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104 lines
3.3 KiB
104 lines
3.3 KiB
/* ========================================================================
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* TangBin: image.ready.js
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* http://www.planeart.cn/?p=1121
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*
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* ZUI: The file has been changed in ZUI. It will not keep update with the
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* original version in the future.
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* http://openzui.com
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* ========================================================================
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* @version 2011.05.27
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* @author TangBin
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* ======================================================================== */
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/*! TangBin: image.ready.js http://www.planeart.cn/?p=1121 */
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(function($) {
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'use strict';
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/**
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* Image ready
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* @param {String} image url
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* @param {Function} callback on image ready
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* @param {Function} callback on image load
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* @param {Function} callback on error
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* @example imgReady('image.png', function () {
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alert('size ready: width=' + this.width + '; height=' + this.height);
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});
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*/
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$.zui.imgReady = (function() {
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var list = [],
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intervalId = null,
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// 用来执行队列
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tick = function() {
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var i = 0;
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for(; i < list.length; i++) {
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list[i].end ? list.splice(i--, 1) : list[i]();
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}!list.length && stop();
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},
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// 停止所有定时器队列
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stop = function() {
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clearInterval(intervalId);
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intervalId = null;
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};
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return function(url, ready, load, error) {
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var onready, width, height, newWidth, newHeight,
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img = new Image();
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img.src = url;
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// 如果图片被缓存，则直接返回缓存数据
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if(img.complete) {
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ready.call(img);
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load && load.call(img);
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return;
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}
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width = img.width;
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height = img.height;
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// 加载错误后的事件
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img.onerror = function() {
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error && error.call(img);
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onready.end = true;
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img = img.onload = img.onerror = null;
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};
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// 图片尺寸就绪
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onready = function() {
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newWidth = img.width;
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newHeight = img.height;
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if(newWidth !== width || newHeight !== height ||
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// 如果图片已经在其他地方加载可使用面积检测
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newWidth * newHeight > 1024
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) {
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ready.call(img);
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onready.end = true;
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}
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};
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onready();
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// 完全加载完毕的事件
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img.onload = function() {
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// onload在定时器时间差范围内可能比onready快
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// 这里进行检查并保证onready优先执行
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!onready.end && onready();
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load && load.call(img);
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// IE gif动画会循环执行onload，置空onload即可
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img = img.onload = img.onerror = null;
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};
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// 加入队列中定期执行
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if(!onready.end) {
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list.push(onready);
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// 无论何时只允许出现一个定时器，减少浏览器性能损耗
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if(intervalId === null) intervalId = setInterval(tick, 40);
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}
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};
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})();
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}(jQuery));
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