From 32cbb35eacdb9ffa4d4b943ccf806ed0a3e15f51 Mon Sep 17 00:00:00 2001
From: Alex Dima <alexdima@microsoft.com>
Date: Wed, 18 Nov 2015 14:56:33 +0100
Subject: [PATCH] Delay handling of mouse events until view has finished
 painting

---
 .../editor/browser/controller/mouseHandler.ts | 68 +++++++++++++++++--
 src/vs/editor/browser/editorBrowser.ts        |  1 +
 src/vs/editor/browser/view/viewImpl.ts        |  4 ++
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/src/vs/editor/browser/controller/mouseHandler.ts b/src/vs/editor/browser/controller/mouseHandler.ts
index 05d7ac9974f..0d7b9cd622b 100644
--- a/src/vs/editor/browser/controller/mouseHandler.ts
+++ b/src/vs/editor/browser/controller/mouseHandler.ts
@@ -35,6 +35,56 @@ function createMouseMoveEventMerger(mouseTargetFactory:MouseTarget.MouseTargetFa
 	};
 }
 
+class EventGateKeeper<T> {
+
+	public handler: (value:T)=>void;
+
+	private _destination: (value:T)=>void;
+	private _condition: ()=>boolean;
+
+	private _retryTimer: number;
+	private _retryValue: T;
+
+	constructor(destination:(value:T)=>void, condition:()=>boolean) {
+		this._destination = destination;
+		this._condition = condition;
+		this._retryTimer = -1;
+		this.handler = (value:T) => this._handle(value);
+	}
+
+	public dispose(): void {
+		if (this._retryTimer !== -1) {
+			clearTimeout(this._retryTimer);
+			this._retryTimer = -1;
+			this._retryValue = null;
+		}
+	}
+
+	private _handle(value:T): void {
+		if (this._condition()) {
+
+			if (this._retryTimer !== -1) {
+				clearTimeout(this._retryTimer);
+				this._retryTimer = -1;
+				this._retryValue = null;
+			}
+
+			this._destination(value);
+
+		} else {
+			this._retryValue = value;
+			if (this._retryTimer === -1) {
+				this._retryTimer = setTimeout(() => {
+					this._retryTimer = -1;
+					let tmp = this._retryValue;
+					this._retryValue = null;
+					this._handle(tmp);
+				}, 10);
+			}
+		}
+	}
+}
+
 export class MouseHandler extends ViewEventHandler implements Lifecycle.IDisposable {
 
 	static CLEAR_MOUSE_DOWN_COUNT_TIME = 400; // ms
@@ -64,6 +114,9 @@ export class MouseHandler extends ViewEventHandler implements Lifecycle.IDisposa
 
 	private lastMouseLeaveTime:number;
 
+	private _mouseMoveEventHandler: EventGateKeeper<Mouse.StandardMouseEvent>;
+	private _mouseDownThenMoveEventHandler: EventGateKeeper<Mouse.StandardMouseEvent>;
+
 	constructor(context:EditorBrowser.IViewContext, viewController:EditorBrowser.IViewController, viewHelper:EditorBrowser.IPointerHandlerHelper) {
 		super();
 
@@ -95,10 +148,15 @@ export class MouseHandler extends ViewEventHandler implements Lifecycle.IDisposa
 		this.listenersToRemove.push(DomUtils.addListener(this.viewHelper.viewDomNode, 'contextmenu',
 			(e: MouseEvent) => this._onContextMenu(e)));
 
+		this._mouseMoveEventHandler = new EventGateKeeper<Mouse.StandardMouseEvent>((e) => this._onMouseMove(e), () => !this.viewHelper.isDirty());
+		this.toDispose.push(this._mouseMoveEventHandler);
 		this.listenersToRemove.push(DomUtils.addThrottledListener(this.viewHelper.viewDomNode, 'mousemove',
-			(e: Mouse.StandardMouseEvent) => this._onMouseMove(e),
+			this._mouseMoveEventHandler.handler,
 			createMouseMoveEventMerger(this.mouseTargetFactory), MouseHandler.MOUSE_MOVE_MINIMUM_TIME));
 
+		this._mouseDownThenMoveEventHandler = new EventGateKeeper<Mouse.StandardMouseEvent>((e) => this._onMouseDownThenMove(e), () => !this.viewHelper.isDirty());
+		this.toDispose.push(this._mouseDownThenMoveEventHandler);
+
 		this.listenersToRemove.push(DomUtils.addListener(this.viewHelper.viewDomNode, 'mouseup',
 			(e: MouseEvent) => this._onMouseUp(e)));
 
@@ -267,15 +325,17 @@ export class MouseHandler extends ViewEventHandler implements Lifecycle.IDisposa
 
 		this.mouseMoveMonitor.startMonitoring(
 			createMouseMoveEventMerger(null),
-			(e:Mouse.StandardMouseEvent) => {
-				this._updateMouse(this.monitoringStartTargetType, e, true);
-			},
+			this._mouseDownThenMoveEventHandler.handler,
 			() => {
 				this._unhook();
 			}
 		);
 	}
 
+	private _onMouseDownThenMove(e:Mouse.StandardMouseEvent): void {
+		this._updateMouse(this.monitoringStartTargetType, e, true);
+	}
+
 	private _unhook(): void {
 		if (this.onScrollTimeout !== -1) {
 			window.clearTimeout(this.onScrollTimeout);
diff --git a/src/vs/editor/browser/editorBrowser.ts b/src/vs/editor/browser/editorBrowser.ts
index 80f19d33738..ff27c0893ba 100644
--- a/src/vs/editor/browser/editorBrowser.ts
+++ b/src/vs/editor/browser/editorBrowser.ts
@@ -52,6 +52,7 @@ export interface IPointerHandlerHelper {
 	linesContentDomNode:HTMLElement;
 
 	focusTextArea(): void;
+	isDirty(): boolean;
 
 	getScrollTop(): number;
 	setScrollTop(scrollTop:number): void;
diff --git a/src/vs/editor/browser/view/viewImpl.ts b/src/vs/editor/browser/view/viewImpl.ts
index 77b9527a3b4..a90f06c2e9d 100644
--- a/src/vs/editor/browser/view/viewImpl.ts
+++ b/src/vs/editor/browser/view/viewImpl.ts
@@ -292,6 +292,10 @@ export class View extends ViewEventHandler implements EditorBrowser.IView, Lifec
 				this.focus();
 			},
 
+			isDirty: (): boolean => {
+				return (this.accumulatedModelEvents.length > 0);
+			},
+
 			getScrollTop: () => {
 				if (this._isDisposed) {
 					throw new Error('ViewImpl.pointerHandler.getScrollTop: View is disposed');