Reflection filter in Imagine

ReflectionFilter.php

<?php

class ReflectionFilter implements Imagine\Filter\FilterInterface
{
    private $imagine;

    public function __construct(Imagine\Image\ImagineInterface $imagine)
    {
        $this->imagine = $imagine;
    }
    
    public function apply(Imagine\Image\ImageInterface $image)
    {
        $size       = $image->getSize();
        $canvas     = new Imagine\Image\Box($size->getWidth(), $size->getHeight() * 2);
        $reflection = $image->copy()
            ->flipVertically()
            ->applyMask($this->getTransparencyMask($size))
        ;

        return $this->imagine->create($canvas, new Imagine\Image\Color('fff', 100))
            ->paste($image, new Imagine\Image\Point(0, 0))
            ->paste($reflection, new Imagine\Image\Point(0, $size->getHeight()));
    }

    private function getTransparencyMask(Imagine\Image\BoxInterface $size)
    {
        $white = new Imagine\Image\Color('fff');
        $fill  = new Imagine\Image\Fill\Gradient\Vertical(
            $size->getHeight(),
            $white->darken(127),
            $white
        );

        return $this->imagine->create($size)
            ->fill($fill)
        ;
    }
}