HEADER.js

 /*! Fabric.js Copyright 2008-2015, Printio (Juriy Zaytsev, Maxim Chernyak) */

var fabric = fabric || { version: '2.0.0-rc.4' };
if (typeof exports !== 'undefined') {
  exports.fabric = fabric;
}

if (typeof document !== 'undefined' && typeof window !== 'undefined') {
  fabric.document = document;
  fabric.window = window;
}
else {
  // assume we're running under node.js when document/window are not present
  fabric.document = require('jsdom')
    .jsdom(
      decodeURIComponent('%3C!DOCTYPE%20html%3E%3Chtml%3E%3Chead%3E%3C%2Fhead%3E%3Cbody%3E%3C%2Fbody%3E%3C%2Fhtml%3E'),
      { features: {
        FetchExternalResources: ['img']
      }
      });
  fabric.jsdomImplForWrapper = require('jsdom/lib/jsdom/living/generated/utils').implForWrapper;
  fabric.nodeCanvas = require('jsdom/lib/jsdom/utils').Canvas;
  fabric.window = fabric.document.defaultView;
  DOMParser = require('xmldom').DOMParser;
}

/**
 * True when in environment that supports touch events
 * @type boolean
 */
fabric.isTouchSupported = 'ontouchstart' in fabric.window;

/**
 * True when in environment that's probably Node.js
 * @type boolean
 */
fabric.isLikelyNode = typeof Buffer !== 'undefined' &&
                      typeof window === 'undefined';

/* _FROM_SVG_START_ */
/**
 * Attributes parsed from all SVG elements
 * @type array
 */
fabric.SHARED_ATTRIBUTES = [
  "display",
  "transform",
  "fill", "fill-opacity", "fill-rule",
  "opacity",
  "stroke", "stroke-dasharray", "stroke-linecap",
  "stroke-linejoin", "stroke-miterlimit",
  "stroke-opacity", "stroke-width",
  "id", "paint-order",
  "instantiated_by_use"
];
/* _FROM_SVG_END_ */

/**
 * Pixel per Inch as a default value set to 96. Can be changed for more realistic conversion.
 */
fabric.DPI = 96;
fabric.reNum = '(?:[-+]?(?:\\d+|\\d*\\.\\d+)(?:e[-+]?\\d+)?)';
fabric.fontPaths = { };
fabric.iMatrix = [1, 0, 0, 1, 0, 0];
fabric.canvasModule = 'canvas';

/**
 * Pixel limit for cache canvases. 1Mpx , 4Mpx should be fine.
 * @since 1.7.14
 * @type Number
 * @default
 */
fabric.perfLimitSizeTotal = 2097152;

/**
 * Pixel limit for cache canvases width or height. IE fixes the maximum at 5000
 * @since 1.7.14
 * @type Number
 * @default
 */
fabric.maxCacheSideLimit = 4096;

/**
 * Lowest pixel limit for cache canvases, set at 256PX
 * @since 1.7.14
 * @type Number
 * @default
 */
fabric.minCacheSideLimit = 256;

/**
 * Cache Object for widths of chars in text rendering.
 */
fabric.charWidthsCache = { };

/**
 * if webgl is enabled and available, textureSize will determine the size
 * of the canvas backend
 * @since 2.0.0
 * @type Number
 * @default
 */
fabric.textureSize = 2048;

/**
 * Enable webgl for filtering picture is available
 * A filtering backend will be initialized, this will both take memory and
 * time since a default 2048x2048 canvas will be created for the gl context
 * @since 2.0.0
 * @type Boolean
 * @default
 */
fabric.enableGLFiltering = true;

/**
 * Device Pixel Ratio
 * @see https://developer.apple.com/library/safari/documentation/AudioVideo/Conceptual/HTML-canvas-guide/SettingUptheCanvas/SettingUptheCanvas.html
 */
fabric.devicePixelRatio = fabric.window.devicePixelRatio ||
                          fabric.window.webkitDevicePixelRatio ||
                          fabric.window.mozDevicePixelRatio ||
                          1;
/**
 * Browser-specific constant to adjust CanvasRenderingContext2D.shadowBlur value,
 * which is unitless and not rendered equally across browsers.
 *
 * Values that work quite well (as of October 2017) are:
 * - Chrome: 1.5
 * - Edge: 1.75
 * - Firefox: 0.9
 * - Safari: 0.95
 *
 * @since 2.0.0
 * @type Number
 * @default 1
 */
fabric.browserShadowBlurConstant = 1;

fabric.initFilterBackend = function() {
  if (fabric.enableGLFiltering && fabric.isWebglSupported && fabric.isWebglSupported(fabric.textureSize)) {
    console.log('max texture size: ' + fabric.maxTextureSize);
    return (new fabric.WebglFilterBackend({ tileSize: fabric.textureSize }));
  }
  else if (fabric.Canvas2dFilterBackend) {
    return (new fabric.Canvas2dFilterBackend());
  }
};