From 13473c9f7ac70d4126f967924ad8920a7dbc511d Mon Sep 17 00:00:00 2001
From: "Amir E. Aharoni" <amir.aharoni@mail.huji.ac.il>
Date: Thu, 3 Jan 2013 09:33:44 +0200
Subject: [PATCH] Render every region only once

Fixes bug
https://bugzilla.wikimedia.org/show_bug.cgi?id=43568
---
 src/jquery.uls.lcd.js          |  7 ++++---
 src/jquery.uls.regionfilter.js | 21 +++++++++++----------
 2 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/src/jquery.uls.lcd.js b/src/jquery.uls.lcd.js
index eff660e..b6f2e15 100644
--- a/src/jquery.uls.lcd.js
+++ b/src/jquery.uls.lcd.js
@@ -268,7 +268,8 @@
 
 			// The region section need to be in sync with the map filter.
 			lcd.$element.scroll( function () {
-				var $ulsLanguageList = $( this ),
+				var inview, inviewRegion,
+					$ulsLanguageList = $( this ),
 					scrollTop = $ulsLanguageList.position().top,
 					scrollBottom = $ulsLanguageList.height();
 
@@ -278,7 +279,7 @@
 					}
 				}
 				// The region section need to be in sync with the map filter.
-				var inviewRegion = 'WW';
+				inviewRegion = 'WW';
 				lcd.$element.find( 'div.uls-lcd-region-section' ).each( function () {
 					var $lcdRegionSection = $( this ),
 						top = $lcdRegionSection.position().top,
@@ -292,7 +293,7 @@
 					}
 				} );
 
-				var inview = $.uls.data.regiongroups[inviewRegion];
+				inview = $.uls.data.regiongroups[inviewRegion];
 				$( '.regionselector' ).removeClass( 'active' );
 				$( '#uls-region-' + inview ).addClass( 'active' );
 			} );
diff --git a/src/jquery.uls.regionfilter.js b/src/jquery.uls.regionfilter.js
index b245f69..b0c8732 100644
--- a/src/jquery.uls.regionfilter.js
+++ b/src/jquery.uls.regionfilter.js
@@ -110,21 +110,22 @@
 		},
 
 		next: function () {
-			if ( !this.$element.hasClass( 'active') ) {
+			var regionSelector = this;
+
+			if ( !this.$element.hasClass( 'active' ) ) {
 				return true;
 			}
 
-			var regionSelector = this;
 			// Do not respond to all scroll end events, but only after a short interval
 			delay( function () {
-				var regiongroup = regionSelector.$element.data( 'regiongroup' );
-				var nextRegiongroup = regiongroup + 1;
+				var nextRegionGroupNumber = regionSelector.$element.data( 'regiongroup' ) + 1,
+					$nextRegion = $( '#uls-region-' + nextRegionGroupNumber ),
+					nextRegionSelector = $nextRegion.length && $nextRegion.data( 'regionselector' );
 
-				var $nextRegion = $( '#uls-region-' + nextRegiongroup );
-				var next = $nextRegion.length && $nextRegion.data( 'regionselector' );
-
-				if ( next ) {
-					next.show();
+				// If cache is defined, then it is already rendered and there's no need
+				// to re-render it.
+				if ( nextRegionSelector && nextRegionSelector.cache === null ) {
+					nextRegionSelector.show();
 				}
 			}, 100 );
 
@@ -133,7 +134,7 @@
 
 		listen: function () {
 			this.$element.on( 'click', $.proxy( this.click, this ) );
-			this.options.$target.$element.bind( 'scrollend', $.proxy( this.next, this) );
+			this.options.$target.$element.bind( 'scrollend', $.proxy( this.next, this ) );
 		},
 
 		click: function ( e ) {