From effd98be7ebaa1f6f0d2c5b524c96ed6e0839a32 Mon Sep 17 00:00:00 2001
From: Derk-Jan Hartman <hartman.wiki@gmail.com>
Date: Tue, 8 Apr 2014 11:55:03 +0200
Subject: [PATCH] Preserve textarea state when building WikiEditor UI

When we are wrapping the textarea in the Editor UI, the focus state,
cursor position and the scrollposition might get lost. This is
especially annoying on slower machines, where users might have started
using the textarea before the WikiEditor UI was constructed.

Bug: 41911
Change-Id: Ie472c6c88d98f7ba89873a2db73463ef01bd995a
---
 modules/jquery.wikiEditor.js | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/modules/jquery.wikiEditor.js b/modules/jquery.wikiEditor.js
index c414e192..0b874098 100644
--- a/modules/jquery.wikiEditor.js
+++ b/modules/jquery.wikiEditor.js
@@ -486,6 +486,9 @@ if ( !context || typeof context === 'undefined' ) {
 		.append( $( '<span>' + mediaWiki.msg( 'wikieditor-loading' ) + '</span>' )
 			.css( 'marginTop', context.$textarea.height() / 2 ) );
 	*/
+	/* Preserving cursor and focus state, which will get lost due to wrapAll */
+	var hasFocus = context.$textarea.is( ':focus' ),
+		cursorPos = context.$textarea.textSelection( 'getCaretPosition', { startAndEnd: true } );
 	// Encapsulate the textarea with some containers for layout
 	context.$textarea
 	/* Disabling our loading div for now
@@ -497,6 +500,14 @@ if ( !context || typeof context === 'undefined' ) {
 		.wrapAll( $( '<div>' ).addClass( 'wikiEditor-ui-left' ) )
 		.wrapAll( $( '<div>' ).addClass( 'wikiEditor-ui-bottom' ) )
 		.wrapAll( $( '<div>' ).addClass( 'wikiEditor-ui-text' ) );
+	// Restore scroll position after this wrapAll (tracked by mediawiki.action.edit)
+	context.$textarea.prop( 'scrollTop', $( '#wpScrolltop' ).val() );
+	// Restore focus and cursor if needed
+	if ( hasFocus ) {
+		context.$textarea.focus();
+		context.$textarea.textSelection( 'setSelection', { start: cursorPos[0], end: cursorPos[1] } );
+	}
+
 	// Get references to some of the newly created containers
 	context.$ui = context.$textarea.parent().parent().parent().parent().parent();
 	context.$wikitext = context.$textarea.parent().parent().parent().parent();