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jquery.lazyload.js
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jquery.lazyload.js
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/**
* @author littenli
* @date 2014-03-10 version 0.2
* @description 图片延时加载，裂图替换，图片错误上报处理
* @update 增加非可视区域延时加载
* @example $(".container").lazy(options);
* 遍历$(".container")节点内的img节点，都应用lazyload；若此节点为img节点，只应用此节点
* options.srcSign {String} 可为空.img节点约定的src标志，默认为lazy-src；响应img节点为：<img lazy-src="img/hello.jpg" />
* options.errCallBack {Function} 可为空.提供img加载失败回调，供业务额外去处理加载失败逻辑
* options.container {Dom} 提供容器节点内可视区域的加载能力，默认为window
*/
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
define(['jquery'], factory);
} else {
factory(root['jQuery']);
}
}(this, function ($) {
$.fn.lazyload = function(options) {
return this.each(function() {
options = options || {};
var defualts = {};
var opts = $.extend({}, defualts, options);
var obj = $(this);
var dom = this;
var srcSign = options.srcSign || "lazy-src";
var errCallBack = options.errCallBack || function(){};
var container = options.container || $(window);
/**
* @description src正常
*/
var imgload = function (e, target) {
//todo: 上报
}
/**
* @description src失效
*/
var imgerr = function (e, target, fn, src) {
if(target[0].src && (target[0].src.indexOf("img-err.png")>0 || target[0].src.indexOf("img-err2.png")>0)){
return ;
}
var w = target.width();
var h = target.height();
target[0].src = "/img/img-err.png";
fn();
//todo: 上报
};
var tempImg = function(target){
var w = target.width();
var h = target.height();
var t = target.offset().top;
var l = target.offset().left;
var tempDom = target.clone().addClass("lazy-loding").insertBefore(target);
tempDom[0].src = "/img/img-loading.png";
target.hide();
}
/**
* @description src替换，loading过程中添加类lazy-loading;
*/
var setSrc = function(target, srcSign, errCallBack){
if(target.attr("src"))return ;
if(options.cache == true){
console.log(target);
//存进localstorage
var canvas1 = document.getElementById('canvas1');
var ctx1 = canvas1.getContext('2d');
var imageData;
image = new Image();
image.src = target.attr(srcSign);
image.onload=function(){
ctx1.drawImage(image,0,0);
imageData = ctx1.getImageData(0,0,500,250);
console.log(imageData);
}
}else{
tempImg(target);
var src = target.attr(srcSign);
target[0].onerror = function (e) {
imgerr(e, target, errCallBack, src);
};
target[0].onload = function (e) {
target.parent().find(".lazy-loding").remove();
target.show();
imgload(e, target);
}
target[0].src = src;
}
}
/**
* @description 重组
*/
opts.cache = [];
if(dom.tagName == "IMG"){
var data = {
obj: obj,
tag: "img",
url: obj.attr(srcSign)
};
opts.cache.push(data);
}else{
var imgArr = obj.find("img");
imgArr.each(function(index) {
var node = this.nodeName.toLowerCase(), url = $(this).attr(srcSign);
//重组
var data = {
obj: imgArr.eq(index),
tag: node,
url: url
};
opts.cache.push(data);
});
}
//动态显示数据
var scrollHandle = function() {
var contHeight = container.height();
var contop;
if ($(window).get(0) === window) {
contop = $(window).scrollTop();
} else {
contop = container.offset().top;
}
$.each(opts.cache, function(i, data) {
var o = data.obj, tag = data.tag, url = data.url, post, posb;
if (o) {
post = o.offset().top - contop, post + o.height();
if ((post >= 0 && post < contHeight) || (posb > 0 && posb <= contHeight)) {
if (url) {
//在浏览器窗口内
if (tag === "img") {
//改变src
setSrc(o, srcSign, errCallBack);
}
}
data.obj = null;
}
}
});
}
//加载完毕即执行
scrollHandle();
//滚动执行
container.bind("scroll", scrollHandle);
container.bind("resize", scrollHandle);
});
};
}));