widget/windows/KeyboardLayout.h
author Masayuki Nakano <masayuki@d-toybox.com>
Thu, 01 Sep 2016 17:29:11 +0900
changeset 348083 befed59939f765b9bb263572d7c16e096612986b
parent 347997 87c57eedbd7f0f4b45c5b421b4a9d434025c0570
child 357366 1c503e563219d716a16ca07c90d93610f5cc0d69
permissions -rw-r--r--
Bug 1297985 - Part 2: KeyboardLayout should handle a composite character produced by 2 dead keys. r=m_kato, a=ritu On some keyboard layouts, a key sequence, a dead key -> another dead key, may produce a composite character instead of two base characters for each key. For example, with "Russian - Mnemonic" keyboard layout on Win 8 or later, both 's' and 'c' are dead keys but key sequence, 's' -> 'c', produces a Unicode character. For solving this issue, this patch fixes 2 bugs: First, KeyboardLayout::GetDeadKeyCombinations() doesn't add dead key entry if 2nd key is a dead key (::ToUnicodeEx() returns -1). In such case, it should add a dead key entry with the first character which is produced when only the 2nd key is pressed (the character is called as "base character" and used for index of the dead key table). Next, KeyboardLayout::InitNativeKey() should check if 2nd dead key press produces a composite character. If it's produced, it should initialize given NativeKey with the composite character. Otherwise, it should initialize with base characters of each key. This patch does it with KeyboardLayout::MaybeInitNativeKeyWithCompositeChar(). Finally, we should add automated test for this. However, unfortunately, it's not available on Win7 and our infra is still using Win7 for running automated tests. Therefore, this patch doesn't include new automated tests. MozReview-Commit-ID: G1DrfkHKNcK

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef KeyboardLayout_h__
#define KeyboardLayout_h__

#include "mozilla/RefPtr.h"
#include "nscore.h"
#include "nsString.h"
#include "nsWindowBase.h"
#include "nsWindowDefs.h"
#include "mozilla/Attributes.h"
#include "mozilla/EventForwards.h"
#include "mozilla/TextEventDispatcher.h"
#include "mozilla/widget/WinMessages.h"
#include "mozilla/widget/WinModifierKeyState.h"
#include <windows.h>

#define NS_NUM_OF_KEYS          70

#define VK_OEM_1                0xBA   // ';:' for US
#define VK_OEM_PLUS             0xBB   // '+' any country
#define VK_OEM_COMMA            0xBC
#define VK_OEM_MINUS            0xBD   // '-' any country
#define VK_OEM_PERIOD           0xBE
#define VK_OEM_2                0xBF
#define VK_OEM_3                0xC0
// '/?' for Brazilian (ABNT)
#define VK_ABNT_C1              0xC1
// Separator in Numpad for Brazilian (ABNT) or JIS keyboard for Mac.
#define VK_ABNT_C2              0xC2
#define VK_OEM_4                0xDB
#define VK_OEM_5                0xDC
#define VK_OEM_6                0xDD
#define VK_OEM_7                0xDE
#define VK_OEM_8                0xDF
#define VK_OEM_102              0xE2
#define VK_OEM_CLEAR            0xFE

class nsIIdleServiceInternal;

namespace mozilla {
namespace widget {

static const uint32_t sModifierKeyMap[][3] = {
  { nsIWidget::CAPS_LOCK, VK_CAPITAL, 0 },
  { nsIWidget::NUM_LOCK,  VK_NUMLOCK, 0 },
  { nsIWidget::SHIFT_L,   VK_SHIFT,   VK_LSHIFT },
  { nsIWidget::SHIFT_R,   VK_SHIFT,   VK_RSHIFT },
  { nsIWidget::CTRL_L,    VK_CONTROL, VK_LCONTROL },
  { nsIWidget::CTRL_R,    VK_CONTROL, VK_RCONTROL },
  { nsIWidget::ALT_L,     VK_MENU,    VK_LMENU },
  { nsIWidget::ALT_R,     VK_MENU,    VK_RMENU }
};

class KeyboardLayout;

struct UniCharsAndModifiers
{
  // Dead-key + up to 4 characters
  char16_t mChars[5];
  Modifiers mModifiers[5];
  uint32_t  mLength;

