[WPEPlatform] Page scrolls at double speed when scrolling with two fingers

obyknovenius · obyknovenius · commit f0af1daa9de5 · 2026-02-26T02:46:03.000-08:00
https://bugs.webkit.org/show_bug.cgi?id=308643 Reviewed by Carlos Garcia Campos. When scrolling begins with one finger and a second finger is placed on the screen and both fingers move together, the page scrolls at twice the expected speed. `WPEGestureDetector` only tracks the first touch sequence and ignores events from other sequences. However, `handleGesture()` did not check whether the event was actually processed and always proceeded to emit a scroll event based on the current gesture state. As a result, touch move events from the second finger triggered a second scroll event, doubling the scroll speed. Fixed by making `wpe_gesture_controller_handle_event()` return a boolean indicating whether the event was consumed. * Source/WebKit/UIProcess/API/wpe/WPEWebViewPlatform.cpp: (WKWPE::ViewPlatform::handleGesture): * Source/WebKit/WPEPlatform/wpe/WPEGestureController.cpp: (wpe_gesture_controller_handle_event): * Source/WebKit/WPEPlatform/wpe/WPEGestureController.h: * Source/WebKit/WPEPlatform/wpe/WPEGestureControllerImpl.cpp: (wpeHandleEvent): * Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.cpp: (WPE::GestureDetector::handleEvent): * Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.h: Canonical link: https://commits.webkit.org/308271@main
diff --git a/Source/WebKit/UIProcess/API/wpe/WPEWebViewPlatform.cpp b/Source/WebKit/UIProcess/API/wpe/WPEWebViewPlatform.cpp
@@ -430,7 +430,8 @@ void ViewPlatform::handleGesture(WPEEvent* event)
     if (!gestureController)
         return;
 
-    wpe_gesture_controller_handle_event(gestureController, event);
+    if (!wpe_gesture_controller_handle_event(gestureController, event))
+        return;
 
     if (wpe_event_get_event_type(event) == WPE_EVENT_TOUCH_DOWN)
         return;
diff --git a/Source/WebKit/WPEPlatform/wpe/WPEGestureController.cpp b/Source/WebKit/WPEPlatform/wpe/WPEGestureController.cpp
@@ -49,14 +49,17 @@ static void wpe_gesture_controller_default_init(WPEGestureControllerInterface*)
  * @event: a #WPEEvent
  *
  * Get the gesture detected by @controller if any was detected during processing of @event.
+ * 
+ * Returns: %TRUE if @event was handled by @controller and gesture information is updated,
+ *    or %FALSE otherwise.
  */
-void wpe_gesture_controller_handle_event(WPEGestureController* controller, WPEEvent* event)
+gboolean wpe_gesture_controller_handle_event(WPEGestureController* controller, WPEEvent* event)
 {
-    g_return_if_fail(controller);
-    g_return_if_fail(event);
+    g_return_val_if_fail(controller, FALSE);
+    g_return_val_if_fail(event, FALSE);
 
     auto* controllerInterface = WPE_GESTURE_CONTROLLER_GET_IFACE(controller);
-    controllerInterface->handle_event(controller, event);
+    return controllerInterface->handle_event(controller, event);
 }
 
 /**
diff --git a/Source/WebKit/WPEPlatform/wpe/WPEGestureController.h b/Source/WebKit/WPEPlatform/wpe/WPEGestureController.h
@@ -57,7 +57,7 @@ struct _WPEGestureControllerInterface
 {
     GTypeInterface parent_interface;
 
-    void        (* handle_event)         (WPEGestureController *controller,
+    gboolean    (* handle_event)         (WPEGestureController *controller,
                                           WPEEvent             *event );
     void        (* cancel)               (WPEGestureController *controller);
     WPEGesture  (* get_gesture)          (WPEGestureController *controller);
@@ -70,7 +70,7 @@ struct _WPEGestureControllerInterface
     gboolean    (* is_drag_begin)        (WPEGestureController *controller);
 };
 
