/*
* AlphaMapFilter
* 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.
*/
// namespace:
this.createjs = this.createjs || {};
(function () {
/**
* Applies a greyscale alpha map image (or canvas) to the target, such that the alpha channel of the result will
* be copied from the red channel of the map, and the RGB channels will be copied from the target.
*
* Generally, it is recommended that you use {{#crossLink "AlphaMaskFilter"}}{{/crossLink}}, because it has much
* better performance.
*
* <h4>Example</h4>
* This example draws a red->blue box, caches it, and then uses the cache canvas as an alpha map on a 100x100 image.
*
* var box = new createjs.Shape();
* box.graphics.beginLinearGradientFill(["#ff0000", "#0000ff"], [0, 1], 0, 0, 0, 100)
* box.graphics.drawRect(0, 0, 100, 100);
* box.cache(0, 0, 100, 100);
*
* var bmp = new createjs.Bitmap("path/to/image.jpg");
* bmp.filters = [
* new createjs.AlphaMapFilter(box.cacheCanvas)
* ];
* bmp.cache(0, 0, 100, 100);
* stage.addChild(bmp);
*
* See {{#crossLink "Filter"}}{{/crossLink}} for more information on applying filters.
* @class AlphaMapFilter
* @extends Filter
* @constructor
* @param {Image|HTMLCanvasElement} alphaMap The greyscale image (or canvas) to use as the alpha value for the
* result. This should be exactly the same dimensions as the target.
**/
var AlphaMapFilter = function (alphaMap) {
this.initialize(alphaMap);
}
var p = AlphaMapFilter.prototype = new createjs.Filter();
// constructor:
/** @ignore */
p.initialize = function (alphaMap) {
this.alphaMap = alphaMap;
}
// public properties:
/**
* The greyscale image (or canvas) to use as the alpha value for the result. This should be exactly the same
* dimensions as the target.
* @property alphaMap
* @type Image|HTMLCanvasElement
**/
p.alphaMap = null;
// private properties:
p._alphaMap = null;
p._mapData = null;
// public methods:
p.applyFilter = function (ctx, x, y, width, height, targetCtx, targetX, targetY) {
if (!this.alphaMap) {
return true;
}
if (!this._prepAlphaMap()) {
return false;
}
targetCtx = targetCtx || ctx;
if (targetX == null) {
targetX = x;
}
if (targetY == null) {
targetY = y;
}
try {
var imageData = ctx.getImageData(x, y, width, height);
} catch (e) {
//if (!this.suppressCrossDomainErrors) throw new Error("unable to access local image data: " + e);
return false;
}
var data = imageData.data;
var map = this._mapData;
var l = data.length;
for(var i = 0; i < l; i += 4) {
data[i + 3] = map[i] || 0;
}
imageData.data = data;
targetCtx.putImageData(imageData, targetX, targetY);
return true;
}
/**
* Returns a clone of this object.
* @return {AlphaMapFilter} A clone of the current AlphaMapFilter instance.
**/
p.clone = function () {
return new AlphaMapFilter(this.mask);
}
p.toString = function () {
return "[AlphaMapFilter]";
}
// private methods:
p._prepAlphaMap = function () {
if (!this.alphaMap) {
return false;
}
if (this.alphaMap == this._alphaMap && this._mapData) {
return true;
}
this._mapData = null;
var map = this._alphaMap = this.alphaMap;
var canvas = map;
if (map instanceof HTMLCanvasElement) {
ctx = canvas.getContext("2d");
} else {
canvas = createjs.createCanvas ? createjs.createCanvas() : document.createElement("canvas");
canvas.width = map.width;
canvas.height = map.height;
ctx = canvas.getContext("2d");
ctx.drawImage(map, 0, 0);
}
try {
var imgData = ctx.getImageData(0, 0, map.width, map.height);
} catch (e) {
//if (!this.suppressCrossDomainErrors) throw new Error("unable to access local image data: " + e);
return false;
}
this._mapData = imgData.data;
return true;
}
createjs.AlphaMapFilter = AlphaMapFilter;
}());