  UniCharsAndModifiers() : mLength(0) {}
  UniCharsAndModifiers operator+(const UniCharsAndModifiers& aOther) const;
  UniCharsAndModifiers& operator+=(const UniCharsAndModifiers& aOther);

  /**
   * Append a pair of unicode character and the final modifier.
   */
  void Append(char16_t aUniChar, Modifiers aModifiers);
  void Clear() { mLength = 0; }
  bool IsEmpty() const { return !mLength; }

  void FillModifiers(Modifiers aModifiers);

  bool UniCharsEqual(const UniCharsAndModifiers& aOther) const;
  bool UniCharsCaseInsensitiveEqual(const UniCharsAndModifiers& aOther) const;

  nsString ToString() const { return nsString(mChars, mLength); }
};

struct DeadKeyEntry;
class DeadKeyTable;


class VirtualKey
{
public:
  //  0 - Normal
  //  1 - Shift
  //  2 - Control
  //  3 - Control + Shift
  //  4 - Alt
  //  5 - Alt + Shift
  //  6 - Alt + Control (AltGr)
  //  7 - Alt + Control + Shift (AltGr + Shift)
  //  8 - CapsLock
  //  9 - CapsLock + Shift
  // 10 - CapsLock + Control
  // 11 - CapsLock + Control + Shift
  // 12 - CapsLock + Alt
  // 13 - CapsLock + Alt + Shift
  // 14 - CapsLock + Alt + Control (CapsLock + AltGr)
  // 15 - CapsLock + Alt + Control + Shift (CapsLock + AltGr + Shift)

  enum ShiftStateFlag
  {
    STATE_SHIFT    = 0x01,
    STATE_CONTROL  = 0x02,
    STATE_ALT      = 0x04,
    STATE_CAPSLOCK = 0x08
  };

  typedef uint8_t ShiftState;

  static ShiftState ModifiersToShiftState(Modifiers aModifiers);
  static Modifiers ShiftStateToModifiers(ShiftState aShiftState);

private:
  union KeyShiftState
  {
    struct
    {
      char16_t Chars[4];
    } Normal;
    struct
    {
      const DeadKeyTable* Table;
      char16_t DeadChar;
    } DeadKey;
  };

  KeyShiftState mShiftStates[16];
  uint16_t mIsDeadKey;

  void SetDeadKey(ShiftState aShiftState, bool aIsDeadKey)
  {
    if (aIsDeadKey) {
      mIsDeadKey |= 1 << aShiftState;
    } else {
      mIsDeadKey &= ~(1 << aShiftState);
    }
  }

public:
  static void FillKbdState(PBYTE aKbdState, const ShiftState aShiftState);

  bool IsDeadKey(ShiftState aShiftState) const
  {
    return (mIsDeadKey & (1 << aShiftState)) != 0;
  }

  void AttachDeadKeyTable(ShiftState aShiftState,
                          const DeadKeyTable* aDeadKeyTable)
  {
    mShiftStates[aShiftState].DeadKey.Table = aDeadKeyTable;
  }

  void SetNormalChars(ShiftState aShiftState, const char16_t* aChars,
                      uint32_t aNumOfChars);
  void SetDeadChar(ShiftState aShiftState, char16_t aDeadChar);
  const DeadKeyTable* MatchingDeadKeyTable(const DeadKeyEntry* aDeadKeyArray,
                                           uint32_t aEntries) const;
  inline char16_t GetCompositeChar(ShiftState aShiftState,
                                    char16_t aBaseChar) const;
  UniCharsAndModifiers GetNativeUniChars(ShiftState aShiftState) const;
  UniCharsAndModifiers GetUniChars(ShiftState aShiftState) const;
};

class MOZ_STACK_CLASS NativeKey final
{
  friend class KeyboardLayout;

public:
  struct FakeCharMsg
  {
    UINT mCharCode;
    UINT mScanCode;
    bool mIsSysKey;
    bool mIsDeadKey;
    bool mConsumed;

    FakeCharMsg()
      : mCharCode(0)
      , mScanCode(0)
      , mIsSysKey(false)
      , mIsDeadKey(false)
      , mConsumed(false)
    {
    }

