Re-enable Eager Gesture Recognition on Aura

ui/aura/window_event_dispatcher.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/aura/window_event_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 141 matching lines @@
 DispatchDetails WindowEventDispatcher::DispatchMouseExitAtPoint(
     const gfx::Point& point) {
   ui::MouseEvent event(ui::ET_MOUSE_EXITED, point, point, ui::EF_NONE,
                        ui::EF_NONE);
   return DispatchMouseEnterOrExit(event, ui::ET_MOUSE_EXITED);
 }
 
 void WindowEventDispatcher::ProcessedTouchEvent(ui::TouchEvent* event,
                                                 Window* window,
                                                 ui::EventResult result) {
-  // TODO(tdresser): Move this to PreDispatchTouchEvent, to enable eager
-  // gesture detection. See crbug.com/410280.
-  if (!ui::GestureRecognizer::Get()
-           ->ProcessTouchEventPreDispatch(*event, window)) {
-    return;
-  }
-
   // Once we've fully migrated to the eager gesture detector, we won't need to
   // pass an event here.

[sadrul, 2014/12/03 21:30:10]

Is this comment still correct?

[tdresser, 2014/12/05 16:44:31]

I'm performing that cleanup in a followup patch:
https://codereview.chromium.org/503883004/

Note that we're only using the touch event unique identifier to double check
that we're acking the right event for the synchronous case.

   scoped_ptr<ui::GestureRecognizer::Gestures> gestures(
-      ui::GestureRecognizer::Get()->ProcessTouchEventOnAsyncAck(
+      ui::GestureRecognizer::Get()->AckAsyncTouchEvent(
           *event, result, window));
   DispatchDetails details = ProcessGestures(gestures.get());
   if (details.dispatcher_destroyed)
     return;
 }
 
 void WindowEventDispatcher::HoldPointerMoves() {
   if (!move_hold_count_)
     held_event_factory_.InvalidateWeakPtrs();
   ++move_hold_count_;
@@ skipping 309 matching lines @@
 #ifndef NDEBUG
   DCHECK(!event_dispatch_target_ || window()->Contains(event_dispatch_target_));
 #endif
 
   if (event.IsTouchEvent() && !details.target_destroyed) {
     // Do not let 'held' touch events contribute to any gestures unless it is
     // being dispatched.
     if (dispatching_held_event_ || !held_move_event_ ||
         !held_move_event_->IsTouchEvent()) {
 
-      // Once we've fully migrated to the eager gesture detector, we won't
-      // need to pass an event here.
-      ui::TouchEvent orig_event(static_cast<const ui::TouchEvent&>(event),
-                                static_cast<Window*>(event.target()),
-                                window());
+      if (!event.synchronous_handling_disabled()) {
+        scoped_ptr<ui::GestureRecognizer::Gestures> gestures;
 
-      if (event.result() & ui::ER_CONSUMED)
-        orig_event.StopPropagation();
+        // Once we've fully migrated to the eager gesture detector, we won't
+        // need to pass an event here.
+        gestures.reset(
+            ui::GestureRecognizer::Get()->AckSyncTouchEvent(
+                static_cast<const ui::TouchEvent&>(event), event.result(),
+                static_cast<Window*>(target)));

[sadrul, 2014/12/03 21:30:10]

This touch-event is being sent in the target's coord space. I believe the rest
of the touch-events are sent in the root-window's coord space. Is this not
problematic?

[tdresser, 2014/12/05 16:44:31]

It isn't problematic because we're only using the touch event's unique_event_id.

I've clarified that we're only using the unique_event_id by only passing the id
- I think strongly typing the id is probably worth it here, though it is a
little ugly.

 
-      // TODO(tdresser): Move this to PreDispatchTouchEvent, to enable eager
-      // gesture detection. See crbug.com/410280.
-      if (!ui::GestureRecognizer::Get()
-               ->ProcessTouchEventPreDispatch(orig_event,
-                                              static_cast<Window*>(target))) {
-        return details;
+        return ProcessGestures(gestures.get());
       }
-
-      scoped_ptr<ui::GestureRecognizer::Gestures> gestures;
-
-      gestures.reset(
-          ui::GestureRecognizer::Get()->ProcessTouchEventPostDispatch(
-              orig_event, event.result(), static_cast<Window*>(target)));
-
-      return ProcessGestures(gestures.get());
     }
   }
 
   return details;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // WindowEventDispatcher, ui::GestureEventHelper implementation:
 
 bool WindowEventDispatcher::CanDispatchToConsumer(
@@ skipping 358 matching lines @@
         event->SetHandled();
         return;
       }
       break;
 
     default:
       NOTREACHED();
       break;
   }
 
+  ui::TouchEvent orig_event(*event, target, window());
+  if (!ui::GestureRecognizer::Get()->ProcessTouchEventPreDispatch(orig_event,
+                                                                  target)) {
+    // The event is invalid - ignore it.
+    event->StopPropagation();
+    event->DisableSynchronousHandling();
+    return;
+  }
+
   PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura