Symfony2 sonata media bundle custom re-sizer that does not lose the image ratio.

ExactResizer.php

<?php namespace Application\Sonata\MediaBundle\Resizer;

use Imagine\Image\ImagineInterface;
use Imagine\Image\Box;
use Gaufrette\File;
use Sonata\MediaBundle\Model\MediaInterface;
use Sonata\MediaBundle\Resizer\ResizerInterface;
use Imagine\Image\ImageInterface;
use Imagine\Image\Point;
use Imagine\Exception\InvalidArgumentException;
use Sonata\MediaBundle\Metadata\MetadataBuilderInterface;


class ExactResizer implements ResizerInterface
{
    protected $adapter;
    protected $mode;
    protected $metadata;

    /**
     * @param ImagineInterface $adapter
     * @param string $mode
     */
    public function __construct(ImagineInterface $adapter, $mode, MetadataBuilderInterface $metadata)
    {
        $this->adapter = $adapter;
        $this->mode = $mode;
        $this->metadata = $metadata;
    }

    /**
     * {@inheritdoc}
     */
    public function resize(MediaInterface $media, File $in, File $out, $format, array $settings)
    {

        if (!(isset($settings['width']) && $settings['width']))
            throw new \RuntimeException(sprintf('Width parameter is missing in context "%s" for provider "%s"', $media->getContext(), $media->getProviderName()));


        $image = $this->adapter->load($in->getContent());

        $size = $media->getBox();


        if (isset($settings['height']) && $settings['height']){

            $ratio = $settings['width']/$settings['height'];

            if($settings['width']>$settings['height']){
                $width = $size->getWidth();
                $height = $width/$ratio;
            }else{
                $height = $size->getHeight();
                $width = $height*$ratio;
            }
            // re adjust if too big
            if($width>$size->getWidth()){
                $width = $size->getWidth();
                $height = $width/$ratio;
            }
            if($height>$size->getHeight()){
                $height = $size->getHeight();
                $width = $height*$ratio;
            }

            $cropBox = new Box($width,$height);

            $y = $size->getHeight() / 2 - $height / 2;
            $x = $size->getWidth() / 2 - $width / 2;
            if($y<0) $y = 0;
            if($x<0) $x = 0;
            $image->crop(new Point($x, $y), $cropBox);

            $image->resize(new Box($settings['width'],$settings['height']));

        }else{
            $thumbBox = $this->getBox($media, $settings);
            $image->thumbnail($thumbBox, $this->mode);
        }







        $content = $image->get($format, array('quality' => $settings['quality']));

        $out->setContent($content, $this->metadata->get($media, $out->getName()));
    }

    /**
     * {@inheritdoc}
     */
    public function getBox(MediaInterface $media, array $settings)
    {
        $size = $media->getBox();
        $hasWidth = isset($settings['width']) && $settings['width'];
        $hasHeight = isset($settings['height']) && $settings['height'];

        if (!$hasWidth && !$hasHeight)
            throw new \RuntimeException(sprintf('Width/Height parameter is missing in context "%s" for provider "%s". Please add at least one parameter.', $media->getContext(), $media->getProviderName()));

        if ($hasWidth && $hasHeight)
            return new Box($settings['width'], $settings['height']);

        if (!$hasHeight)
            $settings['height'] = intval($settings['width'] * $size->getHeight() / $size->getWidth());

        if (!$hasWidth)
            $settings['width'] = intval($settings['height'] * $size->getWidth() / $size->getHeight());

        return $this->computeBox($media, $settings);
    }

    /**
     * @throws InvalidArgumentException
     *
     * @param MediaInterface $media
     * @param array $settings
     *
     * @return Box
     */
    private function computeBox(MediaInterface $media, array $settings)
    {
        if ($this->mode !== ImageInterface::THUMBNAIL_INSET && $this->mode !== ImageInterface::THUMBNAIL_OUTBOUND)
            throw new InvalidArgumentException('Invalid mode specified');

        $size = $media->getBox();

        $ratios = [
            $settings['width'] / $size->getWidth(),
            $settings['height'] / $size->getHeight()
        ];

        if ($this->mode === ImageInterface::THUMBNAIL_INSET)
            $ratio = min($ratios);
        else
            $ratio = max($ratios);

        return $size->scale($ratio);
    }
}