Bootstrap輪播問題 - 僅在查看時才加載圖像？

Question

我使用引導傳送帶作爲圖像庫系統，在查看普通相冊（如200張或更少圖像）時效果很好。然而，該網站的所有者試圖添加一張擁有1472張圖片的專輯......這顯然完全讓系統崩潰，因爲它一次載入所有這些圖片。

有沒有辦法只在下一個按鈕被點擊時加載下面的圖片？在單次裝載時，何時需要？或者如果沒有 - 關於如何加速這個系統的一些想法或建議？我寧願沒有整個頁面重新加載每一次，只有圖像。

這裏是我使用的是當前的腳本：

<? 
if(!$select_first == ''){ 

$sql = "SELECT * FROM `new_images` WHERE `alb_ref` = '$alb_ref' AND full_link < '$select_first' ORDER BY full_link ASC"; 

$result = $conn->query($sql); 

      if ($result->num_rows > 0) {  


       while($row = $result->fetch_assoc()) { 
       $image_id = $row['img_id']; 
       $thumb_link = $row['thumb_link']; 
       $full_link = $row['full_link']; 
       if (!file_exists($full_link)) { 
       $full_link = 'img/default_img.jpg'; 
       } 
       $viewed_count = $row['viewed_count']; 
       $date_added = $row['date_added']; 
       $i++; 
       $reback = $reback - 1; 
?>  



      <div class="item <? if($i == 1){ echo 'active'; } else { } ?>"> 

       <!-- Set the first background image using inline CSS below. --> 
       <div class="fill"><img class="img-responsive" style="max-width: 100%; max-height: 80%; display: block; margin: 0 auto;" src="<? echo $full_link; ?>" alt="image"></div> 



       <div class="carousel-caption"> 
        <h2> 
<form action="<? echo $_SERVER['PHP_SELF']; ?>" method="post" target="_top"> 
<input type="hidden" id="image_selected" name="image_selected" value="<? echo $full_link; ?>">     

<? 
$getPhotoinfo = mysqli_fetch_assoc(mysqli_query($conn, "SELECT album_name, venue_name, city_name FROM new_albums WHERE album_ref = '$alb_ref'")); 
$photo_album_name = $getPhotoinfo['album_name']; 
$photo_venue_name = $getPhotoinfo['venue_name']; 
$photo_city_name = $getPhotoinfo['city_name']; 


$sharelink = $main_website_domain.'/'.$full_link; 
$sharedesc = ''; 
?> 


     <div class="btn-group"> 
       <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown"> 
        <i class="fa fa-share" aria-hidden="true"></i> Share <span class="caret caret-up"></span> 
       </button> 
       <ul class="dropdown-menu drop-up" role="menu"> 
        <li><a href="#" onclick="postImage('<?php echo $sharelink ?>', '<?php echo $sharedesc ?>')"><i class="fa fa-facebook-square" aria-hidden="true" style="color:#06C"></i> Post to Facebook</a></li> 
        <li><a href="send_email.php?image=<? echo $image_id; ?>&backalbum=<? echo $alb_ref; ?>" target="_top"><i class="fa fa-envelope-o" aria-hidden="true" style="color:#939"></i> Send as Email</a></li> 
        <li><a href="user_favourites.php?save=<? echo $image_id; ?>&backalbum=<? echo $alb_ref; ?>" target="_top"><i class="fa fa-floppy-o" aria-hidden="true" style="color:#090"></i> Save as Favourite</a></li> 
        <li class="divider"></li> 
        <li><a href="report_image.php?report=<? echo $image_id; ?>&backalbum=<? echo $alb_ref; ?>" target="_top"><i class="fa fa-flag" aria-hidden="true" style="color:#F00"></i> Report Photo</a></li> 
       </ul> 
      </div> 


<button type="submit" id="download" name="download" class="btn btn-success"><i class="fa fa-download" aria-hidden="true"></i> Download</button> 

<a href="album.php?alb_ref=<? echo $alb_ref; ?>" class="btn btn-default" target="_top"><i class="fa fa-chevron-circle-left" aria-hidden="true"></i> Back</a> 
</form> 
</h2> 
        <p style="color:#666">Image <? echo $starter - $reback; ?>/<? echo $rowcount_total_images; ?></p> 
       </div> 
      </div> 

<? 
    } 
} 
} 
?>   

     </div> 

     <!-- Controls --> 
     <a class="left carousel-control" href="#myCarousel" data-slide="prev"> 
      <span class="icon-prev" style="color:#03C; font-size:70px;"></span> 
     </a> 
     <a class="right carousel-control" href="#myCarousel" data-slide="next"> 
      <span class="icon-next" style="color:#03C; font-size:70px;"></span> 
     </a> 

    </header> 

Answer 1

只加載時要求將需要一個「懶加載」技術的圖像。基本原理是預加載第一個圖像，但不是其他的。然後使用一些JS按需加載其他JS。由於採用拼焊板的jQuery它相對容易，使用此代碼做：

<div id="carousel-example-generic" class="carousel slide" data-ride="carousel"> 
    <ol class="carousel-indicators"> 
    <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li> 
    <li data-target="#carousel-example-generic" data-slide-to="1"></li> 
    </ol> 
    <div class="carousel-inner" role="listbox"> 
    <div class="item active"> 
     <!-- load the first image --> 
     <img src="http://lorempixel.com/640/480/cats/1"> 
    </div> 
    <div class="item"> 
     <!-- don't load the rest --> 
     <img src="your-wait-icon-here.gif" data-lazy-load-src="http://lorempixel.com/640/480/cats/2"> 
    </div> 
    </div> 
    <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev"> 
    <span class="glyphicon glyphicon-chevron-left" aria-hidden="true"></span> 
    </a> 
    <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next"> 
    <span class="glyphicon glyphicon-chevron-right" aria-hidden="true"></span> 
    </a> 
</div> 

$('#carousel-example-generic').on('slide.bs.carousel', function(e) { 

    $(e.relatedTarget).find('img').each(function() { 
    var $this = $(this); 
    var src = $this.data('lazy-load-src'); 

    if (typeof src !== "undefined" && src != "") { 
     $this.attr('src', src) 
     $this.data('lazy-load-src', ''); // clean up 
    } 
    }); 
}); 

一個例子來看看這個JSFiddle。

但要記住的是，1472圖像問題不會自行修復。它正在崩潰，因爲您的瀏覽器內存不足。隨着延遲加載它將與第一批一起工作，但你的瀏覽器很快就會耗盡內存。您可能需要限制在這裏加載的圖像數量...