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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef ASH_WINDOW_USER_DATA_H_
#define ASH_WINDOW_USER_DATA_H_
#include <map>
#include <memory>
#include <utility>
#include "ui/aura/window.h"
#include "ui/aura/window_observer.h"
namespace ash {
// WindowUserData provides a way to associate an object with a Window and have
// that object destroyed when the window is destroyed, or when WindowUserData
// is destroyed (from aura::WindowObserver::OnWindowDestroying()).
//
// NOTE: WindowUserData does not make use of the Set/GetProperty API offered
// on aura::Window. This is done to avoid collisions in the case of multiple
// WindowUserDatas operating on the same Window.
template <typename UserData>
class WindowUserData : public aura::WindowObserver {
public:
WindowUserData() {}
WindowUserData(const WindowUserData&) = delete;
WindowUserData& operator=(const WindowUserData&) = delete;
~WindowUserData() override { clear(); }
void clear() {
// Take care to destroy the data after removing from the map.
while (!window_to_data_.empty()) {
auto iter = window_to_data_.begin();
iter->first->RemoveObserver(this);
std::unique_ptr<UserData> user_data = std::move(iter->second);
window_to_data_.erase(iter);
}
}
// Sets the data associated with window. This destroys any existing data.
// |data| may be null.
void Set(aura::Window* window, std::unique_ptr<UserData> data) {
if (!data) {
if (window_to_data_.erase(window))
window->RemoveObserver(this);
return;
}
if (window_to_data_.count(window) == 0u)
window->AddObserver(this);
window_to_data_[window] = std::move(data);
}
// Returns the data associated with the window, or null if none set. The
// returned object is owned by WindowUserData.
UserData* Get(aura::Window* window) {
auto it = window_to_data_.find(window);
return it == window_to_data_.end() ? nullptr : it->second.get();
}
// Returns the set of windows with data associated with them.
std::set<aura::Window*> GetWindows() {
std::set<aura::Window*> windows;
for (auto& pair : window_to_data_)
windows.insert(pair.first);
return windows;
}
private:
// aura::WindowObserver:
void OnWindowDestroying(aura::Window* window) override {
window->RemoveObserver(this);
window_to_data_.erase(window);
}
std::map<aura::Window*, std::unique_ptr<UserData>> window_to_data_;
};
} // namespace ash
#endif // ASH_WINDOW_USER_DATA_H_
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