Support double-tap to click in touch accessibility controller.

This refactors the touch accessibility controller to work like a state
machine, and implements support for double-tap to send a click to the
last location where the user did touch exploration previously. This also
means reimplementing existing touch interactions so that nothing is
passed through until the double-tap timeout passes or the user moves
outside the slop region.

BUG=377900

Review URL: https://codereview.chromium.org/296403011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275784 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/accessibility/touch_exploration_controller_browsertest.cc

@@ -55,7 +55,13 @@ IN_PROC_BROWSER_TEST_F(TouchExplorationTest, ToggleOnOff) {
   SwitchTouchExplorationMode(true);
   aura::test::EventGenerator generator(root_window);
 
+  generator.set_current_location(gfx::Point(100, 200));
   generator.PressTouchId(1);
+  // Since the touch exploration controller doesn't know if the user is
+  // double-tapping or not, touch exploration is only initiated if the
+  // user moves more than 8 pixels away from the initial location (the "slop"),
+  // or after 300 ms has elapsed.
+  generator.MoveTouchId(gfx::Point(109, 209), 1);
   // Number of mouse events may be greater than 1 because of ET_MOUSE_ENTERED.
   EXPECT_GT(event_handler->num_mouse_events(), 0);
   EXPECT_EQ(0, event_handler->num_touch_events());
@@ -68,7 +74,9 @@ IN_PROC_BROWSER_TEST_F(TouchExplorationTest, ToggleOnOff) {
   event_handler->Reset();
 
   SwitchTouchExplorationMode(true);
+  generator.set_current_location(gfx::Point(500, 600));
   generator.PressTouchId(2);
+  generator.MoveTouchId(gfx::Point(509, 609), 2);
   EXPECT_GT(event_handler->num_mouse_events(), 0);
   EXPECT_EQ(0, event_handler->num_touch_events());
 

ui/aura/test/event_generator.cc

@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/time/default_tick_clock.h"
 #include "ui/aura/client/screen_position_client.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
@@ -69,8 +70,9 @@ class TestTouchEvent : public ui::TouchEvent {
   TestTouchEvent(ui::EventType type,
                  const gfx::Point& root_location,
                  int touch_id,
-                 int flags)
-      : TouchEvent(type, root_location, flags, touch_id, ui::EventTimeForNow(),
+                 int flags,
+                 base::TimeDelta timestamp)
+      : TouchEvent(type, root_location, flags, touch_id, timestamp,
                    1.0f, 1.0f, 1.0f, 1.0f) {
   }
 
@@ -87,7 +89,8 @@ EventGenerator::EventGenerator(Window* root_window)
       current_host_(delegate_->GetHostAt(current_location_)),
       flags_(0),
       grab_(false),
-      async_(false) {
+      async_(false),
+      tick_clock_(new base::DefaultTickClock()) {
 }
 
 EventGenerator::EventGenerator(Window* root_window, const gfx::Point& point)
@@ -96,7 +99,8 @@ EventGenerator::EventGenerator(Window* root_window, const gfx::Point& point)
       current_host_(delegate_->GetHostAt(current_location_)),
       flags_(0),
       grab_(false),
-      async_(false) {
+      async_(false),
+      tick_clock_(new base::DefaultTickClock()) {
 }
 
 EventGenerator::EventGenerator(Window* root_window, Window* window)
@@ -105,7 +109,8 @@ EventGenerator::EventGenerator(Window* root_window, Window* window)
       current_host_(delegate_->GetHostAt(current_location_)),
       flags_(0),
       grab_(false),
-      async_(false) {
+      async_(false),
+      tick_clock_(new base::DefaultTickClock()) {
 }
 
 EventGenerator::EventGenerator(EventGeneratorDelegate* delegate)
@@ -113,7 +118,8 @@ EventGenerator::EventGenerator(EventGeneratorDelegate* delegate)
       current_host_(delegate_->GetHostAt(current_location_)),
       flags_(0),
       grab_(false),
-      async_(false) {
+      async_(false),
+      tick_clock_(new base::DefaultTickClock()) {
 }
 
 EventGenerator::~EventGenerator() {
@@ -219,7 +225,8 @@ void EventGenerator::PressTouch() {
 
 void EventGenerator::PressTouchId(int touch_id) {
   TestTouchEvent touchev(
-      ui::ET_TOUCH_PRESSED, GetLocationInCurrentRoot(), touch_id, flags_);
+      ui::ET_TOUCH_PRESSED, GetLocationInCurrentRoot(), touch_id, flags_,
+      Now());
   Dispatch(&touchev);
 }
 
@@ -230,7 +237,8 @@ void EventGenerator::MoveTouch(const gfx::Point& point) {
 void EventGenerator::MoveTouchId(const gfx::Point& point, int touch_id) {
   current_location_ = point;
   TestTouchEvent touchev(
-      ui::ET_TOUCH_MOVED, GetLocationInCurrentRoot(), touch_id, flags_);
+      ui::ET_TOUCH_MOVED, GetLocationInCurrentRoot(), touch_id, flags_,
+      Now());
   Dispatch(&touchev);
 
   if (!grab_)
@@ -243,7 +251,8 @@ void EventGenerator::ReleaseTouch() {
 
 void EventGenerator::ReleaseTouchId(int touch_id) {
   TestTouchEvent touchev(
-      ui::ET_TOUCH_RELEASED, GetLocationInCurrentRoot(), touch_id, flags_);
+      ui::ET_TOUCH_RELEASED, GetLocationInCurrentRoot(), touch_id, flags_,
+      Now());
   Dispatch(&touchev);
 }
 
@@ -263,7 +272,7 @@ void EventGenerator::GestureEdgeSwipe() {
       0,
       0,
       0,
-      ui::EventTimeForNow(),
+      Now(),
       ui::GestureEventDetails(ui::ET_GESTURE_WIN8_EDGE_SWIPE, 0, 0),
       0);
   Dispatch(&gesture);
@@ -274,7 +283,7 @@ void EventGenerator::GestureTapAt(const gfx::Point& location) {
   ui::TouchEvent press(ui::ET_TOUCH_PRESSED,
                        location,
                        kTouchId,
-                       ui::EventTimeForNow());
+                       Now());
   Dispatch(&press);
 
   ui::TouchEvent release(
@@ -288,7 +297,7 @@ void EventGenerator::GestureTapDownAndUp(const gfx::Point& location) {
   ui::TouchEvent press(ui::ET_TOUCH_PRESSED,
                        location,
                        kTouchId,
-                       ui::EventTimeForNow());
+                       Now());
   Dispatch(&press);
 
   ui::TouchEvent release(
@@ -312,7 +321,7 @@ void EventGenerator::GestureScrollSequenceWithCallback(
     int steps,
     const ScrollStepCallback& callback) {
   const int kTouchId = 5;
-  base::TimeDelta timestamp = ui::EventTimeForNow();
+  base::TimeDelta timestamp = Now();
   ui::TouchEvent press(ui::ET_TOUCH_PRESSED, start, kTouchId, timestamp);
   Dispatch(&press);
 
@@ -367,7 +376,7 @@ void EventGenerator::GestureMultiFingerScrollWithDelays(
     points[i] = start[i];
   }
 
-  base::TimeDelta press_time_first = ui::EventTimeForNow();
+  base::TimeDelta press_time_first = Now();
   base::TimeDelta press_time[kMaxTouchPoints];
   bool pressed[kMaxTouchPoints];
   for (int i = 0; i < count; ++i) {
@@ -417,8 +426,7 @@ void EventGenerator::ScrollSequence(const gfx::Point& start,
                                     float y_offset,
                                     int steps,
                                     int num_fingers) {
-  base::TimeDelta timestamp = base::TimeDelta::FromInternalValue(
-      base::TimeTicks::Now().ToInternalValue());
+  base::TimeDelta timestamp = Now();
   ui::ScrollEvent fling_cancel(ui::ET_SCROLL_FLING_CANCEL,
                                start,
                                timestamp,
@@ -457,7 +465,7 @@ void EventGenerator::ScrollSequence(const gfx::Point& start,
                                     const std::vector<gfx::Point>& offsets,
                                     int num_fingers) {
   int steps = offsets.size();
-  base::TimeDelta timestamp = ui::EventTimeForNow();
+  base::TimeDelta timestamp = Now();
   ui::ScrollEvent fling_cancel(ui::ET_SCROLL_FLING_CANCEL,
                                start,
                                timestamp,
@@ -501,6 +509,17 @@ void EventGenerator::Dispatch(ui::Event* event) {
   DoDispatchEvent(event, async_);
 }
 
