jQuery实现在线文档

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*/
}

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