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// 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_EVENTS_EVENT_HANDLER_H_
#define UI_EVENTS_EVENT_HANDLER_H_
#include <string_view>
#include <vector>
#include "base/containers/stack.h"
#include "base/memory/raw_ptr.h"
#include "ui/events/events_export.h"
namespace ui {
class CancelModeEvent;
class Event;
class EventDispatcher;
class EventTarget;
class GestureEvent;
class KeyEvent;
class MouseEvent;
class ScrollEvent;
class TouchEvent;
// Dispatches events to appropriate targets. The default implementations of
// all of the specific handlers (e.g. OnKeyEvent, OnMouseEvent) do nothing.
class EVENTS_EXPORT EventHandler {
public:
EventHandler();
EventHandler(const EventHandler&) = delete;
EventHandler& operator=(const EventHandler&) = delete;
virtual ~EventHandler();
// This is called for all events. The default implementation routes the event
// to one of the event-specific callbacks (OnKeyEvent, OnMouseEvent etc.). If
// this is overridden, then normally, the override should chain into the
// default implementation for un-handled events.
virtual void OnEvent(Event* event);
virtual void OnKeyEvent(KeyEvent* event);
virtual void OnMouseEvent(MouseEvent* event);
virtual void OnScrollEvent(ScrollEvent* event);
virtual void OnTouchEvent(TouchEvent* event);
virtual void OnGestureEvent(GestureEvent* event);
virtual void OnCancelMode(CancelModeEvent* event);
// Returns information about the implementing class or scope for diagnostic
// logging purposes.
virtual std::string_view GetLogContext() const;
private:
friend class EventDispatcher;
friend class EventTarget;
// EventDispatcher pushes itself on the top of this stack while dispatching
// events to this then pops itself off when done.
base::stack<raw_ptr<EventDispatcher, CtnExperimental>> dispatchers_;
};
using EventHandlerList = std::vector<raw_ptr<EventHandler, VectorExperimental>>;
} // namespace ui
#endif // UI_EVENTS_EVENT_HANDLER_H_
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