get_avatar( mixed $id_or_email, int $size = 96, string $default = '', string $alt = '', array $args = null )

function get_avatar( $id_or_email, $size = 96, $default = '', $alt = '', $args = null ) {
	$defaults = array(
		// get_avatar_data() args.
		'size'          => 96,
		'height'        => null,
		'width'         => null,
		'default'       => get_option( 'avatar_default', 'mystery' ),
		'force_default' => false,
		'rating'        => get_option( 'avatar_rating' ),
		'scheme'        => null,
		'alt'           => '',
		'class'         => null,
		'force_display' => false,
		'extra_attr'    => '',
	);

	if ( empty( $args ) ) {
		$args = array();
	}

	$args['size']    = (int) $size;
	$args['default'] = $default;
	$args['alt']     = $alt;

	$args = wp_parse_args( $args, $defaults );

	if ( empty( $args['height'] ) ) {
		$args['height'] = $args['size'];
	}
	if ( empty( $args['width'] ) ) {
		$args['width'] = $args['size'];
	}

	if ( is_object( $id_or_email ) && isset( $id_or_email->comment_ID ) ) {
		$id_or_email = get_comment( $id_or_email );
	}

	/**
	 * Filters whether to retrieve the avatar URL early.
	 *
	 * Passing a non-null value will effectively short-circuit get_avatar(), passing
	 * the value through the {@see 'get_avatar'} filter and returning early.
	 *
	 * @since WP-4.2.0
	 *
	 * @param string $avatar      HTML for the user's avatar. Default null.
	 * @param mixed  $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
	 *                            user email, WP_User object, WP_Post object, or WP_Comment object.
	 * @param array  $args        Arguments passed to get_avatar_url(), after processing.
	 */
	$avatar = apply_filters( 'pre_get_avatar', null, $id_or_email, $args );

	if ( ! is_null( $avatar ) ) {
		/** This filter is documented in wp-includes/pluggable.php */
		return apply_filters( 'get_avatar', $avatar, $id_or_email, $args['size'], $args['default'], $args['alt'], $args );
	}

	if ( ! $args['force_display'] && ! get_option( 'show_avatars' ) ) {
		return false;
	}

	$url2x = get_avatar_url( $id_or_email, array_merge( $args, array( 'size' => $args['size'] * 2 ) ) );

	$args = get_avatar_data( $id_or_email, $args );

	$url = $args['url'];

	if ( ! $url || is_wp_error( $url ) ) {
		return false;
	}

	$class = array( 'avatar', 'avatar-' . (int) $args['size'], 'photo' );

	if ( ! $args['found_avatar'] || $args['force_default'] ) {
		$class[] = 'avatar-default';
	}

	if ( $args['class'] ) {
		if ( is_array( $args['class'] ) ) {
			$class = array_merge( $class, $args['class'] );
		} else {
			$class[] = $args['class'];
		}
	}

	$avatar = sprintf(
		"<img alt='%s' src='%s' srcset='%s' class='%s' height='%d' width='%d' %s/>",
		esc_attr( $args['alt'] ),
		esc_url( $url ),
		esc_url( $url2x ) . ' 2x',
		esc_attr( join( ' ', $class ) ),
		(int) $args['height'],
		(int) $args['width'],
		$args['extra_attr']
	);

	/**
	 * Filters the avatar to retrieve.
	 *
	 * @since WP-2.5.0
	 * @since WP-4.2.0 The `$args` parameter was added.
	 *
	 * @param string $avatar      &lt;img&gt; tag for the user's avatar.
	 * @param mixed  $id_or_email The Gravatar to retrieve. Accepts a user_id, gravatar md5 hash,
	 *                            user email, WP_User object, WP_Post object, or WP_Comment object.
	 * @param int    $size        Square avatar width and height in pixels to retrieve.
	 * @param string $default     URL for the default image or a default type. Accepts '404', 'retro', 'monsterid',
	 *                            'wavatar', 'indenticon','mystery' (or 'mm', or 'mysteryman'), 'blank', or 'gravatar_default'.
	 *                            Default is the value of the 'avatar_default' option, with a fallback of 'mystery'.
	 * @param string $alt         Alternative text to use in the avatar image tag. Default empty.
	 * @param array  $args        Arguments passed to get_avatar_data(), after processing.
	 */
	return apply_filters( 'get_avatar', $avatar, $id_or_email, $args['size'], $args['default'], $args['alt'], $args );
}