Create Image Thumbnail Function Keep Aspect Ratio Problem

Question

I am working on a Joomla Module and trying to create thumbnails of images. I have a Class and createThumbnail function. I have a $keep_aspect_ratio variable in module settings. I want my images to keep aspect ratio when this variable is true. But it does not work in case of $keep_aspect_ratio=true. Still creates thumbnails with given dimensions. Thanks in advance.

class ThumbImage
{
    private $source;

    public function __construct($sourceImagePath)
    {
        $this->source = $sourceImagePath;
    }

function createThumbnail($src, $dest, $targetWidth, $targetHeight,$keep_aspect_ratio=false) {

    // 1. Load the image from the given $src
    // - see if the file actually exists
    // - check if it's of a valid image type
    // - load the image resource

    // get the type of the image
    // we need the type to determine the correct loader
    $type = exif_imagetype($src);

    // if no valid type or no handler found -> exit
    if (!$type || !IMAGE_HANDLERS[$type]) {
        return null;
    }

    // load the image with the correct loader
    $image = call_user_func(IMAGE_HANDLERS[$type]['load'], $src);

    // no image found at supplied location -> exit
    if (!$image) {
        return null;
    }

    // get original image width and height
    $width = imagesx($image);
    $height = imagesy($image);

    // maintain aspect ratio when no height set
    if ($keep_aspect_ratio=true) {
        // get width to height ratio
        $ratio = $width / $height;

        // if is portrait
        // use ratio to scale height to fit in square
        if ($width > $height) {
            $targetHeight = floor($targetWidth / $ratio);
        }
        // if is landscape
        // use ratio to scale width to fit in square
        else {
            $targetHeight = $targetWidth;
            $targetWidth = floor($targetWidth * $ratio);
        }
    }

    // create duplicate image based on calculated target size
    $thumbnail = imagecreatetruecolor($targetWidth, $targetHeight);

    // set transparency options for GIFs and PNGs
    if ($type == IMAGETYPE_GIF || $type == IMAGETYPE_PNG) {

        // make image transparent
        imagecolortransparent(
            $thumbnail,
            imagecolorallocate($thumbnail, 0, 0, 0)
        );

        // additional settings for PNGs
        if ($type == IMAGETYPE_PNG) {
            imagealphablending($thumbnail, false);
            imagesavealpha($thumbnail, true);
        }
    }

    // copy entire source image to duplicate image and resize
    imagecopyresampled(
        $thumbnail,
        $image,
        0, 0, 0, 0,
        $targetWidth, $targetHeight,
        $width, $height
    );


    // 3. Save the $thumbnail to disk
    // - call the correct save method
    // - set the correct quality level

    // save the duplicate version of the image to disk
    
    if ($type == IMAGETYPE_GIF) {
    return call_user_func(
        IMAGE_HANDLERS[$type]['save'],
        $thumbnail,
        $dest
    );
}
else {
    return call_user_func(
        IMAGE_HANDLERS[$type]['save'],
        $thumbnail,
        $dest,
        IMAGE_HANDLERS[$type]['quality']
    );
    }
}
}