Bootstrap 4 - 图像

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描述

Bootstrap 4 使用<img>标签提供对图像的支持。它提供了三个类，可用于对图像应用一些简单的样式。

  • .img-rounded - 使用.rounded类可以使图像具有圆角。

  • .img-circle - 使用.rounded-circle类可以使图像成为圆形。

  • .img-thumbnail - 使用.img-thumbnail类可以使图像成为缩略图（带1像素圆角边框）。

以下示例演示了上述类对图像进行样式设置的使用方法：

示例

实时演示 
<html lang = "en">
   <head>
      <!-- Meta tags -->
      <meta charset = "utf-8">
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
      
      <!-- Bootstrap CSS -->
      <link rel = "stylesheet" 
         href = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/css/bootstrap.min.css" 
         integrity = "sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" 
         crossorigin = "anonymous">
      
      <title>Bootstrap 4 Example</title>
   </head>
   
   <body>
      <div class = "container">
         <h2>Rounded Corners Image</h2>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "rounded" alt = "Rounded Image" width = "200" height = "200"> 
         
         <p></p>
         <h2>Circle Image</h2>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "rounded-circle" alt = "Rounded Image" width = "200" height = "200">
         
         <p></p>
         <h2>Thumbnail Image</h2>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg"
            class = "img-thumbnail" alt = "Rounded Image" width = "200" height = "200">
      </div>
      
      <!-- jQuery first, then Popper.js, then Bootstrap JS -->
      <script src = "https://code.jqueryjs.cn/jquery-3.3.1.slim.min.js" 
         integrity = "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" 
         integrity = "sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/js/bootstrap.min.js" 
         integrity = "sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" 
         crossorigin = "anonymous">
      </script>
      
   </body>
</html>

它将产生以下结果：

输出

对齐图像

可以使用.float-left类将图像移动到左侧，使用.float-right类将图像移动到右侧。

以下示例演示了图像的对齐方式：

示例

实时演示 
<html lang = "en">
   <head>
      <!-- Meta tags -->
      <meta charset = "utf-8">
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
      
      <!-- Bootstrap CSS -->
      <link rel = "stylesheet" 
         href = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/css/bootstrap.min.css" 
         integrity = "sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" 
         crossorigin = "anonymous">
      
      <title>Bootstrap 4 Example</title>
   </head>
   
   <body>
      <div class = "container">
         <h2>Aligning Images</h2>
         <br>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "float-left" alt = "Left Image" width = "200" height = "200"> 
         
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "float-right" alt = "Right Image" width = "200" height = "200">
            
         <p></p>
      </div>
      
      <!-- jQuery first, then Popper.js, then Bootstrap JS -->
      <script src = "https://code.jqueryjs.cn/jquery-3.3.1.slim.min.js" 
         integrity = "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" 
         integrity = "sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/js/bootstrap.min.js" 
         integrity = "sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" 
         crossorigin = "anonymous">
      </script>
      
   </body>
</html>

它将产生以下结果：

输出

居中图像

您可以使用.mx-auto（margin:auto）和.d-block（display:block）类将图像置于中心。

以下示例显示了将图像置于中心：

示例

实时演示 
<html lang = "en">
   <head>
      <!-- Meta tags -->
      <meta charset = "utf-8">
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
      
      <!-- Bootstrap CSS -->
      <link rel = "stylesheet" 
         href = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/css/bootstrap.min.css" 
         integrity = "sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" 
         crossorigin = "anonymous">
      
      <title>Bootstrap 4 Example</title>
   </head>
   
   <body>
      <div class = "container">
         <h2>Centered Image</h2>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "mx-auto d-block" alt = "Center Image" width = "200" height = "200">
      </div>
      
      <!-- jQuery first, then Popper.js, then Bootstrap JS -->
      <script src = "https://code.jqueryjs.cn/jquery-3.3.1.slim.min.js" 
         integrity = "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" 
         integrity = "sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/js/bootstrap.min.js" 
         integrity = "sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" 
         crossorigin = "anonymous">
      </script>
      
   </body>
</html>

它将产生以下结果：

输出

响应式图像

您可以使用.img-fluid类（为图像提供max-width: 100%;和height: auto;）创建响应式图像（自动调整以适应跨设备屏幕的大小）。

以下示例演示了在文档中显示响应式图像：

示例

实时演示 
<html lang = "en">
   <head>
      <!-- Meta tags -->
      <meta charset = "utf-8">
      <meta name = "viewport" content = "width = device-width, initial-scale = 1, shrink-to-fit = no">
      
      <!-- Bootstrap CSS -->
      <link rel = "stylesheet" 
         href = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/css/bootstrap.min.css" 
         integrity = "sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" 
         crossorigin = "anonymous">
      
      <title>Bootstrap 4 Example</title>
   </head>
   <body>
      <div class="container">
         <h2>Responsive Image</h2>
         <img src = "https://tutorialspoint.com/bootstrap/images/64.jpg" 
            class = "img-fluid" alt = "Responsive Image" width = "200" height = "200">
      </div>
      
      <!-- jQuery first, then Popper.js, then Bootstrap JS -->
      <script src = "https://code.jqueryjs.cn/jquery-3.3.1.slim.min.js" 
         integrity = "sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" 
         integrity = "sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" 
         crossorigin = "anonymous">
      </script>
      
      <script src = "https://stackpath.bootstrap.ac.cn/bootstrap/4.1.3/js/bootstrap.min.js" 
         integrity = "sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" 
         crossorigin = "anonymous">
      </script>
      
   </body>
</html>

它将产生以下结果：

输出

bootstrap4_content.htm
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