Thumbnail Creation with PHP

thumbnail.php

<?php
// Maximum size of the uploaded image
define('MAX_SIZE','100');
// Width & Height of the thumbnail in pixels
define('WIDTH','150');
define('HEIGHT','100');
// Thumbnail creation function
function makeThumb($img_name,$file_name,$new_width,$new_height)
{
	// Get the extension of the image
	$ext =getExtension ($img_name);
	// Creates new image using GD library function
	if (!strcmp("jpg",$ext) || !strcmp("jpeg",$ext))
	{
		$src_img = imagecreatefromjpeg($img_name);
	}
	if (!strcmp("png",$ext))
	{
		$src_img = imagecreatefrompng($img_name);
	}
	// Getthe dimension of the image
	$old_width = imagesx($src_img);
	$old_height = imagesy($src_img);
	// Calculate the width & height ratio of the thumbnail
	$ratio1 = $old_width / $new_width;
	$ratio2 = $old_height / $new_height;
	if ($ratio1 > $ratio2)
	{
		$thumb_width = $new_width;
		$thumb_height = $old_height / $ratio1;
	}
	else
	{
		$thumb_width = $old_width / $ratio2;
		$thumb_height = $new_height;
	}
	// Create a new image with the new dimension
	$dst_img = imagecreatetruecolor($new_width,$new_height);
	// Resize the big image with the new created one 
	imagecopyresampled($dst_img,$src_img,0,0,0,0,$thumb_width,$thumb_height,$new_width,$new_height);
	// Output the created image to the file
	if (!strcmp("png",$ext))
	{
		imagepng ($dst_img,$file_name);
	}
	else
	{
		imagejpeg ($dst_img,$file_name);
	}
	// Destroy the source & destination image
	//imagedestroy($dst_img);
	//imagedestroy($src_img);
}

// Function for checkingthe extension of the file
function getExtension ($str)
{
	$i =strpos($str,".");
	if (!$i)
	{
		return "";
	}
	$j =strlen($str) - $i;
	$ext =substr($str,$i+1,$j);
	return $ext;
}
// Flag
$error = 0;
if (isset($_POST['submit']))
{
	// Read the name of the uploaded file
	$image = $_FILES['image']['name'];
	if ($image)
	{
		// Get the original name of the file
		$file_name = stripslashes($_FILES['image']['name']);
		// Get the extension of the file in lower case
		$extension =getExtension($file_name);
		$extension =strtolower($extension);
		// If extension is not valid print the error msg
		if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "png"))
		{
			echo "Unkown File type.";
			$error = 1;
		}
		else
		{
			// Get the size of the image in bytes
			$size =getimagesize($_FILES['image']['tmp_name']);
			$sizekb =filesize($_FILES['image']['tmp_name']);
			// If the size exceeds to themaximum size,print error
			if ($sizekb > MAX_SIZE * 1024)
			{
				echo "The file size is larger than the maximum allowed size";
				$error = 1;
			}
			// Give the unique time span
			$image_name = time() . '.' . $extension;
			// the new image will be stored in "images" folder
			$new_name = "images/".$image_name;
			$copied = copy($_FILES['image']['tmp_name'],$new_name);
			if (!$copied)
			{
				echo "Copy Unsuccessful";
				$error = 1;
			}
			else
			{
				// The new thumbnail imagewill be placed: images/thumbs folder
				$thumb_name = "images/thumbs/thumb_".$image_name;
				// Call the thumbnail creation function
				$thumb =makeThumb ($new_name,$thumb_name,WIDTH,HEIGHT);
			}
		}
	}	
}

if (isset($_POST['submit']) && !$error)
{
	echo "Thumbnail Created Successfully";
	echo '<img src="'.$thumb_name.'" alt="" />';
}
?>
<form name="imageupload" action="" method="post" enctype="multipart/form-data">
	<input type="file" name="image">
	<input type="submit" name="submit" value="Upload">
</form>