resize-image-keep-aspect-ratio.php

<?php

public function getImageSizeKeepAspectRatio( $imageUrl, $maxWidth, $maxHeight)
{
	$imageDimensions = getimagesize($imageUrl);

	$imageWidth = $imageDimensions[0];
	$imageHeight = $imageDimensions[1];

	$imageSize['width'] = $imageWidth;
	$imageSize['height'] = $imageHeight;

	if($imageWidth > $maxWidth || $imageHeight > $maxHeight)
	{
		if ( $imageWidth > $imageHeight ) {
	    	$imageSize['height'] = floor(($imageHeight/$imageWidth)*$maxWidth);
  			$imageSize['width']  = $maxWidth;
		} else {
			$imageSize['width']  = floor(($imageWidth/$imageHeight)*$maxHeight);
			$imageSize['height'] = $maxHeight;
		}
	}

	return $imageSize;
}
?>