[
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"path": ".editorconfig",
"content": "root = true\n\n[*]\nend_of_line = lf\ninsert_final_newline = false\nindent_style = space\nindent_size = 2\n"
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"path": ".gitignore",
"content": "# Logs\nlogs\n*.log\nnpm-debug.log*\n\n# Runtime data\npids\n*.pid\n*.seed\n\n# Directory for instrumented libs generated by jscoverage/JSCover\nlib-cov\n\n# Coverage directory used by tools like istanbul\ncoverage\n\n# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)\n.grunt\n\n# node-waf configuration\n.lock-wscript\n\n# Compiled binary addons (http://nodejs.org/api/addons.html)\nbuild/Release\n\n# Dependency directory\nnode_modules\n\n# Optional npm cache directory\n.npm\n\n# Optional REPL history\n.node_repl_history\n\n# JetBrains IDEs\n.idea\n\n# Test case output\ntest/output*.svg"
},
{
"path": ".npmignore",
"content": "# Logs\nlogs\n*.log\nnpm-debug.log*\n\n# Runtime data\npids\n*.pid\n*.seed\n\n# Directory for instrumented libs generated by jscoverage/JSCover\nlib-cov\n\n# Coverage directory used by tools like istanbul\ncoverage\n\n# nyc test coverage\n.nyc_output\n\n# Grunt intermediate storage (http://gruntjs.com/creating-plugins#storing-task-files)\n.grunt\n\n# node-waf configuration\n.lock-wscript\n\n# Compiled binary addons (http://nodejs.org/api/addons.html)\nbuild/Release\n\n# IDE files\n.project\n.idea\n*.iml\n\n# Test directory\ntest/\n"
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{
"path": ".travis.yml",
"content": "language: node_js\nnode_js:\n - \"0.12\"\n - \"4\"\n - \"6\"\nsudo: false"
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"path": "LICENSE",
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},
{
"path": "README.md",
"content": "# node-potrace\nA NodeJS-compatible fork of [Potrace in JavaScript][potrace-by-kilobtye] with some additions, which is in turn a port of [the original Potrace][potrace] — a tool for tracing bitmaps.\n\n## Example and demo\n\n| **Original image** | **Potrace output** | **Posterized output** |\n|---------------------------|------------------------------|-----------------------------------------|\n|  |  |  |\n\n(Example image inherited from [online demo of the browser version][potrace-js-demo])\n\n## Usage\n\nInstall\n\n```sh\nnpm install potrace\n```\n\nBasic usage\n\n```js\nvar potrace = require('potrace'),\n fs = require('fs');\n\npotrace.trace('./path/to/image.png', function(err, svg) {\n if (err) throw err;\n fs.writeFileSync('./output.svg', svg);\n});\n```\n\nYou can also provide a configuration object as a second argument.\n\n```js\nvar params = {\n background: '#49ffd2',\n color: 'blue',\n threshold: 120\n};\n\npotrace.trace('./path/to/image.png', params, function(err, svg) {\n /*...*/\n});\n```\n\nIf you want to run Potrace algorithm multiple times on the same image with different threshold setting and merge results together in a single file - `posterize` method does exactly that.\n\n```js\npotrace.posterize('./path/to/image.png', { threshold: 180, steps: 4 }, function(err, svg) {\n /*...*/\n});\n\n// or if you know exactly where you want to break it on different levels\n\npotrace.posterize('./path/to/image.png', { steps: [40, 85, 135, 180] }, function(err, svg) {\n /*...*/\n});\n```\n\n### Advanced usage and configuration\n\nBoth `trace` and `posterize` methods return instances of `Potrace` and `Posterizer` classes respectively to a callback function as third argument. \n\nYou can also instantiate these classes directly:\n\n```js\nvar potrace = require('potrace');\n\n// Tracing\n\nvar trace = new potrace.Potrace();\n\n// You can also pass configuration object to the constructor\ntrace.setParameters({\n threshold: 128,\n color: '#880000'\n});\n\ntrace.loadImage('path/to/image.png', function(err) {\n if (err) throw err;\n\n trace.getSVG(); // returns SVG document contents\n trace.getPathTag(); // will return just tag\n trace.getSymbol('traced-image'); // will return tag with given ID\n});\n\n// Posterization\n\nvar posterizer = new potrace.Posterize();\n\nposterizer.loadImage('path/to/image.png', function(err) {\n if (err) throw err;\n \n posterizer.setParameter({\n color: '#ccc',\n background: '#222',\n steps: 3,\n threshold: 200,\n fillStrategy: potrace.Posterize.FILL_MEAN\n });\n \n posterizer.getSVG();\n // or\n posterizer.getSymbol('posterized-image');\n});\n```\n\nCallback function provided to `loadImage` methods will be executed in context of the `Potrace`/`Posterizer` instance, so if it doesn't go against your code style - you can just do\n\n```js\nnew potrace.Potrace()\n .loadImage('path/to/image.bmp', function() {\n if (err) throw err;\n this.getSymbol('foo');\n });\n```\n\n[Jimp module][jimp] is used on the back end, so first argument accepted by `loadImage` method could be anything Jimp can read: a `Buffer`, local path or a url string. Supported formats are: PNG, JPEG or BMP. It also could be a Jimp instance (provided bitmap is not modified)\n\n### Parameters\n\n`Potrace` class expects following parameters:\n\n- **turnPolicy** - how to resolve ambiguities in path decomposition. Possible values are exported as constants: `TURNPOLICY_BLACK`, `TURNPOLICY_WHITE`, `TURNPOLICY_LEFT`, `TURNPOLICY_RIGHT`, `TURNPOLICY_MINORITY`, `TURNPOLICY_MAJORITY`. Refer to [this document][potrace-algorithm] for more information (page 4) \n (default: `TURNPOLICY_MINORITY`)\n- **turdSize** - suppress speckles of up to this size \n (default: 2)\n- **alphaMax** - corner threshold parameter \n (default: 1)\n- **optCurve** - curve optimization \n (default: true)\n- **optTolerance** - curve optimization tolerance \n (default: 0.2)\n- **threshold** - threshold below which color is considered black.