    MSG GetCharMsg(HWND aWnd) const
    {
      MSG msg;
      msg.hwnd = aWnd;
      msg.message = mIsDeadKey && mIsSysKey ? WM_SYSDEADCHAR :
                                 mIsDeadKey ? WM_DEADCHAR :
                                  mIsSysKey ? WM_SYSCHAR :
                                              WM_CHAR;
      msg.wParam = static_cast<WPARAM>(mCharCode);
      msg.lParam = static_cast<LPARAM>(mScanCode << 16);
      msg.time = 0;
      msg.pt.x = msg.pt.y = 0;
      return msg;
    }
  };

  NativeKey(nsWindowBase* aWidget,
            const MSG& aMessage,
            const ModifierKeyState& aModKeyState,
            HKL aOverrideKeyboardLayout = 0,
            nsTArray<FakeCharMsg>* aFakeCharMsgs = nullptr);

  ~NativeKey();

  /**
   * Handle WM_KEYDOWN message or WM_SYSKEYDOWN message.  The instance must be
   * initialized with WM_KEYDOWN or WM_SYSKEYDOWN.
   * Returns true if dispatched keydown event or keypress event is consumed.
   * Otherwise, false.
   */
  bool HandleKeyDownMessage(bool* aEventDispatched = nullptr) const;

  /**
   * Handles WM_CHAR message or WM_SYSCHAR message.  The instance must be
   * initialized with WM_KEYDOWN, WM_SYSKEYDOWN or them.
   * Returns true if dispatched keypress event is consumed.  Otherwise, false.
   */
  bool HandleCharMessage(const MSG& aCharMsg,
                         bool* aEventDispatched = nullptr) const;

  /**
   * Handles keyup message.  Returns true if the event is consumed.
   * Otherwise, false.
   */
  bool HandleKeyUpMessage(bool* aEventDispatched = nullptr) const;

  /**
   * Handles WM_APPCOMMAND message.  Returns true if the event is consumed.
   * Otherwise, false.
   */
  bool HandleAppCommandMessage() const;

  /**
   * Callback of TextEventDispatcherListener::WillDispatchKeyboardEvent().
   * This method sets alternative char codes of aKeyboardEvent.
   */
  void WillDispatchKeyboardEvent(WidgetKeyboardEvent& aKeyboardEvent,
                                 uint32_t aIndex);

  /**
   * Returns true if aChar is a control character which shouldn't be inputted
   * into focused text editor.
   */
  static bool IsControlChar(char16_t aChar);

private:
  RefPtr<nsWindowBase> mWidget;
  RefPtr<TextEventDispatcher> mDispatcher;
  HKL mKeyboardLayout;
  MSG mMsg;

  uint32_t mDOMKeyCode;
  KeyNameIndex mKeyNameIndex;
  CodeNameIndex mCodeNameIndex;

  ModifierKeyState mModKeyState;

  // mVirtualKeyCode distinguishes left key or right key of modifier key.
  uint8_t mVirtualKeyCode;
  // mOriginalVirtualKeyCode doesn't distinguish left key or right key of
  // modifier key.  However, if the given keycode is VK_PROCESS, it's resolved
  // to a keycode before it's handled by IME.
  uint8_t mOriginalVirtualKeyCode;

  // mCommittedChars indicates the inputted characters which is committed by
  // the key.  If dead key fail to composite a character, mCommittedChars
  // indicates both the dead characters and the base characters.
  UniCharsAndModifiers mCommittedCharsAndModifiers;

  // Following strings are computed by
  // ComputeInputtingStringWithKeyboardLayout() which is typically called
  // before dispatching keydown event.
  // mInputtingStringAndModifiers's string is the string to be
  // inputted into the focused editor and its modifier state is proper
  // modifier state for inputting the string into the editor.
  UniCharsAndModifiers mInputtingStringAndModifiers;
  // mShiftedString is the string to be inputted into the editor with
  // current modifier state with active shift state.
  UniCharsAndModifiers mShiftedString;
  // mUnshiftedString is the string to be inputted into the editor with
  // current modifier state without shift state.
  UniCharsAndModifiers mUnshiftedString;
  // Following integers are computed by
  // ComputeInputtingStringWithKeyboardLayout() which is typically called
  // before dispatching keydown event.  The meaning of these values is same
  // as charCode.
  uint32_t mShiftedLatinChar;
  uint32_t mUnshiftedLatinChar;

