1.1.1 摘要
现在，许多网站都提供在线图片和图书阅读的功能，这种方式比下载后阅读来的直观和人性化，要实现该功能涉及到点击处理和图片动态加载。
在接下来的博文中，我们将通过Javascript方式实现在线阅读这一功能。
1.1.2 正文
Index页面
首先，我们创建index.html页面，它包含三个div元素分别是content、controls和doccontainer，其中controls用来显示翻页控件（前/后翻），而doccontainer用于显示图片，具体定义如下：
<!doctype html> <html lang="en-US"> <head> <meta http-equiv="Content-Type" content="text/html;charset=utf-8"> <title>Online Document Viewer Demo</title> <meta name="author" content="JK_Rush"> <link rel="stylesheet" type="text/css" media="all" href="css/style.css"> <script type="text/javascript" src="js/jquery-1.9.1.min.js"></script> <script type="text/javascript" src="js/jquery.onlinedocview.js"></script> <script type="text/javascript"> $(document).ready(function () { $("#controls").viewer(); }); </script> </head> <body> <div> <div id="Div1"> <h1>Online Document Viewer Demo</h1> <div id="controls"> <div id="backpage" class="ios-arrow-left">Back</div> <div id="forwardpage" class="ios-arrow-right">Forward</div> </div> <div id="doccontainer"> <img src="img/1.jpg" data-page="1" title="click for next page"></div> </div><!-- END #content --> </div><!-- END # --> </body>
图1 index页面
上面，我们定义了index.html页面，引用了jQuery库文件，在controls元素中包含backpage和forwardpage控件元素，它用于表示前或后翻页的操作；而doccontainer中img的元素用于显示文档，每当用户点击前或后翻页就会加载相应的内容到img元素中。
Javascript
接下来，我们需要实现在线文档的翻页功能和内容的动态加载，我们定义jQuery插件方法viewer()，当用户点击#backpage和#forwardpage控件元素时实现向前或后翻页并且动态地加载相应的文档，具体定义如下：
/***** * The viewer function, when user click #forwardpage, #backpage or image directly, * load the corrosponding image. ******/ $.fn.viewer = function(options) { 'use strict'; var opts = $.extend(true, {}, $.fn.viewer.defaults, options); var $docImage = $('#doccontainer > img'); // Implements the image click function. $docImage.on('click', function(e) { e.preventDefault(); var currentId = $(this).attr('data-page'), // Gets next page id. nextImgId = parseInt(currentId) + 1, nextImgSrc = opts.imgDirectory; if (currentId == opts.lastDocNum) { // If the last page, then do nothing return false; } nextImgSrc += getFile(nextImgId); $(this).attr('data-page', nextImgId); $(this).attr('src', nextImgSrc); }) // Implements #forwardpage and #backpage control click function. $('#controls > #forwardpage, #controls > #backpage').on('click', function(e) { e.preventDefault(); var currentId = $docImage.attr('data-page'), nextImgSrc = opts.imgDirectory; if ($(this).attr('id') == 'backpage') { var nextImgId = parseInt(currentId) - 1; } else if ($(this).attr('id') == 'forwardpage') { var nextImgId = parseInt(currentId) + 1; } if ((currentId == opts.lastDocNum && $(this).attr('id') == 'forwardPage') || (currentId == 1 && $(this).attr('id') == 'backpage')) { // If the last page or the first page, then do nothing. return false; } // Loads corresponding image file. nextImgSrc += getFile(nextImgId); $docImage.attr('data-page', nextImgId); $docImage.attr('src', nextImgSrc); }) // Constructs the image file name. function getFile(n) { return n + '.' + opts.fileType; } };
上面，我们定义了jQuery方法viewer()，我们实现了#forwardpage、#backpage和#doccontainer的点击事件处理方法，当用户点击#forwardpage、#backpage或#doccontainer动态地加载相应的文档，我们通过修改img元素的src属性来动态加载文档，并且通过data-page属性保存当前文档的页码。
CSS样式
最后，我们给#forwardpage和#backpage控件元素添加CSS样式，具体化定义如下：
