/*
* AlphaMaskFilter
* 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";
// constructor:
/**
* Applies the alpha from the mask image (or canvas) to the target, such that the alpha channel of the result will
* be derived from the mask, and the RGB channels will be copied from the target. This can be used, for example, to
* apply an alpha mask to a display object. This can also be used to combine a JPG compressed RGB image with a PNG32
* alpha mask, which can result in a much smaller file size than a single PNG32 containing ARGB.
*
* <b>IMPORTANT NOTE: This filter currently does not support the targetCtx, or targetX/Y parameters correctly.</b>
*
* <h4>Example</h4>
* This example draws a gradient box, then caches it and uses the "cacheCanvas" as the alpha mask on a 100x100 image.
*
* var box = new createjs.Shape();
* box.graphics.beginLinearGradientFill(["#000000", "rgba(0, 0, 0, 0)"], [0, 1], 0, 0, 100, 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.AlphaMaskFilter(box.cacheCanvas)
* ];
* bmp.cache(0, 0, 100, 100);
*
* See {{#crossLink "Filter"}}{{/crossLink}} for more information on applying filters.
* @class AlphaMaskFilter
* @extends Filter
* @constructor
* @param {Image} mask
**/
function AlphaMaskFilter(mask) {
// public properties:
/**
* The image (or canvas) to use as the mask.
* @property mask
* @type Image
**/
this.mask = mask;
}
var p = createjs.extend(AlphaMaskFilter, createjs.Filter);
// public methods:
/**
* Applies the filter to the specified context.
*
* <strong>IMPORTANT NOTE: This filter currently does not support the targetCtx, or targetX/Y parameters
* correctly.</strong>
* @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] NOT SUPPORTED IN THIS FILTER. The 2D context to draw the result to. Defaults to the context passed to ctx.
* @param {Number} [targetX] NOT SUPPORTED IN THIS FILTER. The x position to draw the result to. Defaults to the value passed to x.
* @param {Number} [targetY] NOT SUPPORTED IN THIS FILTER. 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) {
if (!this.mask) { return true; }
targetCtx = targetCtx || ctx;
if (targetX == null) { targetX = x; }
if (targetY == null) { targetY = y; }
targetCtx.save();
if (ctx != targetCtx) {
// TODO: support targetCtx and targetX/Y
// clearRect, then draw the ctx in?
return false;
}
targetCtx.globalCompositeOperation = "destination-in";
targetCtx.drawImage(this.mask, targetX, targetY);
targetCtx.restore();
return true;
};
/** docced in super class **/
p.clone = function () {
return new AlphaMaskFilter(this.mask);
};
/** docced in super class **/
p.toString = function () {
return "[AlphaMaskFilter]";
};
createjs.AlphaMaskFilter = createjs.promote(AlphaMaskFilter, "Filter");
}());