svg2ttf/lib/ttf/tables/maxp.js

Converts SVG font to TTF font

'use strict'

// See documentation here: http://www.microsoft.com/typography/otspec/maxp.htm

var _ = require('lodash')
var ByteBuffer = require('microbuffer')

// Find max points in glyph TTF contours.
function getMaxPoints (font) {
  return _.max(_.map(font.glyphs, function (glyph) {
    return _.reduce(glyph.ttfContours, function (sum, ctr) { return sum + ctr.length }, 0)
  }))
}

function getMaxContours (font) {
  return _.max(_.map(font.glyphs, function (glyph) {
    return glyph.ttfContours.length
  }))
}

function createMaxpTable (font) {
  var buf = new ByteBuffer(32)

  buf.writeInt32(0x10000) // version
  buf.writeUint16(font.glyphs.length) // numGlyphs
  buf.writeUint16(getMaxPoints(font)) // maxPoints
  buf.writeUint16(getMaxContours(font)) // maxContours
  buf.writeUint16(0) // maxCompositePoints
  buf.writeUint16(0) // maxCompositeContours
  buf.writeUint16(2) // maxZones
  buf.writeUint16(0) // maxTwilightPoints
  // It is unclear how to calculate maxStorage, maxFunctionDefs and maxInstructionDefs.
  // These are magic constants now, with values exceeding values from FontForge
  buf.writeUint16(10) // maxStorage
  buf.writeUint16(10) // maxFunctionDefs
  buf.writeUint16(0) // maxInstructionDefs
  buf.writeUint16(255) // maxStackElements
  buf.writeUint16(0) // maxSizeOfInstructions
  buf.writeUint16(0) // maxComponentElements
  buf.writeUint16(0) // maxComponentDepth

  return buf
}

module.exports = createMaxpTable