Add Per Soderlind's WCAG validator.

app/admin.php

@@ -136,3 +136,18 @@ add_action('customize_preview_init', function () {
     wp_enqueue_script('aldine/customizer.js', asset_path('scripts/customizer.js'), ['customize-preview'], null, true);
     wp_localize_script('aldine/customizer.js', 'SAGE_DIST_PATH', get_theme_file_uri() . '/dist/');
 });
+
+add_action('customize_controls_enqueue_scripts', function () {
+    $handle = 'wcag-validate-customizer-color-contrast';
+    $src = get_theme_file_uri() . '/lib/customizer-validate-wcag-color-contrast/customizer-validate-wcag-color-contrast.js';
+    $deps = [ 'customize-controls' ];
+    wp_enqueue_script($handle, $src, $deps);
+
+    $exports = [
+        'validate_color_contrast' => [
+            'pb_network_color_primary_fg' => [ 'pb_network_color_primary' ],
+            'pb_network_color_accent_fg' => [ 'pb_network_color_accent' ],
+        ],
+    ];
+    wp_scripts()->add_data($handle, 'data', sprintf('var _validateWCAGColorContrastExports = %s;', wp_json_encode($exports)));
+});

lib/customizer-validate-wcag-color-contrast/README.md

@@ -0,0 +1,59 @@
+# Validate WCAG Color Contrast for Customizer Color Control
+
+The validator measures the color contrast between 2 or more color controls. It will post a warning if the contrast is less than 4.5
+
+BTW, if the contrast >= 7,  the score is a WCAG AAA. If the contrast is between 7 and 4.5 the score is a WCAG AA.
+
+<img src="assets/wcag-color-contrast.gif" width="650" />
+
+## Demo
+
+I've added this validator to my [customizer demo theme](https://github.com/soderlind/2016-customizer-demo).
+
+## Installing the validator
+
+Clone this repository and include the [javascript code](customizer-validate-wcag-color-contrast.js):
+
+```php
+/**
+ * Enqueue customizer control scripts.
+ */
+add_action( 'customize_controls_enqueue_scripts', 'on_customize_controls_enqueue_scripts' );
+
+function on_customize_controls_enqueue_scripts() {
+	$handle = 'wcag-validate-customizer-color-contrast';
+	$src    = get_stylesheet_directory_uri() . '/js/customizer-validate-wcag-color-contrast.js';
+	$deps   = [ 'customize-controls' ];
+	wp_enqueue_script( $handle, $src, $deps );
+
+	$exports = [
+		'validate_color_contrast' => [
+			// key = current color control , values = array with color controls to check color contrast against
+			'page_background_color' => [ 'main_text_color', 'secondary_text_color' ],
+			'main_text_color'       => [ 'page_background_color' ],
+			'secondary_text_color'  => [ 'page_background_color' ],
+		],
+	];
+	wp_scripts()->add_data( $handle, 'data', sprintf( 'var _validateWCAGColorContrastExports = %s;', wp_json_encode( $exports ) ) );
+}
+```
+
+**Note:** You have to add color control setting ids to the `validate_color_contrast` above. See inline comment.
+
+## Credits ##
+
+- [WCAG contrast ratio measurement and scoring](https://github.com/tmcw/wcag-contrast) - Copyright (c) 2017, Tom MacWright. All rights reserved.
+- [hex-rgb](https://github.com/sindresorhus/hex-rgb) - Copyright (c) Sindre Sorhus
+- [relative-luminance](https://github.com/tmcw/relative-luminance)
+
+
+
+## Copyright and License
+
+The Validate WCAG Color Contrast for Customizer Color Control is copyright 2017 Per Soderlind
+
+The Validate WCAG Color Contrast for Customizer Color Control is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.
+
+The Validate WCAG Color Contrast for Customizer Color Control is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along with the Extension. If not, see http://www.gnu.org/licenses/.

