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brentwientjes at NOSPAM dot comcast dot net ¶
15 years ago
Last night I posted the following note under move_upload_file and looked tonight to see if it got into the system.  I happen to also pull up imagecreatefromjpeg and got reminded of many resize scripts in this section.  Unfortunately, my experience was not covered by most of the examples below because each of them assumed less than obvious requirements of the server and browser.  So here is the post again under this section to help others uncover the mystery in file uploading and resizing arbitrary sized images.  I have been testing for several days with hundreds of various size images and it seems to work well.  Many additional features could be added such as transparency, alpha blending, camera specific knowledge, more error checking.  Best of luck.

---  from move_upload_file post ---

I have for a couple of years been stymed to understand how to effectively load images (of more than 2MB) and then create thumbnails.  My note below on general file uploading was an early hint of some of the system default limitations and I have recently discovered the final limit  I offer this as an example of the various missing pieces of information to successfully load images of more than 2MB and then create thumbnails.  This particular example assumes a picture of a user is being uploaded and because of browser caching needs a unique number at the end to make the browser load a new picture for review at the time of upload.  The overall calling program I am using is a Flex based application which calls this php file to upload user thumbnails.

The secret sauce is:

1.  adjust server memory size, file upload size, and post size
2.  convert image to standard formate (in this case jpg) and scale

The server may be adjusted with the .htaccess file or inline code.  This example has an .htaccess file with file upload size and post size and then inline code for dynamic system memory.

htaccess file:
php_value post_max_size 16M
php_value upload_max_filesize 6M

<?php 
//  $img_base = base directory structure for thumbnail images
//  $w_dst = maximum width of thumbnail
//  $h_dst = maximum height of thumbnail
//  $n_img = new thumbnail name
//  $o_img = old thumbnail name
function convertPic($img_base, $w_dst, $h_dst, $n_img, $o_img)
  {ini_set('memory_limit', '100M');   //  handle large images
   unlink($img_base.$n_img);         //  remove old images if present
   unlink($img_base.$o_img);
   $new_img = $img_base.$n_img;
     
   $file_src = $img_base."img.jpg";  //  temporary safe image storage
   unlink($file_src);
   move_uploaded_file($_FILES['Filedata']['tmp_name'], $file_src);
              
   list($w_src, $h_src, $type) = getimagesize($file_src);  // create new dimensions, keeping aspect ratio
   $ratio = $w_src/$h_src;
   if ($w_dst/$h_dst > $ratio) {$w_dst = floor($h_dst*$ratio);} else {$h_dst = floor($w_dst/$ratio);}

   switch ($type)
     {case 1:   //   gif -> jpg
        $img_src = imagecreatefromgif($file_src);
        break;
      case 2:   //   jpeg -> jpg
        $img_src = imagecreatefromjpeg($file_src); 
        break;
      case 3:  //   png -> jpg
        $img_src = imagecreatefrompng($file_src);
        break;
     }
   $img_dst = imagecreatetruecolor($w_dst, $h_dst);  //  resample
   
   imagecopyresampled($img_dst, $img_src, 0, 0, 0, 0, $w_dst, $h_dst, $w_src, $h_src);
   imagejpeg($img_dst, $new_img);    //  save new image

   unlink($file_src);  //  clean up image storage
   imagedestroy($img_src);        
   imagedestroy($img_dst);
  }

$p_id = (Integer) $_POST[uid];
$ver = (Integer) $_POST[ver];
$delver = (Integer) $_POST[delver];
convertPic("your/file/structure/", 150, 150, "u".$p_id."v".$ver.".jpg", "u".$p_id."v".$delver.".jpg");

?>
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