From 26ecba8de1f5205c8a8f577c4ebce687ac23be84 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Mon, 8 Sep 2025 21:03:05 -0700
Subject: [PATCH] Fix sluggish mouse problem. Now similar to trackpad

---
 src/browser/CoreBrowserTerminal.ts      | 4 ++--
 src/common/TestUtils.test.ts            | 2 +-
 src/common/services/CoreMouseService.ts | 5 +++--
 src/common/services/Services.ts         | 2 +-
 4 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/browser/CoreBrowserTerminal.ts b/src/browser/CoreBrowserTerminal.ts
index bd513573..c9349760 100644
--- a/src/browser/CoreBrowserTerminal.ts
+++ b/src/browser/CoreBrowserTerminal.ts
@@ -646,7 +646,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           if (deltaY === 0) {
             return false;
           }
-          const lines = self.coreMouseService.consumeWhellEvent(
+          const lines = self.coreMouseService.consumeWheelEvent(
             ev as WheelEvent,
             self._renderService?.dimensions?.device?.cell?.height,
             self._coreBrowserService?.dpr
@@ -825,7 +825,7 @@ export class CoreBrowserTerminal extends CoreTerminal implements ITerminal {
           return false;
         }
 
-        const lines = self.coreMouseService.consumeWhellEvent(
+        const lines = self.coreMouseService.consumeWheelEvent(
           ev as WheelEvent,
           self._renderService?.dimensions?.device?.cell?.height,
           self._coreBrowserService?.dpr
diff --git a/src/common/TestUtils.test.ts b/src/common/TestUtils.test.ts
index b25a2182..1ee79e75 100644
--- a/src/common/TestUtils.test.ts
+++ b/src/common/TestUtils.test.ts
@@ -66,7 +66,7 @@ export class MockCoreMouseService implements ICoreMouseService {
   public explainEvents(events: CoreMouseEventType): { [event: string]: boolean } {
     throw new Error('Method not implemented.');
   }
-  public consumeWhellEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight: number, dpr: number): number {
     return 1; // Return a simple mock value
   }
 }
diff --git a/src/common/services/CoreMouseService.ts b/src/common/services/CoreMouseService.ts
index a1135a8a..7f3d5f39 100644
--- a/src/common/services/CoreMouseService.ts
+++ b/src/common/services/CoreMouseService.ts
@@ -237,7 +237,7 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
    * Processes a wheel event, accounting for partial scrolls for trackpad, mouse scrolls.
    * This prevents hyper-sensitive scrolling in alt buffer.
    */
-  public consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
+  public consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number {
     // Do nothing if it's not a vertical scroll event
     if (ev.deltaY === 0 || ev.shiftKey) {
       return 0;
@@ -251,7 +251,8 @@ export class CoreMouseService extends Disposable implements ICoreMouseService {
     const targetWheelEventPixels = cellHeight / dpr;
     let amount = 1;
     if (ev.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
-      amount /= targetWheelEventPixels + 0.0; // Prevent integer division
+      const pixelAmount = ev.deltaY;
+      amount = pixelAmount / (targetWheelEventPixels + 0.0); // Prevent integer division
       this._wheelPartialScroll += amount;
       amount = Math.floor(Math.abs(this._wheelPartialScroll)) * (this._wheelPartialScroll > 0 ? 1 : -1);
       this._wheelPartialScroll %= 1;
diff --git a/src/common/services/Services.ts b/src/common/services/Services.ts
index e7ccc241..d47c3bbc 100644
--- a/src/common/services/Services.ts
+++ b/src/common/services/Services.ts
@@ -62,7 +62,7 @@ export interface ICoreMouseService {
   /**
    * Process wheel event taking partial scroll into account.
    */
-  consumeWhellEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
+  consumeWheelEvent(ev: WheelEvent, cellHeight?: number, dpr?: number): number;
 }
 
 export const ICoreService = createDecorator<ICoreService>('CoreService');