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// Copyright 2014 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_MODIFIERS_H_
#define UI_EVENTS_EVENT_MODIFIERS_H_
#include <array>
#include "ui/events/events_export.h"
namespace ui {
enum {
MODIFIER_NONE,
MODIFIER_SHIFT,
MODIFIER_CONTROL,
MODIFIER_ALT,
MODIFIER_COMMAND,
MODIFIER_ALTGR,
MODIFIER_MOD3,
MODIFIER_CAPS_LOCK,
MODIFIER_LEFT_MOUSE_BUTTON,
MODIFIER_MIDDLE_MOUSE_BUTTON,
MODIFIER_RIGHT_MOUSE_BUTTON,
MODIFIER_BACK_MOUSE_BUTTON,
MODIFIER_FORWARD_MOUSE_BUTTON,
MODIFIER_FUNCTION,
MODIFIER_NUM_MODIFIERS
};
// Modifier key state for Evdev.
//
// Chrome relies on the underlying OS to interpret modifier keys such as Shift,
// Ctrl, and Alt. The Linux input subsystem does not assign any special meaning
// to these keys, so this work must happen at a higher layer (normally X11 or
// the console driver). When using evdev directly, we must do it ourselves.
//
// The modifier state is shared between all input devices connected to the
// system. This is to support actions such as Shift-Clicking that use multiple
// devices.
//
// Normally a modifier is set if any of the keys or buttons assigned to it are
// currently pressed. However some keys toggle a persistent "lock" for the
// modifier instead, such as CapsLock. If a modifier is "locked" then its state
// is inverted until it is unlocked.
class EVENTS_EXPORT EventModifiers {
public:
EventModifiers();
EventModifiers(const EventModifiers&) = delete;
EventModifiers& operator=(const EventModifiers&) = delete;
~EventModifiers();
// Record key press or release for regular modifier key (shift, alt, etc).
void UpdateModifier(unsigned int modifier, bool down);
// Record key press or release for locking modifier key (caps lock).
void UpdateModifierLock(unsigned int modifier, bool down);
// Directly set the state of a locking modifier key (caps lock).
void SetModifierLock(unsigned int modifier, bool locked);
// Return current flags to use for incoming events.
int GetModifierFlags();
// Release modifier keys.
void ResetKeyboardModifiers();
// Return the mask for the specified modifier.
static int GetEventFlagFromModifier(unsigned int modifier);
// Return the modifier for the specified mask.
static int GetModifierFromEventFlag(int flag);
private:
// Count of keys pressed for each modifier.
std::array<int, MODIFIER_NUM_MODIFIERS> modifiers_down_;
// Mask of modifier flags currently "locked".
int modifier_flags_locked_ = 0;
// Mask of modifier flags currently active (nonzero keys pressed xor locked).
int modifier_flags_ = 0;
// Update modifier_flags_ from modifiers_down_ and modifier_flags_locked_.
void UpdateFlags(unsigned int modifier);
};
} // namespace ui
#endif // UI_EVENTS_EVENT_MODIFIERS_H_
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