Swipe 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 aa099282d449acfbe89e5e9401239a70d41f1bb6..e1483673051e0ff828e7368ccdbc8ddb94c319ce 100644
--- a/ui/chromeos/touch_exploration_controller.h
+++ b/ui/chromeos/touch_exploration_controller.h
@@ -11,6 +11,7 @@
 #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 {
@@ -21,10 +22,13 @@ namespace ui {
 
 class Event;
 class EventHandler;
+class GestureEvent;
+class GestureProviderAura;
 class TouchEvent;
 
 // TouchExplorationController is used in tandem with "Spoken Feedback" to
-// make the touch UI accessible.
+// make the touch UI accessible. Gestures are mapped to accessible key

[dmazzoni, 2014/06/25 05:06:02]

This comment has a one-sentence intro, then a one-paragraph version, then a
detailed long version.

You should probably leave this one-sentence intro alone, but add one sentence
about gestures to the short version, and probably several sentences about
gestures to the long version. The fact that it sends key events is a temporarily
implementation detail, probably good for the long version only. In the short
version, focus on the user experience.

[lisayin, 2014/06/25 22:51:05]

Done.

+// shortcuts.
 //
 // ** Short version **
 //
@@ -86,7 +90,7 @@ class TouchEvent;
 // 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::EventRewriter, public ui::GestureProviderAuraClient {
  public:
   explicit TouchExplorationController(aura::Window* root_window);
   virtual ~TouchExplorationController();
@@ -94,6 +98,7 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
   void CallTapTimerNowForTesting();
   void SetEventHandlerForTesting(ui::EventHandler* event_handler_for_testing);
   bool IsInNoFingersDownStateForTesting() const;
+  bool IsInGestureInProgressStateForTesting() const;
 
  private:
   // Overridden from ui::EventRewriter
@@ -114,10 +119,13 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
       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 InGestureInProgress(
+      const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InPassthroughMinusOne(
       const ui::TouchEvent& event, scoped_ptr<ui::Event>* rewritten_event);
   ui::EventRewriteStatus InTouchExploreSecondPress(
       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,
@@ -127,6 +135,20 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
   // 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.
+  void OnGestureEvent(ui::GestureEvent* gesture) OVERRIDE;
+
+  void OnSwipeEvent(ui::GestureEvent* swipe_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);
 
@@ -169,6 +191,14 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
     // mode until all fingers are lifted.
     TOUCH_EXPLORATION,
 
+    // If the user moves their finger faster than the threshold velocity after a
+    // single tap, the touch events that follow will be translated into gesture
+    // events. If the user successfully completes a gesture within the grace
+    // period, the gesture will be collected and sent to the GestureClient.

[dmazzoni, 2014/06/25 05:06:02]

"sent to the GestureClient" is an implementation detail. You should say that the
gesture will be interpreted and used to control the UI via discrete actions -
currently by synthesizing key events corresponding to each gesture.

[lisayin, 2014/06/25 22:51:05]

Done.

+    // Otherwise, the collected gestures are discarded and the state changes to
+    // touch_exploration.
+    GESTURE_IN_PROGRESS,
+
     // 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
@@ -231,6 +261,9 @@ class UI_CHROMEOS_EXPORT TouchExplorationController :
   // 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_;