+void EventGenerator::SetTickClock(scoped_ptr<base::TickClock> tick_clock) {
+  tick_clock_ = tick_clock.Pass();
+}
+
+base::TimeDelta EventGenerator::Now() {
+  // This is the same as what EventTimeForNow() does, but here we do it
+  // with a tick clock that can be replaced with a simulated clock for tests.
+  return base::TimeDelta::FromInternalValue(
+      tick_clock_->NowTicks().ToInternalValue());
+}
+
 void EventGenerator::DispatchKeyEvent(bool is_press,
                                       ui::KeyboardCode key_code,
                                       int flags) {
@@ -638,6 +657,5 @@ void EventGenerator::DispatchNextPendingEvent() {
   }
 }
 
-
 }  // namespace test
 }  // namespace aura

ui/aura/test/event_generator.h

@@ -11,12 +11,13 @@
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/keycodes/keyboard_codes.h"
 #include "ui/gfx/point.h"
 
 namespace base {
-class TimeDelta;
+class TickClock;
 }
 
 namespace ui {
@@ -317,6 +318,12 @@ class EventGenerator {
     current_host_ = host;
   }
 
+  // Specify an alternative tick clock to be used for simulating time in tests.
+  void SetTickClock(scoped_ptr<base::TickClock> tick_clock);
+
+  // Get the current time from the tick clock.
+  base::TimeDelta Now();
+
  private:
   // Dispatch a key event to the WindowEventDispatcher.
   void DispatchKeyEvent(bool is_press, ui::KeyboardCode key_code, int flags);
@@ -346,6 +353,7 @@ class EventGenerator {
   std::list<ui::Event*> pending_events_;
   // Set to true to cause events to be posted asynchronously.
   bool async_;
+  scoped_ptr<base::TickClock> tick_clock_;
 
   DISALLOW_COPY_AND_ASSIGN(EventGenerator);
 };

ui/chromeos/touch_exploration_controller.cc

@@ -7,14 +7,34 @@
 #include "base/logging.h"
 #include "ui/aura/client/cursor_client.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_event_dispatcher.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/events/event.h"
+#include "ui/events/event_processor.h"
 
 namespace ui {
 
+namespace {
+// The default value for initial_touch_id_passthrough_mapping_ used
+// when the user has not yet released any fingers yet, so there's no
+// touch id remapping yet.
+const int kTouchIdUnassigned = 0;
+
+// The value for initial_touch_id_passthrough_mapping_ if the user has
+// released the first finger but some other fingers are held down. In this
+// state we don't do any touch id remapping, but we distinguish it from the
+// kTouchIdUnassigned state because we don't want to assign
+// initial_touch_id_passthrough_mapping_ a touch id anymore,
+// until all fingers are released.
+const int kTouchIdNone = -1;
+}  // namespace
+
 TouchExplorationController::TouchExplorationController(
     aura::Window* root_window)
-        : root_window_(root_window) {
+      : root_window_(root_window),
+        initial_touch_id_passthrough_mapping_(kTouchIdUnassigned),
+        state_(NO_FINGERS_DOWN),
+        event_handler_for_testing_(NULL) {
   CHECK(root_window);
   root_window->GetHost()->GetEventSource()->AddEventRewriter(this);
 }
@@ -23,124 +43,287 @@ TouchExplorationController::~TouchExplorationController() {
   root_window_->GetHost()->GetEventSource()->RemoveEventRewriter(this);
 }
 
+void TouchExplorationController::CallTapTimerNowForTesting() {
+  DCHECK(tap_timer_.IsRunning());
+  tap_timer_.Stop();
+  OnTapTimerFired();
+}
+
+void TouchExplorationController::SetEventHandlerForTesting(
+    ui::EventHandler* event_handler_for_testing) {
+  event_handler_for_testing_ = event_handler_for_testing;
+}
+
+bool TouchExplorationController::IsInNoFingersDownStateForTesting() const {
+  return state_ == NO_FINGERS_DOWN;
+}
+
 ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
     const ui::Event& event,
     scoped_ptr<ui::Event>* rewritten_event) {
   if (!event.IsTouchEvent())
     return ui::EVENT_REWRITE_CONTINUE;
-
   const ui::TouchEvent& touch_event =
       static_cast<const ui::TouchEvent&>(event);
+
+  // If the tap timer should have fired by now but hasn't, run it now and
+  // stop the timer. This is important so that behavior is consistent with
+  // the timestamps of the events, and not dependent on the granularity of
+  // the timer.
+  if (tap_timer_.IsRunning() &&
+      touch_event.time_stamp() - initial_press_->time_stamp() >
+          gesture_detector_config_.double_tap_timeout) {
+    tap_timer_.Stop();
+    OnTapTimerFired();
+    // Note: this may change the state. We should now continue and process
+    // this event under this new state.
+  }
+
   const ui::EventType type = touch_event.type();
   const gfx::PointF& location = touch_event.location_f();
   const int touch_id = touch_event.touch_id();
-  const int flags = touch_event.flags();
 
+  // Always update touch ids and touch locations, so we can use those
+  // no matter what state we're in.
   if (type == ui::ET_TOUCH_PRESSED) {
-    touch_ids_.push_back(touch_id);
+    current_touch_ids_.push_back(touch_id);
     touch_locations_.insert(std::pair<int, gfx::PointF>(touch_id, location));
-    // If this is the first and only finger touching - rewrite the touch as a
-    // mouse move. Otherwise let the it go through as is.
-    if (touch_ids_.size() == 1) {
-      *rewritten_event = CreateMouseMoveEvent(location, flags);
-      EnterTouchToMouseMode();
-      return ui::EVENT_REWRITE_REWRITTEN;
-    }
-    return ui::EVENT_REWRITE_CONTINUE;
   } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
-    std::vector<int>::iterator it =
-        std::find(touch_ids_.begin(), touch_ids_.end(), touch_id);
-    // We may fail to find the finger if the exploration mode was turned on
-    // while the user had some fingers touching the screen. We simply ignore
-    // those fingers for the purposes of event transformation.
-    if (it == touch_ids_.end())
+    std::vector<int>::iterator it = std::find(
+        current_touch_ids_.begin(), current_touch_ids_.end(), touch_id);
+
+    // Can happen if touch exploration is enabled while fingers were down.
+    if (it == current_touch_ids_.end())
       return ui::EVENT_REWRITE_CONTINUE;
-    const bool first_finger_released = it == touch_ids_.begin();
-    touch_ids_.erase(it);
-    int num_erased = touch_locations_.erase(touch_id);
-    DCHECK_EQ(num_erased, 1);
-    const int num_fingers_remaining = touch_ids_.size();
-
-    if (num_fingers_remaining == 0) {
-      *rewritten_event = CreateMouseMoveEvent(location, flags);
-      return ui::EVENT_REWRITE_REWRITTEN;
-    }
 
-    // If we are left with one finger - enter the mouse move mode.
-    const bool enter_mouse_move_mode = num_fingers_remaining == 1;
+    current_touch_ids_.erase(it);
+    touch_locations_.erase(touch_id);
+  } else if (type == ui::ET_TOUCH_MOVED) {
+    std::vector<int>::iterator it = std::find(
+        current_touch_ids_.begin(), current_touch_ids_.end(), touch_id);
 
-    if (!enter_mouse_move_mode && !first_finger_released) {
-      // No special handling needed.
+    // Can happen if touch exploration is enabled while fingers were down.
+    if (it == current_touch_ids_.end())
       return ui::EVENT_REWRITE_CONTINUE;
-    }
 
