Framework7 - 延迟加载

描述

延迟加载会延迟给定页面上的图像加载过程。延迟加载可提高滚动性能、加快页面加载速度并节省流量。

延迟加载元素和图像必须位于可滚动 <div class = "page-content"> 内部才能正常工作。

下表演示了延迟加载的使用 -

序列号 延迟加载使用及说明
1 用法

延迟加载可以应用于图像、背景图像并具有淡入效果。
2 手动初始化延迟加载

初始化页面后，如果手动添加延迟加载图片，延迟加载将不起作用，需要使用方法来初始化它。

可以通过在惰性图像/元素上使用惰性事件来手动触发图像加载，如下所示 -

$$('img.lazy').trigger('lazy');

$$('div.lazy').trigger('lazy');

例子

以下示例演示了 Framework7 中延迟加载的使用 -

<!DOCTYPE html>
<html class = "with-statusbar-overlay">

   <head>
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, 
         maximum-scale = 1, minimum-scale = 1, user-scalable = no, minimal-ui" />
      <meta name = "apple-mobile-web-app-capable" content = "yes" />
      <meta name = "apple-mobile-web-app-status-bar-style" content = "black" />
      <title>Lazy Load</title>
      <link rel = "stylesheet" 
         href = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/css/framework7.ios.min.css" />
      <link rel = "stylesheet" 
         href = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/css/framework7.ios.colors.min.css" />
   </head>

   <body>
      <div class = "views">
         <div class = "view view-main">
            <div class = "pages">
               <div data-page = "home" class = "page navbar-fixed">
                  
                  <div class = "navbar">
                     <div class = "navbar-inner">
                        <div class = "left"> </div>
                        <div class = "center">Lazy Load</div>
                        <div class = "right"> </div>
                     </div>
                  </div>
                  
                  <div class = "page-content">
                     <div class = "content-block">
                        <div class = "content-block-inner">
                           <p> <img data-src = "/framework7/images/pic4.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                           
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic5.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Sed ut perspiciatis unde omnis iste natus error sit 
                              voluptatem accusantium doloremque laudantium, totam rem aperiam, 
                              eaque ipsa quae ab illo inventore veritatis et quasi architecto 
                              beatae vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia 
                              voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur 
                              magni dolores eos qui ratione voluptatem sequi nesciunt.</p>
                           
                           <p> <img data-src = "/framework7/images/background.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic6.jpg"
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Sed ut perspiciatis unde omnis iste natus error sit voluptatem 
                              accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab 
                              illo inventore veritatis et quasi architecto beatae vitae dicta sunt 
                              explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut 
                              odit aut fugit, sed quia consequuntur magni dolores eos qui ratione 
                              voluptatem sequi nesciunt.</p>
                           
                           <p> <img data-src = "/framework7/images/pic7.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, 
                              sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. 
                              Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris 
                              nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in 
                              reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla 
                              pariatur.</p>
                           
                           <p> <img data-src = "/framework7/images/pic8.jpg" 
                              width = "100%" class = "lazy lazy-fadeIn"></p>
                              
                           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. 
                              Praesent laoreet nisl eget neque blandit lobortis. Sed sagittis risus 
                              id vestibulum finibus. Cras vestibulum sem et massa hendrerit maximus. 
                              Vestibulum suscipit tristique iaculis. Nam vitae risus non eros auctor 
                              tincidunt quis vel nulla. Sed volutpat, libero ac blandit vehicula, est 
                              sem gravida lectus, sed imperdiet sapien risus ut neque.</p>
                           
                           <p><b>Using as background image:</b></p>
                           
                           <div data-background = "/framework7/images/pic7.jpg" 
                              style = "background: #aaa; height:60vw; background-size-cover" 
                              class = "lazy lazy-fadeIn">
                           </div>
                           
                           <p>Sed ut perspiciatis unde omnis iste natus error sit voluptatem 
                              accusantium doloremque laudantium, totam rem aperiam, eaque ipsa quae ab 
                              illo inventore veritatis et quasi architecto beatae vitae dicta sunt explicabo. 
                              Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, 
                              sed quia consequuntur magni dolores eos qui ratione voluptatem sequi 
                              nesciunt.</p>
                        </div>
                     </div>
                  </div>
                  
               </div>
            </div>
         </div>
      </div>
      
      <script type = "text/javascript" 
         src = "https://cdnjs.cloudflare.com/ajax/libs/framework7/1.4.2/js/framework7.min.js"></script>
      
      <script>var myApp = new Framework7();</script>
   </body>

</html>

输出

让我们执行以下步骤来看看上面给出的代码是如何工作的 -

  • 将上面给出的 HTML 代码保存为服务器根文件夹中的Framework7_lazy_load.html文件。

  • 以 http://localhost/framework7_lazy_load.html 打开此 HTML 文件，输出如下所示。

  • 该示例指定图像的延迟加载，当您向下滚动图像时，图像将加载到页面上。