\n Should be a number in range 0..255 or `THRESHOLD_AUTO` in which case threshold will be selected automatically using [Algorithm For Multilevel Thresholding][multilevel-thresholding] \n (default: `THRESHOLD_AUTO`) \n- **blackOnWhite** - specifies colors by which side from threshold should be turned into vector shape \n (default: `true`) \n- **color** - Fill color. Will be ignored when exporting as \\. (default: `COLOR_AUTO`, which means black or white, depending on `blackOnWhite` property)\n- **background** - Background color. Will be ignored when exporting as \\. By default is not present (`COLOR_TRANSPARENT`)\n\n---------------\n\n`Posterizer` class has same methods as `Potrace`, in exception of `.getPathTag()`. \nConfiguration object is extended with following properties:\n\n- **fillStrategy** - determines how fill color for each layer should be selected. Possible values are exported as constants: \n - `FILL_DOMINANT` - most frequent color in range (used by default), \n - `FILL_MEAN` - arithmetic mean (average), \n - `FILL_MEDIAN` - median color, \n - `FILL_SPREAD` - ignores color information of the image and just spreads colors equally in range 0..\\ (or \\..255 if `blackOnWhite` is set to `false`),\n- **rangeDistribution** - how color stops for each layer should be selected. Ignored if `steps` is an array. Possible values are:\n - `RANGES_AUTO` - Performs automatic thresholding (using [Algorithm For Multilevel Thresholding][multilevel-thresholding]). Preferable method for already posterized sources, but takes long time to calculate 5 or more thresholds (exponential time complexity) \n *(used by default)*\n - `RANGES_EQUAL` - Ignores color information of the image and breaks available color space into equal chunks\n- **steps** - Specifies desired number of layers in resulting image. If a number provided - thresholds for each layer will be automatically calculated according to `rangeDistribution` parameter. If an array provided it expected to be an array with precomputed thresholds for each layer (in range 0..255) \n (default: `STEPS_AUTO` which will result in `3` or `4`, depending on `threshold` value)\n- **threshold** - Breaks image into foreground and background (and only foreground being broken into desired number of layers). Basically when provided it becomes a threshold for last (least opaque) layer and then `steps - 1` intermediate thresholds calculated. If **steps** is an array of thresholds and every value from the array is lower (or larger if **blackOnWhite** parameter set to `false`) than threshold - threshold will be added to the array, otherwise just ignored. \n (default: `Potrace.THRESHOLD_AUTO`)\n- *all other parameters that Potrace class accepts*\n\n**Notes:**\n\n- When number of `steps` is greater than 10 - an extra layer could be added to ensure presence of darkest/brightest colors if needed to ensure presence of probably-important-at-this-point details like shadows or line art.\n- With big number of layers produced image will be looking brighter overall than original due to math error at the rendering phase because of how layers are composited.\n- With default configuration `steps`, `threshold` and `rangeDistribution` settings all set to auto, resulting in a 4 thresholds/color stops being calculated with Multilevel Thresholding algorithm mentioned above. Calculation of 4 thresholds takes 3-5 seconds on average laptop. You may want to explicitly limit number of `steps` to 3 to moderately improve processing speed. \n\n## Thanks to\n\n- Peter Selinger for [original Potrace tool and algorithm][potrace]\n- @kilobtye for original [javascript port][potrace-by-kilobtye]\n\n## License\n\nThe GNU General Public License version 2 (GPLv2). Please see [License File](LICENSE) for more information.\n\n[potrace]: http://potrace.sourceforge.net/\n[potrace-algorithm]: http://potrace.sourceforge.net/potrace.pdf\n[multilevel-thresholding]: http://www.iis.sinica.edu.tw/page/jise/2001/200109_01.pdf\n[potrace-by-kilobtye]: https://github.com/kilobtye/potrace\n[potrace-js-demo]: http://kilobtye.github.io/potrace/\n[jimp]: https://github.com/oliver-moran/jimp"
},
{
"path": "lib/Posterizer.js",
