Add option to use grab-and-move action for scrolling

src/APILayer/APILayer.cpp

@@ -345,10 +345,8 @@ XrResult APILayer::xrWaitFrame(
       rightHand.mActions.mPrimary = r.mActions.mPrimary;
       rightHand.mActions.mSecondary = r.mActions.mSecondary;
     }
-    if (Config::PinchToScroll) {
-      leftHand.mActions.mValueChange = l.mActions.mValueChange;
-      rightHand.mActions.mValueChange = r.mActions.mValueChange;
-    }
+    leftHand.mActions.mValueChange = l.mActions.mValueChange;
+    rightHand.mActions.mValueChange = r.mActions.mValueChange;
   }
 
   if (mPointCtrl) {

src/APILayer/HandTrackingSource.cpp

@@ -345,6 +345,41 @@ void HandTrackingSource::UpdateHand(const FrameInfo& frameInfo, Hand* hand) {
       state.mPose = {};
       break;
   }
+
+// --- Grab-and-Move Scroll Gesture ---
+  if (Config::GrabMoveToScroll) {
+    bool pinchActive = state.mActions.mPrimary;
+
+    if (pinchActive && state.mPose) {
+      float currentY = state.mPose->position.y;
+
+      if (!hand->mScrolling) {
+        // Start scroll mode
+        hand->mScrolling = true;
+        hand->mLastScrollY = currentY;
+      } else {
+        float delta = currentY - hand->mLastScrollY;
+
+        // Apply grab-and-move scroll scale for different applications
+        delta *= Config::GrabMoveScrollScale;
+
+        // Threshold to avoid jitter
+        constexpr float scrollThreshold = 0.01f;
+
+        if (delta > scrollThreshold) {
+          state.mActions.mValueChange = ActionState::ValueChange::Increase;
+          hand->mLastScrollY = currentY;
+        } else if (delta < -scrollThreshold) {
+          state.mActions.mValueChange = ActionState::ValueChange::Decrease;
+          hand->mLastScrollY = currentY;
+        }
+      }
+    } else {
+      // Pinch released → stop scrolling
+      hand->mScrolling = false;
+      hand->mLastScrollY = 0.0f;
+    }
+  }
 }
 
 void HandTrackingSource::InitHandTracker(Hand* hand) {

src/APILayer/HandTrackingSource.h

@@ -45,6 +45,10 @@ class HandTrackingSource final : public InputSource {
 
     ActionState mRawActions {};
     XrTime mRawActionsSince {};
+
+    // --- Added for grab‑and‑move scroll ---
+    float mLastScrollY = 0.0f;
+    bool mScrolling = false;
   };
 
   bool mHibernating {false};

src/SettingsApp/HTCCSettingsApp.cpp

@@ -270,9 +270,15 @@ static void OpenXRGUI() {
       HTCC::Config::SavePinchToClick();
     }
 
-    if (ToggleSwitch(&HTCC::Config::PinchToScroll).Caption("Pinch to scroll")) {
+    if (ToggleSwitch(&HTCC::Config::PinchToScroll)
+        .Caption("Pinch to scroll")) {
       HTCC::Config::SavePinchToScroll();
     }
+
+    if (ToggleSwitch(&HTCC::Config::GrabMoveToScroll)
+        .Caption("Grab and move to scroll")) {
+      HTCC::Config::SaveGrabMoveToScroll();
+    }
   }
 
   EndVStackPanel();
@@ -469,4 +475,4 @@ int WINAPI wWinMain(
         },
       },
     });
-}
+}

src/lib/Config.h

@@ -66,6 +66,7 @@ enum class HandTrackingHands : DWORD {
   IT(XrHandJointEXT, HandTrackingAimJoint, XR_HAND_JOINT_INDEX_PROXIMAL_EXT) \
   IT(bool, PinchToClick, true) \
   IT(bool, PinchToScroll, true) \
+  IT(bool, GrabMoveToScroll, false) \
   IT(uint16_t, ShortPressLongPressMilliseconds, 200) \
   IT(uint16_t, ScrollWheelDelayMilliseconds, 600) \
   IT(uint16_t, ScrollWheelIntervalMilliseconds, 50) \
@@ -150,6 +151,7 @@ enum class HandTrackingHands : DWORD {
   IT(HandTrackingActionHFOV, std::numbers::pi_v<float> / 2) \
   IT(HandTrackingHibernateCutoff, std::numbers::pi_v<float> / 8) \
   IT(SmoothingFactor, 1.0f) \
+  IT(GrabMoveScrollScale, 1.0f) \
   IT(LeftEyeFOVLeft, 0.0f) \
   IT(LeftEyeFOVRight, 0.0f) \
   IT(LeftEyeFOVUp, 0.0f) \