Sync ui/events to chromium @ https://codereview.chromium.org/1210203002

ui/events/ozone/evdev/event_modifiers_evdev.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_
+#define UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_
+
+#include "base/basictypes.h"
+#include "ui/events/ozone/evdev/events_ozone_evdev_export.h"
+
+namespace ui {
+
+enum {
+  EVDEV_MODIFIER_NONE,
+  EVDEV_MODIFIER_CAPS_LOCK,
+  EVDEV_MODIFIER_SHIFT,
+  EVDEV_MODIFIER_CONTROL,
+  EVDEV_MODIFIER_ALT,
+  EVDEV_MODIFIER_LEFT_MOUSE_BUTTON,
+  EVDEV_MODIFIER_MIDDLE_MOUSE_BUTTON,
+  EVDEV_MODIFIER_RIGHT_MOUSE_BUTTON,
+  EVDEV_MODIFIER_BACK_MOUSE_BUTTON,
+  EVDEV_MODIFIER_FORWARD_MOUSE_BUTTON,
+  EVDEV_MODIFIER_COMMAND,
+  EVDEV_MODIFIER_ALTGR,
+  EVDEV_MODIFIER_MOD3,
+  EVDEV_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_OZONE_EVDEV_EXPORT EventModifiersEvdev {
+ public:
+  EventModifiersEvdev();
+  ~EventModifiersEvdev();
+
+  // 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();
+
+  // Return the mask for the specified modifier.
+  static int GetEventFlagFromModifier(unsigned int modifier);
+
+ private:
+  // Count of keys pressed for each modifier.
+  int modifiers_down_[EVDEV_NUM_MODIFIERS];
+
+  // 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);
+
+  DISALLOW_COPY_AND_ASSIGN(EventModifiersEvdev);
+};
+
+}  // namspace ui
+
+#endif  // UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_