-    // If the finger which was released was the first one, - we need to rewrite
-    // the release event as a release of the was second / now first finger.
-    // This is the finger which will now be getting "substracted".
-    if (first_finger_released) {
-      int rewritten_release_id = touch_ids_[0];
-      const gfx::PointF& rewritten_release_location =
-          touch_locations_[rewritten_release_id];
-      ui::TouchEvent* rewritten_release_event = new ui::TouchEvent(
-          ui::ET_TOUCH_RELEASED,
-          rewritten_release_location,
-          rewritten_release_id,
-          event.time_stamp());
-      rewritten_release_event->set_flags(touch_event.flags());
-      rewritten_event->reset(rewritten_release_event);
-    } else if (enter_mouse_move_mode) {
-      // Dispatch the release event as is.
-      // TODO(mfomitchev): We can get rid of this clause once we have
-      // EVENT_REWRITE_DISPATCH_ANOTHER working without having to set
-      // rewritten_event.
-      rewritten_event->reset(new ui::TouchEvent(touch_event));
-    }
+    touch_locations_[*it] = location;
+  }
+
+  // The rest of the processing depends on what state we're in.
+  switch(state_) {
+    case NO_FINGERS_DOWN:
+      return InNoFingersDown(touch_event, rewritten_event);
+    case SINGLE_TAP_PRESSED:
+      return InSingleTapPressed(touch_event, rewritten_event);
+    case SINGLE_TAP_RELEASED:
+      return InSingleTapReleased(touch_event, rewritten_event);
+    case DOUBLE_TAP_PRESSED:
+      return InDoubleTapPressed(touch_event, rewritten_event);
+    case TOUCH_EXPLORATION:
+      return InTouchExploration(touch_event, rewritten_event);
+    case PASSTHROUGH_MINUS_ONE:
+      return InPassthroughMinusOne(touch_event, rewritten_event);
+  }
 
-    if (enter_mouse_move_mode) {
-      // Since we are entering the mouse move mode - also dispatch a mouse move
-      // event at the location of the one remaining finger. (num_fingers == 1)
-      const gfx::PointF& mouse_move_location = touch_locations_[touch_ids_[0]];
-      next_dispatch_event_ =
-          CreateMouseMoveEvent(mouse_move_location, flags).Pass();
-      return ui::EVENT_REWRITE_DISPATCH_ANOTHER;
+  NOTREACHED();
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::NextDispatchEvent(
+    const ui::Event& last_event, scoped_ptr<ui::Event>* new_event) {
+  NOTREACHED();
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InNoFingersDown(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  const ui::EventType type = event.type();
+  if (type == ui::ET_TOUCH_PRESSED) {
+    initial_press_.reset(new TouchEvent(event));
+    tap_timer_.Start(FROM_HERE,
+                     gesture_detector_config_.double_tap_timeout,
+                     this,
+                     &TouchExplorationController::OnTapTimerFired);
+    state_ = SINGLE_TAP_PRESSED;
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+
+  NOTREACHED();
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InSingleTapPressed(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  const ui::EventType type = event.type();
+
+  if (type == ui::ET_TOUCH_PRESSED) {
+    // Adding a second finger within the timeout period switches to
+    // passthrough.
+    state_ = PASSTHROUGH_MINUS_ONE;
+    return InPassthroughMinusOne(event, rewritten_event);
+  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    DCHECK_EQ(0U, current_touch_ids_.size());
+    state_ = SINGLE_TAP_RELEASED;
+    return EVENT_REWRITE_DISCARD;
+  } else if (type == ui::ET_TOUCH_MOVED) {
+    // If the user moves far enough from the initial touch location (outside
+    // the "slop" region, jump to the touch exploration mode early.
+    // TODO(evy, lisayin): Add gesture recognition here instead -
+    // we should probably jump to gesture mode here if the velocity is
+    // high enough, and touch exploration if the velocity is lower.
+    float delta = (event.location() - initial_press_->location()).Length();
+    if (delta > gesture_detector_config_.touch_slop) {
+      EnterTouchToMouseMode();
+      state_ = TOUCH_EXPLORATION;
+      return InTouchExploration(event, rewritten_event);
     }
+
+    return EVENT_REWRITE_DISCARD;
+  }
+  NOTREACHED() << "Unexpected event type received.";
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InSingleTapReleased(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  const ui::EventType type = event.type();
+  if (type == ui::ET_TOUCH_PRESSED) {
+    // This is the second tap in a double-tap (or double tap-hold).
+    // Rewrite at location of last touch exploration.
+    ui::TouchEvent* rewritten_press_event = new ui::TouchEvent(
+        ui::ET_TOUCH_PRESSED,
+        last_touch_exploration_location_,
+        event.touch_id(),
+        event.time_stamp());
+    rewritten_press_event->set_flags(event.flags());
+    rewritten_event->reset(rewritten_press_event);
+    state_ = DOUBLE_TAP_PRESSED;
+    return ui::EVENT_REWRITE_REWRITTEN;
+  }
+
+  NOTREACHED();
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InDoubleTapPressed(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  const ui::EventType type = event.type();
+  if (type == ui::ET_TOUCH_PRESSED) {
+    return ui::EVENT_REWRITE_DISCARD;
+  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    if (current_touch_ids_.size() != 0)
+      return EVENT_REWRITE_DISCARD;
+
+    // Rewrite at location of last touch exploration.
+    ui::TouchEvent* rewritten_release_event = new ui::TouchEvent(
+        ui::ET_TOUCH_RELEASED,
+        last_touch_exploration_location_,
+        event.touch_id(),
+        event.time_stamp());
+    rewritten_release_event->set_flags(event.flags());
+    rewritten_event->reset(rewritten_release_event);
+    ResetToNoFingersDown();
     return ui::EVENT_REWRITE_REWRITTEN;
   } else if (type == ui::ET_TOUCH_MOVED) {
-    std::vector<int>::iterator it =
-        std::find(touch_ids_.begin(), touch_ids_.end(), touch_id);
-    // We may fail to find the finger if the exploration mode was turned on
-    // while the user had some fingers touching the screen. We simply ignore
-    // those fingers for the purposes of event transformation.
-    if (it == touch_ids_.end())
-      return ui::EVENT_REWRITE_CONTINUE;
-    touch_locations_[*it] = location;
-    if (touch_ids_.size() == 1) {
-      // Touch moves are rewritten as mouse moves when there's only one finger
-      // touching the screen.
-      *rewritten_event = CreateMouseMoveEvent(location, flags).Pass();
-      return ui::EVENT_REWRITE_REWRITTEN;
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+  NOTREACHED() << "Unexpected event type received.";
+  return ui::EVENT_REWRITE_CONTINUE;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InTouchExploration(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  const ui::EventType type = event.type();
+  if (type == ui::ET_TOUCH_PRESSED) {
+    // Ignore any additional fingers when we're already in touch exploration
+    // mode. TODO(evy, lisayin): Support "split-tap" here instead.
+    return ui::EVENT_REWRITE_DISCARD;
+  } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    if (current_touch_ids_.size() == 0)
+      ResetToNoFingersDown();
+  } else if (type != ui::ET_TOUCH_MOVED) {
+    NOTREACHED() << "Unexpected event type received.";
+    return ui::EVENT_REWRITE_CONTINUE;
+  }
+
+  // Rewrite as a mouse-move event.
+  *rewritten_event = CreateMouseMoveEvent(event.location(), event.flags());
+  last_touch_exploration_location_ = event.location();
+  return ui::EVENT_REWRITE_REWRITTEN;
+}
+
+ui::EventRewriteStatus TouchExplorationController::InPassthroughMinusOne(
+    const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
+  ui::EventType type = event.type();
+  gfx::PointF location = event.location_f();
+
+  if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    if (current_touch_ids_.size() == 0)
+      ResetToNoFingersDown();
+
+    if (initial_touch_id_passthrough_mapping_ == kTouchIdUnassigned) {
+      if (event.touch_id() == initial_press_->touch_id()) {
+        initial_touch_id_passthrough_mapping_ = kTouchIdNone;
+      } else {
+        // If the only finger now remaining is the first finger,
+        // rewrite as a move to the location of the first finger.
+        initial_touch_id_passthrough_mapping_ = event.touch_id();
+        ui::TouchEvent* rewritten_passthrough_event = new ui::TouchEvent(
+            ui::ET_TOUCH_MOVED,
+            touch_locations_[initial_press_->touch_id()],
+            initial_touch_id_passthrough_mapping_,
+            event.time_stamp());
+        rewritten_passthrough_event->set_flags(event.flags());
+        rewritten_event->reset(rewritten_passthrough_event);
+        return ui::EVENT_REWRITE_REWRITTEN;
+      }
     }
-    if (touch_id == touch_ids_.front()) {
-      // Touch moves of the first finger are discarded when there's more than
-      // one finger touching.
+  }
+
+  if (event.touch_id() == initial_press_->touch_id()) {
+    if (initial_touch_id_passthrough_mapping_ == kTouchIdNone ||
+        initial_touch_id_passthrough_mapping_ == kTouchIdUnassigned) {
       return ui::EVENT_REWRITE_DISCARD;
     }
-    return ui::EVENT_REWRITE_CONTINUE;
+
+    ui::TouchEvent* rewritten_passthrough_event = new ui::TouchEvent(
+        type,
+        location,
+        initial_touch_id_passthrough_mapping_,
+        event.time_stamp());
+    rewritten_passthrough_event->set_flags(event.flags());
+    rewritten_event->reset(rewritten_passthrough_event);
+    return ui::EVENT_REWRITE_REWRITTEN;
   }
-  NOTREACHED() << "Unexpected event type received.";
+
   return ui::EVENT_REWRITE_CONTINUE;
 }
 
