Create Thumbnail on Fly with Data URI in PHP

Wednesday, August 17, 2011

Thumbnail on fly is very useful trick to reduce page load also gain page loading speed when loading a page from server. But Thumbnail is also stored as a Image file and retrieved from server with http request. If your website getting high volume traffic you need to consider http request by reducing number of Request. Now days the Modern browsers support Image Data URI. data URIs have now been implemented in most browsers.


Here is the Function to Generate Thumbnail on Fly with Data URI

<?php
// Funtion to prepare Data URI:
// @ parm: Image filepath, Image Size
// reutn : data_uri string
function thumbnail_data_uri($filename,$width=0,$height=0) 
{
 
 // Get Image Header Type
      $image_info = getimagesize($filename);
      $image_type = $image_info[2];

 // Check the Size is Specified
 if($width!=0 and $height!=0)
 {
      if( $image_type == IMAGETYPE_JPEG ) {
         $image = imagecreatefromjpeg($filename);
      } elseif( $image_type == IMAGETYPE_GIF ) {
         $image = imagecreatefromgif($filename);
      } elseif( $image_type == IMAGETYPE_PNG ) {
         $image = imagecreatefrompng($filename);
   imagealphablending($image, true);

      } 

 $new_image = imagecreatetruecolor($width, $height);
 imagealphablending($new_image, false);
 imagesavealpha($new_image, true);     
      imagecopyresampled($new_image, $image, 0, 0, 0, 0, $width, $height, imagesx($image),imagesy($image));
      $image = $new_image; 
   
 ob_start();
      if( $image_type == IMAGETYPE_JPEG ) {
         imagejpeg($image);
      } elseif( $image_type == IMAGETYPE_GIF ) {
         imagegif($image);         
      } elseif( $image_type == IMAGETYPE_PNG ) {
         imagepng($image);
      } 
 $content=ob_get_clean();   
   
   
 }else
 $content=file_get_contents($filename,true);
 
 
 
 $base64 = base64_encode($content); 
 return "data:$image_type;base64,$base64";
}

?>
<img src="<?php echo thumbnail_data_uri('images/sample.png',200,200);?>" alt="An Earth">
<img src="<?php echo thumbnail_data_uri('images/sample.png',100,100);?>" alt="An Earth">
<img src="<?php echo thumbnail_data_uri('images/sample.png',150,150);?>" alt="An Earth">

<img src="<?php echo thumbnail_data_uri('images/sample.png',100,100);?>" alt="An Earth">
Data URI Advantages

  • HTTP request and header traffic is not required for embedded data, so data URIs consume less bandwidth whenever the overhead of encoding the inline content as a data URI is smaller than the HTTP overhead. For example, the required base64 encoding for an image 600 bytes long would be 800 bytes, so if an HTTP request required more than 200 bytes of overhead, the data URI would be more efficient
  • For transferring many small files (less than a few kilobytes each), this can be faster. TCP transfers tend to start slowly. If each file requires a new TCP connection, the transfer speed is limited by the round-trip time rather than the available bandwidth. Using HTTP keep-alive improves the situation, but may not entirely alleviate the bottleneck.
  •  When browsing a secure HTTPS web site, web browsers commonly require that all elements of a web page be downloaded over secure connections, or the user will be notified of reduced security due to a mixture of secure and insecure elements. On badly configured servers, HTTPS requests have significant overhead over common HTTP requests, so embedding data in data URIs may improve speed in this case.
  • Web browsers are usually configured to make only a certain number (often two) of concurrent HTTP connections to a domain,[6] so inline data frees up a download connection for other content.
  • Environments with limited or restricted access to external resources may embed content when it is disallowed or impractical to reference it externally. For example, an advanced HTML editing field could accept a pasted or inserted image and convert it to a data URI to hide the complexity of external resources from the user. Alternatively, a browser can convert (encode) image based data from the clipboard to a data URI and paste it in a HTML editing field. Mozilla Firefox 4 supports this functionality.
  • It is possible to manage a multimedia page as a single file.
  • Email message templates can contain images (for backgrounds or signatures) without the image appearing to be an "attachment".
  • Data URIs make it more difficult for security software to filter content

1 comment:

Anonymous said...

And what about SEO and data URI???

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