svg2ttf/lib/sfnt.js

Converts SVG font to TTF font

'use strict'

var _ = require('lodash')

function Font () {
  this.ascent = 850
  this.copyright = ''
  this.createdDate = new Date()
  this.glyphs = []
  this.ligatures = []
  // Maping of code points to glyphs.
  // Keys are actually numeric, thus should be `parseInt`ed.
  this.codePoints = {}
  this.isFixedPitch = 0
  this.italicAngle = 0
  this.familyClass = 0 // No Classification
  this.familyName = ''

  // 0x40 - REGULAR - Characters are in the standard weight/style for the font
  // 0x80 - USE_TYPO_METRICS - use OS/2.sTypoAscender - OS/2.sTypoDescender + OS/2.sTypoLineGap as the default line spacing
  // https://docs.microsoft.com/en-us/typography/opentype/spec/os2#fsselection
  // https://github.com/fontello/svg2ttf/issues/95
  this.fsSelection = 0x40 | 0x80

  // Non zero value can cause issues in IE, https://github.com/fontello/svg2ttf/issues/45
  this.fsType = 0
  this.lowestRecPPEM = 8
  this.macStyle = 0
  this.modifiedDate = new Date()
  this.panose = {
    familyType: 2, // Latin Text
    serifStyle: 0, // any
    weight: 5, // book
    proportion: 3, // modern
    contrast: 0, // any
    strokeVariation: 0, // any,
    armStyle: 0, // any,
    letterform: 0, // any,
    midline: 0, // any,
    xHeight: 0 // any,
  }
  this.revision = 1
  this.sfntNames = []
  this.underlineThickness = 0
  this.unitsPerEm = 1000
  this.weightClass = 400 // normal
  this.width = 1000
  this.widthClass = 5 // Medium (normal)
  this.ySubscriptXOffset = 0
  this.ySuperscriptXOffset = 0
  this.int_descent = -150
  this.xHeight = 0
  this.capHeight = 0

  // getters and setters

  Object.defineProperty(this, 'descent', {
    get: function () {
      return this.int_descent
    },
    set: function (value) {
      this.int_descent = parseInt(Math.round(-Math.abs(value)), 10)
    }
  })

  this.__defineGetter__('avgCharWidth', function () {
    if (this.glyphs.length === 0) {
      return 0
    }
    var widths = _.map(this.glyphs, 'width')

    return parseInt(widths.reduce(function (prev, cur) {
      return prev + cur
    }) / widths.length, 10)
  })

  Object.defineProperty(this, 'ySubscriptXSize', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySubscriptXSize) ? this.int_ySubscriptXSize : (this.width * 0.6347), 10)
    },
    set: function (value) {
      this.int_ySubscriptXSize = value
    }
  })

  Object.defineProperty(this, 'ySubscriptYSize', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySubscriptYSize) ? this.int_ySubscriptYSize : ((this.ascent - this.descent) * 0.7), 10)
    },
    set: function (value) {
      this.int_ySubscriptYSize = value
    }
  })

  Object.defineProperty(this, 'ySubscriptYOffset', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySubscriptYOffset) ? this.int_ySubscriptYOffset : ((this.ascent - this.descent) * 0.14), 10)
    },
    set: function (value) {
      this.int_ySubscriptYOffset = value
    }
  })

  Object.defineProperty(this, 'ySuperscriptXSize', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySuperscriptXSize) ? this.int_ySuperscriptXSize : (this.width * 0.6347), 10)
    },
    set: function (value) {
      this.int_ySuperscriptXSize = value
    }
  })

  Object.defineProperty(this, 'ySuperscriptYSize', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySuperscriptYSize) ? this.int_ySuperscriptYSize : ((this.ascent - this.descent) * 0.7), 10)
    },
    set: function (value) {
      this.int_ySuperscriptYSize = value
    }
  })

  Object.defineProperty(this, 'ySuperscriptYOffset', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_ySuperscriptYOffset) ? this.int_ySuperscriptYOffset : ((this.ascent - this.descent) * 0.48), 10)
    },
    set: function (value) {
      this.int_ySuperscriptYOffset = value
    }
  })

  Object.defineProperty(this, 'yStrikeoutSize', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_yStrikeoutSize) ? this.int_yStrikeoutSize : ((this.ascent - this.descent) * 0.049), 10)
    },
    set: function (value) {
      this.int_yStrikeoutSize = value
    }
  })

  Object.defineProperty(this, 'yStrikeoutPosition', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_yStrikeoutPosition) ? this.int_yStrikeoutPosition : ((this.ascent - this.descent) * 0.258), 10)
    },
    set: function (value) {
      this.int_yStrikeoutPosition = value
    }
  })

  Object.defineProperty(this, 'minLsb', {
    get: function () {
      return parseInt(_.min(_.map(this.glyphs, 'xMin')), 10)
    }
  })

  Object.defineProperty(this, 'minRsb', {
    get: function () {
      if (!this.glyphs.length) return parseInt(this.width, 10)

      return parseInt(_.reduce(this.glyphs, function (minRsb, glyph) {
        return Math.min(minRsb, glyph.width - glyph.xMax)
      }, 0), 10)
    }
  })

  Object.defineProperty(this, 'xMin', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (xMin, glyph) {
        return Math.min(xMin, glyph.xMin)
      }, 0)
    }
  })

