Corner Passthrough for Accessibility

ui/chromeos/touch_exploration_controller.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/chromeos/touch_exploration_controller.h"
 
 #include "base/strings/string_number_conversions.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"
 #include "ui/gfx/geometry/rect.h"
 
 #define VLOG_STATE() if (VLOG_IS_ON(0)) VlogState(__func__)
 #define VLOG_EVENT(event) if (VLOG_IS_ON(0)) VlogEvent(event, __func__)
 
 namespace ui {
 
 namespace {
 
 // Delay between adjustment sounds.
 const base::TimeDelta kSoundDelay = base::TimeDelta::FromMilliseconds(150);
 
+// Delay before corner passthrough activates.
+const base::TimeDelta kCornerPassthroughDelay =
+    base::TimeDelta::FromMilliseconds(500);
+
 // In ChromeOS, VKEY_LWIN is synonymous for the search key.
 const ui::KeyboardCode kChromeOSSearchKey = ui::VKEY_LWIN;
 }  // namespace
 
 TouchExplorationController::TouchExplorationController(
     aura::Window* root_window,
     TouchExplorationControllerDelegate* delegate)
     : root_window_(root_window),
       delegate_(delegate),
       state_(NO_FINGERS_DOWN),
       event_handler_for_testing_(NULL),
       gesture_provider_(this),
       prev_state_(NO_FINGERS_DOWN),
-      VLOG_on_(true) {
+      VLOG_on_(true),
+      waiting_for_corner_passthrough_(false) {
   CHECK(root_window);
   root_window->GetHost()->GetEventSource()->AddEventRewriter(this);
 }
 
 TouchExplorationController::~TouchExplorationController() {
   root_window_->GetHost()->GetEventSource()->RemoveEventRewriter(this);
 }
 
 ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
     const ui::Event& event,
@@ skipping 75 matching lines @@
     case DOUBLE_TAP_PRESSED:
       return InDoubleTapPressed(touch_event, rewritten_event);
     case TOUCH_EXPLORATION:
       return InTouchExploration(touch_event, rewritten_event);
     case GESTURE_IN_PROGRESS:
       return InGestureInProgress(touch_event, rewritten_event);
     case TOUCH_EXPLORE_SECOND_PRESS:
       return InTouchExploreSecondPress(touch_event, rewritten_event);
     case TWO_TO_ONE_FINGER:
       return InTwoToOneFinger(touch_event, rewritten_event);
+    case CORNER_PASSTHROUGH:
+      return InCornerPassthrough(touch_event, rewritten_event);
     case PASSTHROUGH:
       return InPassthrough(touch_event, rewritten_event);
     case WAIT_FOR_RELEASE:
       return InWaitForRelease(touch_event, rewritten_event);
     case SLIDE_GESTURE:
       return InSlideGesture(touch_event, rewritten_event);
   }
   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));
-    last_unused_finger_event_.reset(new TouchEvent(event));
-    tap_timer_.Start(FROM_HERE,
-                     gesture_detector_config_.double_tap_timeout,
-                     this,
-                     &TouchExplorationController::OnTapTimerFired);
-    gesture_provider_.OnTouchEvent(event);
-    gesture_provider_.OnTouchEventAck(false);
-    ProcessGestureEvents();
-    state_ = SINGLE_TAP_PRESSED;
-    VLOG_STATE();
-    return ui::EVENT_REWRITE_DISCARD;
+  if (type != ui::ET_TOUCH_PRESSED) {
+    NOTREACHED() << "Unexpected event type received: " << event.name();
+    return ui::EVENT_REWRITE_CONTINUE;
   }
-  NOTREACHED() << "Unexpected event type received: " << event.name();;
-  return ui::EVENT_REWRITE_CONTINUE;
+  int location = FindEdgesWithinBounds(event.location(), kSlopDistanceFromEdge);
+  base::TimeDelta timeout;
+
+  // If the press was at a corner, the user might go into corner passthrough
+  // instead.
+  bool in_a_bottom_corner =
+      (BOTTOM_LEFT_CORNER == location) || (BOTTOM_RIGHT_CORNER == location);
+  if (in_a_bottom_corner) {
+    VLOG(0) << "Location: " << location;
+    timeout = kCornerPassthroughDelay;
+    waiting_for_corner_passthrough_ = true;
+  } else {
+    timeout = gesture_detector_config_.double_tap_timeout;
+    waiting_for_corner_passthrough_ = false;
+  }
+
+  initial_press_.reset(new TouchEvent(event));
+  last_unused_finger_event_.reset(new TouchEvent(event));
+  tap_timer_.Start(
+      FROM_HERE, timeout, this, &TouchExplorationController::OnTapTimerFired);
+  gesture_provider_.OnTouchEvent(event);
+  gesture_provider_.OnTouchEventAck(false);
+  ProcessGestureEvents();
+  state_ = SINGLE_TAP_PRESSED;
+  VLOG_STATE();
+  return ui::EVENT_REWRITE_DISCARD;
 }
 
