Side Slide Gestures for Accessibility

ui/chromeos/touch_exploration_controller.h

 // 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.
 
 #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.h"
 #include "ui/events/event_rewriter.h"
 #include "ui/events/gesture_detection/gesture_detector.h"
 #include "ui/events/gestures/gesture_provider_aura.h"
 #include "ui/gfx/geometry/point.h"
 
 namespace aura {
 class Window;
 }
 
 namespace ui {
 
 class Event;
 class EventHandler;
 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 **
 //
 // 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 single tap while the user
 // is in touch exploration or a double-tap simulates a click, and gestures
 // can be used to send high-level accessibility commands. For example, a swipe
 // 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 **
 //
 // 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
@@ skipping 30 matching lines @@
 // their touch exploration finger by tapping anywhere else on the screen with
 // a second finger, while the touch exploration finger is still pressed.
 //
 // If the user adds a second finger during the grace period, they enter
 // two to one finger passthrough mode. In this mode, the first finger is
 // ignored and the user can scroll or drag with the second finger. If either
 // finger is released, nothing happens until all fingers are up. If the user
 // 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.
 //
 // 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
     : 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:
   friend class TouchExplorationControllerTestApi;
 
   // Overridden from ui::EventRewriter
   virtual ui::EventRewriteStatus RewriteEvent(
       const ui::Event& event,
       scoped_ptr<ui::Event>* rewritten_event) OVERRIDE;
   virtual ui::EventRewriteStatus NextDispatchEvent(
@@ skipping 13 matching lines @@
   ui::EventRewriteStatus InTwoToOneFinger(
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InPassthrough(
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InGestureInProgress(
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InTouchExploreSecondPress(
       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).
   // 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);
 
   // Overridden from GestureProviderAuraClient.
   //
   // The gesture provider keeps track of all the touch events after
   // the user moves fast enough to trigger a gesture. After the user
   // completes their gesture, this method will decide what keyboard
   // input their gesture corresponded to.
   virtual void OnGestureEvent(ui::GestureEvent* gesture) OVERRIDE;
 
   // Process the gesture events that have been created.
   void ProcessGestureEvents();
 
   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);
 
   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();
 
+  void PlaySoundForTimer();
+
   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
@@ skipping 46 matching lines @@
     // If the user is in TWO_TO_ONE_FINGER with two fingers down and presses
     // a third finger, every finger and touch event is passed through until
     // all fingers are released.
     PASSTHROUGH,
 
     // If the user lifted a finger in TWO_TO_ONE_FINGER, they must release
     // all fingers before completing any more actions. This state is
     // 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.
+    RIGHT_EDGE = 0x1,

[aboxhall, 2014/07/22 17:20:42]

Optional: these don't really need to be hex since they're all <10 :)
You could make them regular decimal, or else go with something like 
https://code.google.com/p/chromium/codesearch#chromium/src/ui/gfx/canvas.h&l=...
- using bit shift operators to set each bit directly.

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

Done.

+    TOP_EDGE = 0x2,
+    LEFT_EDGE = 0x4,
+    BOTTOM_EDGE = 0x8,
+    SCREEN_CENTER = 0x0,

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

Suggest renaming this to NONE or NO_EDGE and moving it to the top.

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

Done.

+  };
+
+  // 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 WithinBoundsOfEdge(gfx::Point point, float bounds);

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

This method confused me; I thought it was going to return a bool. Perhaps
something like FindEdgesWithinBounds?

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

Done.

+
   void VlogState(const char* function_name);
 
   void VlogEvent(const ui::TouchEvent& event, const char* function_name);
 
   // Gets enum name from integer value.
   const char* EnumStateToString(State state);
 
   aura::Window* root_window_;
 
+  // Handles volume control. Not owned.

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

Nice comment :)

+  ui::TouchExplorationControllerDelegate* delegate_;
+
   // A set of touch ids for fingers currently touching the screen.
   std::vector<int> current_touch_ids_;
 
   // Map of touch ids to their last known location.
   std::map<int, gfx::PointF> touch_locations_;
 
   // The current state.
   State state_;
 
   // A copy of the event from the initial touch press.
   scoped_ptr<ui::TouchEvent> initial_press_;
 
   // Stores the most recent event from a finger that is currently not
   // sending events through, but might in the future (e.g. TwoToOneFinger
   // to Passthrough state).
   scoped_ptr<ui::TouchEvent> last_unused_finger_event_;
 
   // The last synthesized mouse move event. When the user double-taps,
   // we send the passed-through tap to the location of this event.
   scoped_ptr<ui::TouchEvent> last_touch_exploration_;
 
   // The last event from the finger that is being passed through in
   // TWO_TO_ONE_FINGER. When the user lifts a finger during two to one,
   // the location and id of the touch release is from here.
   scoped_ptr<ui::TouchEvent> last_two_to_one_;
 
   // A timer to fire the mouse move event after the double-tap delay.
   base::OneShotTimer<TouchExplorationController> tap_timer_;
 
+  // A timer to fire a indicating sound when sliding to change volume.

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

nit: an indicating

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

Done.

+  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_;
 
   // A default gesture detector config, so we can share the same
   // timeout and pixel slop constants.
   ui::GestureDetector::Config gesture_detector_config_;
 
   // Gesture Handler to interpret the touch events.
   ui::GestureProviderAura gesture_provider_;
 
   // The previous state entered.
   State prev_state_;
 
   // A copy of the previous event passed.
   scoped_ptr<ui::TouchEvent> prev_event_;
 
   // This toggles whether VLOGS are turned on or not.
   bool VLOG_on_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchExplorationController);
 };
 
 }  // namespace ui
 
 #endif  // UI_CHROMEOS_TOUCH_EXPLORATION_CONTROLLER_H_