chromium/ui/events/event.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_EVENTS_EVENT_H_
#define UI_EVENTS_EVENT_H_

#include <cstdint>
#include <memory>
#include <string>
#include <vector>

#include "base/containers/flat_map.h"
#include "base/gtest_prod_util.h"
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "ui/events/event_constants.h"
#include "ui/events/gesture_event_details.h"
#include "ui/events/gestures/gesture_types.h"
#include "ui/events/keycodes/dom/dom_key.h"
#include "ui/events/keycodes/keyboard_codes.h"
#include "ui/events/platform_event.h"
#include "ui/events/pointer_details.h"
#include "ui/events/types/event_type.h"
#include "ui/gfx/geometry/point.h"
#include "ui/gfx/geometry/point_conversions.h"
#include "ui/latency/latency_info.h"

namespace gfx {
class Transform;
}

namespace ui {

class CancelModeEvent;
class Event;
class EventRewriter;
class EventTarget;
class KeyEvent;
class LocatedEvent;
class MouseEvent;
class MouseWheelEvent;
class ScrollEvent;
class TouchEvent;

enum class DomCode : uint32_t;

// Note: In order for Clone() to work properly, every concrete class
// transitively inheriting Event must implement Clone() explicitly, even if any
// ancestors have provided an implementation.
class EVENTS_EXPORT Event { … };

class EVENTS_EXPORT CancelModeEvent : public Event { … };

class EVENTS_EXPORT LocatedEvent : public Event { … };

class EVENTS_EXPORT MouseEvent : public LocatedEvent { … };

class ScrollEvent;

class EVENTS_EXPORT MouseWheelEvent : public MouseEvent { … };

// NOTE: Pen (stylus) events use TouchEvent with kPen. They were
// originally implemented as MouseEvent but switched to TouchEvent when UX
// decided not to show hover effects for pen.
class EVENTS_EXPORT TouchEvent : public LocatedEvent { … };

// A KeyEvent is really two distinct classes, melded together due to the
// DOM legacy of Windows key events: a keystroke event (is_char_ == false),
// or a character event (is_char_ == true).
//
// For a keystroke event,
// -- |bool is_char_| is false.
// -- |EventType Event::type()| can be EventType::kKeyPressed or
// EventType::kKeyReleased.
// -- |DomCode code_| and |int Event::flags()| represent the physical key event.
//    - code_ is a platform-independent representation of the physical key,
//      based on DOM UI Events KeyboardEvent |code| values. It does not
//      vary depending on key layout.
//      http://www.w3.org/TR/DOM-Level-3-Events-code/
//    - Event::flags() provides the active modifiers for the physical key
//      press. Its value reflects the state after the event; that is, for
//      a modifier key, a press includes the corresponding flag and a release
//      does not.
// -- |DomKey key_| provides the meaning (character or action) of the key
//    event, in the context of the active layout and modifiers. It corresponds
//    to DOM UI Events KeyboardEvent |key| values.
//    http://www.w3.org/TR/DOM-Level-3-Events-key/
// -- |KeyboardCode key_code_| supports the legacy web event |keyCode| field,
//    and its VKEY_ values are chosen to match Windows/IE for compatibility.
//    For printable characters, this may or may not be a layout-mapped value,
//    imitating MS Windows: if the mapped key generates a character that has
//    an associated VKEY_ code, then key_code_ is that code; if not, then
//    key_code_ is the unmapped VKEY_ code. For example, US, Greek, Cyrillic,
//    Japanese, etc. all use VKEY_Q for the key beside Tab, while French uses
//    VKEY_A. The stored key_code_ is non-located (e.g. VKEY_SHIFT rather than
//    VKEY_LSHIFT, VKEY_1 rather than VKEY_NUMPAD1).
// -- |uint32_t scan_code_| [IS_OZONE only] supports remapping of the top
//    function row based on a sysfs attribute provided by the kernel. This
//    allows devices to have a custom top row layout and still be able to
//    perform translation back and forth between F-Key and Action-Key. The
//    value of this scan code is device specific.
//
// For a character event,
// -- |bool is_char_| is true.
// -- |EventType Event::type()| is EventType::kKeyPressed.
// -- |DomCode code_| is DomCode::NONE.
// -- |DomKey key_| is a UTF-16 code point.
// -- |KeyboardCode key_code_| is conflated with the character-valued key_
//    by some code, because both arrive in the wParam field of a Windows event.
//
class EVENTS_EXPORT KeyEvent : public Event { … };

class EVENTS_EXPORT ScrollEvent : public MouseEvent { … };

class EVENTS_EXPORT GestureEvent : public LocatedEvent { … };

}  // namespace ui

#endif  // UI_EVENTS_EVENT_H_