"content": "'use strict';\n\nvar Potrace = require('./Potrace');\nvar utils = require('./utils');\n\n/**\n * Takes multiple samples using {@link Potrace} with different threshold\n * settings and combines output into a single file.\n *\n * @param {Posterizer~Options} [options]\n * @constructor\n */\nfunction Posterizer(options) {\n this._potrace = new Potrace();\n\n this._calculatedThreshold = null;\n \n this._params = {\n threshold: Potrace.THRESHOLD_AUTO,\n blackOnWhite: true,\n steps: Posterizer.STEPS_AUTO,\n background: Potrace.COLOR_TRANSPARENT,\n fillStrategy: Posterizer.FILL_DOMINANT,\n rangeDistribution: Posterizer.RANGES_AUTO\n };\n\n if (options) {\n this.setParameters(options);\n }\n}\n\n// Inherit constants from Potrace class\nfor (var key in Potrace) {\n if (Object.prototype.hasOwnProperty.call(Potrace, key) && key === key.toUpperCase()) {\n Posterizer[key] = Potrace[key];\n }\n}\n\nPosterizer.STEPS_AUTO = -1;\nPosterizer.FILL_SPREAD = 'spread';\nPosterizer.FILL_DOMINANT = 'dominant';\nPosterizer.FILL_MEDIAN = 'median';\nPosterizer.FILL_MEAN = 'mean';\n\nPosterizer.RANGES_AUTO = 'auto';\nPosterizer.RANGES_EQUAL = 'equal';\n\nPosterizer.prototype = {\n /**\n * Fine tuning to color ranges.\n *\n * If last range (featuring most saturated color) is larger than 10% of color space (25 units)\n * then we want to add another color stop, that hopefully will include darkest pixels, improving presence of\n * shadows and line art\n *\n * @param ranges\n * @private\n */\n _addExtraColorStop: function(ranges) {\n var blackOnWhite = this._params.blackOnWhite;\n var lastColorStop = ranges[ranges.length - 1];\n var lastRangeFrom = blackOnWhite ? 0 : lastColorStop.value;\n var lastRangeTo = blackOnWhite ? lastColorStop.value : 255;\n\n if (lastRangeTo - lastRangeFrom > 25 && lastColorStop.colorIntensity !== 1) {\n var histogram = this._getImageHistogram();\n var levels = histogram.getStats(lastRangeFrom, lastRangeTo).levels;\n\n var newColorStop = levels.mean + levels.stdDev <= 25 ? levels.mean + levels.stdDev\n : levels.mean - levels.stdDev <= 25 ? levels.mean - levels.stdDev\n : 25;\n\n var newStats = (blackOnWhite ? histogram.getStats(0, newColorStop) : histogram.getStats(newColorStop, 255));\n var color = newStats.levels.mean;\n\n ranges.push({\n value: Math.abs((blackOnWhite ? 0 : 255) - newColorStop),\n colorIntensity: isNaN(color) ? 0 : ((blackOnWhite ? 255 - color : color) / 255)\n });\n }\n\n return ranges;\n },\n\n\n /**\n * Calculates color intensity for each element of numeric array\n * \n * @param {number[]} colorStops\n * @returns {{ levels: number, colorIntensity: number }[]}\n * @private\n */\n _calcColorIntensity: function(colorStops) {\n var blackOnWhite = this._params.blackOnWhite;\n var colorSelectionStrat = this._params.fillStrategy;\n var histogram = colorSelectionStrat !== Posterizer.FILL_SPREAD ? this._getImageHistogram() : null;\n var fullRange = Math.abs(this._paramThreshold() - (blackOnWhite ? 0 : 255));\n\n return colorStops.map(function(threshold, index) {\n var nextValue = index + 1 === colorStops.length ? (blackOnWhite ? -1 : 256) : colorStops[index + 1];\n var rangeStart = Math.round(blackOnWhite ? nextValue + 1 : threshold);\n var rangeEnd = Math.round(blackOnWhite ? threshold : nextValue - 1);\n var factor = index / (colorStops.length - 1);\n var intervalSize = rangeEnd - rangeStart;\n var stats = histogram.getStats(rangeStart, rangeEnd);\n var color = -1;\n\n if (stats.pixels === 0) {\n return {\n value: threshold,\n colorIntensity: 0\n };\n }\n\n switch (colorSelectionStrat) {\n case Posterizer.FILL_SPREAD:\n // We want it to be 0 (255 when white on black) at the most saturated end, so...\n color = (blackOnWhite ? rangeStart : rangeEnd)\n + (blackOnWhite ? 1 : -1) * intervalSize * Math.max(0.5, fullRange / 255) * factor;\n break;\n case Posterizer.FILL_DOMINANT:\n color = histogram.getDominantColor(rangeStart, rangeEnd, utils.clamp(intervalSize, 1, 5));\n break;\n case Posterizer.FILL_MEAN:\n color = stats.levels.mean;\n break;\n case Posterizer.FILL_MEDIAN:\n color = stats.levels.median;\n break;\n }\n\n // We don't want colors to be too close to each other, so we introduce some spacing in between\n if (index !== 0) {\n color = blackOnWhite\n ? utils.clamp(color, rangeStart, rangeEnd - Math.round(intervalSize * 0.1))\n : utils.clamp(color, rangeStart + Math.round(intervalSize * 0.1), rangeEnd);\n }\n\n return {\n value: threshold,\n colorIntensity: color === -1 ? 0 : ((blackOnWhite ? 255 - color : color) / 255)\n };\n });\n },\n\n /**\n * @returns {Histogram}\n * @private\n */\n _getImageHistogram: function() {\n return this._potrace._luminanceData.histogram();\n },\n\n /**\n * Processes threshold, steps and rangeDistribution parameters and returns normalized array of color stops\n * @returns {*}\n * @private\n */\n _getRanges: function() {\n var steps = this._paramSteps();\n\n if (!Array.isArray(steps)) {\n return this._params.rangeDistribution === Posterizer.RANGES_AUTO\n ? this._getRangesAuto()\n : this._getRangesEquallyDistributed();\n }\n\n // Steps is array of thresholds and we want to preprocess it\n\n var colorStops = [];\n var threshold = this._paramThreshold();\n var lookingForDarkPixels = this._params.blackOnWhite;\n\n steps.forEach(function(item) {\n if (colorStops.indexOf(item) === -1 && utils.between(item, 0, 255)) {\n colorStops.push(item);\n }\n });\n\n if (!colorStops.length) {\n colorStops.push(threshold);\n }\n\n colorStops = colorStops.sort(function (a, b) {\n return a < b === lookingForDarkPixels ? 