php function crop image

1$image = imagecreatefromjpeg($_GET['src']);
2$filename = 'images/cropped_whatever.jpg';
3
4$thumb_width = 200;
5$thumb_height = 150;
6
7$width = imagesx($image);
8$height = imagesy($image);
9
10$original_aspect = $width / $height;
11$thumb_aspect = $thumb_width / $thumb_height;
12
13if ( $original_aspect >= $thumb_aspect )
14{
15   // If image is wider than thumbnail (in aspect ratio sense)
16   $new_height = $thumb_height;
17   $new_width = $width / ($height / $thumb_height);
18}
19else
20{
21   // If the thumbnail is wider than the image
22   $new_width = $thumb_width;
23   $new_height = $height / ($width / $thumb_width);
24}
25
26$thumb = imagecreatetruecolor( $thumb_width, $thumb_height );
27
28// Resize and crop
29imagecopyresampled($thumb,
30                   $image,
31                   0 - ($new_width - $thumb_width) / 2, // Center the image horizontally
32                   0 - ($new_height - $thumb_height) / 2, // Center the image vertically
33                   0, 0,
34                   $new_width, $new_height,
35                   $width, $height);
36imagejpeg($thumb, $filename, 80);