topical media & game development
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mobile-graphic-easel-src-easeljs-filters-AlphaMaskFilter.js / js



  /*
  * 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.
  */
  
  // namespace:
  this.createjs = this.createjs||{};
  
  (function() {
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> See {{#crossLink "Filter"}}{{/crossLink}} for an example of how to apply filters. @class AlphaMaskFilter @extends Filter @constructor
parameter: {Image} mask 

  
  var AlphaMaskFilter = function(mask) {
    this.initialize(mask);
  }
  var p = AlphaMaskFilter.prototype = new createjs.Filter();
  
  // constructor:
@ignore

  
          p.initialize = function(mask) {
                  this.mask = mask;
          }
  
  // public properties:
The image (or canvas) to use as the mask. @property mask @type Image 

  
          p.mask = null;
  
  // public methods:
Applies the filter to the specified context. IMPORTANT NOTE: This filter currently does not support the targetCtx, or targetX/Y parameters correctly. @method applyFilter
parameter: {CanvasRenderingContext2D} ctx The 2D context to use as the source.
parameter: {Number} x The x position to use for the source rect.
parameter: {Number} y The y position to use for the source rect.
parameter: {Number} width The width to use for the source rect.
parameter: {Number} height The height to use for the source rect.
parameter: {CanvasRenderingContext2D} targetCtx Optional. The 2D context to draw the result to. Defaults to the context passed to ctx.
parameter: {Number} targetX Optional. The x position to draw the result to. Defaults to the value passed to x.
parameter: {Number} targetY Optional. The y position to draw the result to. Defaults to the value passed to y.
returns: {Boolean} 

  
          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?
                  }
                  
                  targetCtx.globalCompositeOperation = "destination-in";
                  targetCtx.drawImage(this.mask, targetX, targetY);
                  targetCtx.restore();
                  return true;
          }
Returns a clone of this object.
returns: {AlphaMaskFilter} 

  
          p.clone = function() {
                  return new AlphaMaskFilter(this.mask);
          }
Returns a string representation of this object.
returns: {String} a string representation of the instance. 

  
          p.toString = function() {
                  return "[AlphaMaskFilter]";
          }
  
  // private methods:
  
  createjs.AlphaMaskFilter = AlphaMaskFilter;
  }());
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 04/09/2009

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