From 9c31d708a21cc23209da10d6dd6de586d3161afd Mon Sep 17 00:00:00 2001
From: filtered <176114999+webfiltered@users.noreply.github.com>
Date: Wed, 13 Aug 2025 03:15:32 +1000
Subject: [PATCH] Add automatic trackpad / mouse sensing (#4913)

---
 src/lib/litegraph/src/CanvasPointer.ts   | 45 +++++++++++++++++++
 src/lib/litegraph/src/LGraphCanvas.ts    | 55 +++++++++++-------------
 src/lib/litegraph/src/LiteGraphGlobal.ts |  2 +
 3 files changed, 72 insertions(+), 30 deletions(-)

diff --git a/src/lib/litegraph/src/CanvasPointer.ts b/src/lib/litegraph/src/CanvasPointer.ts
index 0e1af314d1..380e50f41b 100644
--- a/src/lib/litegraph/src/CanvasPointer.ts
+++ b/src/lib/litegraph/src/CanvasPointer.ts
@@ -43,6 +43,19 @@ export class CanvasPointer {
   /** {@link maxClickDrift} squared.  Used to calculate click drift without `sqrt`. */
   static #maxClickDrift2 = this.#maxClickDrift ** 2
 
+  /** Assume that "wheel" events with both deltaX and deltaY less than this value are trackpad gestures. */
+  static trackpadThreshold = 60
+
+  /**
+   * The minimum time between "wheel" events to allow switching between trackpad
+   * and mouse modes.
+   *
+   * This prevents trackpad "flick" panning from registering as regular mouse wheel.
+   * After a flick gesture is complete, the automatic wheel events are sent with
+   * reduced frequency, but much higher deltaX and deltaY values.
+   */
+  static trackpadMaxGap = 200
+
   /** The element this PointerState should capture input against when dragging. */
   element: Element
   /** Pointer ID used by drag capture. */
@@ -77,6 +90,9 @@ export class CanvasPointer {
   /** The last pointerup event for the primary button */
   eUp?: CanvasPointerEvent
 
+  /** The last pointermove event that was treated as a trackpad gesture. */
+  lastTrackpadEvent?: WheelEvent
+
   /**
    * If set, as soon as the mouse moves outside the click drift threshold, this action is run once.
    * @param pointer [DEPRECATED] This parameter will be removed in a future release.
@@ -257,6 +273,35 @@ export class CanvasPointer {
     delete this.onDragStart
   }
 
+  /**
+   * Checks if the given wheel event is part of a continued trackpad gesture.
+   * @param e The wheel event to check
+   * @returns `true` if the event is part of a continued trackpad gesture, otherwise `false`
+   */
+  #isContinuationOfGesture(e: WheelEvent): boolean {
+    const { lastTrackpadEvent } = this
+    if (!lastTrackpadEvent) return false
+
+    return (
+      e.timeStamp - lastTrackpadEvent.timeStamp < CanvasPointer.trackpadMaxGap
+    )
+  }
+
+  /**
+   * Checks if the given wheel event is part of a trackpad gesture.
+   * @param e The wheel event to check
+   * @returns `true` if the event is part of a trackpad gesture, otherwise `false`
+   */
+  isTrackpadGesture(e: WheelEvent): boolean {
+    if (this.#isContinuationOfGesture(e)) {
+      this.lastTrackpadEvent = e
+      return true
+    }
+
+    const threshold = CanvasPointer.trackpadThreshold
+    return Math.abs(e.deltaX) < threshold && Math.abs(e.deltaY) < threshold
+  }
+
   /**
    * Resets the state of this {@link CanvasPointer} instance.
    *
diff --git a/src/lib/litegraph/src/LGraphCanvas.ts b/src/lib/litegraph/src/LGraphCanvas.ts
index 27f0f43b8f..a4ff279221 100644
--- a/src/lib/litegraph/src/LGraphCanvas.ts
+++ b/src/lib/litegraph/src/LGraphCanvas.ts
@@ -3456,10 +3456,6 @@ export class LGraphCanvas
   processMouseWheel(e: WheelEvent): void {
     if (!this.graph || !this.allow_dragcanvas) return
 
