blossom/application/text/formatter.js

Modern, Cross-Platform Application Framework

/*global linebreak*/

sc_require('text/object');
sc_require('text/array');
sc_require('text/linebreak');

/*!
 * Knuth and Plass line breaking algorithm in JavaScript
 *
 * Licensed under the new BSD License.
 * Copyright 2009-2010, Bram Stein
 * All rights reserved.
 */
var formatter = function (measureText, options) {
  var spaceWidth = measureText(' '),
    o = Object.extend({}, formatter.defaults, options);
  //console.log(emWidth);
  //emWidth = 12;

  return {
    center: function (text) {
      var nodes = [],
        words = text.split(/\s/),
        spaceStretch = (spaceWidth * o.space.width) / o.space.stretch,
        spaceShrink = (spaceWidth * o.space.width) / o.space.shrink;

      // Although not specified in the Knuth and Plass whitepaper, this box is necessary
      // to keep the glue from disappearing.
      nodes.push(linebreak.box(0, ''));
      nodes.push(linebreak.glue(0, 12, 0));

      words.forEach(function (word, index, array) {
        nodes.push(linebreak.box(measureText(word), word));

        if (index === array.length - 1) {
          nodes.push(linebreak.glue(0, 12, 0));
          nodes.push(linebreak.penalty(0, -linebreak.defaults.infinity, 0));
        } else {
          nodes.push(linebreak.glue(0, 12, 0));
          nodes.push(linebreak.penalty(0, 0, 0));
          nodes.push(linebreak.glue(spaceWidth, -24, 0));
          nodes.push(linebreak.box(0, ''));
          nodes.push(linebreak.penalty(0, linebreak.defaults.infinity, 0));
          nodes.push(linebreak.glue(0, 12, 0));
        }
      });
      return nodes;
    },
    justify: function (text) {
      var nodes = [],
        words = text.split(/\s/),
        spaceStretch = (spaceWidth * o.space.width) / o.space.stretch,
        spaceShrink = (spaceWidth * o.space.width) / o.space.shrink;

      words.forEach(function (word, index, array) {
        nodes.push(linebreak.box(measureText(word), word));

        if (index === array.length - 1) {
          nodes.push(linebreak.glue(0, linebreak.defaults.infinity, 0));
          nodes.push(linebreak.penalty(0, -linebreak.defaults.infinity, 1)); 
        } else {
          nodes.push(linebreak.glue(spaceWidth, spaceStretch, spaceShrink));
        }
      });
      return nodes;
    },
    left: function (text) {
      var nodes = [],
        words = text.split(/\s/),
        spaceStretch = (spaceWidth * o.space.width) / o.space.stretch,
        spaceShrink = (spaceWidth * o.space.width) / o.space.shrink;

      words.forEach(function (word, index, array) {
        nodes.push(linebreak.box(measureText(word), word));

        if (index === array.length - 1) {
          nodes.push(linebreak.glue(0, linebreak.defaults.infinity, 0));
          nodes.push(linebreak.penalty(0, -linebreak.defaults.infinity, 1)); 
        } else {
          nodes.push(linebreak.glue(0, 12, 0));
          nodes.push(linebreak.penalty(0, 0, 0));
          nodes.push(linebreak.glue(spaceWidth, -12, 0)); 
        }
      });
      return nodes;
    }
  };
};

Object.extend(formatter, {
  defaults: {
    space: {
      width: 3,
      stretch: 6,
      shrink: 9
    }
  }
});