Add respecting OS setting for natural scroll direction

interface.d.ts

@@ -69,6 +69,7 @@ export interface IElectronAPI {
   kittycad: (access: string, args: any) => any
   listMachines: () => Promise<MachinesListing>
   getMachineApiIp: () => Promise<string | null>
+  readNaturalScrollDirection: () => Promise<boolean>
   onUpdateDownloaded: (
     callback: (value: string) => void
   ) => Electron.IpcRenderer

src/clientSideScene/CameraControls.ts

@@ -22,7 +22,12 @@ import {
   UnreliableSubscription,
 } from 'lang/std/engineConnection'
 import { EngineCommand } from 'lang/std/artifactGraph'
-import { toSync, uuidv4 } from 'lib/utils'
+import {
+  cachedNaturalScrollDirection,
+  refreshNaturalScrollDirection,
+  toSync,
+  uuidv4,
+} from 'lib/utils'
 import { deg2Rad } from 'lib/utils2d'
 import { isReducedMotion, roundOff, throttle } from 'lib/utils'
 import * as TWEEN from '@tweenjs/tween.js'
@@ -34,6 +39,9 @@ const ORTHOGRAPHIC_CAMERA_SIZE = 20
 const FRAMES_TO_ANIMATE_IN = 30
 const ORTHOGRAPHIC_MAGIC_FOV = 4
 
+// Load the setting from the OS.
+refreshNaturalScrollDirection().catch(reportRejection)
+
 const tempQuaternion = new Quaternion() // just used for maths
 
 type interactionType = 'pan' | 'rotate' | 'zoom'
@@ -522,15 +530,25 @@ export class CameraControls {
     }
   }
 
+  zoomDirection = (event: WheelEvent): 1 | -1 => {
+    if (!this.interactionGuards.zoom.scrollAllowInvertY) return 1
+    // Safari provides the updated user setting on every event, so it's more
+    // accurate than our cached value.
+    if ('webkitDirectionInvertedFromDevice' in event) {
+      return event.webkitDirectionInvertedFromDevice ? -1 : 1
+    }
+    return cachedNaturalScrollDirection ? -1 : 1
+  }
+
   onMouseWheel = (event: WheelEvent) => {
     const interaction = this.getInteractionType(event)
     if (interaction === 'none') return
     event.preventDefault()
 
-    const zoomDirection = this.interactionGuards.zoom.scrollReverseY ? -1 : 1
     if (this.syncDirection === 'engineToClient') {
       if (interaction === 'zoom') {
-        this.zoomDataFromLastFrame = event.deltaY * zoomDirection
+        const zoomDir = this.zoomDirection(event)
+        this.zoomDataFromLastFrame = event.deltaY * zoomDir
       } else {
         this.moveDataFromLastFrame = [
           'wheel',
@@ -551,8 +569,9 @@ export class CameraControls {
 
     this.handleStart()
     if (interaction === 'zoom') {
+      const zoomDir = this.zoomDirection(event)
       this.pendingZoom =
-        1 + (event.deltaY / window.devicePixelRatio) * 0.001 * zoomDirection
+        1 + (event.deltaY / window.devicePixelRatio) * 0.001 * zoomDir
     } else {
       this.isDragging = true
       this.mouseDownPosition.set(event.clientX, event.clientY)

src/lib/cameraControls.ts

@@ -66,7 +66,7 @@ interface MouseGuardZoomHandler {
   description: string
   dragCallback: (e: MouseEvent) => boolean
   scrollCallback: (e: WheelEvent) => boolean
-  scrollReverseY?: boolean
+  scrollAllowInvertY?: boolean
   lenientDragStartButton?: number
 }
 
@@ -157,7 +157,7 @@ export const cameraMouseDragGuards: Record<CameraSystem, MouseGuard> = {
         !e.ctrlKey &&
         !e.altKey &&
         !e.metaKey,
-      scrollReverseY: true,
+      scrollAllowInvertY: true,
     },
     rotate: {
       description: `${ALT} + Scroll`,

src/lib/desktop.ts

@@ -565,3 +565,7 @@ export const getUser = async (
   }
   return Promise.reject(new Error('unreachable'))
 }
+
+export async function readNaturalScrollDirection() {
+  return window.electron.readNaturalScrollDirection()
+}

src/lib/utils.ts

@@ -4,6 +4,7 @@ import { v4 } from 'uuid'
 import { isDesktop } from './isDesktop'
 import { AnyMachineSnapshot } from 'xstate'
 import { AsyncFn } from './types'
+import { readNaturalScrollDirection } from './desktop'
 
 export const uuidv4 = v4
 
@@ -262,6 +263,19 @@ export function isReducedMotion(): boolean {
   )
 }
 
+/**
+ * True if Apple Trackpad scroll should move the content. I.e. if this is true,
+ * and the user scrolls down, the viewport moves up relative to the content.
+ */
+export let cachedNaturalScrollDirection = platform() === 'macos'
+
+export async function refreshNaturalScrollDirection() {
+  if (!isDesktop()) return cachedNaturalScrollDirection
+  const isNatural = await readNaturalScrollDirection()
+  cachedNaturalScrollDirection = isNatural
+  return isNatural
+}
+
 export function XOR(bool1: boolean, bool2: boolean): boolean {
   return (bool1 || bool2) && !(bool1 && bool2)
 }

src/preload.ts

@@ -5,6 +5,7 @@ import os from 'node:os'
 import fsSync from 'node:fs'
 import packageJson from '../package.json'
 import { MachinesListing } from 'lib/machineManager'
+import { exec } from 'child_process'
 import chokidar from 'chokidar'
 
 const open = (args: any) => ipcRenderer.invoke('dialog.showOpenDialog', args)
@@ -81,6 +82,25 @@ const listMachines = async (): Promise<MachinesListing> => {
 const getMachineApiIp = async (): Promise<String | null> =>
   ipcRenderer.invoke('find_machine_api')
 
+async function readNaturalScrollDirection(): Promise<boolean> {
+  if (os.platform() !== 'darwin') {
+    // TODO: Detect this on other OS's.
+    return false
+  }
+  return new Promise((resolve, reject) => {
+    exec(
+      'defaults read -globalDomain com.apple.swipescrolldirection',
+      (err, stdout) => {
+        if (err) {
+          reject(err)
+        } else {
+          resolve(stdout.trim() === '1')
+        }
+      }
+    )
+  })
+}
+
 contextBridge.exposeInMainWorld('electron', {
   startDeviceFlow,
   loginWithDeviceFlow,
@@ -144,6 +164,7 @@ contextBridge.exposeInMainWorld('electron', {
   kittycad,
   listMachines,
   getMachineApiIp,
+  readNaturalScrollDirection,
   onUpdateDownloaded,
   appRestart,
 })