1 : -1;\n });\n\n if (lookingForDarkPixels && colorStops[0] < threshold) {\n colorStops.unshift(threshold);\n } else if (!lookingForDarkPixels && colorStops[colorStops.length - 1] < threshold) {\n colorStops.push(threshold);\n }\n\n return this._calcColorIntensity(colorStops);\n },\n\n /**\n * Calculates given (or lower) number of thresholds using automatic thresholding algorithm\n * @returns {*}\n * @private\n */\n _getRangesAuto: function() {\n var histogram = this._getImageHistogram();\n var steps = this._paramSteps(true);\n var colorStops;\n\n if (this._params.threshold === Potrace.THRESHOLD_AUTO) {\n colorStops = histogram.multilevelThresholding(steps);\n } else {\n var threshold = this._paramThreshold();\n\n colorStops = this._params.blackOnWhite\n ? histogram.multilevelThresholding(steps - 1, 0, threshold)\n : histogram.multilevelThresholding(steps - 1, threshold, 255);\n\n if (this._params.blackOnWhite) {\n colorStops.push(threshold);\n } else {\n colorStops.unshift(threshold);\n }\n }\n\n if (this._params.blackOnWhite) {\n colorStops = colorStops.reverse();\n }\n\n return this._calcColorIntensity(colorStops);\n },\n\n /**\n * Calculates color stops and color representing each segment, returning them\n * from least to most intense color (black or white, depending on blackOnWhite parameter)\n *\n * @private\n */\n _getRangesEquallyDistributed: function() {\n var blackOnWhite = this._params.blackOnWhite;\n var colorsToThreshold = blackOnWhite ? this._paramThreshold() : 255 - this._paramThreshold();\n var steps = this._paramSteps();\n\n var stepSize = colorsToThreshold / steps;\n var colorStops = [];\n var i = steps - 1,\n factor,\n threshold;\n\n while (i >= 0) {\n factor = i / (steps - 1);\n threshold = Math.min(colorsToThreshold, (i + 1) * stepSize);\n threshold = blackOnWhite ? threshold : 255 - threshold;\n i--;\n\n colorStops.push(threshold);\n }\n\n return this._calcColorIntensity(colorStops);\n },\n\n /**\n * Returns valid steps value\n * @param {Boolean} [count=false]\n * @returns {number|number[]}\n * @private\n */\n _paramSteps: function(count) {\n var steps = this._params.steps;\n\n if (Array.isArray(steps)) {\n return count ? steps.length : steps;\n }\n\n if (steps === Posterizer.STEPS_AUTO && this._params.threshold === Potrace.THRESHOLD_AUTO) {\n return 4;\n }\n\n var blackOnWhite = this._params.blackOnWhite;\n var colorsCount = blackOnWhite ? this._paramThreshold() : 255 - this._paramThreshold();\n\n return steps === Posterizer.STEPS_AUTO\n ? (colorsCount > 200 ? 4 : 3)\n : Math.min(colorsCount, Math.max(2, steps));\n },\n\n /**\n * Returns valid threshold value\n * @returns {number}\n * @private\n */\n _paramThreshold: function() {\n if (this._calculatedThreshold !== null) {\n return this._calculatedThreshold;\n }\n\n if (this._params.threshold !== Potrace.THRESHOLD_AUTO) {\n this._calculatedThreshold = this._params.threshold;\n return this._calculatedThreshold;\n }\n\n var twoThresholds = this._getImageHistogram().multilevelThresholding(2);\n this._calculatedThreshold = this._params.blackOnWhite ? twoThresholds[1] : twoThresholds[0];\n this._calculatedThreshold = this._calculatedThreshold || 128;\n\n return this._calculatedThreshold;\n },\n\n /**\n * Running potrace on the image multiple times with different thresholds and returns an array\n * of path tags\n *\n * @param {Boolean} [noFillColor]\n * @returns {string[]}\n * @private\n */\n _pathTags: function(noFillColor) {\n var ranges = this._getRanges();\n var potrace = this._potrace;\n var blackOnWhite = this._params.blackOnWhite;\n\n if (ranges.length >= 10) {\n ranges = this._addExtraColorStop(ranges);\n }\n\n potrace.setParameters({ blackOnWhite: blackOnWhite });\n\n var actualPrevLayersOpacity = 0;\n\n return ranges.map(function(colorStop) {\n var thisLayerOpacity = colorStop.colorIntensity;\n\n if (thisLayerOpacity === 0) {\n return '';\n }\n\n // NOTE: With big number of layers (something like 70) there will be noticeable math error on rendering side.\n // In Chromium at least image will end up looking brighter overall compared to the same layers painted in solid colors.\n // However it works fine with sane number of layers, and it's not like we can do much about it.\n\n var calculatedOpacity = (!actualPrevLayersOpacity || thisLayerOpacity === 1)\n ? thisLayerOpacity\n : ((actualPrevLayersOpacity - thisLayerOpacity) / (actualPrevLayersOpacity - 1));\n\n calculatedOpacity = utils.clamp(parseFloat(calculatedOpacity.toFixed(3)), 0, 1);\n actualPrevLayersOpacity = actualPrevLayersOpacity + (1 - actualPrevLayersOpacity) * calculatedOpacity;\n\n potrace.setParameters({ threshold: colorStop.value });\n\n var element = noFillColor ? potrace.getPathTag('') : potrace.getPathTag();\n element = utils.setHtmlAttr(element, 'fill-opacity', calculatedOpacity.toFixed(3));\n\n var canBeIgnored = calculatedOpacity === 0 || element.indexOf(' d=\"\"') !== -1;\n\n // var c = Math.round(Math.abs((blackOnWhite ? 