Side Slide Gestures for Accessibility

ui/chromeos/touch_exploration_controller.h

Index: ui/chromeos/touch_exploration_controller.h
diff --git a/ui/chromeos/touch_exploration_controller.h b/ui/chromeos/touch_exploration_controller.h
index 17731ffcdb79dc3d22a644021dc49906dfedbba4..12f0bfa2fcebe0e32d1289d5343f9a0d1dfb0552 100644
--- a/ui/chromeos/touch_exploration_controller.h
+++ b/ui/chromeos/touch_exploration_controller.h
@@ -26,9 +26,25 @@ class GestureEvent;
 class GestureProviderAura;
 class TouchEvent;
 
+// A delegate to handle commands in response to detected accessibility gesture
+// events.
+class TouchExplorationControllerDelegate {
+ public:
+  virtual ~TouchExplorationControllerDelegate() {}
+
+  // This function should be called whenever the delegate wants to play a sound
+  // when the volume adjusts.
+  virtual void PlayVolumeAdjustSound() = 0;
+
+  // Takes an int from 0.0 to 100.0 that indicates the percent the volume
+  // should be set to.
+  virtual void SetOutputLevel(int volume) = 0;
+};
+
 // TouchExplorationController is used in tandem with "Spoken Feedback" to
-// make the touch UI accessible. Gestures are mapped to accessiblity key
-// shortcuts.
+// make the touch UI accessible. Gestures performed in the middle of the screen
+// are mapped to accessiblity key shortcuts while gestures performed on the edge
+// of the screen can change settings.
 //
 // ** Short version **
 //
@@ -40,7 +56,10 @@ class TouchEvent;
 // right would correspond to the keyboard short cut shift+search+right.
 // 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.
+// down with two fingers, the running app will see a one-finger swipe. Slide
+// gestures performed on the edge of the screen can change settings
+// continuously. For example, sliding a finger along the right side of the
+// screen will change the volume.
 //
 // ** Long version **
 //
@@ -91,6 +110,24 @@ class TouchEvent;
 // adds a third finger while in two to one finger mode, all fingers and touch
 // events are passed through from then on.
 //
+// If the user places a finger on the edge of the screen and moves their finger
+// past slop, a slide gesture is performed. The user can then slide one finger
+// along an edge of the screen and continuously control a setting. Once the user
+// enters this state, the boundaries that define an edge expand so that the user
+// can now adjust the setting within a slightly bigger width along the screen.
+// If the user exits this area without lifting their finger, they will not be
+// able to perform any actions, however if they keep their finger down and
+// return to the "hot edge," then they can still adjust the setting. In order to
+// perform other touch accessibility movements, the user must lift their finger.
+// If additional fingers are added while in this state, the user will transition
+// to passthrough.
+//
+// Currently, only the right edge is mapped to control the volume. Volume
+// control along the edge of the screen is directly proportional to where the
+// user's finger is located on the screen. The top right corner of the screen
+// automatically sets the volume to 100% and the bottome right corner of the
+// screen automatically sets the volume to 0% once the user has moved past slop.
+//
 // Once touch exploration mode has been activated,
 // it remains in that mode until all fingers have been released.
 //
@@ -100,7 +137,9 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
     : public ui::EventRewriter,
       public ui::GestureProviderAuraClient {
  public:
-  explicit TouchExplorationController(aura::Window* root_window);
+  explicit TouchExplorationController(
+      aura::Window* root_window,
+      ui::TouchExplorationControllerDelegate* delegate);
   virtual ~TouchExplorationController();
 
  private:
@@ -134,6 +173,8 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InWaitForRelease(
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
+  ui::EventRewriteStatus InSlideGesture(
+      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).
@@ -157,6 +198,8 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
 
   void OnSwipeEvent(ui::GestureEvent* swipe_gesture);
 
+  void SideSlideControl(ui::GestureEvent* gesture);
+
   // Dispatches the keyboard short cut Shift+Search+<arrow key>
   // outside the event rewritting flow.
   void DispatchShiftSearchKeyEvent(const ui::KeyboardCode direction);
@@ -170,6 +213,22 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
   // default value.
   void ResetToNoFingersDown();
 
+  void PlaySoundForTimer();
+
+  // Some constants used in touch_exploration_controller:
+
+  // Within this many dips of the screen edge, the release event generated will
+  // reset the state to NoFingersDown.
+  const float kLeavingScreenEdge = 6;
+
+  // Swipe/scroll gestures within these bounds (in DIPs) will change preset
+  // settings.
+  const float kMaxDistanceFromEdge = 75;
+
+  // 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;
+
   enum State {
     // No fingers are down and no events are pending.
     NO_FINGERS_DOWN,
@@ -236,8 +295,28 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
     // generally useful for developing new features, because it creates a
     // simple way to handle a dead end in user flow.
     WAIT_FOR_RELEASE,
+
+    // If the user is within the given bounds from an edge of the screen, not
+    // including corners, then the resulting movements will be interpreted as
+    // slide gestures.
+    SLIDE_GESTURE,
   };
 
+  enum ScreenLocation {
+    // Hot "edges" of the screen are each represented by a respective bit.
+    NO_EDGE = 0,
+    RIGHT_EDGE = 1 << 0,
+    TOP_EDGE = 1 << 1,
+    LEFT_EDGE = 1 << 2,
+    BOTTOM_EDGE = 1 << 3,
+  };
+
+  // Given a point, if it is within the given bounds of an edge, returns the
+  // edge. If it is within the given bounds of two edges, returns an int with
+  // both bits that represent the respective edges turned on. Otherwise returns
+  // SCREEN_CENTER.
+  int FindEdgesWithinBounds(gfx::Point point, float bounds);
+
   void VlogState(const char* function_name);
 
   void VlogEvent(const ui::TouchEvent& event, const char* function_name);
@@ -247,6 +326,9 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
 
   aura::Window* root_window_;
 
+  // Handles volume control. Not owned.
+  ui::TouchExplorationControllerDelegate* delegate_;
+
   // A set of touch ids for fingers currently touching the screen.
   std::vector<int> current_touch_ids_;
 
@@ -276,6 +358,9 @@ class UI_CHROMEOS_EXPORT TouchExplorationController
   // A timer to fire the mouse move event after the double-tap delay.
   base::OneShotTimer<TouchExplorationController> tap_timer_;
 
+  // A timer to fire an indicating sound when sliding to change volume.
+  base::RepeatingTimer<TouchExplorationController> sound_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_;