  Object.defineProperty(this, 'yMin', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (yMin, glyph) {
        return Math.min(yMin, glyph.yMin)
      }, 0)
    }
  })

  Object.defineProperty(this, 'xMax', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (xMax, glyph) {
        return Math.max(xMax, glyph.xMax)
      }, 0)
    }
  })

  Object.defineProperty(this, 'yMax', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (yMax, glyph) {
        return Math.max(yMax, glyph.yMax)
      }, 0)
    }
  })

  Object.defineProperty(this, 'avgWidth', {
    get: function () {
      var len = this.glyphs.length

      if (len === 0) {
        return this.width
      }

      var sumWidth = _.reduce(this.glyphs, function (sumWidth, glyph) {
        return sumWidth + glyph.width
      }, 0)

      return Math.round(sumWidth / len)
    }
  })

  Object.defineProperty(this, 'maxWidth', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (maxWidth, glyph) {
        return Math.max(maxWidth, glyph.width)
      }, 0)
    }
  })

  Object.defineProperty(this, 'maxExtent', {
    get: function () {
      if (!this.glyphs.length) return this.width

      return _.reduce(this.glyphs, function (maxExtent, glyph) {
        return Math.max(maxExtent, glyph.xMax /* - glyph.xMin */)
      }, 0)
    }
  })

  // Property used for `sTypoLineGap` in OS/2 and not used for `lineGap` in HHEA, because
  // non zero lineGap causes bad offset in IE, https://github.com/fontello/svg2ttf/issues/37
  Object.defineProperty(this, 'lineGap', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_lineGap) ? this.int_lineGap : ((this.ascent - this.descent) * 0.09), 10)
    },
    set: function (value) {
      this.int_lineGap = value
    }
  })

  Object.defineProperty(this, 'underlinePosition', {
    get: function () {
      return parseInt(!_.isUndefined(this.int_underlinePosition) ? this.int_underlinePosition : ((this.ascent - this.descent) * 0.01), 10)
    },
    set: function (value) {
      this.int_underlinePosition = value
    }
  })
}


function Glyph () {
  this.contours = []
  this.d = ''
  this.id = ''
  this.codes = [] // needed for nice validator error output
  this.height = 0
  this.name = ''
  this.width = 0
}

Object.defineProperty(Glyph.prototype, 'xMin', {
  get: function () {
    var xMin = 0
    var hasPoints = false

    _.forEach(this.contours, function (contour) {
      _.forEach(contour.points, function (point) {
        xMin = Math.min(xMin, Math.floor(point.x))
        hasPoints = true
      })
    })

    if (xMin < -32768) {
      throw new Error('xMin value for glyph ' + (this.name ? ('"' + this.name + '"') : JSON.stringify(this.codes)) +
                      ' is out of bounds (actual ' + xMin + ', expected -32768..32767, d="' + this.d + '")')
    }
    return hasPoints ? xMin : 0
  }
})

Object.defineProperty(Glyph.prototype, 'xMax', {
  get: function () {
    var xMax = 0
    var hasPoints = false

    _.forEach(this.contours, function (contour) {
      _.forEach(contour.points, function (point) {
        xMax = Math.max(xMax, -Math.floor(-point.x))
        hasPoints = true
      })
    })

    if (xMax > 32767) {
      throw new Error('xMax value for glyph ' + (this.name ? ('"' + this.name + '"') : JSON.stringify(this.codes)) +
                      ' is out of bounds (actual ' + xMax + ', expected -32768..32767, d="' + this.d + '")')
    }
    return hasPoints ? xMax : this.width
  }
})

Object.defineProperty(Glyph.prototype, 'yMin', {
  get: function () {
    var yMin = 0
    var hasPoints = false

    _.forEach(this.contours, function (contour) {
      _.forEach(contour.points, function (point) {
        yMin = Math.min(yMin, Math.floor(point.y))
        hasPoints = true
      })
    })

    if (yMin < -32768) {
      throw new Error('yMin value for glyph ' + (this.name ? ('"' + this.name + '"') : JSON.stringify(this.codes)) +
                      ' is out of bounds (actual ' + yMin + ', expected -32768..32767, d="' + this.d + '")')
    }
    return hasPoints ? yMin : 0
  }
})

Object.defineProperty(Glyph.prototype, 'yMax', {
  get: function () {
    var yMax = 0
    var hasPoints = false

    _.forEach(this.contours, function (contour) {
      _.forEach(contour.points, function (point) {
        yMax = Math.max(yMax, -Math.floor(-point.y))
        hasPoints = true
      })
    })

    if (yMax > 32767) {
      throw new Error('yMax value for glyph ' + (this.name ? ('"' + this.name + '"') : JSON.stringify(this.codes)) +
                      ' is out of bounds (actual ' + yMax + ', expected -32768..32767, d="' + this.d + '")')
    }
    return hasPoints ? yMax : 0
  }
})

function Contour () {
  this.points = []
}

function Point () {
  this.onCurve = true
  this.x = 0
  this.y = 0
}

function SfntName () {
  this.id = 0
  this.value = ''
}

module.exports.Font = Font
module.exports.Glyph = Glyph
module.exports.Contour = Contour
module.exports.Point = Point
module.exports.SfntName = SfntName
module.exports.toTTF = require('./ttf')