| // Copyright 2017 The Cobalt Authors. All Rights Reserved. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| |
| #ifndef COBALT_PAGE_VISIBILITY_PAGE_VISIBILITY_STATE_H_ |
| #define COBALT_PAGE_VISIBILITY_PAGE_VISIBILITY_STATE_H_ |
| |
| #include "base/observer_list.h" |
| #include "cobalt/base/application_state.h" |
| #include "cobalt/page_visibility/visibility_state.h" |
| |
| namespace cobalt { |
| namespace page_visibility { |
| |
| // The visibility state of the Window and Document as controlled by the current |
| // application state. |
| class PageVisibilityState { |
| public: |
| // Pure virtual interface for classes that want to observe page visibility |
| // state changes. |
| class Observer : public base::CheckedObserver { |
| public: |
| // Called when the window focus state changes. |
| virtual void OnWindowFocusChanged(bool has_focus) = 0; |
| // Called when the VisibilityState changes. |
| virtual void OnVisibilityStateChanged(VisibilityState visibility_state) = 0; |
| |
| protected: |
| virtual ~Observer() {} |
| }; |
| |
| PageVisibilityState(); |
| explicit PageVisibilityState( |
| base::ApplicationState initial_application_state); |
| |
| base::ApplicationState application_state() const { |
| return application_state_; |
| } |
| |
| // Whether the current window has focus based on the current application |
| // state. |
| bool HasWindowFocus() const; |
| |
| // Whether the current window has focus based on the current application |
| // state. |
| VisibilityState GetVisibilityState() const; |
| |
| // Sets the current application state, and dispatches appropriate observation |
| // events. |
| void SetApplicationState(base::ApplicationState state); |
| |
| // Adds a PageVisibiltyState::Observer to this PageVisibilityState. |
| void AddObserver(Observer* observer) { observer_list_.AddObserver(observer); } |
| |
| // Removes a PageVisibiltyState::Observer from this PageVisibilityState, if it |
| // is registered. |
| void RemoveObserver(Observer* observer) { |
| observer_list_.RemoveObserver(observer); |
| } |
| |
| // Returns whether a PageVisibiltyState::Observer is registered on this |
| // PageVisibilityState. |
| bool HasObserver(Observer* observer) const { |
| return observer_list_.HasObserver(observer); |
| } |
| |
| // Clears all registered PageVisibiltyState::Observers, if any. |
| void ClearObservers() { observer_list_.Clear(); } |
| |
| private: |
| void DispatchWindowFocusChanged(bool has_focus); |
| void DispatchVisibilityStateChanged(VisibilityState visibility_state); |
| |
| // The current application state. |
| base::ApplicationState application_state_; |
| |
| // The list of registered PageVisibiltyState::Observers; |
| base::ObserverList<Observer> observer_list_; |
| }; |
| |
| } // namespace page_visibility |
| } // namespace cobalt |
| |
| #endif // COBALT_PAGE_VISIBILITY_PAGE_VISIBILITY_STATE_H_ |