Do not allow split view to be engaged by a bezel gesture

athena/wm/bezel_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 ATHENA_WM_BEZEL_CONTROLLER_H_
-#define ATHENA_WM_BEZEL_CONTROLLER_H_
-
-#include "ui/events/event_handler.h"
-
-namespace aura {
-class Window;
-}
-
-namespace gfx {
-class PointF;
-}
-
-namespace ui {
-class EventTarget;
-}
-
-namespace athena {
-
-// Responsible for detecting bezel gestures and notifying the delegate(s)
-// subscribed to them.
-class BezelController : public ui::EventHandler {
- public:
-  enum Bezel { BEZEL_NONE, BEZEL_LEFT, BEZEL_RIGHT, BEZEL_TOP, BEZEL_BOTTOM };
-
-  // Responsible for handling scroll gestures initiated from the bezel.
-  // Two touch points are need to perform the bezel scroll gesture from
-  // the left and right bezel.
-  class ScrollDelegate {
-   public:
-    ~ScrollDelegate() {}
-
-    // Beginning of a bezel scroll gesture started from the |bezel|.
-    // |delta| is the difference between the x-coordinate of the current scroll
-    // position and the bezel. It will be zero or negative for the right bezel.
-    virtual void BezelScrollBegin(Bezel bezel, float delta) = 0;
-
-    // End of the current bezel scroll with velocity |velocity|.
-    virtual void BezelScrollEnd(float velocity) = 0;
-
-    // Update of the scroll position for the currently active bezel scroll.
-    // |delta| has the same meaning as in ScrollBegin().
-    virtual void BezelScrollUpdate(float delta) = 0;
-
-    // Should return false if the delegate isn't going to react to the scroll
-    // events.
-    virtual bool BezelCanScroll() = 0;
-  };
-
-  explicit BezelController(aura::Window* container);
-  ~BezelController() override {}
-
-  // Set the delegate to handle the gestures from left and right bezels.
-  // Two touch points are need to perform the bezel scroll gesture from
-  // the left and right bezel.
-  void set_left_right_delegate(ScrollDelegate* delegate) {
-    left_right_delegate_ = delegate;
-  }
-
- private:
-  enum State {
-    NONE,
-    IGNORE_CURRENT_SCROLL,
-    BEZEL_GESTURE_STARTED,
-    BEZEL_SCROLLING_ONE_FINGER,
-    BEZEL_SCROLLING_TWO_FINGERS,
-  };
-
-  void SetState(State state);
-  // |scroll_delta| only needs to be passed when |state| is one of the
-  // BEZEL_SROLLING states.
-  void SetState(State state, float scroll_delta);
-
-  // ui::EventHandler overrides
-  void OnGestureEvent(ui::GestureEvent* event) override;
-
-  aura::Window* container_;
-
-  State state_;
-
-  // The bezel where the currently active scroll was started.
-  Bezel scroll_bezel_;
-
-  // The target of the bezel scroll gesture. Used to filter out other gestures
-  // when the bezel scroll is in progress.
-  ui::EventTarget* scroll_target_;
-
-  // Responsible for handling gestures started from the left and right bezels.
-  // Not owned.
-  ScrollDelegate* left_right_delegate_;
-
-  DISALLOW_COPY_AND_ASSIGN(BezelController);
-};
-
-}  // namespace athena
-
-#endif  // ATHENA_WM_BEZEL_CONTROLLER_H_