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_MODIFIER_MOD3,
  25   EVDEV_NUM_MODIFIERS
  26 };
  27
  28 // Modifier key state for Evdev.
  29 //
  30 // Chrome relies on the underlying OS to interpret modifier keys such as Shift,
  31 // Ctrl, and Alt. The Linux input subsystem does not assign any special meaning
  32 // to these keys, so this work must happen at a higher layer (normally X11 or
  33 // the console driver). When using evdev directly, we must do it ourselves.
  34 //
  35 // The modifier state is shared between all input devices connected to the
  36 // system. This is to support actions such as Shift-Clicking that use multiple
  37 // devices.
  38 //
  39 // Normally a modifier is set if any of the keys or buttons assigned to it are
  40 // currently pressed. However some keys toggle a persistent "lock" for the
  41 // modifier instead, such as CapsLock. If a modifier is "locked" then its state
  42 // is inverted until it is unlocked.
  43 class EVENTS_OZONE_EVDEV_EXPORT EventModifiersEvdev {
  44  public:
  45   EventModifiersEvdev();
  46   ~EventModifiersEvdev();
  47
  48   // Record key press or release for regular modifier key (shift, alt, etc).
  49   void UpdateModifier(unsigned int modifier, bool down);
  50
  51   // Record key press or release for locking modifier key (caps lock).
  52   void UpdateModifierLock(unsigned int modifier, bool down);
  53
  54   // Directly set the state of a locking modifier key (caps lock).
  55   void SetModifierLock(unsigned int modifier, bool locked);
  56
  57   // Return current flags to use for incoming events.
  58   int GetModifierFlags();
  59
  60   // Return the mask for the specified modifier.
  61   static int GetEventFlagFromModifier(unsigned int modifier);
  62
  63  private:
  64   // Count of keys pressed for each modifier.
  65   int modifiers_down_[EVDEV_NUM_MODIFIERS];
  66
  67   // Mask of modifier flags currently "locked".
  68   int modifier_flags_locked_;
  69
  70   // Mask of modifier flags currently active (nonzero keys pressed xor locked).
  71   int modifier_flags_;
  72
  73   // Update modifier_flags_ from modifiers_down_ and modifier_flags_locked_.
  74   void UpdateFlags(unsigned int modifier);
  75
  76   DISALLOW_COPY_AND_ASSIGN(EventModifiersEvdev);
  77 };
  78
  79 }  // namspace ui
  80
  81 #endif  // UI_EVENTS_OZONE_EVDEV_EVENT_MODIFIERS_EVDEV_H_