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Old July 10th, 2006, 01:36 AM
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Default Image Resize after Upload

Hi everyone,

Here is the challenge I am facing. I have a page that uploads two graphic files to the server. Currently I can get the dimensions of the images, and warn the user is they exceed the size limits (350x350). I think that instead of a warning, I could just resize the images to the correct size, and the user will never know.

I am sure I am close, but would someone be able to direct as to the best way to do this?

I figure I can either resize after the upload process, or once the upload is complete and the images have been removed to the specific folders.

Thanks in advance,


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Old July 12th, 2006, 06:19 AM
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I use the GD library to resample my digital camera pictures for thumbnails, medium view, and large view JPGs for hosting on my website. It takes a bit of work to get set up, but once you do, it works great. You can specify the JPEG quality level and even do graphic manipulation.

You can get the installation instructions and learn more here: http://www.php.net/manual/en/ref.image.php

Jon Emerson
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Old July 13th, 2006, 12:16 AM
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I actually figured this one out. The trick was getting the image and then getting it saved back over itself once it was resaved.

I got this code from a comment posted on the PHP.net site, and tweaked it to get the desired functionality.

    function ResizeImage($file,$maxwdt,$maxhgt, $dest) {

      switch($otype) {
       case 1:  $newimg=imagecreatefromgif($file); break;
       case 2:  $newimg=imagecreatefromjpeg($file); break;
       case 3:  $newimg=imagecreatefrompng($file); break;
       default: echo "Unkown filetype (file $file, typ $otype)"; return;

      if($newimg) {
       if($owdt>1500 || $ohgt>1200)
           list($owdt, $ohgt) = Resample($newimg, $owdt, $ohgt, 1024,768,0);

       Resample($newimg, $owdt, $ohgt, $maxwdt, $maxhgt);

           if(!$dest) return $newimg;


       switch($otype) {
         case 1: imagegif($newimg,dest); break;    
         case 2: imagejpeg($newimg,$dest,90); break; 
         case 3: imagepng($newimg,$dest);  break; 



    function Resample(&$img, $owdt, $ohgt, $maxwdt, $maxhgt, $quality=1) { 
      if(!$maxwdt) $divwdt=0;
       else $divwdt=Max(1,$owdt/$maxwdt);

      if(!$maxhgt) $divhgt=0;
       else $divhgt=Max(1,$ohgt/$maxhgt);

      if($divwdt>=$divhgt) {
      } else {



       $img = $tn;

       return array($newwdt, $newhgt);
To use it, I just use the following line...

ResizeImage($imageName,350,350, $imageName);

Which would resize and resample so that the longest side is set at 350 pixels.

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