-ui::EventRewriteStatus TouchExplorationController::NextDispatchEvent(
-    const ui::Event& last_event,
-    scoped_ptr<ui::Event>* new_event) {
-  CHECK(next_dispatch_event_);
-  DCHECK(last_event.IsTouchEvent());
-  *new_event = next_dispatch_event_.Pass();
-  // Enter the mouse move mode if needed
-  if ((*new_event)->IsMouseEvent())
+void TouchExplorationController::OnTapTimerFired() {
+  if (state_ != SINGLE_TAP_RELEASED && state_ != SINGLE_TAP_PRESSED)
+    return;
+
+  if (state_ == SINGLE_TAP_RELEASED) {
+    ResetToNoFingersDown();
+  } else {
     EnterTouchToMouseMode();
-  return ui::EVENT_REWRITE_REWRITTEN;
+    state_ = TOUCH_EXPLORATION;
+  }
+
+  scoped_ptr<ui::Event> mouse_move = CreateMouseMoveEvent(
+      initial_press_->location(), initial_press_->flags());
+  DispatchEvent(mouse_move.get());
+  last_touch_exploration_location_ = initial_press_->location();
+}
+
+void TouchExplorationController::DispatchEvent(ui::Event* event) {
+  if (event_handler_for_testing_) {
+    event_handler_for_testing_->OnEvent(event);
+    return;
+  }
+
+  ui::EventDispatchDetails result ALLOW_UNUSED =
+      root_window_->GetHost()->dispatcher()->OnEventFromSource(event);
 }
 
 scoped_ptr<ui::Event> TouchExplorationController::CreateMouseMoveEvent(
@@ -164,4 +347,11 @@ void TouchExplorationController::EnterTouchToMouseMode() {
     cursor_client->HideCursor();
 }
 
+void TouchExplorationController::ResetToNoFingersDown() {
+  state_ = NO_FINGERS_DOWN;
+  initial_touch_id_passthrough_mapping_ = kTouchIdUnassigned;
+  if (tap_timer_.IsRunning())
+    tap_timer_.Stop();
+}
+
 }  // namespace ui

ui/chromeos/touch_exploration_controller.h

@@ -5,9 +5,11 @@
 #ifndef UI_CHROMEOS_TOUCH_EXPLORATION_CONTROLLER_H_
 #define UI_CHROMEOS_TOUCH_EXPLORATION_CONTROLLER_H_
 
+#include "base/timer/timer.h"
 #include "base/values.h"
 #include "ui/chromeos/ui_chromeos_export.h"
 #include "ui/events/event_rewriter.h"
+#include "ui/events/gesture_detection/gesture_detector.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace aura {
@@ -17,17 +19,58 @@ class Window;
 namespace ui {
 
 class Event;
+class EventHandler;
+class TouchEvent;
 
 // TouchExplorationController is used in tandem with "Spoken Feedback" to
-// make the touch UI accessible. TouchExplorationController rewrites the
-// incoming touch events as follows:
-// - When one finger is touching the screen, touch events are converted to mouse
-//   moves. This is the "Touch Exploration Mode". (The idea is that mouse moves
-//   will be subsequently used by another component to move focus between UI
-//   elements, and the elements will be read out to the user.)
-// - When more than one finger is touching the screen, touches from the
-//   first (i.e. "oldest") finger are ignored, and the other touches go through
-//   as is.
+// make the touch UI accessible.
+//
+// ** Short version **
+//
+// At a high-level, single-finger events are used for accessibility -
+// exploring the screen gets turned into mouse moves (which can then be
+// spoken by an accessibility service running), a double-tap simulates a
+// click, and gestures can be used to send high-level accessibility commands.
+// When two or more fingers are pressed initially, from then on the events
+// are passed through, but with the initial finger removed - so if you swipe
+// down with two fingers, the running app will see a one-finger swipe.
+//
+// ** Long version **
+//
+// Here are the details of the implementation:
+//
+// When the first touch is pressed, a 300 ms grace period timer starts.
+//
+// If the user keeps their finger down for more than 300 ms and doesn't
+// perform a supported accessibility gesture in that time (e.g. swipe right),
+// they enter touch exploration mode, and all movements are translated into
+// synthesized mouse move events.
+//
+// Also, if the user moves their single finger outside a certain slop region
+// (without performing a gesture), they enter touch exploration mode earlier
+// than 300 ms.
+//
+// If the user taps and releases their finger, after 300 ms from the initial
+// touch, a single mouse move is fired.
+//
+// If the user double-taps, the second tap is passed through, allowing the
+// user to click - however, the double-tap location is changed to the location
+// of the last successful touch exploration - that allows the user to explore
+// anywhere on the screen, hear its description, then double-tap anywhere
+// to activate it.
+//
+// If the user adds a second finger during the grace period, they enter
+// passthrough mode. In this mode, the first finger is ignored but all
+// additional touch events are mostly passed through unmodified. So a
+// two-finger scroll gets passed through as a one-finger scroll. However,
+// once in passthrough mode, if one finger is released, the remaining fingers
+// continue to pass through events, allowing the user to start a scroll
+// with two fingers but finish it with one. Sometimes this requires rewriting
+// the touch ids.
+//
+// Once either touch exploration or passthrough mode has been activated,
+// it remains in that mode until all fingers have been released.
+//
 // The caller is expected to retain ownership of instances of this class and
 // destroy them before |root_window| is destroyed.
 class UI_CHROMEOS_EXPORT TouchExplorationController :
@@ -36,28 +79,120 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
   explicit TouchExplorationController(aura::Window* root_window);
   virtual ~TouchExplorationController();
 
- private:
-  scoped_ptr<ui::Event> CreateMouseMoveEvent(const gfx::PointF& location,
-                                             int flags);
-
-  void EnterTouchToMouseMode();
+  void CallTapTimerNowForTesting();
+  void SetEventHandlerForTesting(ui::EventHandler* event_handler_for_testing);
+  bool IsInNoFingersDownStateForTesting() const;
 
+ private:
   // Overridden from ui::EventRewriter
   virtual ui::EventRewriteStatus RewriteEvent(
       const ui::Event& event, scoped_ptr<ui::Event>* rewritten_event) OVERRIDE;
   virtual ui::EventRewriteStatus NextDispatchEvent(
       const ui::Event& last_event, scoped_ptr<ui::Event>* new_event) OVERRIDE;
 
+  // Event handlers based on the current state - see State, below.
+  ui::EventRewriteStatus InNoFingersDown(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InSingleTapPressed(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InSingleTapReleased(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InDoubleTapPressed(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InTouchExploration(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InPassthroughMinusOne(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+
+  // This timer is started every time we get the first press event, and
+  // it fires after the double-click timeout elapses (300 ms by default).
+  // If the user taps and releases within 300 ms and doesn't press again,
+  // we treat that as a single mouse move (touch exploration) event.
+  void OnTapTimerFired();
+
+  // Dispatch a new event outside of the event rewriting flow.
+  void DispatchEvent(ui::Event* event);
+
+  scoped_ptr<ui::Event> CreateMouseMoveEvent(const gfx::PointF& location,
+                                             int flags);
+
+  void EnterTouchToMouseMode();
+
+  // Set the state to NO_FINGERS_DOWN and reset any other fields to their
+  // default value.
+  void ResetToNoFingersDown();
+
+  enum State {
+    // No fingers are down and no events are pending.
+    NO_FINGERS_DOWN,
+
+    // A single finger is down, but we're not yet sure if this is going
+    // to be touch exploration or something else.
+    SINGLE_TAP_PRESSED,
+
+    // The user pressed and released a single finger - a tap - but we have
+    // to wait until the end of the grace period to allow the user to tap the
+    // second time. If the second tap doesn't occurs within the grace period,
+    // we dispatch a mouse move at the location of the first tap.
+    SINGLE_TAP_RELEASED,
+
+    // The user tapped once, and before the grace period expired, pressed
+    // one finger down to begin a double-tap, but has not released it yet.
+    DOUBLE_TAP_PRESSED,
+
+    // We're in touch exploration mode. Anything other than the first finger
+    // is ignored, and movements of the first finger are rewritten as mouse
+    // move events. This mode is entered if a single finger is pressed and
+    // after the grace period the user hasn't added a second finger or
+    // moved the finger outside of the slop region. We'll stay in this
+    // mode until all fingers are lifted.
+    TOUCH_EXPLORATION,
+
+    // The user placed two or more fingers down within the grace period.
+    // We're now in passthrough mode until all fingers are lifted. Initially
+    // the first finger is ignored and other fingers are passed through
+    // as-is. If a finger other than the initial one is the first to be
+    // released, we rewrite the first finger with the touch id of the finger
+    // that was released, from now on. The motivation for this is that if
+    // the user starts a scroll with 2 fingers, they can release either one
+    // and continue the scrolling.
+    PASSTHROUGH_MINUS_ONE,
+  };
+
+  aura::Window* root_window_;
+
   // A set of touch ids for fingers currently touching the screen.
-  std::vector<int> touch_ids_;
+  std::vector<int> current_touch_ids_;
 