 ui::EventRewriteStatus TouchExplorationController::InSingleTapPressed(
     const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event) {
   const ui::EventType type = event.type();
 
+  int location = FindEdgesWithinBounds(event.location(), kMaxDistanceFromEdge);
+  bool in_a_bottom_corner =
+      (location == BOTTOM_LEFT_CORNER) || (location == BOTTOM_RIGHT_CORNER);
+  // If the event is from the initial press and the location is no longer in the
+  // corner, then we are not waiting for a corner passthrough anymore.
+  if (event.touch_id() == initial_press_->touch_id() && in_a_bottom_corner) {

[aboxhall, 2014/07/24 18:26:34]

I think |in_a_bottom_corner| should be negated...

[lisayin, 2014/07/25 20:11:57]

Opps...

+    waiting_for_corner_passthrough_ = false;
+    // If the initial press was in a corner, then more than the double tap
+    // timeout could have elapsed.
+    if (tap_timer_.IsRunning() &&
+        event.time_stamp() - initial_press_->time_stamp() >
+            gesture_detector_config_.double_tap_timeout) {
+      tap_timer_.Stop();
+      OnTapTimerFired();
+      return EVENT_REWRITE_DISCARD;
+    }
+  }
+
   if (type == ui::ET_TOUCH_PRESSED) {
     // Adding a second finger within the timeout period switches to
     // passing through every event from the second finger and none form the
     // first. The event from the first finger is still saved in initial_press_.
     state_ = TWO_TO_ONE_FINGER;
     last_two_to_one_.reset(new TouchEvent(event));
     rewritten_event->reset(new ui::TouchEvent(ui::ET_TOUCH_PRESSED,
                                               event.location(),
                                               event.touch_id(),
                                               event.time_stamp()));
@@ skipping 208 matching lines @@
                                                 event.time_stamp()));
       (*rewritten_event)->set_flags(event.flags());
       state_ = WAIT_FOR_RELEASE;
       return ui::EVENT_REWRITE_REWRITTEN;
     }
   } else if (type == ui::ET_TOUCH_PRESSED) {
     DCHECK(current_touch_ids_.size() == 3);
     // If a third finger is pressed, we are now going into passthrough mode
     // and now need to dispatch the first finger into a press, as well as the
     // recent press.
-    if (current_touch_ids_.size() == 3){
+    if (current_touch_ids_.size() == 3) {
       state_ = PASSTHROUGH;
       scoped_ptr<ui::TouchEvent> first_finger_press;
       first_finger_press.reset(
           new ui::TouchEvent(ui::ET_TOUCH_PRESSED,
                              last_unused_finger_event_->location(),
                              last_unused_finger_event_->touch_id(),
                              event.time_stamp()));
       DispatchEvent(first_finger_press.get());
       rewritten_event->reset(new ui::TouchEvent(ui::ET_TOUCH_PRESSED,
                                                 event.location(),
@@ skipping 18 matching lines @@
                                                 event.touch_id(),
                                                 event.time_stamp()));
       (*rewritten_event)->set_flags(event.flags());
       return ui::EVENT_REWRITE_REWRITTEN;
     }
   }
   NOTREACHED() << "Unexpected event type received: " << event.name();
   return ui::EVENT_REWRITE_CONTINUE;
 }
 
+ui::EventRewriteStatus TouchExplorationController::InCornerPassthrough(
+    const ui::TouchEvent& event,
+    scoped_ptr<ui::Event>* rewritten_event) {
+  ui::EventType type = event.type();
+  if (current_touch_ids_.size() == 0) {
+    ResetToNoFingersDown();
+  }
+
+  if (event.touch_id() == initial_press_->touch_id()) {

[aboxhall, 2014/07/24 18:26:34]

Some comments explaining this block would be helpful. I gather it's detecting
where you've slightly moved the original finger within the corner and discarding
that event, and also discarding any events on that finger which follow from
moving it out of the corner?

