class Convert

class Convert extends GDImageToolkitOperationBase {
  
  /**
   * {@inheritdoc}
   */
  protected function arguments() {
    return [
      'extension' => [
        'description' => 'The new extension of the converted image',
      ],
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  protected function validateArguments(array $arguments) {
    if (!in_array($arguments['extension'], $this->getToolkit()
      ->getSupportedExtensions())) {
      throw new \InvalidArgumentException("Invalid extension ({$arguments['extension']}) specified for the image 'convert' operation");
    }
    return $arguments;
  }
  
  /**
   * {@inheritdoc}
   */
  protected function execute(array $arguments) {
    // Create a new resource of the required dimensions and format, and copy
    // the original resource on it with resampling. Destroy the original
    // resource upon success.
    $width = $this->getToolkit()
      ->getWidth();
    $height = $this->getToolkit()
      ->getHeight();
    $original_resource = $this->getToolkit()
      ->getResource();
    $original_type = $this->getToolkit()
      ->getType();
    $data = [
      'width' => $width,
      'height' => $height,
      'extension' => $arguments['extension'],
      'transparent_color' => $this->getToolkit()
        ->getTransparentColor(),
      'is_temp' => TRUE,
    ];
    if ($this->getToolkit()
      ->apply('create_new', $data)) {
      if (imagecopyresampled($this->getToolkit()
        ->getResource(), $original_resource, 0, 0, 0, 0, $width, $height, $width, $height)) {
        imagedestroy($original_resource);
        return TRUE;
      }
      // In case of error, reset resource and type to as it was.
      $this->getToolkit()
        ->setResource($original_resource);
      $this->getToolkit()
        ->setType($original_type);
    }
    return FALSE;
  }

}