Side Slide Gestures for Accessibility

ui/chromeos/touch_exploration_controller.cc

Index: ui/chromeos/touch_exploration_controller.cc
diff --git a/ui/chromeos/touch_exploration_controller.cc b/ui/chromeos/touch_exploration_controller.cc
index 1a3b8fad4447ffd8eab56e8e7c1be57745109896..c9e4537e5c06b8ead2e3c010374e630b6f1f1e24 100644
--- a/ui/chromeos/touch_exploration_controller.cc
+++ b/ui/chromeos/touch_exploration_controller.cc
@@ -4,7 +4,6 @@
 
 #include "ui/chromeos/touch_exploration_controller.h"
 
-#include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
 #include "ui/aura/client/cursor_client.h"
 #include "ui/aura/window.h"
@@ -12,6 +11,7 @@
 #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__)
@@ -19,13 +19,31 @@
 namespace ui {
 
 namespace {
+
+// Delay between adjustment sounds.
+const base::TimeDelta kSoundDelay = base::TimeDelta::FromMilliseconds(150);
+
+// Within these bounds, the release event generated will reset the state to

[dmazzoni, 2014/07/22 17:14:54]

Nit: something like "within this many dips of the screen edge"

[lisayin, 2014/07/22 18:06:26]

Done.

+// NoFingersDown.
+const float kLeavingScreenEdge = 6;
+
+// Swipe/scroll gestures within these bounds (in dips) will change preset
+// settings.
+const float kMaxDistanceFromEdge = 75;

[aboxhall, 2014/07/22 17:20:41]

Where do these numbers come from? What are the units? Will they work on all
devices?

[lisayin, 2014/07/22 18:06:25]

Dip stands for device independent pixels so they should work for all devices.
The numbers are from letting Peter and David try it out and tweaking the numbers
from there.

+
+// After a slide gesture has been triggered, if the finger is still within these
+// bounds (in DIPs), the preset settings will still change.
+const float kSlopDistanceFromEdge = kMaxDistanceFromEdge + 40;
+
 // In ChromeOS, VKEY_LWIN is synonymous for the search key.
 const ui::KeyboardCode kChromeOSSearchKey = ui::VKEY_LWIN;
 }  // namespace
 
 TouchExplorationController::TouchExplorationController(
-    aura::Window* root_window)
+    aura::Window* root_window,
+    TouchExplorationControllerDelegate* delegate)
     : root_window_(root_window),
+      delegate_(delegate),
       state_(NO_FINGERS_DOWN),
       event_handler_for_testing_(NULL),
       gesture_provider_(this),
@@ -77,6 +95,15 @@ ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
     current_touch_ids_.push_back(touch_id);
     touch_locations_.insert(std::pair<int, gfx::PointF>(touch_id, location));
   } else if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    // In order to avoid accidentally double tapping when moving off the edge of
+    // the screen, the state will be rewritten to NoFingersDown.
+    TouchEvent touch_event = static_cast<const TouchEvent&>(event);
+    if (WithinBoundsOfEdge(touch_event.location(), kLeavingScreenEdge) !=
+        SCREEN_CENTER) {
+      if (current_touch_ids_.size() == 0)
+        ResetToNoFingersDown();
+    }
+
     std::vector<int>::iterator it = std::find(
         current_touch_ids_.begin(), current_touch_ids_.end(), touch_id);
 
@@ -121,6 +148,8 @@ ui::EventRewriteStatus TouchExplorationController::RewriteEvent(
       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;
@@ -191,6 +220,14 @@ ui::EventRewriteStatus TouchExplorationController::InSingleTapPressed(
             << "\n Minimum swipe velocity: "
             << gesture_detector_config_.minimum_swipe_velocity;
 
+    // Change to slide gesture if the slide occurred at the right edge.
+    int where = WithinBoundsOfEdge(event.location(), kMaxDistanceFromEdge);

[aboxhall, 2014/07/22 17:20:41]

Similarly, I think 'where' here is a little misleading. How about 'edges'?

[lisayin, 2014/07/22 18:06:25]

Done.

+    if (where & RIGHT_EDGE) {
+      state_ = SLIDE_GESTURE;
+      VLOG_STATE();
+      return InSlideGesture(event, rewritten_event);
+    }
+
     // If the user moves fast enough from the initial touch location, start
     // gesture detection. Otherwise, jump to the touch exploration mode early.
     if (velocity > gesture_detector_config_.minimum_swipe_velocity) {
@@ -497,6 +534,69 @@ ui::EventRewriteStatus TouchExplorationController::InWaitForRelease(
   return EVENT_REWRITE_DISCARD;
 }
 