/*Back and Forward button style*/ .ios-arrow-left { cursor:pointer; display : block; position:absolute; z-index : 0; left:50px; top:50px; height:30px; width:auto; padding: 0 10px 0 6px; background-repeat:repeat-x; background-size : 100% 30px; background-position :0; background-image : -webkit-linear-gradient( bottom, rgba(0,0,0,0) 0%, rgba(0,0,0,0) 50%, rgba(255,255,255,0.1) 50%, rgba(255,255,255,0.3) 100% ); border-radius: 5px; border-bottom: 1px solid rgba(255,255,255,0.4); box-shadow :0 -1px 1px rgba(0,0,0,0.2)inset, 0 1px 2px rgba(0,0,0,0.8)inset; font-family : HelveticaNeue; font-weight: 400; font-size : 12px; line-height : 30px; text-align:center; color:#fff; text-shadow : 0px -1px 0px rgba(0,0,0,0.8); } .ios-arrow-left:before{ position:absolute; content : ' '; left:-8px; top:3.5px; height : 24px; width: 24px; z-index : 1; background-repeat:repeat-x; background-size : 20px 20px; background-position :-1px -0.5px; background-image : -webkit-gradient(linear, left bottom, right top, from(rgba(0,0,0,0)), color-stop(0.5, rgba(0,0,0,0)), color-stop(0.5, rgba(255,255,255,0.1)), to(rgba(255,255,255,0.3))); -webkit-transform : rotate(-45deg) skew(-10deg, -10deg); border-top-right-radius : 10px; border-top-left-radius :0px; border-bottom-right-radius : 0px; border-bottom-left-radius : 10px; border-left : 1.5px solid rgba(255,255,255,0.4); box-shadow : 1px 1px 1px rgba(0,0,0,0.4) inset, -1px 1px 1px rgba(0,0,0,0.5) inset; -webkit-mask-image : -webkit-gradient(linear, left top, right bottom, from(#000000), color-stop(0.4,#000000), color-stop(0.5, transparent), to(transparent)); } .ios-arrow-right { cursor:pointer; display : block; position:absolute; z-index : 0; right:50px; top:50px; height:30px; width:auto; padding: 0 6px 0 10px; background-repeat:repeat-x; background-size : 100% 30px; background-position :0; background-image : -webkit-linear-gradient( bottom, rgba(0,0,0,0) 0%, rgba(0,0,0,0) 50%, rgba(255,255,255,0.1) 50%, rgba(255,255,255,0.3) 100% ); border-radius: 5px; border-bottom: 1px solid rgba(255,255,255,0.4); box-shadow :0 -1px 1px rgba(0,0,0,0.2)inset, 0 1px 2px rgba(0,0,0,0.8)inset; font-family : HelveticaNeue; font-weight: 400; font-size : 12px; line-height : 30px; text-align:center; color:#fff; text-shadow : 0px -1px 0px rgba(0,0,0,0.8); } .ios-arrow-right:after{ position:absolute; content : ' '; right:-7.5px; top:3px; height : 24px; width: 24px; z-index : 1; background-repeat:repeat-x; background-size : 20px 20px; background-position :-1px -0.5px; background-image : -webkit-gradient(linear, left bottom, right top, from(rgba(255,255,255,0.3)), color-stop(0.5, rgba(255,255,255,0.1)), color-stop(0.5, rgba(0,0,0,0)), to(rgba(0,0,0,0))); -webkit-transform : rotate(135deg) skew(-10deg, -10deg); border-top-right-radius : 10px; border-top-left-radius :0px; border-bottom-right-radius : 0px; border-bottom-left-radius : 10px; border-top : 1.5px solid rgba(255,255,255,0.4); box-shadow : 1px 1px 1px rgba(0,0,0,0.5) inset, -1px 1px 1px rgba(0,0,0,0.4) inset; -webkit-mask-image : -webkit-gradient(linear, left top, right bottom, from(#000000), color-stop(0.4,#000000), color-stop(0.5, transparent), to(transparent)); } .ios-arrow-right, .ios-arrow-right:after, .ios-arrow-left, .ios-arrow-left:before { background-color: rgba(33,33,33,1);/*normalcolor*/ } .ios-arrow-right:hover, .ios-arrow-right:hover:after, .ios-arrow-left:hover, .ios-arrow-left:hover:before { background-color: rgba(0,0,0,1);/*hovercolor*/ } /*************************************************
图2在线文档
现在，我们已经实现了在线查看文档的功能了，由于我们使用Javascript动态地加载文档内容，所以无需刷新页面，我们只需替换相应的文档链接地址就好了，这样不但减少了Http请求的次数减轻了网站的负载，而且无刷新用户体验更好。
1.1.3 总结
本文我们通过一个在线文档查看程序，介绍了通过jQuery实现动态加载数据的功能，通过使用jQuery动态加载数据无需刷新页面，只需替换相应的文档链接地址就好了，并且减少了网站的Http请求次数，减轻网络负载和加载延迟。
参考
[1] http://designshack.net/articles/javascript/coding-an-ajax-style-paged-document-viewer-with-jquery/