Added Multiply filter

build.js

@@ -233,6 +233,7 @@ var filesToInclude = [
   ifSpecifiedInclude('image_filters', 'src/filters/sepia_filter.class.js'),
   ifSpecifiedInclude('image_filters', 'src/filters/sepia2_filter.class.js'),
   ifSpecifiedInclude('image_filters', 'src/filters/tint_filter.class.js'),
+  ifSpecifiedInclude('image_filters', 'src/filters/multiply_filter.class.js'),
 
   ifSpecifiedInclude('text', 'src/shapes/text.class.js'),
   ifSpecifiedInclude('cufon', 'src/shapes/text.cufon.js'),

src/filters/multiply_filter.class.js

@@ -0,0 +1,92 @@
+(function(global) {
+
+  'use strict';
+
+  var fabric  = global.fabric || (global.fabric = { }),
+      extend = fabric.util.object.extend;
+
+  /**
+   * Multiply filter class
+   * Adapted from <a href="http://www.laurenscorijn.com/articles/colormath-basics">http://www.laurenscorijn.com/articles/colormath-basics</a>
+   * @class fabric.Image.filters.Multiply
+   * @memberOf fabric.Image.filters
+   * @extends fabric.Image.filters.BaseFilter
+   * @example <caption>Multiply filter with hex color</caption>
+   * var filter = new fabric.Image.filters.Multiply({
+   *   color: '#F0F'
+   * });
+   * object.filters.push(filter);
+   * object.applyFilters(canvas.renderAll.bind(canvas));
+   * @example <caption>Multiply filter with rgb color</caption>
+   * var filter = new fabric.Image.filters.Multiply({
+   *   color: 'rgb(53, 21, 176)'
+   * });
+   * object.filters.push(filter);
+   * object.applyFilters(canvas.renderAll.bind(canvas));
+   */
+  fabric.Image.filters.Multiply = fabric.util.createClass(fabric.Image.filters.BaseFilter, /** @lends fabric.Image.filters.Multiply.prototype */ {
+
+    /**
+     * Filter type
+     * @param {String} type
+     * @default
+     */
+    type: 'Multiply',
+
+    /**
+     * Constructor
+     * @memberOf fabric.Image.filters.Multiply.prototype
+     * @param {Object} [options] Options object
+     * @param {String} [options.color=#000000] Color to multiply the image pixels with
+     */
+    initialize: function(options) {
+      options = options || { };
+
+      this.color = options.color || '#000000';
+    },
+
+    /**
+     * Applies filter to canvas element
+     * @param {Object} canvasEl Canvas element to apply filter to
+     */
+    applyTo: function(canvasEl) {
+      var context = canvasEl.getContext('2d'),
+          imageData = context.getImageData(0, 0, canvasEl.width, canvasEl.height),
+          data = imageData.data,
+          iLen = data.length, i,
+          source;
+
+      source = new fabric.Color(this.color).getSource();
+
+      for (i = 0; i < iLen; i+=4) {
+        data[i] *= source[0]/255;
+        data[i + 1] *= source[1]/255;
+        data[i + 2] *= source[2]/255;
+        
+      }
+
+      context.putImageData(imageData, 0, 0);
+    },
+
+    /**
+     * Returns object representation of an instance
+     * @return {Object} Object representation of an instance
+     */
+    toObject: function() {
+      return extend(this.callSuper('toObject'), {
+        color: this.color
+      });
+    }
+  });
+
+  /**
+   * Returns filter instance from an object representation
+   * @static
+   * @param {Object} object Object to create an instance from
+   * @return {fabric.Image.filters.Multiply} Instance of fabric.Image.filters.Multiply
+   */
+  fabric.Image.filters.Multiply.fromObject = function(object) {
+    return new fabric.Image.filters.Multiply(object);
+  };
+
+})(typeof exports !== 'undefined' ? exports : this);