   // Map of touch ids to their last known location.
   std::map<int, gfx::PointF> touch_locations_;
 
-  // Initialized from RewriteEvent() and dispatched in NextDispatchEvent().
-  scoped_ptr<ui::Event> next_dispatch_event_;
+  // The touch id that any events on the initial finger should be rewritten
+  // as in passthrough-minus-one mode. If kTouchIdUnassigned, events on the
+  // initial finger are discarded. If kTouchIdNone, the initial finger
+  // has been released and no more rewriting will be done.
+  int initial_touch_id_passthrough_mapping_;
 
-  aura::Window* root_window_;
+  // The current state.
+  State state_;
+
+  // A copy of the event from the initial touch press.
+  scoped_ptr<ui::TouchEvent> initial_press_;
+
+  // The last location where we synthesized a mouse move event.
+  // When the user double-taps, we send the passed-through tap here.
+  gfx::PointF last_touch_exploration_location_;
+
+  // A timer to fire the mouse move event after the double-tap delay.
+  base::OneShotTimer<TouchExplorationController> tap_timer_;
+
+  // For testing only, an event handler to use for generated events
+  // outside of the normal event rewriting flow.
+  ui::EventHandler* event_handler_for_testing_;
+
+  // A default gesture detector config, so we can share the same
+  // timeout and pixel slop constants.
+  ui::GestureDetector::Config gesture_detector_config_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchExplorationController);
 };

ui/chromeos/touch_exploration_controller_unittest.cc

@@ -4,6 +4,7 @@
 
 #include "ui/chromeos/touch_exploration_controller.h"
 
+#include "base/test/simple_test_tick_clock.h"
 #include "base/time/time.h"
 #include "ui/aura/client/cursor_client.h"
 #include "ui/aura/test/aura_test_base.h"
@@ -60,7 +61,8 @@ class EventCapturer : public ui::EventHandler {
 
 class TouchExplorationTest : public aura::test::AuraTestBase {
  public:
-  TouchExplorationTest() {}
+  TouchExplorationTest()
+      : simulated_clock_(new base::SimpleTestTickClock()) {}
   virtual ~TouchExplorationTest() {}
 
   virtual void SetUp() OVERRIDE {
@@ -69,6 +71,11 @@ class TouchExplorationTest : public aura::test::AuraTestBase {
     aura::test::AuraTestBase::SetUp();
     cursor_client_.reset(new aura::test::TestCursorClient(root_window()));
     root_window()->AddPreTargetHandler(&event_capturer_);
+    generator_.reset(new aura::test::EventGenerator(root_window()));
+    // The generator takes ownership of the clock.
+    generator_->SetTickClock(scoped_ptr<base::TickClock>(simulated_clock_));
+    cursor_client()->ShowCursor();
+    cursor_client()->DisableMouseEvents();
   }
 
   virtual void TearDown() OVERRIDE {
@@ -78,23 +85,43 @@ class TouchExplorationTest : public aura::test::AuraTestBase {
     aura::test::AuraTestBase::TearDown();
   }
 
+ protected:
+  aura::client::CursorClient* cursor_client() { return cursor_client_.get(); }
+
   const ScopedVector<ui::LocatedEvent>& GetCapturedEvents() {
     return event_capturer_.captured_events();
   }
 
+  std::vector<ui::LocatedEvent*> GetCapturedEventsOfType(int type) {
+    const ScopedVector<ui::LocatedEvent>& all_events = GetCapturedEvents();
+    std::vector<ui::LocatedEvent*> events;
+    for (size_t i = 0; i < all_events.size(); ++i) {
+      if (type == all_events[i]->type())
+        events.push_back(all_events[i]);
+    }
+    return events;
+  }
+
   void ClearCapturedEvents() {
     event_capturer_.Reset();
   }
 
- protected:
-  aura::client::CursorClient* cursor_client() { return cursor_client_.get(); }
+  void AdvanceSimulatedTimePastTapDelay() {
+    simulated_clock_->Advance(base::TimeDelta::FromMilliseconds(1000));
+    touch_exploration_controller_->CallTapTimerNowForTesting();
+  }
 
   void SwitchTouchExplorationMode(bool on) {
-    if (!on && touch_exploration_controller_.get())
+    if (!on && touch_exploration_controller_.get()) {
       touch_exploration_controller_.reset();
-    else if (on && !touch_exploration_controller_.get())
+    } else if (on && !touch_exploration_controller_.get()) {
       touch_exploration_controller_.reset(
           new ui::TouchExplorationController(root_window()));
+      touch_exploration_controller_->SetEventHandlerForTesting(
+          &event_capturer_);
+      cursor_client()->ShowCursor();
+      cursor_client()->DisableMouseEvents();
+    }
   }
 
   bool IsInTouchToMouseMode() {
@@ -105,6 +132,22 @@ class TouchExplorationTest : public aura::test::AuraTestBase {
            !cursor_client->IsCursorVisible();
   }
 
+  bool IsInNoFingersDownState() {
+    return touch_exploration_controller_->IsInNoFingersDownStateForTesting();
+  }
+
+  base::TimeDelta Now() {
+    // This is the same as what EventTimeForNow() does, but here we do it
+    // with our simulated clock.
+    return base::TimeDelta::FromInternalValue(
+        simulated_clock_->NowTicks().ToInternalValue());
+  }
+
+  scoped_ptr<aura::test::EventGenerator> generator_;
+  ui::GestureDetector::Config gesture_detector_config_;
+  // Owned by |generator_|.
+  base::SimpleTestTickClock* simulated_clock_;
+
  private:
   EventCapturer event_capturer_;
   scoped_ptr<ui::TouchExplorationController> touch_exploration_controller_;
@@ -150,50 +193,90 @@ void ConfirmEventsAreMouseAndEqual(ui::Event* e1, ui::Event* e2) {
 // events when running these tests as part of ui_unittests. We do get them when
 // the tests are run as part of ash unit tests.
 