255 : 0) - 255 * thisLayerOpacity));\n // element = utils.setHtmlAttr(element, 'fill', 'rgb('+c+', '+c+', '+c+')');\n // element = utils.setHtmlAttr(element, 'fill-opacity', '');\n\n return canBeIgnored ? '' : element;\n });\n },\n\n /**\n * Loads image.\n *\n * @param {string|Buffer|Jimp} target Image source. Could be anything that {@link Jimp} can read (buffer, local path or url). Supported formats are: PNG, JPEG or BMP\n * @param {Function} callback\n */\n loadImage: function(target, callback) {\n var self = this;\n\n this._potrace.loadImage(target, function(err) {\n self._calculatedThreshold = null;\n callback.call(self, err);\n });\n },\n\n /**\n * Sets parameters. Accepts same object as {Potrace}\n *\n * @param {Posterizer~Options} params\n */\n setParameters: function(params) {\n if (!params) {\n return;\n }\n\n this._potrace.setParameters(params);\n\n if (params.steps && !Array.isArray(params.steps) && (!utils.isNumber(params.steps) || !utils.between(params.steps, 1, 255))) {\n throw new Error('Bad \\'steps\\' value');\n }\n\n for (var key in this._params) {\n if (this._params.hasOwnProperty(key) && params.hasOwnProperty(key)) {\n this._params[key] = params[key];\n }\n }\n\n this._calculatedThreshold = null;\n },\n\n /**\n * Returns image as tag. Always has viewBox specified\n *\n * @param {string} id\n */\n getSymbol: function(id) {\n var width = this._potrace._luminanceData.width;\n var height = this._potrace._luminanceData.height;\n var paths = this._pathTags(true);\n\n return '' +\n paths.join('') +\n '';\n },\n\n /**\n * Generates SVG image\n * @returns {String}\n */\n getSVG: function() {\n var width = this._potrace._luminanceData.width,\n height = this._potrace._luminanceData.height;\n\n var tags = this._pathTags(false);\n\n var svg = '';\n\n return svg.replace(/\\n(?:\\t*\\n)+(\\t*)/g, '\\n$1');\n }\n};\n\nmodule.exports = Posterizer;\n\n/**\n * Posterizer options\n *\n * @typedef {Potrace~Options} Posterizer~Options\n * @property {Number} [steps] - Number of samples that needs to be taken (and number of layers in SVG). (default: Posterizer.STEPS_AUTO, which most likely will result in 3, sometimes 4)\n * @property {*} [fillStrategy] - How to select fill color for color ranges - equally spread or dominant. (default: Posterizer.FILL_DOMINANT)\n * @property {*} [rangeDistribution] - How to choose thresholds in-between - after equal intervals or automatically balanced. (default: Posterizer.RANGES_AUTO)\n */\n"
},
{
"path": "lib/Potrace.js",
"content": "'use strict';\n\nvar Jimp = require('jimp');\nvar Bitmap = require('./types/Bitmap');\nvar Curve = require('./types/Curve');\nvar Point = require('./types/Point');\nvar Path = require('./types/Path');\nvar Quad = require('./types/Quad');\nvar Sum = require('./types/Sum');\nvar Opti = require('./types/Opti');\n\nvar utils = require('./utils');\n\n/**\n * Potrace class\n *\n * @param {Potrace~Options} [options]\n * @constructor\n */\nfunction Potrace (options) {\n this._luminanceData = null;\n this._pathlist = [];\n\n this._imageLoadingIdentifier = null;\n this._imageLoaded = false;\n this._processed = false;\n\n this._params = {\n turnPolicy: Potrace.TURNPOLICY_MINORITY,\n turdSize: 2,\n alphaMax: 1,\n optCurve: true,\n optTolerance: 0.2,\n threshold: Potrace.THRESHOLD_AUTO,\n blackOnWhite: true,\n color: Potrace.COLOR_AUTO,\n background: Potrace.COLOR_TRANSPARENT\n };\n\n if (options) {\n this.setParameters(options);\n }\n}\n\nPotrace.COLOR_AUTO = 'auto';\nPotrace.COLOR_TRANSPARENT = 'transparent';\nPotrace.THRESHOLD_AUTO = -1;\nPotrace.TURNPOLICY_BLACK = 'black';\nPotrace.TURNPOLICY_WHITE = 'white';\nPotrace.TURNPOLICY_LEFT = 'left';\nPotrace.TURNPOLICY_RIGHT = 'right';\nPotrace.TURNPOLICY_MINORITY = 'minority';\nPotrace.TURNPOLICY_MAJORITY = 'majority';\n\nvar SUPPORTED_TURNPOLICY_VALUES = [\n Potrace.TURNPOLICY_BLACK, Potrace.TURNPOLICY_WHITE,\n Potrace.TURNPOLICY_LEFT, Potrace.TURNPOLICY_RIGHT,\n Potrace.TURNPOLICY_MINORITY, Potrace.TURNPOLICY_MAJORITY\n];\n\nPotrace.prototype = {\n /**\n * Creating a new {@link Path} for every group of black pixels.\n * @private\n */\n _bmToPathlist: function() {\n var self = this,\n threshold = this._params.threshold,\n blackOnWhite = this._params.blackOnWhite,\n blackMap,\n currentPoint = new Point(0, 0),\n path;\n\n if (threshold === Potrace.THRESHOLD_AUTO) {\n threshold = this._luminanceData.histogram().autoThreshold() || 128;\n }\n\n blackMap = this._luminanceData.copy(function(lum) {\n var pastTheThreshold = blackOnWhite\n ? lum > threshold\n : lum < threshold;\n\n return pastTheThreshold ? 0 : 1;\n });\n \n /**\n * finds next black pixel of the image\n *\n * @param {Point} point\n * @returns {boolean}\n * @private\n */\n function findNext(point) {\n var i = blackMap.pointToIndex(point);\n\n while (i < blackMap.size && blackMap.data[i] !== 1) {\n i++;\n }\n\n return i < blackMap.size && blackMap.indexToPoint(i);\n }\n\n function majority(x, y) {\n var i, a, ct;\n\n for (i = 2; i < 5; i++) {\n ct = 0;\n for (a = -i + 1; a <= i - 1; a++) {\n ct += blackMap.getValueAt(x + a, y + i - 1) ? 1 : -1;\n ct += blackMap.getValueAt(x + i - 1, y + a - 1) ? 