php

using this code we can resize the image by height , width and both but i want get the out put like when we use constrain proportions in photo shop because when i resize using this code the image looks like stretched or compressed is it possible to write code to get the image without stressing or compressing?

<?php
if(isset($_POST['Submit']))
{
$a=$_REQUEST['aaa'];
//error_reporting(0);
include "db.php";
$current_image=$_FILES['image']['name'];
$extension = substr(strrchr($current_image, '.'), 1);
if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "png") && ($extension != "gif"))
{
header('loaction:uploads.php?a=sorry UR logo is not supported try again');
}
else
{
include 'sampleimage.php';
$current_image=$_FILES['image']['name'];
$image = new SimpleImage();
$image->load($_FILES['image']['tmp_name']);
//$image->resize(168,102);
$image->scale(50);

//$image->resizeToWidth(168);

$image->save("logos/$current_image");
$conn = mysql_connect("$hostname","$username", "$password") or die("sorry");
mysql_select_db($database,$conn) or die("not connected to database");
$current_image=$_FILES['image']['name'];
$sql = "update school_tbl SET logo = '$current_image' WHERE school_name='$a'";
//echo $sql;exit;
$a=mysql_query($sql);
if($a==1)
{
header('location:listing_ad.php');
}
else
{
echo "sorry";
//header('location:uploads.php');
}
}
}

?>

<?php
/*
* File: SimpleImage.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 08/11/06
* Link: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details:
* http://www.gnu.org/licenses/gpl.html
*
*/

class SimpleImage {

var $image;
var $image_type;

function load($filename) {
$image_info = getimagesize($filename);
//echo $image_info[1];exit;
$this->image_type = $image_info[2];
if( $this->image_type == IMAGETYPE_JPEG ) {
$this->image = imagecreatefromjpeg($filename);
} elseif( $this->image_type == IMAGETYPE_GIF ) {
$this->image = imagecreatefromgif($filename);
} elseif( $this->image_type == IMAGETYPE_PNG ) {
$this->image = imagecreatefrompng($filename);
}
}
function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image,$filename,$compression);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image,$filename);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image,$filename);
}
if( $permissions != null) {
chmod($filename,$permissions);
}
}
function output($image_type=IMAGETYPE_JPEG) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image);
}
}
function getWidth() {
return imagesx($this->image);
}
function getHeight() {
return imagesy($this->image);
}
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width,$height);
}
function resizeToWidth($width) {
$ratio = $width / $this->getWidth();
$height = $this->getheight() * $ratio;
$this->resize($width,$height);
}
function scale($scale) {
$width = $this->getWidth() * $scale/100;
$height = $this->getheight() * $scale/100;
$this->resize($width,$height);
}
function resize($width,$height) {
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
}
}
?>