[lisayin, 2014/07/25 20:11:57]

Done.

+    int edge = FindEdgesWithinBounds(event.location(), kSlopDistanceFromEdge);

[aboxhall, 2014/07/24 18:26:34]

suggestion: s/edge/edges/

[lisayin, 2014/07/25 20:11:57]

Done.

+    bool in_a_bottom_corner = (edge == BOTTOM_LEFT_CORNER) ||
+                              (edge == BOTTOM_RIGHT_CORNER);
+    if (type == ui::ET_TOUCH_MOVED && in_a_bottom_corner)
+      return ui::EVENT_REWRITE_DISCARD;
+
+    waiting_for_corner_passthrough_ = false;
+    state_ = WAIT_FOR_RELEASE;
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+
+  rewritten_event->reset(new ui::TouchEvent(
+      type, event.location(), event.touch_id(), event.time_stamp()));
+  (*rewritten_event)->set_flags(event.flags());
+
+  return ui::EVENT_REWRITE_REWRITTEN;
+}
+
 ui::EventRewriteStatus TouchExplorationController::InPassthrough(
     const ui::TouchEvent& event,
     scoped_ptr<ui::Event>* rewritten_event) {
   ui::EventType type = event.type();
 
   if (!(type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED ||
         type == ui::ET_TOUCH_MOVED || type == ui::ET_TOUCH_PRESSED)) {
     NOTREACHED() << "Unexpected event type received: " << event.name();
     return ui::EVENT_REWRITE_CONTINUE;
   }
@@ skipping 125 matching lines @@
     if (current_touch_ids_.size() == 0)
       ResetToNoFingersDown();
     return ui::EVENT_REWRITE_DISCARD;
   }
 
   ProcessGestureEvents();
   return ui::EVENT_REWRITE_DISCARD;
 }
 
 void TouchExplorationController::OnTapTimerFired() {
+  if (waiting_for_corner_passthrough_) {
+    delegate_->PlayEarCon();
+    delete gesture_provider_.GetAndResetPendingGestures();
+    state_ = CORNER_PASSTHROUGH;
+    VLOG_STATE();
+    return;
+  }
+
   switch (state_) {
     case SINGLE_TAP_RELEASED:
       ResetToNoFingersDown();
       break;
     case TOUCH_EXPLORE_RELEASED:
       ResetToNoFingersDown();
       last_touch_exploration_.reset(new TouchEvent(*initial_press_));
       return;
     case SINGLE_TAP_PRESSED:
     case GESTURE_IN_PROGRESS:
@@ skipping 199 matching lines @@
 void TouchExplorationController::EnterTouchToMouseMode() {
   aura::client::CursorClient* cursor_client =
       aura::client::GetCursorClient(root_window_);
   if (cursor_client && !cursor_client->IsMouseEventsEnabled())
     cursor_client->EnableMouseEvents();
   if (cursor_client && cursor_client->IsCursorVisible())
     cursor_client->HideCursor();
 }
 
 void TouchExplorationController::ResetToNoFingersDown() {
+  waiting_for_corner_passthrough_ = false;
   ProcessGestureEvents();
   if (sound_timer_.IsRunning())
     sound_timer_.Stop();
   state_ = NO_FINGERS_DOWN;
   VLOG_STATE();
   if (tap_timer_.IsRunning())
     tap_timer_.Stop();
 }
 
 void TouchExplorationController::VlogState(const char* function_name) {
@@ skipping 50 matching lines @@
     case DOUBLE_TAP_PRESSED:
       return "DOUBLE_TAP_PRESSED";
     case TOUCH_EXPLORATION:
       return "TOUCH_EXPLORATION";
     case GESTURE_IN_PROGRESS:
       return "GESTURE_IN_PROGRESS";
     case TOUCH_EXPLORE_SECOND_PRESS:
       return "TOUCH_EXPLORE_SECOND_PRESS";
     case TWO_TO_ONE_FINGER:
       return "TWO_TO_ONE_FINGER";
+    case CORNER_PASSTHROUGH:
+      return "CORNER_PASSTHROUGH";
     case PASSTHROUGH:
       return "PASSTHROUGH";
     case WAIT_FOR_RELEASE:
       return "WAIT_FOR_RELEASE";
     case SLIDE_GESTURE:
       return "SLIDE_GESTURE";
   }
   return "Not a state";
 }
 
 }  // namespace ui