Eager Gesture Recognition on Aura

ui/events/gestures/gesture_provider_aura.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/events/gestures/gesture_provider_aura.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "ui/events/event.h"
 #include "ui/events/gesture_detection/gesture_config_helper.h"
 #include "ui/events/gesture_detection/gesture_event_data.h"
 #include "ui/events/gestures/gesture_configuration.h"
 
 namespace ui {
 
 GestureProviderAura::GestureProviderAura(GestureProviderAuraClient* client)
     : client_(client),
       filtered_gesture_provider_(ui::DefaultGestureProviderConfig(), this),
       handling_event_(false) {
   filtered_gesture_provider_.SetDoubleTapSupportForPlatformEnabled(false);
 }
 
 GestureProviderAura::~GestureProviderAura() {}
 
 bool GestureProviderAura::OnTouchEvent(const TouchEvent& event) {
-  bool pointer_id_is_active =
-      pointer_state_.FindPointerIndexOfId(event.touch_id()) != -1;
+  int index = pointer_state_.FindPointerIndexOfId(event.touch_id());
+  bool pointer_id_is_active = index != -1;
 
   if (event.type() == ET_TOUCH_PRESSED && pointer_id_is_active) {
     // Ignore touch press events if we already believe the pointer is down.
     return false;
   } else if (event.type() != ET_TOUCH_PRESSED && !pointer_id_is_active) {
     // We could have an active touch stream transfered to us, resulting in touch
     // move or touch up events without associated touch down events. Ignore
     // them.
     return false;
   }
 
+  // If this is a touchmove event, and it isn't different from the last
+  // event, ignore it.
+  if (event.type() == ET_TOUCH_MOVED &&
+      event.x() == pointer_state_.GetX(index) &&
+      event.y() == pointer_state_.GetY(index)) {
+    return false;
+  }
+
   last_touch_event_flags_ = event.flags();
   last_touch_event_latency_info_ = *event.latency();
   pointer_state_.OnTouch(event);
 
   bool result = filtered_gesture_provider_.OnTouchEvent(pointer_state_);
   pointer_state_.CleanupRemovedTouchPoints(event);
   return result;
 }
 
 void GestureProviderAura::OnTouchEventAck(bool event_consumed) {
@@ skipping 73 matching lines @@
 
   double double_tap_slop_square =
       GestureConfiguration::max_distance_between_taps_for_double_tap();
   double_tap_slop_square *= double_tap_slop_square;
   const float delta_x = previous_tap.x - current_tap.x;
   const float delta_y = previous_tap.y - current_tap.y;
   return (delta_x * delta_x + delta_y * delta_y < double_tap_slop_square);
 }
 
 }  // namespace content