fitImageInBox

<?php

/**
    Fits an image in a given box, scaling it up or down as needed, retaining the aspect ratio of the image

    Input:
    $width, the width of the box
    $heigth, the height of the box
    $img->width, the width of the image
    $img->height, the height of the image

    Output:
    $width, the width of the scaled image
    $height, the height of the scaled image
    */
    private function fitImageInBox(&$width,&$height,$img) {
        $ar=$img->width/$img->height;

        $newW=$height*$ar;
        $newH=$width/$ar;

        if($newW>$width) {
            $height=$newH;
        } else {
            $width=$newW;
        }
    }