Fixes #63458: Restore stable mouse wheel logic

src/vs/base/browser/mouseEvent.ts

@@ -3,7 +3,9 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
+import * as browser from 'vs/base/browser/browser';
 import { IframeUtils } from 'vs/base/browser/iframe';
+import * as platform from 'vs/base/common/platform';
 
 export interface IMouseEvent {
 	readonly browserEvent: MouseEvent;
@@ -111,14 +113,30 @@ export class DragMouseEvent extends StandardMouseEvent {
 
 }
 
+export interface IMouseWheelEvent extends MouseEvent {
+	readonly wheelDelta: number;
+}
+
+interface IWebKitMouseWheelEvent {
+	wheelDeltaY: number;
+	wheelDeltaX: number;
+}
+
+interface IGeckoMouseWheelEvent {
+	HORIZONTAL_AXIS: number;
+	VERTICAL_AXIS: number;
+	axis: number;
+	detail: number;
+}
+
 export class StandardWheelEvent {
 
-	public readonly browserEvent: WheelEvent | null;
+	public readonly browserEvent: IMouseWheelEvent | null;
 	public readonly deltaY: number;
 	public readonly deltaX: number;
 	public readonly target: Node;
 
-	constructor(e: WheelEvent | null, deltaX: number = 0, deltaY: number = 0) {
+	constructor(e: IMouseWheelEvent | null, deltaX: number = 0, deltaY: number = 0) {
 
 		this.browserEvent = e || null;
 		this.target = e ? (e.target || (<any>e).targetNode || e.srcElement) : null;
@@ -127,12 +145,30 @@ export class StandardWheelEvent {
 		this.deltaX = deltaX;
 
 		if (e) {
-			if (e.deltaMode === e.DOM_DELTA_LINE) {
-				this.deltaX = -e.deltaX / 3;
-				this.deltaY = -e.deltaY / 3;
-			} else if (e.deltaMode === e.DOM_DELTA_PIXEL) {
-				this.deltaX = -e.deltaX / 40;
-				this.deltaY = -e.deltaY / 40;
+			let e1 = <IWebKitMouseWheelEvent><any>e;
+			let e2 = <IGeckoMouseWheelEvent><any>e;
+
+			// vertical delta scroll
+			if (typeof e1.wheelDeltaY !== 'undefined') {
+				this.deltaY = e1.wheelDeltaY / 120;
+			} else if (typeof e2.VERTICAL_AXIS !== 'undefined' && e2.axis === e2.VERTICAL_AXIS) {
+				this.deltaY = -e2.detail / 3;
+			}
+
+			// horizontal delta scroll
+			if (typeof e1.wheelDeltaX !== 'undefined') {
+				if (browser.isSafari && platform.isWindows) {
+					this.deltaX = - (e1.wheelDeltaX / 120);
+				} else {
+					this.deltaX = e1.wheelDeltaX / 120;
+				}
+			} else if (typeof e2.HORIZONTAL_AXIS !== 'undefined' && e2.axis === e2.HORIZONTAL_AXIS) {
+				this.deltaX = -e.detail / 3;
+			}
+
+			// Assume a vertical scroll if nothing else worked
+			if (this.deltaY === 0 && this.deltaX === 0 && e.wheelDelta) {
+				this.deltaY = e.wheelDelta / 120;
 			}
 		}
 	}
@@ -152,4 +188,4 @@ export class StandardWheelEvent {
 			}
 		}
 	}
-}
+}
\ No newline at end of file

src/vs/base/browser/ui/scrollbar/scrollableElement.ts

@@ -6,7 +6,7 @@
 import 'vs/css!./media/scrollbars';
 import * as dom from 'vs/base/browser/dom';
 import { FastDomNode, createFastDomNode } from 'vs/base/browser/fastDomNode';
-import { IMouseEvent, StandardWheelEvent } from 'vs/base/browser/mouseEvent';
+import { IMouseEvent, StandardWheelEvent, IMouseWheelEvent } from 'vs/base/browser/mouseEvent';
 import { ScrollbarHost } from 'vs/base/browser/ui/scrollbar/abstractScrollbar';
 import { HorizontalScrollbar } from 'vs/base/browser/ui/scrollbar/horizontalScrollbar';
 import { ScrollableElementChangeOptions, ScrollableElementCreationOptions, ScrollableElementResolvedOptions } from 'vs/base/browser/ui/scrollbar/scrollableElementOptions';
@@ -307,11 +307,11 @@ export abstract class AbstractScrollableElement extends Widget {
 
 		// Start listening (if necessary)
 		if (shouldListen) {
-			let onMouseWheel = (browserEvent: WheelEvent) => {
+			let onMouseWheel = (browserEvent: IMouseWheelEvent) => {
 				this._onMouseWheel(new StandardWheelEvent(browserEvent));
 			};
 
-			this._mouseWheelToDispose.push(dom.addDisposableListener(this._listenOnDomNode, 'wheel', onMouseWheel));
+			this._mouseWheelToDispose.push(dom.addDisposableListener(this._listenOnDomNode, 'mousewheel', onMouseWheel));
 		}
 	}
 

src/vs/editor/browser/controller/mouseHandler.ts

@@ -5,7 +5,7 @@
 
 import * as browser from 'vs/base/browser/browser';
 import * as dom from 'vs/base/browser/dom';
-import { StandardWheelEvent } from 'vs/base/browser/mouseEvent';
+import { StandardWheelEvent, IMouseWheelEvent } from 'vs/base/browser/mouseEvent';
 import { RunOnceScheduler, TimeoutTimer } from 'vs/base/common/async';
 import { Disposable } from 'vs/base/common/lifecycle';
 import * as platform from 'vs/base/common/platform';
@@ -108,7 +108,7 @@ export class MouseHandler extends ViewEventHandler {
 
 		this._register(mouseEvents.onMouseDown(this.viewHelper.viewDomNode, (e) => this._onMouseDown(e)));
 
-		let onMouseWheel = (browserEvent: WheelEvent) => {
+		let onMouseWheel = (browserEvent: IMouseWheelEvent) => {
 			if (!this._context.configuration.editor.viewInfo.mouseWheelZoom) {
 				return;
 			}
@@ -121,7 +121,7 @@ export class MouseHandler extends ViewEventHandler {
 				e.stopPropagation();
 			}
 		};
-		this._register(dom.addDisposableListener(this.viewHelper.viewDomNode, 'wheel', onMouseWheel, true));
+		this._register(dom.addDisposableListener(this.viewHelper.viewDomNode, 'mousewheel', onMouseWheel, true));
 
 		this._context.addEventHandler(this);
 	}