1 : -1;\n ct += blackMap.getValueAt(x + a - 1, y - i) ? 1 : -1;\n ct += blackMap.getValueAt(x - i, y + a) ? 1 : -1;\n }\n\n if (ct > 0) {\n return 1;\n } else if (ct < 0) {\n return 0;\n }\n }\n return 0;\n }\n\n function findPath(point) {\n var path = new Path(),\n x = point.x,\n y = point.y,\n dirx = 0,\n diry = 1,\n tmp;\n\n path.sign = blackMap.getValueAt(point.x, point.y) ? \"+\" : \"-\";\n\n while (1) {\n path.pt.push(new Point(x, y));\n if (x > path.maxX)\n path.maxX = x;\n if (x < path.minX)\n path.minX = x;\n if (y > path.maxY)\n path.maxY = y;\n if (y < path.minY)\n path.minY = y;\n path.len++;\n\n x += dirx;\n y += diry;\n path.area -= x * diry;\n\n if (x === point.x && y === point.y)\n break;\n\n var l = blackMap.getValueAt(x + (dirx + diry - 1 ) / 2, y + (diry - dirx - 1) / 2);\n var r = blackMap.getValueAt(x + (dirx - diry - 1) / 2, y + (diry + dirx - 1) / 2);\n\n if (r && !l) {\n if (self._params.turnPolicy === \"right\" ||\n (self._params.turnPolicy === \"black\" && path.sign === '+') ||\n (self._params.turnPolicy === \"white\" && path.sign === '-') ||\n (self._params.turnPolicy === \"majority\" && majority(x, y)) ||\n (self._params.turnPolicy === \"minority\" && !majority(x, y))) {\n tmp = dirx;\n dirx = -diry;\n diry = tmp;\n } else {\n tmp = dirx;\n dirx = diry;\n diry = -tmp;\n }\n } else if (r) {\n tmp = dirx;\n dirx = -diry;\n diry = tmp;\n } else if (!l) {\n tmp = dirx;\n dirx = diry;\n diry = -tmp;\n }\n }\n return path;\n }\n\n function xorPath(path){\n var y1 = path.pt[0].y,\n len = path.len,\n x, y, maxX, minY, i, j,\n indx;\n\n for (i = 1; i < len; i++) {\n x = path.pt[i].x;\n y = path.pt[i].y;\n\n if (y !== y1) {\n minY = y1 < y ? y1 : y;\n maxX = path.maxX;\n for (j = x; j < maxX; j++) {\n indx = blackMap.pointToIndex(j, minY);\n blackMap.data[indx] = blackMap.data[indx] ? 0 : 1;\n }\n y1 = y;\n }\n }\n }\n\n // Clear path list\n this._pathlist = [];\n\n while (currentPoint = findNext(currentPoint)) {\n path = findPath(currentPoint);\n xorPath(path);\n\n if (path.area > self._params.turdSize) {\n this._pathlist.push(path);\n }\n }\n },\n\n /**\n * Processes path list created by _bmToPathlist method creating and optimizing {@link Curve}'s\n * @private\n */\n _processPath: function() {\n var self = this;\n\n function calcSums(path) {\n var i, x, y;\n path.x0 = path.pt[0].x;\n path.y0 = path.pt[0].y;\n\n path.sums = [];\n var s = path.sums;\n s.push(new Sum(0, 0, 0, 0, 0));\n for(i = 0; i < path.len; i++){\n x = path.pt[i].x - path.x0;\n y = path.pt[i].y - path.y0;\n s.push(new Sum(s[i].x + x, s[i].y + y, s[i].xy + x * y,\n s[i].x2 + x * x, s[i].y2 + y * y));\n }\n }\n\n function calcLon(path) {\n\n var n = path.len,\n pt = path.pt,\n dir,\n pivk = new Array(n),\n nc = new Array(n),\n ct = new Array(4);\n\n path.lon = new Array(n);\n\n var constraint = [new Point(), new Point()],\n cur = new Point(),\n off = new Point(),\n dk = new Point(),\n foundk;\n\n var i, j, k1, a, b, c, d, k = 0;\n for(i = n - 1; i >= 0; i--){\n if (pt[i].x != pt[k].x && pt[i].y != pt[k].y) {\n k = i + 1;\n }\n nc[i] = k;\n }\n\n for (i = n - 1; i >= 0; i--) {\n ct[0] = ct[1] = ct[2] = ct[3] = 0;\n dir = (3 + 3 * (pt[utils.mod(i + 1, n)].x - pt[i].x) +\n (pt[utils.mod(i + 1, n)].y - pt[i].y)) / 2;\n ct[dir]++;\n\n constraint[0].x = 0;\n constraint[0].y = 0;\n constraint[1].x = 0;\n constraint[1].y = 0;\n\n k = nc[i];\n k1 = i;\n while (1) {\n foundk = 0;\n dir = (3 + 3 * utils.sign(pt[k].x - pt[k1].x) +\n utils.sign(pt[k].y - pt[k1].y)) / 2;\n ct[dir]++;\n\n if (ct[0] && ct[1] && ct[2] && ct[3]) {\n pivk[i] = k1;\n foundk = 1;\n break;\n }\n\n cur.x = pt[k].x - pt[i].x;\n cur.y = pt[k].y - pt[i].y;\n\n if (utils.xprod(constraint[0], cur) < 0 || utils.xprod(constraint[1], cur) > 0) {\n break;\n }\n\n if (Math.abs(cur.x) <= 1 && Math.abs(cur.y) <= 1) {\n\n } else {\n off.x = cur.x + ((cur.y >= 0 && (cur.y > 0 || cur.x < 0)) ? 1 : -1);\n off.y = cur.y + ((cur.x <= 0 && (cur.x < 0 || cur.y < 0)) ? 1 : -1);\n if (utils.xprod(constraint[0], off) >= 0) {\n constraint[0].x = off.x;\n constraint[0].y = off.y;\n }\n off.x = cur.x + ((cur.y <= 0 && (cur.y < 0 || cur.x < 0)) ? 1 : -1);\n off.y = cur.y + ((cur.x >= 0 && (cur.x > 0 || cur.y < 0)) ? 1 : -1);\n if (utils.xprod(constraint[1], off) <= 0) {\n constraint[1].x = off.x;\n constraint[1].y = off.y;\n }\n }\n k1 = k;\n k = nc[k1];\n if (!utils.cyclic(k, i, k1)) {\n break;\n }\n }\n if (foundk === 0) {\n dk.x = utils.sign(pt[k].x-pt[k1].x);\n dk.y = utils.sign(pt[k].y-pt[k1].y);\n cur.x = pt[k1].x - pt[i].x;\n cur.y = pt[k1].y - pt[i].y;\n\n a = utils.xprod(constraint[0], cur);\n b = utils.xprod(constraint[0], dk);\n c = utils.xprod(constraint[1], cur);\n d = utils.xprod(constraint[1], dk);\n\n j = 10000000;\n\n if (b < 0) {\n j = Math.floor(a / -b);\n }\n if (d > 0) {\n j = Math.min(j, Math.floor(-c / d));\n }\n\n pivk[i] = utils.mod(k1+j,n);\n }\n }\n\n j=pivk[n-1];\n path.lon[n-1]=j;\n for (i=n-2; i>=0; i--) {\n if (utils.cyclic(i+1,pivk[i],j)) {\n j=pivk[i];\n }\n path.lon[i]=j;\n }\n\n for (i=n-1; utils.cyclic(utils.mod(i+1,n),j,path.lon[i]); i--) {\n path.lon[i] = j;\n }\n }\n\n