-// Simple test to confirm one-finger touches are transformed into mouse moves.
-TEST_F(TouchExplorationTest, OneFingerTouch) {
+TEST_F(TouchExplorationTest, EntersTouchToMouseModeAfterPressAndDelay) {
+  SwitchTouchExplorationMode(true);
+  EXPECT_FALSE(IsInTouchToMouseMode());
+  generator_->PressTouch();
+  AdvanceSimulatedTimePastTapDelay();
+  EXPECT_TRUE(IsInTouchToMouseMode());
+}
+
+TEST_F(TouchExplorationTest, EntersTouchToMouseModeAfterMoveOutsideSlop) {
+  int slop = gesture_detector_config_.touch_slop;
+  int half_slop = slop / 2;
+
   SwitchTouchExplorationMode(true);
-  cursor_client()->ShowCursor();
-  cursor_client()->DisableMouseEvents();
-  aura::test::EventGenerator generator(root_window());
-  gfx::Point location_start = generator.current_location();
-  gfx::Point location_end(11, 12);
-  generator.PressTouch();
+  EXPECT_FALSE(IsInTouchToMouseMode());
+  generator_->set_current_location(gfx::Point(11, 12));
+  generator_->PressTouch();
+  generator_->MoveTouch(gfx::Point(11 + half_slop, 12));
+  EXPECT_FALSE(IsInTouchToMouseMode());
+  generator_->MoveTouch(gfx::Point(11, 12 + half_slop));
+  EXPECT_FALSE(IsInTouchToMouseMode());
+  generator_->MoveTouch(gfx::Point(11 + slop + 1, 12));
   EXPECT_TRUE(IsInTouchToMouseMode());
-  generator.MoveTouch(location_end);
-  // Confirm the actual mouse moves are unaffected.
+}
+
+TEST_F(TouchExplorationTest, OneFingerTap) {
+  SwitchTouchExplorationMode(true);
+  gfx::Point location(11, 12);
+  generator_->set_current_location(location);
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+  AdvanceSimulatedTimePastTapDelay();
+
+  std::vector<ui::LocatedEvent*> events =
+      GetCapturedEventsOfType(ui::ET_MOUSE_MOVED);
+  ASSERT_EQ(1U, events.size());
+
+  EXPECT_EQ(location, events[0]->location());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[0]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+  EXPECT_TRUE(IsInNoFingersDownState());
+}
+
+TEST_F(TouchExplorationTest, ActualMouseMovesUnaffected) {
+  SwitchTouchExplorationMode(true);
+
+  gfx::Point location_start(11, 12);
+  gfx::Point location_end(13, 14);
+  generator_->set_current_location(location_start);
+  generator_->PressTouch();
+  AdvanceSimulatedTimePastTapDelay();
+  generator_->MoveTouch(location_end);
+
+  gfx::Point location_real_mouse_move(15, 16);
   ui::MouseEvent mouse_move(ui::ET_MOUSE_MOVED,
-                            gfx::Point(13, 14),
-                            gfx::Point(13, 14),
+                            location_real_mouse_move,
+                            location_real_mouse_move,
                             0,
                             0);
-  generator.Dispatch(&mouse_move);
-  generator.ReleaseTouch();
-
-  const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
-  ScopedVector<ui::LocatedEvent>::const_iterator it;
-  // TODO(mfomitchev): mouse enter/exit events
-  int num_mouse_moves = 0;
-  for (it = captured_events.begin(); it != captured_events.end(); ++it) {
-    int type = (*it)->type();
-    // Ignore enter and exit mouse events synthesized when the mouse cursor is
-    // shown or hidden.
-    if (type == ui::ET_MOUSE_ENTERED || type == ui::ET_MOUSE_EXITED)
-      continue;
-    EXPECT_EQ(ui::ET_MOUSE_MOVED, (*it)->type());
-    if (num_mouse_moves == 0)
-      EXPECT_EQ(location_start, (*it)->location());
-    if (num_mouse_moves == 1 || num_mouse_moves == 3)
-      EXPECT_EQ(location_end, (*it)->location());
-    if (num_mouse_moves == 2)
-      CONFIRM_EVENTS_ARE_MOUSE_AND_EQUAL(*it, &mouse_move);
-    if (num_mouse_moves != 2) {
-      EXPECT_TRUE((*it)->flags() & ui::EF_IS_SYNTHESIZED);
-      EXPECT_TRUE((*it)->flags() & ui::EF_TOUCH_ACCESSIBILITY);
-    }
-    num_mouse_moves++;
-  }
-  EXPECT_EQ(4, num_mouse_moves);
+  generator_->Dispatch(&mouse_move);
+  generator_->ReleaseTouch();
+
+  std::vector<ui::LocatedEvent*> events =
+      GetCapturedEventsOfType(ui::ET_MOUSE_MOVED);
+  ASSERT_EQ(4U, events.size());
+
+  EXPECT_EQ(location_start, events[0]->location());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[0]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+
+  EXPECT_EQ(location_end, events[1]->location());
+  EXPECT_TRUE(events[1]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[1]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+
+  // The real mouse move goes through.
+  EXPECT_EQ(location_real_mouse_move, events[2]->location());
+  CONFIRM_EVENTS_ARE_MOUSE_AND_EQUAL(events[2], &mouse_move);
+  EXPECT_FALSE(events[2]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_FALSE(events[2]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+
+  // The touch release gets written as a mouse move.
+  EXPECT_EQ(location_end, events[3]->location());
+  EXPECT_TRUE(events[3]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[3]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+  EXPECT_TRUE(IsInNoFingersDownState());
 }
 
 // Turn the touch exploration mode on in the middle of the touch gesture.
@@ -201,12 +284,8 @@ TEST_F(TouchExplorationTest, OneFingerTouch) {
 // turned on don't get rewritten.
 TEST_F(TouchExplorationTest, TurnOnMidTouch) {
   SwitchTouchExplorationMode(false);
-  cursor_client()->ShowCursor();
-  cursor_client()->DisableMouseEvents();
-  aura::test::EventGenerator generator(root_window());
-  generator.PressTouchId(1);
+  generator_->PressTouchId(1);
   EXPECT_TRUE(cursor_client()->IsCursorVisible());
-  EXPECT_FALSE(cursor_client()->IsMouseEventsEnabled());
   ClearCapturedEvents();
 
   // Enable touch exploration mode while the first finger is touching the
@@ -217,8 +296,8 @@ TEST_F(TouchExplorationTest, TurnOnMidTouch) {
   ui::TouchEvent touch_move(ui::ET_TOUCH_MOVED,
                             gfx::Point(11, 12),
                             1,
-                            ui::EventTimeForNow());
-  generator.Dispatch(&touch_move);
+                            Now());
+  generator_->Dispatch(&touch_move);
   EXPECT_TRUE(cursor_client()->IsCursorVisible());
   EXPECT_FALSE(cursor_client()->IsMouseEventsEnabled());
   const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
@@ -227,9 +306,9 @@ TEST_F(TouchExplorationTest, TurnOnMidTouch) {
   ClearCapturedEvents();
 
   // The press from the second finger should get rewritten.
-  generator.PressTouchId(2);
+  generator_->PressTouchId(2);
+  AdvanceSimulatedTimePastTapDelay();
   EXPECT_TRUE(IsInTouchToMouseMode());
-  // TODO(mfomitchev): mouse enter/exit events
   ScopedVector<ui::LocatedEvent>::const_iterator it;
   for (it = captured_events.begin(); it != captured_events.end(); ++it) {
     if ((*it)->type() == ui::ET_MOUSE_MOVED)
@@ -242,34 +321,33 @@ TEST_F(TouchExplorationTest, TurnOnMidTouch) {
   ui::TouchEvent touch_release(ui::ET_TOUCH_RELEASED,
                                gfx::Point(11, 12),
                                1,
-                               ui::EventTimeForNow());
-  generator.Dispatch(&touch_release);
+                               Now());
+  generator_->Dispatch(&touch_release);
   ASSERT_EQ(1u, captured_events.size());
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[0], &touch_release);
   ClearCapturedEvents();
 
   // The move and release from the second finger should get rewritten.
-  generator.MoveTouchId(gfx::Point(13, 14), 2);
-  generator.ReleaseTouchId(2);
+  generator_->MoveTouchId(gfx::Point(13, 14), 2);
+  generator_->ReleaseTouchId(2);
   ASSERT_EQ(2u, captured_events.size());
   EXPECT_EQ(ui::ET_MOUSE_MOVED, captured_events[0]->type());
   EXPECT_EQ(ui::ET_MOUSE_MOVED, captured_events[1]->type());
+  EXPECT_TRUE(IsInNoFingersDownState());
 }
 
 TEST_F(TouchExplorationTest, TwoFingerTouch) {
   SwitchTouchExplorationMode(true);
-  aura::test::EventGenerator generator(root_window());
-  generator.PressTouchId(1);
+  generator_->PressTouchId(1);
   ClearCapturedEvents();
 