+void TouchExplorationController::PlaySoundForTimer() {
+  delegate_->PlayVolumeAdjustSound();
+}
+
+ui::EventRewriteStatus TouchExplorationController::InSlideGesture(
+    const ui::TouchEvent& event,
+    scoped_ptr<ui::Event>* rewritten_event) {
+  // The timer should not fire when sliding.
+  if (tap_timer_.IsRunning())
+    tap_timer_.Stop();
+
+  ui::EventType type = event.type();
+  // If additional fingers are added before a swipe gesture has been registered,
+  // then wait until all fingers have been lifted.
+  if (type == ui::ET_TOUCH_PRESSED ||
+      event.touch_id() != initial_press_->touch_id()) {
+    if (sound_timer_.IsRunning())
+      sound_timer_.Stop();
+    // Discard any pending gestures.
+    ignore_result(gesture_provider_.GetAndResetPendingGestures());
+    state_ = WAIT_FOR_RELEASE;
+    return EVENT_REWRITE_DISCARD;
+  }
+
+  // Allows user to return to the edge to adjust the sound if they have left the
+  // boundaries.
+  int where = WithinBoundsOfEdge(event.location(), kSlopDistanceFromEdge);
+  if (!(where & RIGHT_EDGE) && (type != ui::ET_TOUCH_RELEASED)) {
+    if (sound_timer_.IsRunning()) {
+      sound_timer_.Stop();
+    }
+    return EVENT_REWRITE_DISCARD;
+  }
+
+  // This can occur if the user leaves the screen edge and then returns to it to
+  // continue adjusting the sound.
+  if (!sound_timer_.IsRunning()) {
+    sound_timer_.Start(FROM_HERE,
+                       kSoundDelay,
+                       this,
+                       &ui::TouchExplorationController::PlaySoundForTimer);
+    delegate_->PlayVolumeAdjustSound();
+  }
+
+  // There should not be more than one finger down.
+  DCHECK(current_touch_ids_.size() <= 1);
+  if (type == ui::ET_TOUCH_MOVED) {
+    gesture_provider_.OnTouchEvent(event);
+    gesture_provider_.OnTouchEventAck(false);
+  }
+  if (type == ui::ET_TOUCH_RELEASED || type == ui::ET_TOUCH_CANCELLED) {
+    gesture_provider_.OnTouchEvent(event);
+    gesture_provider_.OnTouchEventAck(false);
+    ignore_result(gesture_provider_.GetAndResetPendingGestures());
+    if (current_touch_ids_.size() == 0)
+      ResetToNoFingersDown();
+    return ui::EVENT_REWRITE_DISCARD;
+  }
+
+  ProcessGestureEvents();
+  return ui::EVENT_REWRITE_DISCARD;
+}
+
 void TouchExplorationController::OnTapTimerFired() {
   switch (state_) {
     case SINGLE_TAP_RELEASED:
@@ -521,7 +621,7 @@ void TouchExplorationController::OnTapTimerFired() {
       CreateMouseMoveEvent(initial_press_->location(), initial_press_->flags());
   DispatchEvent(mouse_move.get());
   last_touch_exploration_.reset(new TouchEvent(*initial_press_));
- }
+}
 
 void TouchExplorationController::DispatchEvent(ui::Event* event) {
   if (event_handler_for_testing_) {
@@ -532,12 +632,14 @@ void TouchExplorationController::DispatchEvent(ui::Event* event) {
       root_window_->GetHost()->dispatcher()->OnEventFromSource(event);
 }
 
-void TouchExplorationController::OnGestureEvent(ui::GestureEvent* gesture) {
+void TouchExplorationController::OnGestureEvent(
+    ui::GestureEvent* gesture) {
   CHECK(gesture->IsGestureEvent());
+  ui::EventType type = gesture->type();
   VLOG(0) << " \n Gesture Triggered: " << gesture->name();
-  if (gesture->type() == ui::ET_GESTURE_SWIPE) {
-    if (tap_timer_.IsRunning())
-      tap_timer_.Stop();
+  if (type == ui::ET_GESTURE_SWIPE && state_ != SLIDE_GESTURE) {
+    VLOG(0) << "Swipe!";
+    ignore_result(gesture_provider_.GetAndResetPendingGestures());
     OnSwipeEvent(gesture);
     return;
   }
@@ -550,11 +652,64 @@ void TouchExplorationController::ProcessGestureEvents() {
     for (ScopedVector<GestureEvent>::iterator i = gestures->begin();
          i != gestures->end();
          ++i) {
-      OnGestureEvent(*i);
+      if (state_ == SLIDE_GESTURE)
+        SideSlideControl(*i);
+      else
+        OnGestureEvent(*i);
     }
   }
 }
 
