Resizing Uploaded Files - PHP

In this tutorial, I will teach you how to resize uploaded files to make them have either a fixed size, or a certain percent of its former size. The advantage of resizing uploaded files are many:

The File's size would greatly reduce, enabling better performance.
General fitness and a more elegant look especially for a photo gallery.

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This tutorial requires the two plugins below:

jQuery-1.5.1.min.js
jQuery.form.js

We will also create two files below:

index.php
upload.php

You will create two folders- uploads(store normal image) and thumb(contain resized images). I'm sure you will like this. Don't forget to leave behind a comment, or post us an update.

Index.php

<html>
<head>
<title>Ajax file upload with image resizing - Ohwofosirai Desmond</title>
<script type="text/javascript" src="jquery-1.5.1.min.js"></script>
<script type="text/javascript" src="jquery.form.js"></script>
<script>
$(document).ready(function() {
$('#uploader').live('change', function()           {
$("#msg").html('');
$("#msg").text('Uploading....');
$("#upload").ajaxForm({
           target: '#msg'
                       }).submit();

           });
        });
</script>
</head>
<body>
<DIV id="uploadfile" style="font-size:12px">
<div>
<p style="margin:2px; font-weight:bold; font-size:16px;">
Ajax file upload with image resizing.</p>
This ajax uploader uses the AjaxForm plugin.
</div>
<form id="upload" method="post" action="upload.php" enctype="multipart/form-data">
<p/><label>Upload profile picture</label>
<br/><input type="file" id="uploader" name="file"/>
</form>
<DIV id="msg"></DIV>
</DIV>

</body>
</html>

Upload.php - php image resizing

<?php
/*initialize values($h=new height, $w=new width, $dir=storage location)*/
   $h=60; $w=60;
   extract($_POST);
   //file format validation
   $arr=array();
   $valid_formats = array("jpg", "png", "gif", "bmp");
   $filename=$_FILES['file']['name'];
   $arr = explode(".",$filename);
   $ext=$arr[count($arr)-1];
   if(!in_array($ext, $valid_formats))
   quit("Invalid file format");

   //validate filesize
   if ($_FILES['file']['size']>2048)
   quit("File too large. Max: 2MB");

   if(is_uploaded_file($_FILES['file']['tmp_name']))
   move_uploaded_file($_FILES['file']['tmp_name'],"upload/".$filename);

   //call function to resize and upload file
   $resize=resize("upload/".$filename, "thumb/".$filename, 100);
   if ($resize) quit('<img src="thumb/'.$filename.'" alt="image" id="msg"/>');
   else quit('Unknown Error! Please Retry');

   /*------------------------------------------------------------------------------------------
   NOTE: This php function called "resize" had been copied from elsewhere on the internet.
   help me if you have some info that can help me link them.
   ------------------------------------------------------------------------------------------*/
   /* This function resizes an image by calculating percentage of new height using width specified.
   resize(file_location, file_destination, new_width) */
function resize($orig_file,$thumb_file,$prop){
   $img = $orig_file;
   $constrain = true;
   $w = $prop;
   $h = $prop;
    $percent=0;
   // get image size of img
   $x = @getimagesize($img);
   // image width
   $sw = $x[0];
   // image height
   $sh = $x[1];

   if ($percent > 0) {
       // calculate resized height and width if percent is defined
       $percent = $percent * 0.01;
       $w = $sw * $percent;
       $h = $sh * $percent;
   } else {
       if (isset ($w) AND !isset ($h)) {
           // autocompute height if only width is set
           $h = (100 / ($sw / $w)) * .01;
           $h = @round ($sh * $h);
       } elseif (isset ($h) AND !isset ($w)) {
           // autocompute width if only height is set
           $w = (100 / ($sh / $h)) * .01;
           $w = @round ($sw * $w);
       } elseif (isset ($h) AND isset ($w) AND isset ($constrain)) {
           // get the smaller resulting image dimension if both height
           // and width are set and $constrain is also set
           $hx = (100 / ($sw / $w)) * .01;
           $hx = @round ($sh * $hx);
           $wx = (100 / ($sh / $h)) * .01;
           $wx = @round ($sw * $wx);
           if ($hx < $h) {
               $h = (100 / ($sw / $w)) * .01;
               $h = @round ($sh * $h);
           } else {
               $w = (100 / ($sh / $h)) * .01;
               $w = @round ($sw * $w);
           }
       }
   }
   $im = @ImageCreateFromJPEG ($img) or // Read JPEG Image
   $im = @ImageCreateFromPNG ($img) or // or PNG Image
   $im = @ImageCreateFromGIF ($img) or // or GIF Image
   $im = false; // If image is not JPEG, PNG, or GIF
   if (!$im) {
       // We get errors from PHP's ImageCreate functions...
       // So let's echo back the contents of the actual image.
       readfile ($img);
   } else {
       // Create the resized image destination
       $thumb = @ImageCreateTrueColor ($w, $h);
       // Copy from image source, resize it, and paste to image destination
       @ImageCopyResampled ($thumb, $im, 0, 0, 0, 0, $w, $h, $sw, $sh);
       // Output resized image
       @ImageJPEG ($thumb,$thumb_file);
   }
return true;
}//resize function end here

   //echo errors and quit, if any.
   function quit($msg){
   echo $msg;
   exit;
   }
?>

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