lib/customizer-validate-wcag-color-contrast/customizer-validate-wcag-color-contrast.js

@@ -0,0 +1,210 @@
+/* global wp, _validateWCAGColorContrastExports */
+/* exported validateWCAGColorContrast */
+var validateWCAGColorContrast = ( function( $, api, exports ) {
+	var self = {
+		validate_color_contrast: []
+	};
+	if ( exports ) {
+		$.extend( self, exports );
+	}
+	/**
+	 * Add contrast validation to a control if it is entitled (is a valid color control).
+	 *
+	 * @param {wp.customize.Control} setting                   - Control.
+	 * @param {wp.customize.Value}   setting.validationMessage - Validation message.
+	 * @return {boolean} Whether validation was added.
+	 */
+	self.addWCAGColorContrastValidation = function( setting ) {
+		var initialValidate;
+
+		if ( ! self.isColorControl( setting ) ) {
+			return false;
+		}
+		initialValidate = setting.validate;
+
+		/**
+		 * Wrap the setting's validate() method to do validation on the value to be sent to the server.
+		 *
+		 * @param {mixed} value   - New value being assigned to the setting.
+		 * @returns {*}
+		 */
+		setting.validate = function( value ) {
+			var setting       = this, title, validationError;
+			var current_color = value;
+			var current_id    = this.id;
+
+			var all_color_controls = _.union( _.flatten( _.values( self.validate_color_contrast  ) ) );
+
+			// remove other (old) notifications
+			_.each ( _.without ( all_color_controls , current_id ), function( other_color_control_id ) {
+				 var other_control = api.control.instance( other_color_control_id );
+				 notice            = other_control.container.find('.notice');
+				 notice.hide();
+			} );
+
+			// find other color controls and check contrast with current color control
+			var other_color_controls =  self.validate_color_contrast[ current_id ];
+
+			_.each ( other_color_controls, function( other_color_control_id ) {
+				var other_control = api.control.instance( other_color_control_id);
+				var other_color   = other_control.container.find('.color-picker-hex').val();
+				var name          = $( '#customize-control-' + other_color_control_id + ' .customize-control-title').text();
+				var contrast      = self.hex( current_color, other_color );
+				var score         = self.score( contrast );
+
+				// contrast >= 7 ? "AAA" : contrast >= 4.5 ? "AA" : ""
+				if ( contrast <  4.5 ) {
+					setting.notifications.remove( other_color_control_id );
+					validationWarning = new api.Notification( other_color_control_id, { message: self.sprintf( 'WCAG conflict with "%s"<br/>contrast: %s' ,name, contrast), type: 'warning' } );
+					setting.notifications.add( validationWarning.code, validationWarning );
+					// console.log(  color_control_id + ' ' + color + ' ' + contrast + ' ' + score );
+				} else {
+					setting.notifications.remove( other_color_control_id );
+				}
+			} );
+
+			return value;
+		};
+
+		return true;
+	};
+
+	/**
+	 * Return whether the setting is entitled (i.e. if it is a title or has a title).
+	 *
+	 * @param {wp.customize.Setting} setting - Setting.
+	 * @returns {boolean}
+	 */
+	self.isColorControl = function( setting ) {
+		 return _.findKey( self.validate_color_contrast, function( key, value ) {
+			return value == setting.id;
+		} );
+	};
+
+	api.bind( 'add', function( setting ) {
+		self.addWCAGColorContrastValidation( setting );
+	} );
+
+
