add filters for backstretch settings

includes/class-displayfeaturedimagegenesis-output.php

@@ -121,10 +121,22 @@ class Display_Featured_Image_Genesis_Output {
 		$displaysetting = get_option( 'displayfeaturedimagegenesis' );
 		$keep_titles    = $displaysetting['keep_titles'];
 
-		wp_localize_script( 'displayfeaturedimage-backstretch-set', 'BackStretchVars', array(
+		// backstretch settings from plugin/featured image settings
+		$backstretch_settings = array(
 			'src'    => esc_url( $item->backstretch[0] ),
 			'height' => esc_attr( $item->reduce ),
-		) );
+		);
+		// backstretch settings which can be filtered
+		$backstretch_variables = array(
+			'centeredX' => true,
+			'centeredY' => true,
+			'fade'      => 750,
+		);
+
+		$backstretch_variables = apply_filters( 'display_featured_image_genesis_backstretch_variables', $backstretch_variables );
+		$output = array_merge( $backstretch_settings, $backstretch_variables );
+
+		wp_localize_script( 'displayfeaturedimage-backstretch-set', 'BackStretchVars', $output );
 
 		if ( ! $keep_titles ) {
 			if ( is_singular() && ! is_front_page() && ! is_page_template( 'page_blog.php' ) ) {

includes/js/backstretch-set.js

@@ -2,6 +2,12 @@
 	'use strict';
 
 	$( '.big-leader' ).css( { 'height': ( $(window).height() ) - ([BackStretchVars.height]) + 'px' });
-	$( '.big-leader' ).backstretch( [BackStretchVars.src], { 'fade':750 } );
+	$( '.big-leader' ).backstretch(
+		[BackStretchVars.src], {
+			centeredX: BackStretchVars.centeredX,
+			centeredY: BackStretchVars.centeredY,
+			fade: BackStretchVars.fade
+		}
+	);
 
 })( this, jQuery );