   // Confirm events from the second finger go through as is.
-  cursor_client()->ShowCursor();
-  cursor_client()->DisableMouseEvents();
-  ui::TouchEvent touch_press(ui::ET_TOUCH_PRESSED,
-                             gfx::Point(10, 11),
-                             2,
-                             ui::EventTimeForNow());
-  generator.Dispatch(&touch_press);
+  ui::TouchEvent touch_press(
+      ui::ET_TOUCH_PRESSED,
+      gfx::Point(10, 11),
+      2,
+      Now());
+  generator_->Dispatch(&touch_press);
   EXPECT_TRUE(cursor_client()->IsCursorVisible());
   EXPECT_FALSE(cursor_client()->IsMouseEventsEnabled());
   const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
@@ -285,11 +363,12 @@ TEST_F(TouchExplorationTest, TwoFingerTouch) {
   }
   EXPECT_NE(captured_events.end(), it);
   ClearCapturedEvents();
-  ui::TouchEvent touch_move(ui::ET_TOUCH_MOVED,
-                            gfx::Point(20, 21),
-                            2,
-                            ui::EventTimeForNow());
-  generator.Dispatch(&touch_move);
+  ui::TouchEvent touch_move(
+      ui::ET_TOUCH_MOVED,
+      gfx::Point(20, 21),
+      2,
+      Now());
+  generator_->Dispatch(&touch_move);
   ASSERT_EQ(1u, captured_events.size());
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[0], &touch_move);
   ClearCapturedEvents();
@@ -300,7 +379,7 @@ TEST_F(TouchExplorationTest, TwoFingerTouch) {
                             gfx::Point(13, 14),
                             0,
                             0);
-  generator.Dispatch(&mouse_move);
+  generator_->Dispatch(&mouse_move);
   // TODO(mfomitchev): mouse enter/exit events
   // Ignore synthesized ET_MOUSE_ENTERED/ET_MOUSE_EXITED
   for (it = captured_events.begin(); it != captured_events.end(); ++it) {
@@ -312,87 +391,71 @@ TEST_F(TouchExplorationTest, TwoFingerTouch) {
   EXPECT_NE(captured_events.end(), it);
   ClearCapturedEvents();
 
-  // Have some other fingers touch/move/release
-  generator.PressTouchId(3);
-  generator.PressTouchId(4);
-  generator.MoveTouchId(gfx::Point(30, 31), 3);
-  generator.ReleaseTouchId(3);
-  generator.ReleaseTouchId(4);
-  ClearCapturedEvents();
-
   // Events from the first finger should not go through while the second finger
   // is touching.
   gfx::Point touch1_location = gfx::Point(15, 16);
-  generator.MoveTouchId(touch1_location, 1);
+  generator_->MoveTouchId(touch1_location, 1);
   EXPECT_EQ(0u, GetCapturedEvents().size());
 
   EXPECT_TRUE(cursor_client()->IsCursorVisible());
   EXPECT_FALSE(cursor_client()->IsMouseEventsEnabled());
 
-  // A release of the second finger should go through, plus there should be a
-  // mouse move at |touch1_location| generated.
-  ui::TouchEvent touch_release(ui::ET_TOUCH_RELEASED,
-                               gfx::Point(25, 26),
-                               2,
-                               ui::EventTimeForNow());
-  generator.Dispatch(&touch_release);
-  EXPECT_TRUE(IsInTouchToMouseMode());
-  ASSERT_GE(captured_events.size(), 2u);
-  CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[0], &touch_release);
-  // TODO(mfomitchev): mouse enter/exit events
-  // Ignore synthesized ET_MOUSE_ENTERED/ET_MOUSE_EXITED
-  for (it = captured_events.begin(); it != captured_events.end(); ++it) {
-    if ((*it)->type() == ui::ET_MOUSE_MOVED) {
-      EXPECT_EQ(touch1_location, (*it)->location());
-      break;
-    }
-  }
-  EXPECT_NE(captured_events.end(), it);
+  // A release of the second finger should be rewritten as a mouse move
+  // of that finger to the |touch1_location| and we stay in passthrough
+  // mode.
+  ui::TouchEvent touch_release(
+      ui::ET_TOUCH_RELEASED,
+      gfx::Point(25, 26),
+      2,
+      Now());
+  generator_->Dispatch(&touch_release);
+  EXPECT_FALSE(IsInTouchToMouseMode());
+  ASSERT_EQ(captured_events.size(), 1u);
+  EXPECT_EQ(touch1_location, captured_events[0]->location());
 }
 
 TEST_F(TouchExplorationTest, MultiFingerTouch) {
   SwitchTouchExplorationMode(true);
-  aura::test::EventGenerator generator(root_window());
-  generator.PressTouchId(1);
-  generator.PressTouchId(2);
+  generator_->PressTouchId(1);
+  generator_->PressTouchId(2);
   ClearCapturedEvents();
 
   // Confirm events from other fingers go through as is.
   ui::TouchEvent touch3_press(ui::ET_TOUCH_PRESSED,
                               gfx::Point(10, 11),
                               3,
-                              ui::EventTimeForNow());
+                              Now());
   ui::TouchEvent touch3_move1(ui::ET_TOUCH_MOVED,
                               gfx::Point(12, 13),
                               3,
-                              ui::EventTimeForNow());
+                              Now());
   ui::TouchEvent touch4_press(ui::ET_TOUCH_PRESSED,
                               gfx::Point(20, 21),
                               4,
-                              ui::EventTimeForNow());
+                              Now());
   ui::TouchEvent touch3_move2(ui::ET_TOUCH_MOVED,
                               gfx::Point(14, 15),
                               3,
-                              ui::EventTimeForNow());
+                              Now());
   ui::TouchEvent touch4_move(ui::ET_TOUCH_MOVED,
                              gfx::Point(22, 23),
                              4,
-                             ui::EventTimeForNow());
+                             Now());
   ui::TouchEvent touch3_release(ui::ET_TOUCH_RELEASED,
                                 gfx::Point(14, 15),
                                 3,
-                                ui::EventTimeForNow());
+                                Now());
   ui::TouchEvent touch4_release(ui::ET_TOUCH_RELEASED,
                                 gfx::Point(22, 23),
                                 4,
-                                ui::EventTimeForNow());
-  generator.Dispatch(&touch3_press);
-  generator.Dispatch(&touch3_move1);
-  generator.Dispatch(&touch4_press);
-  generator.Dispatch(&touch3_move2);
-  generator.Dispatch(&touch4_move);
-  generator.Dispatch(&touch3_release);
-  generator.Dispatch(&touch4_release);
+                                Now());
+  generator_->Dispatch(&touch3_press);
+  generator_->Dispatch(&touch3_move1);
+  generator_->Dispatch(&touch4_press);
+  generator_->Dispatch(&touch3_move2);
+  generator_->Dispatch(&touch4_move);
+  generator_->Dispatch(&touch3_release);
+  generator_->Dispatch(&touch4_release);
 
   const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
   ASSERT_EQ(7u, captured_events.size());
@@ -401,59 +464,191 @@ TEST_F(TouchExplorationTest, MultiFingerTouch) {
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[2], &touch4_press);
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[3], &touch3_move2);
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[4], &touch4_move);
-  CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[5], &touch3_release);
+
+  // The release of finger 3 is rewritten as a move to the former location
+  // of finger 1.
+  EXPECT_EQ(ui::ET_TOUCH_MOVED, captured_events[5]->type());
   CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[6], &touch4_release);
 }
 
 // Test the case when there are multiple fingers on the screen and the first
-// finger is released. This should be rewritten as a release of the second
-// finger. Additionally, if the second finger is the only finger left touching,
-// we should enter a mouse move mode, and a mouse move event should be
-// dispatched.
+// finger is released. This should be ignored, but then the second finger
+// release should be passed through.
 TEST_F(TouchExplorationTest, FirstFingerLifted) {
   SwitchTouchExplorationMode(true);
-  aura::test::EventGenerator generator(root_window());
-  generator.PressTouchId(1);
-  generator.PressTouchId(2);
+  generator_->PressTouchId(1);
+  generator_->PressTouchId(2);
   gfx::Point touch2_location(10, 11);
-  generator.MoveTouchId(touch2_location, 2);
-  generator.PressTouchId(3);
+  generator_->MoveTouchId(touch2_location, 2);
+  generator_->PressTouchId(3);
   gfx::Point touch3_location(20, 21);
-  generator.MoveTouchId(touch3_location, 3);
+  generator_->MoveTouchId(touch3_location, 3);
   ClearCapturedEvents();
 
-  // Release of finger 1 should be rewritten as a release of finger 2.
-  generator.ReleaseTouchId(1);
+  // Release of finger 1 should be ignored.
+  generator_->ReleaseTouchId(1);
   const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
+  ASSERT_EQ(0u, captured_events.size());
+
+  // Move of finger 2 should be passed through.
+  gfx::Point touch2_new_location(20, 11);
+  generator_->MoveTouchId(touch2_new_location, 2);
   ASSERT_EQ(1u, captured_events.size());
-  EXPECT_EQ(ui::ET_TOUCH_RELEASED, captured_events[0]->type());
-  ui::TouchEvent* touch_event =
-      static_cast<ui::TouchEvent*>(captured_events[0]);
-  EXPECT_EQ(2, touch_event->touch_id());
-  EXPECT_EQ(touch2_location, touch_event->location());
+  EXPECT_EQ(ui::ET_TOUCH_MOVED, captured_events[0]->type());
+  EXPECT_EQ(touch2_new_location, captured_events[0]->location());
   ClearCapturedEvents();
 
