From 2d70a8b8423847ed1fea2ab360c4ec632354f4b2 Mon Sep 17 00:00:00 2001
From: Szymon Cofalik <s.cofalik@cksource.com>
Date: Wed, 4 Oct 2017 10:18:06 +0200
Subject: [PATCH] Change: Force rendering view document after `selectionchange`
 event instead of doing this in asynchronous timeout callback.

---
 src/view/observer/focusobserver.js     | 23 ++++-------------------
 src/view/observer/selectionobserver.js | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/src/view/observer/focusobserver.js b/src/view/observer/focusobserver.js
index e2fd03fcb..ee21c503a 100644
--- a/src/view/observer/focusobserver.js
+++ b/src/view/observer/focusobserver.js
@@ -7,9 +7,8 @@
  * @module engine/view/observer/focusobserver
  */
 
-/* globals setTimeout, clearTimeout */
-
 import DomEventObserver from './domeventobserver';
+import SelectionObserver from './selectionobserver';
 
 /**
  * {@link module:engine/view/document~Document#event:focus Focus}
@@ -28,14 +27,11 @@ export default class FocusObserver extends DomEventObserver {
 		this.domEventType = [ 'focus', 'blur' ];
 		this.useCapture = true;
 
+		const selectionObserver = document.getObserver( SelectionObserver );
+
 		document.on( 'focus', () => {
 			document.isFocused = true;
-
-			// Unfortunately native `selectionchange` event is fired asynchronously.
-			// We need to wait until `SelectionObserver` handle the event and then render. Otherwise rendering will
-			// overwrite new DOM selection with selection from the view.
-			// See https://github.com/ckeditor/ckeditor5-engine/issues/795 for more details.
-			this._renderTimeoutId = setTimeout( () => document.render(), 0 );
+			selectionObserver._forceRenderAfterNextChange = true;
 		} );
 
 		document.on( 'blur', ( evt, data ) => {
@@ -48,13 +44,6 @@ export default class FocusObserver extends DomEventObserver {
 				document.render();
 			}
 		} );
-
-		/**
-		 * Identifier of the timeout currently used by focus listener to delay rendering execution.
-		 *
-		 * @private
-		 * @member {Number} #_renderTimeoutId
-		 */
 	}
 
 	onDomEvent( domEvent ) {
@@ -65,10 +54,6 @@ export default class FocusObserver extends DomEventObserver {
 	 * @inheritDoc
 	 */
 	destroy() {
-		if ( this._renderTimeoutId ) {
-			clearTimeout( this._renderTimeoutId );
-		}
-
 		super.destroy();
 	}
 }
diff --git a/src/view/observer/selectionobserver.js b/src/view/observer/selectionobserver.js
index 239db6130..3c1182b77 100644
--- a/src/view/observer/selectionobserver.js
+++ b/src/view/observer/selectionobserver.js
@@ -94,6 +94,17 @@ export default class SelectionObserver extends Observer {
 		 * @member {Number} module:engine/view/observer/selectionobserver~SelectionObserver#_loopbackCounter
 		 */
 		this._loopbackCounter = 0;
+
+		/**
+		 * Property used to force view render after the next `selectionchange` event.
+		 *
+		 * Because `selectionchange` is an asynchronous event, other parts of code may use this property to
+		 * force rendering view document after DOM selection is changed.
+		 *
+		 * @protected
+		 * @member {Boolean} module:engine/view/observer/selectionobserver~SelectionObserver#_forceRenderAfterNextChange
+		 */
+		this._forceRenderAfterNextChange = false;
 	}
 
 	/**
@@ -109,6 +120,11 @@ export default class SelectionObserver extends Observer {
 
 		this.listenTo( domDocument, 'selectionchange', () => {
 			this._handleSelectionChange( domDocument );
+
+			if ( this._forceRenderAfterNextChange ) {
+				this._forceRenderAfterNextChange = false;
+				this.document.render();
+			}
 		} );
 
 		this._documents.add( domDocument );