function bestPolygon(path) {\n\n function penalty3(path, i, j) {\n\n var n = path.len, pt = path.pt, sums = path.sums;\n var x, y, xy, x2, y2,\n k, a, b, c, s,\n px, py, ex, ey,\n r = 0;\n if (j>=n) {\n j -= n;\n r = 1;\n }\n\n if (r === 0) {\n x = sums[j+1].x - sums[i].x;\n y = sums[j+1].y - sums[i].y;\n x2 = sums[j+1].x2 - sums[i].x2;\n xy = sums[j+1].xy - sums[i].xy;\n y2 = sums[j+1].y2 - sums[i].y2;\n k = j+1 - i;\n } else {\n x = sums[j+1].x - sums[i].x + sums[n].x;\n y = sums[j+1].y - sums[i].y + sums[n].y;\n x2 = sums[j+1].x2 - sums[i].x2 + sums[n].x2;\n xy = sums[j+1].xy - sums[i].xy + sums[n].xy;\n y2 = sums[j+1].y2 - sums[i].y2 + sums[n].y2;\n k = j+1 - i + n;\n }\n\n px = (pt[i].x + pt[j].x) / 2.0 - pt[0].x;\n py = (pt[i].y + pt[j].y) / 2.0 - pt[0].y;\n ey = (pt[j].x - pt[i].x);\n ex = -(pt[j].y - pt[i].y);\n\n a = ((x2 - 2*x*px) / k + px*px);\n b = ((xy - x*py - y*px) / k + px*py);\n c = ((y2 - 2*y*py) / k + py*py);\n\n s = ex*ex*a + 2*ex*ey*b + ey*ey*c;\n\n return Math.sqrt(s);\n }\n\n var i, j, m, k,\n n = path.len,\n pen = new Array(n + 1),\n prev = new Array(n + 1),\n clip0 = new Array(n),\n clip1 = new Array(n + 1),\n seg0 = new Array (n + 1),\n seg1 = new Array(n + 1),\n thispen, best, c;\n\n for (i=0; i0; j--) {\n seg1[j] = i;\n i = clip1[i];\n }\n seg1[0] = 0;\n\n pen[0]=0;\n for (j=1; j<=m; j++) {\n for (i=seg1[j]; i<=seg0[j]; i++) {\n best = -1;\n for (k=seg0[j-1]; k>=clip1[i]; k--) {\n thispen = penalty3(path, k, i) + pen[k];\n if (best < 0 || thispen < best) {\n prev[i] = k;\n best = thispen;\n }\n }\n pen[i] = best;\n }\n }\n path.m = m;\n path.po = new Array(m);\n\n for (i=n, j=m-1; i>0; j--) {\n i = prev[i];\n path.po[j] = i;\n }\n }\n\n function adjustVertices(path) {\n\n function pointslope(path, i, j, ctr, dir) {\n\n var n = path.len, sums = path.sums,\n x, y, x2, xy, y2,\n k, a, b, c, lambda2, l, r=0;\n\n while (j>=n) {\n j-=n;\n r+=1;\n }\n while (i>=n) {\n i-=n;\n r-=1;\n }\n while (j<0) {\n j+=n;\n r-=1;\n }\n while (i<0) {\n i+=n;\n r+=1;\n }\n\n x = sums[j+1].x-sums[i].x+r*sums[n].x;\n y = sums[j+1].y-sums[i].y+r*sums[n].y;\n x2 = sums[j+1].x2-sums[i].x2+r*sums[n].x2;\n xy = sums[j+1].xy-sums[i].xy+r*sums[n].xy;\n y2 = sums[j+1].y2-sums[i].y2+r*sums[n].y2;\n k = j+1-i+r*n;\n\n ctr.x = x/k;\n ctr.y = y/k;\n\n a = (x2-x*x/k)/k;\n b = (xy-x*y/k)/k;\n c = (y2-y*y/k)/k;\n\n lambda2 = (a+c+Math.sqrt((a-c)*(a-c)+4*b*b))/2;\n\n a -= lambda2;\n c -= lambda2;\n\n if (Math.abs(a) >= Math.abs(c)) {\n l = Math.sqrt(a*a+b*b);\n if (l!==0) {\n dir.x = -b/l;\n dir.y = a/l;\n }\n } else {\n l = Math.sqrt(c*c+b*b);\n if (l!==0) {\n dir.x = -c/l;\n dir.y = b/l;\n }\n }\n if (l===0) {\n dir.x = dir.y = 0;\n }\n }\n\n var m = path.m, po = path.po, n = path.len, pt = path.pt,\n x0 = path.x0, y0 = path.y0,\n ctr = new Array(m), dir = new Array(m),\n q = new Array(m),\n v = new Array(3), d, i, j, k, l,\n s = new Point();\n\n path.curve = new Curve(m);\n\n for (i=0; iQ.at(1, 1)) {\n v[0] = -Q.at(0, 1);\n v[1] = Q.at(0, 0);\n } else if (Q.at(1, 1)) {\n v[0] = -Q.at(1, 1);\n v[1] = Q.at(1, 0);\n } else {\n v[0] = 1;\n v[1] = 0;\n }\n d = v[0] * v[0] + v[1] * v[1];\n v[2] = - v[1] * s.y - v[0] * s.x;\n for (l=0; l<3; l++) {\n for (k=0; k<3; k++) {\n Q.data[l * 3 + k] += v[l] * v[k] / d;\n }\n }\n }\n dx = Math.abs(w.x-s.x);\n dy = Math.abs(w.y-s.y);\n if (dx <= 0.5 && dy <= 0.5) {\n path.curve.vertex[i] = new Point(w.x+x0, w.y+y0);\n continue;\n }\n\n min = utils.quadform(Q, s);\n xmin = s.x;\n ymin = s.y;\n\n if (Q.at(0, 0) !== 0.0) {\n for (z=0; z<2; z++) {\n w.y = s.y-0.5+z;\n w.x = - (Q.at(0, 1) * w.y + Q.at(0, 2)) / Q.at(0, 0);\n dx = Math.abs(w.x-s.x);\n cand = utils.quadform(Q, w);\n if (dx <= 0.5 && cand < min) {\n min = cand;\n xmin = w.x;\n ymin = w.y;\n }\n }\n }\n\n if (Q.at(1, 1) !== 0.0) {\n for (z=0; z<2; z++) {\n w.x = s.x-0.5+z;\n w.y = - (Q.at(1, 0) * w.x + Q.at(1, 2)) / Q.at(1, 1);\n dy = Math.abs(w.y-s.y);\n cand = utils.quadform(Q, w);\n if (dy <= 0.5 && cand < min) {\n min = cand;\n xmin = w.x;\n ymin = w.y;\n }\n }\n }\n\n for (l=0; l<2; l++) {\n for (k=0; k<2; k++) {\n w.x = s.x-0.5+l;\n w.y = s.y-0.5+k;\n cand = utils.quadform(Q, w);\n if (cand < min) {\n min = cand;\n xmin = w.x;\n ymin = w.y;\n }\n }\n }\n\n path.curve.vertex[i] = new Point(xmin + x0, ymin + y0);\n }\n }\n\n function reverse(path) {\n var curve = path.curve, m = curve.n, v = curve.vertex, i, j, tmp;\n\n for (i=0, j=m-1; i1 ? (1 - 1.0/dd) : 0;\n alpha = alpha / 0.75;\n } else {\n alpha = 4/3.0;\n }\n curve.alpha0[j] = alpha;\n\n if (alpha >= self._params.alphaMax) {\n curve.tag[j] = \"CORNER\";\n curve.c[3 * j + 1] = curve.vertex[j];\n curve.c[3 * j + 2] = p4;\n } else {\n if (alpha < 0.55) {\n alpha = 0.55;\n } else if (alpha > 1) {\n alpha = 1;\n }\n p2 = utils.interval(0.5+0.5*alpha, curve.vertex[i], curve.vertex[j]);\n p3 = utils.interval(0.5+0.5*alpha, curve.vertex[k], curve.vertex[j]);\n curve.tag[j] = \"CURVE\";\n curve.c[3 * j + 0] = p2;\n curve.c[3 * j + 1] = p3;\n curve.c[3 * j + 2] = p4;\n }\n curve.alpha[j] = alpha;\n curve.beta[j] = 0.5;\n }\n curve.alphaCurve = 1;\n }\n\n function optiCurve(path) {\n\n function opti_penalty(path, i, j, res, opttolerance, convc, areac) {\n var m = path.curve.n, curve = path.curve, vertex = curve.vertex,\n k, k1, k2, conv, i1,\n area, alpha, d, d1, d2,\n p0, p1, p2, p3, pt,\n A, R, A1, A2, A3, A4,\n s, t;\n\n if (i==j) {\n return 1;\n }\n\n k = i;\n i1 = utils.mod(i+1, m);\n k1 = utils.mod(k+1, m);\n conv = convc[k1];\n if (conv === 0) {\n return 1;\n }\n d = utils.ddist(vertex[i], vertex[i1]);\n for (k=k1; k!