src/Uploadcare/File.php
public function preview($width, $height)
    {
        if (!$width || !$height) {
            throw new \Exception('Please, provide both width and height for preview');
        }
        $result = clone $this;
        $result->operations[]['preview'] = array(
            'width' => $width,
            'height' => $height,
        );
        return $result;
    }
public function preview($width, $height)
    {
        if (!$width || !$height) {
            throw new \Exception('Please, provide both width and height for preview');
        }
        $result = clone $this;
        $result->operations[]['preview'] = array(
            'width' => $width,
            'height' => $height,
        );
        return $result;
    }
Get object with preview parameters.
Provide both width and height.
If no width and height are provided exceptions will be thrown!

@param int $width Preview image width.
@param int $height Preview image height.
@throws \Exception
@return File