
      "content": [
        "1 234 567 890"
      ],
      "font": "serif_oldstyle_figures",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 249.0,
        "urx": 535.0,
        "ury": 265.0
      },
      "content": [
        "Kerning"
      ],
      "font": "serif",
      "font_size": 12.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 237.0,
        "urx": 535.0,
        "ury": 249.0
      },
      "content": [
        "Each pair of glyphs moved as far apart as the font asks."
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 211.0,
        "urx": 535.0,
        "ury": 223.0
      },
      "content": [
        "off"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 199.0,
        "urx": 581.0,
        "ury": 223.0
      },
      "content": [
        "Wavy TAXI Today"
      ],
      "font": "serif",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 185.0,
        "urx": 535.0,
        "ury": 197.0
      },
      "content": [
        "on"
      ],
      "font": "serif",
      "font_size": 9.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 106.0,
        "lly": 173.0,
        "urx": 581.0,
        "ury": 197.0
      },
      "content": [
        "Wavy TAXI Today"
      ],
      "font": "serif_kerning",
      "font_size": 18.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 120.0,
        "urx": 535.0,
        "ury": 150.0
      },
      "content": [
        "The first sample takes 23 glyphs as it stands and 18 with the ligatures on: the pairs the font joins are one glyph each."
      ],
      "font": "serif",
      "font_size": 10.0,
      "leading": 14.0
    },
    {
      "type": "text",
      "rect": {
        "llx": 60.0,
        "lly": 90.0,
        "urx": 535.0,
        "ury": 120.0
      },
      "content": [
        "The last sample is drawn 2.2 points narrower with kerning on, and it is measured that way too, so the line is as wide as it looks."
      ],
      "font": "serif",
      "font_size": 10.0,
      "leading": 14.0
    }
  ]
}