* @return float
     */
    function get_text_width($text, $font, $size, $word_spacing = 0.0, $char_spacing = 0.0);

    /**
     * Calculates font height, in points
     *
     * @param string $font The font file to use
     * @param float  $size The font size, in points
     *
     * @return float
     */
    function get_font_height($font, $size);

    /**
     * Returns the font x-height, in points
     *
     * @param string $font The font file to use
     * @param float  $size The font size, in points
     *
     * @return float
     */
    //function get_font_x_height($font, $size);

    /**
     * Calculates font baseline, in points
     *
     * @param string $font The font file to use
     * @param float  $size The font size, in points
     *
     * @return float
     */
    function get_font_baseline($font, $size);

    /**
     * Returns the PDF's width in points
     *
     * @return float
     */
    function get_width();

    /**
     * Returns the PDF's height in points
     *
     * @return float
     */
    function get_height();

    /**
     * Sets the opacity
     *
     * @param float  $opacity
     * @param string $mode
     */
    public function set_opacity(float $opacity, string $mode = "Normal"): void;

    /**
     * Sets the default view
     *
     * @param string $view
     * 'XYZ'  left, top, zoom
     * 'Fit'
     * 'FitH' top
     * 'FitV' left
     * 'FitR' left,bottom,right
     * 'FitB'
     * 'FitBH' top
     * 'FitBV' left
     * @param array $options
     */
    function set_default_view($view, $options = []);

    /**
     * @param string $code
     */
    function javascript($code);

    /**
     * Starts a new page
     *
     * Subsequent drawing operations will appear on the new page.
     */
    function new_page();

    /**
     * Streams the PDF to the client.
     *
     * @param string $filename The filename to present to the client.
     * @param array  $options  Associative array: 'compress' => 1 or 0 (default 1); 'Attachment' => 1 or 0 (default 1).
     */
    function stream($filename, $options = []);

    /**
     * Returns the PDF as a string.
     *
     * @param array $options Associative array: 'compress' => 1 or 0 (default 1).
     *
     * @return string
     */
    function output($options = []);
}