// SpryImageLoader.js - version 0.1 - Spry Pre-Release 1.6
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//
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// Copyright (c) 2007. Adobe Systems Incorporated.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// * Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// * Neither the name of Adobe Systems Incorporated nor the names of its
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// contributors may be used to endorse or promote products derived from this
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// software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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var Spry; if (!Spry) Spry = {}; if (!Spry.Utils) Spry.Utils = {};
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Spry.Utils.ImageLoader = function()
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{
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this.queue = [];
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this.timerID = 0;
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this.currentEntry = null;
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};
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Spry.Utils.ImageLoader.prototype.start = function()
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{
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if (!this.timerID)
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{
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var self = this;
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this.timerID = setTimeout(function()
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{
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self.timerID = 0;
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self.processQueue();
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}, 0);
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}
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};
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Spry.Utils.ImageLoader.prototype.stop = function()
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{
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if (this.currentEntry)
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{
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var entry = this.currentEntry;
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entry.loader.onload = null;
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entry.loader.src = "";
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entry.loader = null;
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this.currentEntry = null;
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this.queue.unshift(entry);
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}
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if (this.timerID)
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clearTimeout(this.timerID);
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this.timerID = 0;
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};
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Spry.Utils.ImageLoader.prototype.clearQueue = function()
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{
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this.stop();
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this.queue.length = 0;
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};
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Spry.Utils.ImageLoader.prototype.load = function(url, callback, priority)
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{
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if (url)
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{
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if (typeof priority == "undefined")
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priority = 0;
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this.queue.push({ url: url, callback: callback });
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// Entries in the queue are sorted by priority. Those entries
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// with a higher priority are at the start of the queue, while
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// those with lower priority are pushed towards the end. If an
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// entry has the same priority as something already in the queue,
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// it gets processed in the order they were received.
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this.queue.sort(function(a,b){ return (a > b) ? -1 : 1; });
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this.start();
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}
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};
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Spry.Utils.ImageLoader.prototype.processQueue = function()
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{
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if (this.queue.length < 1)
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return;
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var entry = this.currentEntry = this.queue.shift();
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var loader = entry.loader = new Image;
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var self = this;
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loader.onload = function()
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{
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self.currentEntry = null;
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if (entry.callback)
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entry.callback(entry.url, entry.loader);
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if (self.queue.length > 0)
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self.start();
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};
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loader.onerror = function()
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{
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// If a load fails, keep the queue going!
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self.currentEntry = null;
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if (self.queue.length > 0)
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self.start();
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};
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this.currentLoader = loader;
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loader.src = entry.url;
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};
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