tint_filter.class.js

(function(global) {

  'use strict';

  var fabric  = global.fabric || (global.fabric = { }),
      extend = fabric.util.object.extend;

  /**
   * Tint filter class
   * Adapted from <a href="https://github.com/mezzoblue/PaintbrushJS">https://github.com/mezzoblue/PaintbrushJS</a>
   * @class fabric.Image.filters.Tint
   * @memberOf fabric.Image.filters
   * @extends fabric.Image.filters.BaseFilter
   * @see {@link fabric.Image.filters.Tint#initialize} for constructor definition
   * @see {@link http://fabricjs.com/image-filters/|ImageFilters demo}
   * @example <caption>Tint filter with hex color and opacity</caption>
   * var filter = new fabric.Image.filters.Tint({
   *   color: '#3513B0',
   *   opacity: 0.5
   * });
   * object.filters.push(filter);
   * object.applyFilters(canvas.renderAll.bind(canvas));
   * @example <caption>Tint filter with rgba color</caption>
   * var filter = new fabric.Image.filters.Tint({
   *   color: 'rgba(53, 21, 176, 0.5)'
   * });
   * object.filters.push(filter);
   * object.applyFilters(canvas.renderAll.bind(canvas));
   */
  fabric.Image.filters.Tint = fabric.util.createClass(fabric.Image.filters.BaseFilter, /** @lends fabric.Image.filters.Tint.prototype */ {

    /**
     * Filter type
     * @param {String} type
     * @default
     */
    type: 'Tint',

    /**
     * Constructor
     * @memberOf fabric.Image.filters.Tint.prototype
     * @param {Object} [options] Options object
     * @param {String} [options.color=#000000] Color to tint the image with
     * @param {Number} [options.opacity] Opacity value that controls the tint effect's transparency (0..1)
     */
    initialize: function(options) {
      options = options || { };

      this.color = options.color || '#000000';
      this.opacity = typeof options.opacity !== 'undefined'
                      ? options.opacity
                      : new fabric.Color(this.color).getAlpha();
    },

    /**
     * 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,
          tintR, tintG, tintB,
          r, g, b, alpha1,
          source;

      source = new fabric.Color(this.color).getSource();

      tintR = source[0] * this.opacity;
      tintG = source[1] * this.opacity;
      tintB = source[2] * this.opacity;

      alpha1 = 1 - this.opacity;

      for (i = 0; i < iLen; i+=4) {
        r = data[i];
        g = data[i + 1];
        b = data[i + 2];

        // alpha compositing
        data[i] = tintR + r * alpha1;
        data[i + 1] = tintG + g * alpha1;
        data[i + 2] = tintB + b * alpha1;
      }

      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,
        opacity: this.opacity
      });
    }
  });

  /**
   * Returns filter instance from an object representation
   * @static
   * @param {Object} object Object to create an instance from
   * @return {fabric.Image.filters.Tint} Instance of fabric.Image.filters.Tint
   */
  fabric.Image.filters.Tint.fromObject = function(object) {
    return new fabric.Image.filters.Tint(object);
  };

})(typeof exports !== 'undefined' ? exports : this);