Laser tool blocks events from propagating.

ash/laser/laser_pointer_controller.h

+// Copyright 2016 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 ASH_LASER_LASER_POINTER_CONTROLLER_H_
+#define ASH_LASER_LASER_POINTER_CONTROLLER_H_
+
+#include <memory>
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+#include "ui/aura/window_observer.h"
+#include "ui/events/event.h"
+#include "ui/events/event_handler.h"
+#include "ui/gfx/geometry/point.h"
+
+namespace base {
+class Timer;
+}
+
+namespace ui {
+class LocatedEvent;
+class MouseEvent;
+class TouchEvent;
+}
+
+namespace ash {
+
+class LaserPointerView;
+
+// Controller for the laser pointer functionality. Enables/disables laser
+// pointer as well as receives points and passes them off to be rendered.
+class ASH_EXPORT LaserPointerController : public ui::EventHandler,
+                                          public aura::WindowObserver {
+ public:
+  LaserPointerController();
+  ~LaserPointerController() override;
+
+  // Turns the laser pointer feature on or off. The user still has to press and
+  // drag to see the laser pointer.
+  void SetEnabled(bool enabled);
+
+ private:
+  friend class LaserPointerControllerTestApi;
+
+  // ui::EventHandler:
+  void OnMouseEvent(ui::MouseEvent* event) override;
+
+  // aura::WindowObserver:
+  void OnWindowDestroying(aura::Window* window) override;
+
+  void StopTimer();
+
+  // Helper method to create a new LaserPointerView with a new root window when
+  // the current root window changes because the user is on multiple screens and
+  // switched focus to a different screen.
+  void SwitchTargetRootWindowIfNeeded();
+
+  // Timer callback which adds a point where the mouse was last seen. This
+  // allows the trail to fade away when the mouse is stationary.
+  void AddStationaryPoint();
+
+  // Timer which will add a new stationary point when the mouse stops moving.
+  // This will remove points that are too old.
+  std::unique_ptr<base::Timer> stationary_timer_;
+  int stationary_timer_repeat_count_ = 0;
+
+  bool enabled_ = false;
+
+  // The last seen mouse location in screen coordinates.
+  gfx::Point current_mouse_location_;
+
+  // |laser_pointer_view_| will only hold an instance when the laser pointer is
+  // enabled and activated (pressed or dragged).
+  std::unique_ptr<LaserPointerView> laser_pointer_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(LaserPointerController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_LASER_LASER_POINTER_CONTROLLER_H_