+	self.sprintf = function( format ) {
+		for( var i=1; i < arguments.length; i++ ) {
+			format = format.replace( /%s/, arguments[i] );
+		}
+		return format;
+	};
+
+	/**
+	 * Methods used to calculate WCAG Color Contrast
+	 */
+
+	// from https://github.com/sindresorhus/hex-rgb
+	self.hexRgb = function (hex) {
+		if (typeof hex !== 'string') {
+			throw new TypeError('Expected a string');
+		}
+
+		hex = hex.replace(/^#/, '');
+
+		if (hex.length === 3) {
+			hex = hex[0] + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
+		}
+
+		var num = parseInt(hex, 16);
+
+		return [num >> 16, num >> 8 & 255, num & 255];
+	};
+
+	// from https://github.com/tmcw/relative-luminance
+	// # Relative luminance
+	//
+	// http://www.w3.org/TR/2008/REC-WCAG20-20081211/#relativeluminancedef
+	// https://en.wikipedia.org/wiki/Luminance_(relative)
+	// https://en.wikipedia.org/wiki/Luminosity_function
+	// https://en.wikipedia.org/wiki/Rec._709#Luma_coefficients
+
+	// red, green, and blue coefficients
+	var rc = 0.2126,
+	  gc = 0.7152,
+	  bc = 0.0722,
+	  // low-gamma adjust coefficient
+	  lowc = 1 / 12.92;
+
+	self.adjustGamma = function( g ) {
+	  return Math.pow((g + 0.055) / 1.055, 2.4);
+	};
+
+	/**
+	 * Given a 3-element array of R, G, B varying from 0 to 255, return the luminance
+	 * as a number from 0 to 1.
+	 * @param {Array<number>} rgb 3-element array of a color
+	 * @returns {number} luminance, between 0 and 1
+	 * @example
+	 * var luminance = require('relative-luminance');
+	 * var black_lum = luminance([0, 0, 0]); // 0
+	 */
+	self.relativeLuminance = function (rgb) {
+	  var rsrgb = rgb[0] / 255;
+	  var gsrgb = rgb[1] / 255;
+	  var bsrgb = rgb[2] / 255;
+
+	  var r = rsrgb <= 0.03928 ? rsrgb * lowc : self.adjustGamma(rsrgb),
+	    g = gsrgb <= 0.03928 ? gsrgb * lowc : self.adjustGamma(gsrgb),
+	    b = bsrgb <= 0.03928 ? bsrgb * lowc : self.adjustGamma(bsrgb);
+
+	  return r * rc + g * gc + b * bc;
+	};
+
+
+	// from https://github.com/tmcw/wcag-contrast
+	/**
+	 * Get the contrast ratio between two relative luminance values
+	 * @param {number} a luminance value
+	 * @param {number} b luminance value
+	 * @returns {number} contrast ratio
+	 * @example
+	 * luminance(1, 1); // = 1
+	 */
+	self.luminance = function(a, b) {
+	  var l1 = Math.max(a, b);
+	  var l2 = Math.min(a, b);
+	  return (l1 + 0.05) / (l2 + 0.05);
+	};
+
+	/**
+	 * Get a score for the contrast between two colors as rgb triplets
+	 * @param {array} a
+	 * @param {array} b
+	 * @returns {number} contrast ratio
+	 * @example
+	 * rgb([0, 0, 0], [255, 255, 255]); // = 21
+	 */
+	self.rgb = function(a, b) {
+	  return self.luminance(self.relativeLuminance(a), self.relativeLuminance(b));
+	};
+
+	/**
+	 * Get a score for the contrast between two colors as hex strings
+	 * @param {string} a hex value
+	 * @param {string} b hex value
+	 * @returns {number} contrast ratio
+	 * @example
+	 * hex('#000', '#fff'); // = 21
+	 */
+	self.hex = function(a, b) {
+	  return self.rgb(self.hexRgb(a), self.hexRgb(b));
+	};
+
+	/**
+	 * Get a textual score from a numeric contrast value
+	 * @param {number} contrast
+	 * @returns {string} score
+	 * @example
+	 * score(10); // = 'AAA'
+	 */
+	self.score = function(contrast) {
+	  return contrast >= 7 ? "AAA" : contrast >= 4.5 ? "AA" : "";
+	};
+
+	return self;
+
+}( jQuery, wp.customize, _validateWCAGColorContrastExports ) );