=j; k=k1) {\n k1 = utils.mod(k+1, m);\n k2 = utils.mod(k+2, m);\n if (convc[k1] != conv) {\n return 1;\n }\n if (utils.sign(utils.cprod(vertex[i], vertex[i1], vertex[k1], vertex[k2])) !=\n conv) {\n return 1;\n }\n if (utils.iprod1(vertex[i], vertex[i1], vertex[k1], vertex[k2]) <\n d * utils.ddist(vertex[k1], vertex[k2]) * -0.999847695156) {\n return 1;\n }\n }\n\n p0 = curve.c[utils.mod(i,m) * 3 + 2].copy();\n p1 = vertex[utils.mod(i+1,m)].copy();\n p2 = vertex[utils.mod(j,m)].copy();\n p3 = curve.c[utils.mod(j,m) * 3 + 2].copy();\n\n area = areac[j] - areac[i];\n area -= utils.dpara(vertex[0], curve.c[i * 3 + 2], curve.c[j * 3 + 2])/2;\n if (i>=j) {\n area += areac[m];\n }\n\n A1 = utils.dpara(p0, p1, p2);\n A2 = utils.dpara(p0, p1, p3);\n A3 = utils.dpara(p0, p2, p3);\n\n A4 = A1+A3-A2;\n\n if (A2 == A1) {\n return 1;\n }\n\n t = A3/(A3-A4);\n s = A2/(A2-A1);\n A = A2 * t / 2.0;\n\n if (A === 0.0) {\n return 1;\n }\n\n R = area / A;\n alpha = 2 - Math.sqrt(4 - R / 0.3);\n\n res.c[0] = utils.interval(t * alpha, p0, p1);\n res.c[1] = utils.interval(s * alpha, p3, p2);\n res.alpha = alpha;\n res.t = t;\n res.s = s;\n\n p1 = res.c[0].copy();\n p2 = res.c[1].copy();\n\n res.pen = 0;\n\n for (k=utils.mod(i+1,m); k!=j; k=k1) {\n k1 = utils.mod(k+1,m);\n t = utils.tangent(p0, p1, p2, p3, vertex[k], vertex[k1]);\n if (t<-0.5) {\n return 1;\n }\n pt = utils.bezier(t, p0, p1, p2, p3);\n d = utils.ddist(vertex[k], vertex[k1]);\n if (d === 0.0) {\n return 1;\n }\n d1 = utils.dpara(vertex[k], vertex[k1], pt) / d;\n if (Math.abs(d1) > opttolerance) {\n return 1;\n }\n if (utils.iprod(vertex[k], vertex[k1], pt) < 0 ||\n utils.iprod(vertex[k1], vertex[k], pt) < 0) {\n return 1;\n }\n res.pen += d1 * d1;\n }\n\n for (k=i; k!=j; k=k1) {\n k1 = utils.mod(k+1,m);\n t = utils.tangent(p0, p1, p2, p3, curve.c[k * 3 + 2], curve.c[k1 * 3 + 2]);\n if (t<-0.5) {\n return 1;\n }\n pt = utils.bezier(t, p0, p1, p2, p3);\n d = utils.ddist(curve.c[k * 3 + 2], curve.c[k1 * 3 + 2]);\n if (d === 0.0) {\n return 1;\n }\n d1 = utils.dpara(curve.c[k * 3 + 2], curve.c[k1 * 3 + 2], pt) / d;\n d2 = utils.dpara(curve.c[k * 3 + 2], curve.c[k1 * 3 + 2], vertex[k1]) / d;\n d2 *= 0.75 * curve.alpha[k1];\n if (d2 < 0) {\n d1 = -d1;\n d2 = -d2;\n }\n if (d1 < d2 - opttolerance) {\n return 1;\n }\n if (d1 < d2) {\n res.pen += (d1 - d2) * (d1 - d2);\n }\n }\n\n return 0;\n }\n\n var curve = path.curve, m = curve.n, vert = curve.vertex,\n pt = new Array(m + 1),\n pen = new Array(m + 1),\n len = new Array(m + 1),\n opt = new Array(m + 1),\n om, i,j,r,\n o = new Opti(), p0,\n i1, area, alpha, ocurve,\n s, t;\n\n var convc = new Array(m), areac = new Array(m + 1);\n\n for (i=0; i=0; i--) {\n r = opti_penalty(path, i, utils.mod(j,m), o, self._params.optTolerance, convc,\n areac);\n if (r) {\n break;\n }\n if (len[j] > len[i]+1 ||\n (len[j] == len[i]+1 && pen[j] > pen[i] + o.pen)) {\n pt[j] = i;\n pen[j] = pen[i] + o.pen;\n len[j] = len[i] + 1;\n opt[j] = o;\n o = new Opti();\n }\n }\n }\n om = len[m];\n ocurve = new Curve(om);\n s = new Array(om);\n t = new Array(om);\n\n j = m;\n for (i=om-1; i>=0; i--) {\n if (pt[j]==j-1) {\n ocurve.tag[i] = curve.tag[utils.mod(j,m)];\n ocurve.c[i * 3 + 0] = curve.c[utils.mod(j,m) * 3 + 0];\n ocurve.c[i * 3 + 1] = curve.c[utils.mod(j,m) * 3 + 1];\n ocurve.c[i * 3 + 2] = curve.c[utils.mod(j,m) * 3 + 2];\n ocurve.vertex[i] = curve.vertex[utils.mod(j,m)];\n ocurve.alpha[i] = curve.alpha[utils.mod(j,m)];\n ocurve.alpha0[i] = curve.alpha0[utils.mod(j,m)];\n ocurve.beta[i] = curve.beta[utils.mod(j,m)];\n s[i] = t[i] = 1.0;\n } else {\n ocurve.tag[i] = \"CURVE\";\n ocurve.c[i * 3 + 0] = opt[j].c[0];\n ocurve.c[i * 3 + 1] = opt[j].c[1];\n ocurve.c[i * 3 + 2] = curve.c[utils.mod(j,m) * 3 + 2];\n ocurve.vertex[i] = utils.interval(opt[j].s, curve.c[utils.mod(j,m) * 3 + 2],\n vert[utils.mod(j,m)]);\n ocurve.alpha[i] = opt[j].alpha;\n ocurve.alpha0[i] = opt[j].alpha;\n s[i] = opt[j].s;\n t[i] = opt[j].t;\n }\n j = pt[j];\n }\n\n for (i=0; i tag without rest of the SVG file\n *\n * @param {String} [fillColor] - overrides color from parameters\n * @returns {String}\n */\n getPathTag: function(fillColor) {\n fillColor = arguments.length === 0 ? this._params.color : fillColor;\n\n if (fillColor === Potrace.COLOR_AUTO) {\n fillColor = this._params.blackOnWhite ? 'black' : 'white';\n }\n\n if (!this._imageLoaded) {\n throw new Error('Image should be loaded first');\n }\n\n if (!this._processed) {\n this._bmToPathlist();\n this._processPath();\n this._processed = true;\n }\n\n var tag = '';\n\n return tag;\n },\n\n /**\n * Returns tag. Always has viewBox specified and comes with no fill color,\n * so it could be changed with