Quick image resizing script

uploadResizeCrop.php

<?php

ini_set("memory_limit", "128M");

$target_path = 'full/';
$thumb_path = 'thumbs/';

$formats = array('jpg', 'gif', 'png');

/* Grab the extension of the uploaded file, and sanitise the rest of the
 * basename, which should prevent any potential attacks.
 */

$ext = strtolower(pathinfo($_FILES['Filedata']['name'], PATHINFO_EXTENSION));
$name = strtolower(pathinfo($_FILES['Filedata']['name'], PATHINFO_FILENAME));
$name = preg_replace('/[^a-z0-9]/', '', $name) . '.' . $ext;

if(!in_array($ext, $formats))
{
	die('File format not supported');
}

resizeImage($_FILES['Filedata']['tmp_name'], $ext, $target_path . $name, 900, 0, 80);
resizeImage($_FILES['Filedata']['tmp_name'], $ext, $thumb_path . $name, 300, 300, 100);

function loadImage($sourceFile, $sourceFormat, &$dimensions)
{
	$img = null;
	switch($sourceFormat)
	{
		case 'jpg':
			$img = imagecreatefromjpeg($sourceFile);
			break;
		case 'png':
			$img = imagecreatefrompng($sourceFile);
			break;
		case 'gif':
			$img = imagecreatefromgif($sourceFile);
			break;
	}
	if(!$img)
	{
		return null;
	}
	$dimensions[0] = imagesx($img);
	$dimensions[1] = imagesy($img);
	return $img;
}

function resizeImage($sourceFile, $sourceFormat, $destFile, $destWidth, $destHeight, $quality)
{
	$dims = array();
	if(!($source = loadImage($sourceFile, $sourceFormat, $dims)))
	{
		return false;
	}
	if(!$destWidth && !$destHeight)
	{
		/* No resizing required */
		$destWidth = $dims[0];
		$destHeight = $dims[1];
	}
	/* $destWidth and $destHeight are the size of the actual output image.
	 * $targetWidth and $targetHeight is what we resample the source to be.
	 * Where $dest... is smaller than $target..., cropping occurs.
	 */
	if(!$destWidth)
	{
		/* Destination will be whatever width is required to match height */
		$targetHeight = $destHeight;
		$targetWidth = $destWidth = $dims[0] * ($destHeight / $dims[1]);
	}
	else if(!$destHeight)
	{
		/* Destination will be whatever height is required to match width */
		$targetWidth = $destWidth;
		$targetHeight = $destHeight = $dims[1] * ($destWidth / $dims[0]);
	}
	else
	{
		/* Fixed output bounding box; find smallest side and resize
		 * proportionally, cropping as necessary.
		 */
		if($dims[1] > $dims[0])
		{
			/* Image is taller than it is wide */
			$targetWidth = $destWidth;
			$targetHeight = $dims[1] * ($destWidth / $dims[0]);
		}
		else
		{
			$targetHeight = $destHeight;
			$targetWidth = $dims[0] * ($destHeight / $dims[1]);
		}
	}
	$targetWidth = floor($targetWidth);
	$targetHeight = floor($targetHeight);
	$destWidth = floor($destWidth);
	$destHeight = floor($destHeight);
	echo "<p>Source is " . $dims[0] . " x " . $dims[1] . "<br />";
	echo "Target is " . $targetWidth . " x " . $targetHeight . "<br />";
	echo "...which will be cropped to " . $destWidth . " x " . $destHeight . "</p>";
	
	$dest = imagecreatetruecolor($destWidth, $destHeight);
	imagecolorallocate($dest, 0xff, 0xff, 0xff);	
	$dx = 0 - floor(($targetWidth - $destWidth) / 2);
	$dy = 0 - floor(($targetHeight - $destHeight) / 2);
	imagecopyresampled($dest, $source, $dx, $dy, 0, 0, $targetWidth, $targetHeight, $dims[0], $dims[1]);
	imagejpeg($dest, $destFile, $quality);
	imagedestroy($source);
	imagedestroy($dest);
}