ui/events/ozone/evdev/event_modifiers_evdev.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_
   6 #define UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_
   7
   8 #include "base/basictypes.h"
   9 #include "ui/events/ozone/evdev/events_ozone_evdev_export.h"
  10
  11 namespace ui {
  12
  13 enum {
  14   EVDEV_MODIFIER_NONE,
  15   EVDEV_MODIFIER_CAPS_LOCK,
  16   EVDEV_MODIFIER_SHIFT,
  17   EVDEV_MODIFIER_CONTROL,
  18   EVDEV_MODIFIER_ALT,
  19   EVDEV_MODIFIER_LEFT_MOUSE_BUTTON,
  20   EVDEV_MODIFIER_MIDDLE_MOUSE_BUTTON,
  21   EVDEV_MODIFIER_RIGHT_MOUSE_BUTTON,
  22   EVDEV_MODIFIER_COMMAND,
  23   EVDEV_MODIFIER_ALTGR,
  24   EVDEV_NUM_MODIFIERS
  25 };
  26
  27 // Modifier key state for Evdev.
  28 //
  29 // Chrome relies on the underlying OS to interpret modifier keys such as Shift,
  30 // Ctrl, and Alt. The Linux input subsystem does not assign any special meaning
  31 // to these keys, so this work must happen at a higher layer (normally X11 or
  32 // the console driver). When using evdev directly, we must do it ourselves.
  33 //
  34 // The modifier state is shared between all input devices connected to the
  35 // system. This is to support actions such as Shift-Clicking that use multiple
  36 // devices.
  37 //
  38 // Normally a modifier is set if any of the keys or buttons assigned to it are
  39 // currently pressed. However some keys toggle a persistent "lock" for the
  40 // modifier instead, such as CapsLock. If a modifier is "locked" then its state
  41 // is inverted until it is unlocked.
  42 class EVENTS_OZONE_EVDEV_EXPORT EventModifiersEvdev {
  43  public:
  44   EventModifiersEvdev();
  45   ~EventModifiersEvdev();
  46
  47   // Record key press or release for regular modifier key (shift, alt, etc).
  48   void UpdateModifier(unsigned int modifier, bool down);
  49
  50   // Record key press or release for locking modifier key (caps lock).
  51   void UpdateModifierLock(unsigned int modifier, bool down);
  52
  53   // Return current flags to use for incoming events.
  54   int GetModifierFlags();
  55
  56   // Return the mask for the specified modifier.
  57   static int GetEventFlagFromModifier(unsigned int modifier);
  58
  59  private:
  60   // Count of keys pressed for each modifier.
  61   int modifiers_down_[EVDEV_NUM_MODIFIERS];
  62
  63   // Mask of modifier flags currently "locked".
  64   int modifier_flags_locked_;
  65
  66   // Mask of modifier flags currently active (nonzero keys pressed xor locked).
  67   int modifier_flags_;
  68
  69   // Update modifier_flags_ from modifiers_down_ and modifier_flags_locked_.
  70   void UpdateFlags(unsigned int modifier);
  71
  72   DISALLOW_COPY_AND_ASSIGN(EventModifiersEvdev);
  73 };
  74
  75 }  // namspace ui
  76
  77 #endif  // UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_