如何检查缓存的图像是否与url图像具有相同的宽度和高度？

问题描述：

I am writing a script where I am just resizing images from the requested image url and caching them. I am also giving width & height as optional params for the request. I am caching the images by their filenames & I want to cover one use case when user requests the same image with different width or height.

Since I am using Codeigniter's image resizing library, the filenames are appended with _thumb. That's how I am storing the images.

What should I do in that case? One solution would be to check the md5 hash of the resized image and cached image.

Here's what I am thinking to do:

            $ch = curl_init($url); //initialize cURL

            curl_setopt($ch, CURLOPT_HEADER, 0); 
            curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
            curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1); 
            $dataToWrite = curl_exec($ch); //Execute the given cURL session. 

            curl_close ($ch); //close the given cURL session
            $fp = fopen($dirPath.$filename,'w');
            fwrite($fp, $dataToWrite); 
            fclose($fp);

Finally,

           if (md5_file($dirPath.$filename) == md5_file($dirPath.$resizedImage){
                serveimagefromcache() & deletethedownloadedfile();
           } else {
               resizetheimage() && serveit(); 
           }

I am concerned about the performance as well, I would appreciate any other suggestions.

我正在编写一个脚本，我只是从请求的图像URL调整图像并缓存它们。我也给宽度＆amp; height作为请求的可选参数。我通过他们的文件名＆amp;缓存图像当用户请求具有不同宽度或高度的相同图像时，我想要涵盖一个用例。 p>

由于我使用的是Codeigniter的图像大小调整库，因此文件名附加了_thumb。这就是我存储图像的方式。 p>

在这种情况下我该怎么办？一种解决方案是检查已调整大小的图像和缓存图像的md5 code>哈希。 p>

这是我想要做的事情： p> \ n


  $ ch = curl_init（$ url）;  //初始化cURL 
 
 curl_setopt（$ ch，CURLOPT_HEADER，0）;  
 curl_setopt（$ ch，CURLOPT_RETURNTRANSFER，1）;  
 curl_setopt（$ ch，CURLOPT_BINARYTRANSFER，1）;  
 $ dataToWrite = curl_exec（$ ch）;  //执行给定的cURL会话。  
 
 curl_close（$ ch）;  //关闭给定的cURL会话
 $ fp = fopen（$ dirPath。$ filename，'w'）; 
 fwrite（$ fp，$ dataToWrite）;  
 fclose（$ fp）; 
  code>  pre> 
 
 最后， p> 
 
 
  if（md5_file（$ dirPath。$ filename）  ）== md5_file（$ dirPath。$ resizedImage）{
 serveimagefromcache（）＆amp; deletethedownloadedfile（）; 
} else {
 resizetheimage（）＆amp;＆amp; serveit（）; 
} 
  code>   pre> 
 
 我也很关注表现，我将不胜感激任何其他建议。 p> 
  div>

答

Even though @arkascha's suggestion was quite good but saving the file as filename hash is much more better.

With this,

$ext   = pathinfo($filename, PATHINFO_EXTENSION);    
$filehash = sha1($filename.$width.$height);
$filename = $filehash.".".$ext

you can prevent the issue that I was having.

如何检查缓存的图像是否与url图像具有相同的宽度和高度？

相关推荐