-    // TODO: Mouse wheel zoom rewrite
-    // @ts-expect-error wheelDeltaY is non-standard property on WheelEvent
-    const delta = e.wheelDeltaY ?? e.detail * -60
-
     this.adjustMouseEvent(e)
 
     const pos: Point = [e.clientX, e.clientY]
@@ -3467,35 +3463,34 @@ export class LGraphCanvas
 
     let { scale } = this.ds
 
-    if (
-      LiteGraph.canvasNavigationMode === 'legacy' ||
-      (LiteGraph.canvasNavigationMode === 'standard' && e.ctrlKey)
-    ) {
-      if (delta > 0) {
-        scale *= this.zoom_speed
-      } else if (delta < 0) {
-        scale *= 1 / this.zoom_speed
-      }
-      this.ds.changeScale(scale, [e.clientX, e.clientY])
-    } else if (
-      LiteGraph.macTrackpadGestures &&
-      (!LiteGraph.macGesturesRequireMac || navigator.userAgent.includes('Mac'))
-    ) {
-      if (e.metaKey && !e.ctrlKey && !e.shiftKey && !e.altKey) {
-        if (e.deltaY > 0) {
-          scale *= 1 / this.zoom_speed
-        } else if (e.deltaY < 0) {
-          scale *= this.zoom_speed
-        }
-        this.ds.changeScale(scale, [e.clientX, e.clientY])
-      } else if (e.ctrlKey) {
+    // Detect if this is a trackpad gesture or mouse wheel
+    const isTrackpad = this.pointer.isTrackpadGesture(e)
+
+    if (e.ctrlKey || LiteGraph.canvasNavigationMode === 'legacy') {
+      // Legacy mode or standard mode with ctrl - use wheel for zoom
+      if (isTrackpad) {
+        // Trackpad gesture - use smooth scaling
         scale *= 1 + e.deltaY * (1 - this.zoom_speed) * 0.18
         this.ds.changeScale(scale, [e.clientX, e.clientY], false)
-      } else if (e.shiftKey) {
-        this.ds.offset[0] -= e.deltaY * 1.18 * (1 / scale)
       } else {
-        this.ds.offset[0] -= e.deltaX * 1.18 * (1 / scale)
-        this.ds.offset[1] -= e.deltaY * 1.18 * (1 / scale)
+        // Mouse wheel - use stepped scaling
+        if (e.deltaY < 0) {
+          scale *= this.zoom_speed
+        } else if (e.deltaY > 0) {
+          scale *= 1 / this.zoom_speed
+        }
+        this.ds.changeScale(scale, [e.clientX, e.clientY])
+      }
+    } else {
+      // Standard mode without ctrl - use wheel / gestures to pan
+      // Trackpads and mice work on significantly different scales
+      const factor = isTrackpad ? 0.18 : 0.008_333
+
+      if (!isTrackpad && e.shiftKey && e.deltaX === 0) {
+        this.ds.offset[0] -= e.deltaY * (1 + factor) * (1 / scale)
+      } else {
+        this.ds.offset[0] -= e.deltaX * (1 + factor) * (1 / scale)
+        this.ds.offset[1] -= e.deltaY * (1 + factor) * (1 / scale)
       }
     }
 
diff --git a/src/lib/litegraph/src/LiteGraphGlobal.ts b/src/lib/litegraph/src/LiteGraphGlobal.ts
index e27377fedf..42ad95877d 100644
--- a/src/lib/litegraph/src/LiteGraphGlobal.ts
+++ b/src/lib/litegraph/src/LiteGraphGlobal.ts
@@ -284,6 +284,7 @@ export class LiteGraphGlobal {
   ]
 
   /**
+   * @deprecated Removed; has no effect.
    * If `true`, mouse wheel events will be interpreted as trackpad gestures.
    * Tested on MacBook M4 Pro.
    * @default false
@@ -292,6 +293,7 @@ export class LiteGraphGlobal {
   macTrackpadGestures: boolean = false
 
   /**
+   * @deprecated Removed; has no effect.
    * If both this setting and {@link macTrackpadGestures} are `true`, trackpad gestures will
    * only be enabled when the browser user agent includes "Mac".
    * @default true