-  // Release of finger 2 should be rewritten as a release of finger 3, plus
-  // we should enter the mouse move mode and a mouse move event should be
-  // dispatched.
-  cursor_client()->ShowCursor();
-  cursor_client()->DisableMouseEvents();
-  generator.ReleaseTouchId(2);
-  EXPECT_TRUE(IsInTouchToMouseMode());
-  ASSERT_GE(2u, captured_events.size());
+  // Release of finger 2 should be passed through.
+  ui::TouchEvent touch2_release(
+      ui::ET_TOUCH_RELEASED,
+      gfx::Point(14, 15),
+      2,
+      Now());
+  generator_->Dispatch(&touch2_release);
+  ASSERT_EQ(1u, captured_events.size());
+  CONFIRM_EVENTS_ARE_TOUCH_AND_EQUAL(captured_events[0], &touch2_release);
+}
+
+// Test the case when there are multiple fingers on the screen and the
+// second finger is released. This should be rewritten as a move to the
+// location of the first finger.
+TEST_F(TouchExplorationTest, SecondFingerLifted) {
+  SwitchTouchExplorationMode(true);
+  gfx::Point touch1_location(0, 11);
+  generator_->set_current_location(touch1_location);
+  generator_->PressTouchId(1);
+  generator_->PressTouchId(2);
+  gfx::Point touch2_location(10, 11);
+  generator_->MoveTouchId(touch2_location, 2);
+  generator_->PressTouchId(3);
+  gfx::Point touch3_location(20, 21);
+  generator_->MoveTouchId(touch3_location, 3);
+  ClearCapturedEvents();
+
+  // Release of finger 2 should be rewritten as a move to the location
+  // of the first finger.
+  generator_->ReleaseTouchId(2);
+  const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
+  ASSERT_EQ(1u, captured_events.size());
+  EXPECT_EQ(ui::ET_TOUCH_MOVED, captured_events[0]->type());
+  EXPECT_EQ(2, static_cast<ui::TouchEvent*>(captured_events[0])->touch_id());
+  EXPECT_EQ(touch1_location, captured_events[0]->location());
+  ClearCapturedEvents();
+
+  // Move of finger 1 should be rewritten as a move of finger 2.
+  gfx::Point touch1_new_location(0, 41);
+  generator_->MoveTouchId(touch1_new_location, 1);
+  ASSERT_EQ(1u, captured_events.size());
+  EXPECT_EQ(ui::ET_TOUCH_MOVED, captured_events[0]->type());
+  EXPECT_EQ(2, static_cast<ui::TouchEvent*>(captured_events[0])->touch_id());
+  EXPECT_EQ(touch1_new_location, captured_events[0]->location());
+  ClearCapturedEvents();
+
+  // Release of finger 1 should be rewritten as release of finger 2.
+  gfx::Point touch1_final_location(0, 41);
+  ui::TouchEvent touch1_release(
+      ui::ET_TOUCH_RELEASED,
+      touch1_final_location,
+      1,
+      Now());
+  generator_->Dispatch(&touch1_release);
+  ASSERT_EQ(1u, captured_events.size());
   EXPECT_EQ(ui::ET_TOUCH_RELEASED, captured_events[0]->type());
-  touch_event = static_cast<ui::TouchEvent*>(captured_events[0]);
-  EXPECT_EQ(3, touch_event->touch_id());
-  EXPECT_EQ(touch3_location, touch_event->location());
-  // TODO(mfomitchev): mouse enter/exit events
-  ScopedVector<ui::LocatedEvent>::const_iterator it;
-  for (it = captured_events.begin(); it != captured_events.end(); ++it) {
-    if ((*it)->type() == ui::ET_MOUSE_MOVED) {
-      EXPECT_EQ(touch3_location, (*it)->location());
-      break;
-    }
-  }
-  EXPECT_NE(captured_events.end(), it);
+  EXPECT_EQ(2, static_cast<ui::TouchEvent*>(captured_events[0])->touch_id());
+  EXPECT_EQ(touch1_final_location, captured_events[0]->location());
+}
+
+// If an event is received after the double-tap timeout has elapsed, but
+// before the timer has fired, a mouse move should still be generated.
+TEST_F(TouchExplorationTest, TimerFiresLateDuringTouchExploration) {
+  SwitchTouchExplorationMode(true);
+
+  // Send a press, then add another finger after the double-tap timeout.
+  generator_->PressTouchId(1);
+  simulated_clock_->Advance(base::TimeDelta::FromMilliseconds(1000));
+  generator_->PressTouchId(2);
+  std::vector<ui::LocatedEvent*> events =
+      GetCapturedEventsOfType(ui::ET_MOUSE_MOVED);
+  ASSERT_EQ(1U, events.size());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[0]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+
+  generator_->ReleaseTouchId(2);
+  generator_->ReleaseTouchId(1);
+  EXPECT_TRUE(IsInNoFingersDownState());
+}
+
+// If a new tap is received after the double-tap timeout has elapsed from
+// a previous tap, but before the timer has fired, a mouse move should
+// still be generated from the old tap.
+TEST_F(TouchExplorationTest, TimerFiresLateAfterTap) {
+  SwitchTouchExplorationMode(true);
+
+  // Send a tap at location1.
+  gfx::Point location0(11, 12);
+  generator_->set_current_location(location0);
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+
+  // Send a tap at location2, after the double-tap timeout, but before the
+  // timer fires.
+  gfx::Point location1(33, 34);
+  generator_->set_current_location(location1);
+  simulated_clock_->Advance(base::TimeDelta::FromMilliseconds(301));
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+  AdvanceSimulatedTimePastTapDelay();
+
+  std::vector<ui::LocatedEvent*> events =
+      GetCapturedEventsOfType(ui::ET_MOUSE_MOVED);
+  ASSERT_EQ(2U, events.size());
+  EXPECT_EQ(location0, events[0]->location());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[0]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+  EXPECT_EQ(location1, events[1]->location());
+  EXPECT_TRUE(events[1]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[1]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+  EXPECT_TRUE(IsInNoFingersDownState());
+}
+
+// Double-tapping should send a touch press and release through to the location
+// of the last successful touch exploration.
+TEST_F(TouchExplorationTest, DoubleTap) {
+  SwitchTouchExplorationMode(true);
+
+  // Tap at one location, and get a mouse move event.
+  gfx::Point tap_location(11, 12);
+  generator_->set_current_location(tap_location);
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+  AdvanceSimulatedTimePastTapDelay();
+
+  std::vector<ui::LocatedEvent*> events =
+      GetCapturedEventsOfType(ui::ET_MOUSE_MOVED);
+  ASSERT_EQ(1U, events.size());
+
+  EXPECT_EQ(tap_location, events[0]->location());
+  EXPECT_TRUE(events[0]->flags() & ui::EF_IS_SYNTHESIZED);
+  EXPECT_TRUE(events[0]->flags() & ui::EF_TOUCH_ACCESSIBILITY);
+  ClearCapturedEvents();
+
+  // Now double-tap at a different location. This should result in
+  // a single touch press and release at the location of the tap,
+  // not at the location of the double-tap.
+  gfx::Point double_tap_location(33, 34);
+  generator_->set_current_location(double_tap_location);
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+  generator_->PressTouch();
+  generator_->ReleaseTouch();
+
+  const ScopedVector<ui::LocatedEvent>& captured_events = GetCapturedEvents();
+  ASSERT_EQ(2U, captured_events.size());
+  EXPECT_EQ(ui::ET_TOUCH_PRESSED, captured_events[0]->type());
+  EXPECT_EQ(tap_location, captured_events[0]->location());
+  EXPECT_EQ(ui::ET_TOUCH_RELEASED, captured_events[1]->type());
+  EXPECT_EQ(tap_location, captured_events[1]->location());
+  EXPECT_TRUE(IsInNoFingersDownState());
 }
 
 }  // namespace ui

ui/ui_unittests.gyp

@@ -218,6 +218,7 @@
             '../chromeos/chromeos.gyp:chromeos',
             'aura/aura.gyp:aura_test_support',
             'chromeos/ui_chromeos.gyp:ui_chromeos',
+            'events/events.gyp:gesture_detection',
           ],
           'sources': [
             'chromeos/touch_exploration_controller_unittest.cc'