-WPE_API void        wpe_gesture_controller_handle_event         (WPEGestureController *controller,
+WPE_API gboolean    wpe_gesture_controller_handle_event         (WPEGestureController *controller,
                                                                  WPEEvent             *event);
 WPE_API void        wpe_gesture_controller_cancel               (WPEGestureController *controller);
 WPE_API WPEGesture  wpe_gesture_controller_get_gesture          (WPEGestureController *controller);
diff --git a/Source/WebKit/WPEPlatform/wpe/WPEGestureControllerImpl.cpp b/Source/WebKit/WPEPlatform/wpe/WPEGestureControllerImpl.cpp
@@ -39,9 +39,9 @@ WEBKIT_DEFINE_FINAL_TYPE_WITH_CODE(
     WPEGestureControllerImpl, wpe_gesture_controller_impl, G_TYPE_OBJECT, GObject,
     G_IMPLEMENT_INTERFACE(WPE_TYPE_GESTURE_CONTROLLER, wpe_gesture_controller_interface_init))
 
-static void wpeHandleEvent(WPEGestureController* controller, WPEEvent* event)
+static gboolean wpeHandleEvent(WPEGestureController* controller, WPEEvent* event)
 {
-    WPE_GESTURE_CONTROLLER_IMPL(controller)->priv->detector.handleEvent(event);
+    return WPE_GESTURE_CONTROLLER_IMPL(controller)->priv->detector.handleEvent(event);
 }
 
 static void wpeCancel(WPEGestureController* controller)
diff --git a/Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.cpp b/Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.cpp
@@ -32,10 +32,10 @@
 
 namespace WPE {
 
-void GestureDetector::handleEvent(WPEEvent* event)
+bool GestureDetector::handleEvent(WPEEvent* event)
 {
     if (m_sequenceId && *m_sequenceId != wpe_event_touch_get_sequence_id(event))
-        return;
+        return false;
 
     switch (wpe_event_get_event_type(event)) {
     case WPE_EVENT_TOUCH_DOWN:
@@ -50,6 +50,8 @@ void GestureDetector::handleEvent(WPEEvent* event)
         reset();
         break;
     case WPE_EVENT_TOUCH_MOVE:
+        if (!m_sequenceId)
+            return false;
         if (double x, y; wpe_event_get_position(event, &x, &y) && m_position) {
             auto* settings = wpe_display_get_settings(wpe_view_get_display(wpe_event_get_view(event)));
             auto dragActivationThresholdPx = wpe_settings_get_uint32(settings, WPE_SETTING_DRAG_THRESHOLD, nullptr);
@@ -67,6 +69,8 @@ void GestureDetector::handleEvent(WPEEvent* event)
             reset();
         break;
     case WPE_EVENT_TOUCH_UP:
+        if (!m_sequenceId)
+            return false;
         if (double x, y; wpe_event_get_position(event, &x, &y) && m_position) {
             if (m_gesture == WPE_GESTURE_DRAG)
                 m_delta = { x - m_nextDeltaReferencePosition->x, y - m_nextDeltaReferencePosition->y };
@@ -77,6 +81,8 @@ void GestureDetector::handleEvent(WPEEvent* event)
     default:
         RELEASE_ASSERT_NOT_REACHED();
     }
+
+    return true;
 }
 
 void GestureDetector::reset()
diff --git a/Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.h b/Source/WebKit/WPEPlatform/wpe/WPEGestureDetector.h
@@ -32,7 +32,7 @@ namespace WPE {
 
 class GestureDetector final {
 public:
-    void handleEvent(WPEEvent*);
+    bool handleEvent(WPEEvent*);
     WPEGesture gesture() const { return m_gesture; }
     void reset();
 

Original file line number	Diff line number	Diff line change
`@@ -39,9 +39,9 @@ WEBKIT_DEFINE_FINAL_TYPE_WITH_CODE(`
`39`	`39`	`WPEGestureControllerImpl, wpe_gesture_controller_impl, G_TYPE_OBJECT, GObject,`
`40`	`40`	`G_IMPLEMENT_INTERFACE(WPE_TYPE_GESTURE_CONTROLLER, wpe_gesture_controller_interface_init))`
`41`	`41`
`42`		`-static void wpeHandleEvent(WPEGestureController* controller, WPEEvent* event)`
	`42`	`+static gboolean wpeHandleEvent(WPEGestureController* controller, WPEEvent* event)`
`43`	`43`	`{`
`44`		`- WPE_GESTURE_CONTROLLER_IMPL(controller)->priv->detector.handleEvent(event);`
	`44`	`+ return WPE_GESTURE_CONTROLLER_IMPL(controller)->priv->detector.handleEvent(event);`
`45`	`45`	`}`
`46`	`46`
`47`	`47`	`static void wpeCancel(WPEGestureController* controller)`