thumbnails.php

<?php 
#--THUMBNAIL CREATION CODE--runs if thumbnail does not exist (consider cronjob)
#TODO test type of image

function generateThumbnail($photo, $photosDir, $thumbnailsDir, $thumbnailWidth, $thumbnailHeight, $thumbnailRatio) {
		if (!file_exists($thumbnailsDir."/".$photo)) {
			list($width,$height) = getimagesize($photosDir."/".$photo);
			$aspectRatio = $width/$height;
			$thumb = imagecreatetruecolor($thumbnailWidth,$thumbnailHeight);
								
			$src_x = 0;
			$src_y = 0;
			$src_w = $width;
			$src_h = $height;
			if ($aspectRatio < $thumbnailRatio) {
				//Take all width but only some of height
				$src_h = intval($width/$thumbnailRatio);
				$src_y = intval(($height-$src_h)/2);

			} elseif ($aspectRatio > $thumbnailRatio) {	
				//Take all height but only some of width
				$src_w = intval($height*$thumbnailRatio);
				$src_x = intval(($width-$src_w)/2);
			}

			$image = imagecreatefromjpeg($photosDir."/".$photo);
			
			imagecopyresampled($thumb, $image, 0, 0, $src_x, $src_y, $thumbnailWidth, $thumbnailHeight, $src_w, $src_h);
			imagejpeg($thumb, $thumbnailsDir."/".$photo);
			imagedestroy($thumb);
		}
}
?>