+void TouchExplorationController::SideSlideControl(ui::GestureEvent* gesture) {
+  ui::EventType type = gesture->type();
+  if (!gesture->IsScrollGestureEvent())
+    return;
+
+  if (type == ET_GESTURE_SCROLL_BEGIN) {
+    delegate_->PlayVolumeAdjustSound();
+  }
+
+  if (type == ET_GESTURE_SCROLL_END) {
+    if (sound_timer_.IsRunning())
+      sound_timer_.Stop();
+    delegate_->PlayVolumeAdjustSound();
+  }
+
+  // If the user is in the corner of the right side of the screen, the volume
+  // will be automatically set to 100% or muted depending on which corner they
+  // are in. Otherwise, the user will be able to adjust the volume by sliding
+  // their finger along the right side of the screen. Volume is relative to
+  // where they are on the right side of the screen.
+  gfx::Point location = gesture->location();
+  int where = WithinBoundsOfEdge(location, kSlopDistanceFromEdge);
+  if (!(where & RIGHT_EDGE))
+    return;
+
+  if (where == RIGHT_EDGE) {
+    location = gesture->location();
+    root_window_->GetHost()->ConvertPointFromNativeScreen(&location);
+    float volume_adjust_height =
+        root_window_->bounds().height() - 2 * kMaxDistanceFromEdge;
+    float ratio = (location.y() - kMaxDistanceFromEdge) / volume_adjust_height;
+    float volume = 100 - 100 * ratio;
+    VLOG(0) << "\n Volume = " << volume
+            << "\n Location = " << location.ToString()
+            << "\n Bounds = " << root_window_->bounds().right();
+
+    delegate_->SetOutputLevel(int(volume));
+    return;
+  }
+  else if (where & TOP_EDGE) {

[dmazzoni, 2014/07/22 17:14:54]

nit: belongs on previous line after }

[aboxhall, 2014/07/22 17:20:41]

Trivial, optional suggestion: move this and the below if blocks above the above
if block; since you can't be on the top and bottom at once, you can early out
and won't need any elses, then the above block becomes the default case and
doesn't need to go in an if block at all (unless you want to assert that it's
not in some impossible state).

[lisayin, 2014/07/22 18:06:25]

Done.

+    delegate_->SetOutputLevel(100);
+    return;
+  } else if (where & BOTTOM_EDGE) {
+    delegate_->SetOutputLevel(0);
+    return;
+  }
+  NOTREACHED() << "Invalid location " << where;
+}
+
+
 void TouchExplorationController::OnSwipeEvent(ui::GestureEvent* swipe_gesture) {
   // A swipe gesture contains details for the direction in which the swipe
   // occurred.
@@ -574,6 +729,34 @@ void TouchExplorationController::OnSwipeEvent(ui::GestureEvent* swipe_gesture) {
   }
 }
 
+int TouchExplorationController::WithinBoundsOfEdge(gfx::Point point,
+                                                   float bounds) {
+  // Since GetBoundsInScreen is in DIPs but point is not, then point needs to be
+  // converted.
+  root_window_->GetHost()->ConvertPointFromNativeScreen(&point);
+  gfx::Rect window = root_window_->GetBoundsInScreen();
+
+  float left_edge_limit = window.x() + bounds;
+  float right_edge_limit = window.right() - bounds;
+  float top_edge_limit = window.y() + bounds;
+  float bottom_edge_limit = window.bottom() - bounds;
+
+  // Bitwise manipulation in order to determine where on the screen the point
+  // lies. If more than one bit is turned on, then it is a corner where the two
+  // bit/edges intersect. Otherwise, if no bits are turned on, the point must be
+  // in the center of the screen.
+  int result = SCREEN_CENTER;
+  if (point.x() < left_edge_limit)
+    result |= LEFT_EDGE;
+  if (point.x() > right_edge_limit)
+    result |= RIGHT_EDGE;
+  if (point.y() < top_edge_limit)
+    result |= TOP_EDGE;
+  if (point.y() > bottom_edge_limit)
+    result |= BOTTOM_EDGE;
+  return result;
+}
+
 void TouchExplorationController::DispatchShiftSearchKeyEvent(
     const ui::KeyboardCode direction) {
   // In order to activate the shortcut shift+search+<arrow key>
@@ -623,6 +806,9 @@ void TouchExplorationController::EnterTouchToMouseMode() {
 }
 
 void TouchExplorationController::ResetToNoFingersDown() {
+  ProcessGestureEvents();
+  if (sound_timer_.IsRunning())
+    sound_timer_.Stop();
   state_ = NO_FINGERS_DOWN;
   VLOG_STATE();
   if (tap_timer_.IsRunning())
@@ -694,6 +880,8 @@ const char* TouchExplorationController::EnumStateToString(State state) {
       return "PASSTHROUGH";
     case WAIT_FOR_RELEASE:
       return "WAIT_FOR_RELEASE";
+    case SLIDE_GESTURE:
+      return "SLIDE_GESTURE";
   }
   return "Not a state";
 }