chromium/ui/display/display_observer.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_DISPLAY_DISPLAY_OBSERVER_H_
#define UI_DISPLAY_DISPLAY_OBSERVER_H_

#include <stdint.h>

#include <vector>

#include "base/memory/raw_ptr.h"
#include "base/observer_list_types.h"
#include "ui/display/display_export.h"

namespace display {
class Display;
enum class TabletState;

Displays;

// Observers for display configuration changes.
class DISPLAY_EXPORT DisplayObserver : public base::CheckedObserver { … };

// Caller must ensure the lifetime of `observer` outlives ScopedDisplayObserver
// and ScopedOptionalDisplayObserver.  The "Optional" version does not care
// whether there is a display::Screen::GetScreen() to observe or not and will
// silently noop when there is not.  The non-optional ScopedDisplayObserver
// will CHECK that display::Screen::GetScreen() exists on construction to
// receive events from.
class DISPLAY_EXPORT ScopedOptionalDisplayObserver { … };

class DISPLAY_EXPORT ScopedDisplayObserver
    : public ScopedOptionalDisplayObserver { … };

}  // namespace display

#endif  // UI_DISPLAY_DISPLAY_OBSERVER_H_