themes-wordpress/ixion/inc/customizer.php

<?php
/**
 * Ixion Theme Customizer.
 *
 * @package Ixion
 */

/**
 * Add postMessage support for site title and description for the Theme Customizer.
 *
 * @param WP_Customize_Manager $wp_customize Theme Customizer object.
 */
function ixion_customize_register( $wp_customize ) {
	$wp_customize->get_setting( 'blogname' )->transport		 = 'postMessage';
	$wp_customize->get_setting( 'blogdescription' )->transport  = 'postMessage';
	$wp_customize->get_setting( 'header_textcolor' )->transport = 'postMessage';

	/**
	 * Add the Theme Options section
	 */
	$wp_customize->add_section( 'ixion_theme_options', array(
		'title' => esc_html__( 'Theme Options', 'ixion' ),
		'description' => esc_html( 'Customize your front page with these options.', 'ixion' ),
	) );

	$wp_customize->add_setting( 'ixion_button_text', array(
		'default'           => '',
		'sanitize_callback' => 'sanitize_text_field',
		'transport'         => 'postMessage',
	) );

	$wp_customize->add_control( 'ixion_button_text', array(
		'label'   => esc_html__( 'Call-to-Action Button Text', 'ixion' ),
		'section' => 'ixion_theme_options',
		'type'    => 'text',
	) );

	$wp_customize->add_setting( 'ixion_button_link', array(
		'default'           => '',
		'sanitize_callback' => 'esc_url_raw',
	) );

	$wp_customize->add_control( 'ixion_button_link', array(
		'label'   => esc_html__( 'Call-to-Action Button URL', 'ixion' ),
		'section' => 'ixion_theme_options',
		'type'    => 'text',
	) );

	$wp_customize->add_setting( 'ixion_header_overlay_opacity', array(
		'default'           => 'dark',
		'sanitize_callback' => 'ixion_sanitize_opacity',
		'transport'         => 'postMessage',
	) );

	$wp_customize->add_control( 'ixion_header_overlay_opacity', array(
		'label'       => esc_html__( 'Header Image Overlay', 'ixion' ),
		'section'     => 'ixion_theme_options',
		'type'        => 'select',
		'description' => esc_html( 'Adjust the darkness of the overlay over the header image.', 'ixion' ),
		'choices'     => array(
			'none'    => esc_html__( 'None', 'ixion' ),
			'light'   => esc_html__( 'Light', 'ixion' ),
			'medium'  => esc_html__( 'Medium', 'ixion' ),
			'dark'    => esc_html__( 'Dark', 'ixion' ), /* 0.7 */
		),
	) );

	$wp_customize->add_setting( 'ixion_featured_overlay_opacity', array(
		'default'           => 'medium',
		'sanitize_callback' => 'ixion_sanitize_opacity',
		'transport'         => 'postMessage',
	) );

	$wp_customize->add_control( 'ixion_featured_overlay_opacity', array(
		'label'       => esc_html__( 'Featured Content Image Overlay', 'ixion' ),
		'section'     => 'ixion_theme_options',
		'type'        => 'select',
		'description' => esc_html( 'Adjust the darkness of the overlay over the featured content images.', 'ixion' ),
		/* Technically this one changes the opacity of the image, not the overlay, but let's not complicate things. */
		'choices'     => array(
			'none'    => esc_html__( 'None', 'ixion' ),
			'light'   => esc_html__( 'Light', 'ixion' ),
			'medium'  => esc_html__( 'Medium', 'ixion' ), /* 0.4 */
			'dark'    => esc_html__( 'Dark', 'ixion' ),
		),
	) );
}
add_action( 'customize_register', 'ixion_customize_register' );


/*
 * Sanitize our opacity values
 */
function ixion_sanitize_opacity( $input ) {

	$choices = array( 'none', 'light', 'medium', 'dark' );

	if ( ! in_array( $input, $choices ) ) {
		$input = 'dark';
	}

	return $input;
}

/**
 * Binds JS handlers to make Theme Customizer preview reload changes asynchronously.
 */
function ixion_customize_preview_js() {
	wp_enqueue_script( 'ixion-customizer', get_template_directory_uri() . '/assets/js/customizer.js', array( 'customize-preview' ), '20151215', true );
}
add_action( 'customize_preview_init', 'ixion_customize_preview_js' );