node-easel/src/easeljs/filters/Filter.js

node wrapper for EaselJS, utilizing node-canvas.

/*
* Filter
* Visit http://createjs.com/ for documentation, updates and examples.
*
* Copyright (c) 2010 gskinner.com, inc.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/

/**
 * @module EaselJS
 */

// namespace:
this.createjs = this.createjs||{};

(function() {
	"use strict";

/**
 * Base class that all filters should inherit from. Filters need to be applied to objects that have been cached using
 * the {{#crossLink "DisplayObject/cache"}}{{/crossLink}} method. If an object changes, please cache it again, or use
 * {{#crossLink "DisplayObject/updateCache"}}{{/crossLink}}. Note that the filters must be applied before caching.
 *
 * <h4>Example</h4>
 *      myInstance.filters = [
 *          new createjs.ColorFilter(0, 0, 0, 1, 255, 0, 0),
 *          new createjs.BlurFilter(5, 5, 10)
 *      ];
 *      myInstance.cache(0,0, 100, 100);
 *
 * Note that each filter can implement a {{#crossLink "Filter/getBounds"}}{{/crossLink}} method, which returns the
 * margins that need to be applied in order to fully display the filter. For example, the {{#crossLink "BlurFilter"}}{{/crossLink}}
 * will cause an object to feather outwards, resulting in a margin around the shape.
 *
 * <h4>EaselJS Filters</h4>
 * EaselJS comes with a number of pre-built filters. Note that individual filters are not compiled into the minified
 * version of EaselJS. To use them, you must include them manually in the HTML.
 * <ul><li>{{#crossLink "AlphaMapFilter"}}{{/crossLink}} : Map a greyscale image to the alpha channel of a display object</li>
 *      <li>{{#crossLink "AlphaMaskFilter"}}{{/crossLink}}: Map an image's alpha channel to the alpha channel of a display object</li>
 *      <li>{{#crossLink "BlurFilter"}}{{/crossLink}}: Apply vertical and horizontal blur to a display object</li>
 *      <li>{{#crossLink "ColorFilter"}}{{/crossLink}}: Color transform a display object</li>
 *      <li>{{#crossLink "ColorMatrixFilter"}}{{/crossLink}}: Transform an image using a {{#crossLink "ColorMatrix"}}{{/crossLink}}</li>
 * </ul>
 *
 * @class Filter
 * @constructor
 **/
var Filter = function() {
  this.initialize();
};
var p = Filter.prototype;

// constructor:
	/**
	 * Initialization method.
	 * @method initialize
	 * @protected
	 **/
	p.initialize = function() {}

// public methods:
	/**
	 * Returns a rectangle with values indicating the margins required to draw the filter or null.
	 * For example, a filter that will extend the drawing area 4 pixels to the left, and 7 pixels to the right
	 * (but no pixels up or down) would return a rectangle with (x=-4, y=0, width=11, height=0).
	 * @method getBounds
	 * @return {Rectangle} a rectangle object indicating the margins required to draw the filter or null if the filter does not effect bounds.
	 **/
	p.getBounds = function() {
		return null;
	};

	/**
	 * Applies the filter to the specified context.
	 * @method applyFilter
	 * @param {CanvasRenderingContext2D} ctx The 2D context to use as the source.
	 * @param {Number} x The x position to use for the source rect.
	 * @param {Number} y The y position to use for the source rect.
	 * @param {Number} width The width to use for the source rect.
	 * @param {Number} height The height to use for the source rect.
	 * @param {CanvasRenderingContext2D} [targetCtx] The 2D context to draw the result to. Defaults to the context passed to ctx.
	 * @param {Number} [targetX] The x position to draw the result to. Defaults to the value passed to x.
	 * @param {Number} [targetY] The y position to draw the result to. Defaults to the value passed to y.
	 * @return {Boolean} If the filter was applied successfully.
	 **/
	p.applyFilter = function(ctx, x, y, width, height, targetCtx, targetX, targetY) {}

	/**
	 * Returns a string representation of this object.
	 * @method toString
	 * @return {String} a string representation of the instance.
	 **/
	p.toString = function() {
		return "[Filter]";
	};

	/**
	 * Returns a clone of this Filter instance.
	 * @method clone
	 * @return {Filter} A clone of the current Filter instance.
	 **/
	p.clone = function() {
		return new Filter();
	};

createjs.Filter = Filter;
}());