  WORD    mScanCode;
  bool    mIsExtended;
  bool    mIsDeadKey;
  // mIsPrintableKey is true if the key may be a printable key without
  // any modifier keys.  Otherwise, false.
  // Please note that the event may not cause any text input even if this
  // is true.  E.g., it might be dead key state or Ctrl key may be pressed.
  bool    mIsPrintableKey;
  // mIsOverridingKeyboardLayout is true if the instance temporarily overriding
  // keyboard layout with specified by the constructor.
  bool    mIsOverridingKeyboardLayout;
  // mIsFollowedByNonControlCharMessage may be true when mMsg is a keydown
  // message.  When the keydown message is followed by a char message, this
  // is true.
  bool    mIsFollowedByNonControlCharMessage;

  nsTArray<FakeCharMsg>* mFakeCharMsgs;

  // When a keydown event is dispatched at handling WM_APPCOMMAND, the computed
  // virtual keycode is set to this.  Even if we consume WM_APPCOMMAND message,
  // Windows may send WM_KEYDOWN and WM_KEYUP message for them.
  // At that time, we should not dispatch key events for them.
  static uint8_t sDispatchedKeyOfAppCommand;

  NativeKey()
  {
    MOZ_CRASH("The default constructor of NativeKey isn't available");
  }

  void InitWithAppCommand();

  /**
   * Returns true if the key event is caused by auto repeat.
   */
  bool IsRepeat() const
  {
    switch (mMsg.message) {
      case WM_KEYDOWN:
      case WM_SYSKEYDOWN:
      case WM_CHAR:
      case WM_SYSCHAR:
      case WM_DEADCHAR:
      case WM_SYSDEADCHAR:
      case MOZ_WM_KEYDOWN:
        return ((mMsg.lParam & (1 << 30)) != 0);
      case WM_APPCOMMAND:
        if (mVirtualKeyCode) {
          // If we can map the WM_APPCOMMAND to a virtual keycode, we can trust
          // the result of GetKeyboardState().
          BYTE kbdState[256];
          memset(kbdState, 0, sizeof(kbdState));
          ::GetKeyboardState(kbdState);
          return !!kbdState[mVirtualKeyCode];
        }
        // If there is no virtual keycode for the command, we dispatch both
        // keydown and keyup events from WM_APPCOMMAND handler.  Therefore,
        // even if WM_APPCOMMAND is caused by auto key repeat, web apps receive
        // a pair of DOM keydown and keyup events.  I.e., KeyboardEvent.repeat
        // should be never true of such keys.
        return false;
      default:
        return false;
    }
  }

  UINT GetScanCodeWithExtendedFlag() const;

  // The result is one of nsIDOMKeyEvent::DOM_KEY_LOCATION_*.
  uint32_t GetKeyLocation() const;

  /**
   * "Kakutei-Undo" of ATOK or WXG (both of them are Japanese IME) causes
   * strange WM_KEYDOWN/WM_KEYUP/WM_CHAR message pattern.  So, when this
   * returns true, the caller needs to be careful for processing the messages.
   */
  bool IsIMEDoingKakuteiUndo() const;

  bool IsKeyDownMessage() const
  {
    return (mMsg.message == WM_KEYDOWN ||
            mMsg.message == WM_SYSKEYDOWN ||
            mMsg.message == MOZ_WM_KEYDOWN);
  }
  bool IsKeyUpMessage() const
  {
    return (mMsg.message == WM_KEYUP ||
            mMsg.message == WM_SYSKEYUP ||
            mMsg.message == MOZ_WM_KEYUP);
  }
  bool IsPrintableCharMessage(const MSG& aMSG) const
  {
    return IsPrintableCharMessage(aMSG.message);
  }
  bool IsPrintableCharMessage(UINT aMessage) const
  {
    return (aMessage == WM_CHAR || aMessage == WM_SYSCHAR);
  }
  bool IsCharMessage(const MSG& aMSG) const
  {
    return IsCharMessage(aMSG.message);
  }
  bool IsCharMessage(UINT aMessage) const
  {
    return (IsPrintableCharMessage(aMessage) || IsDeadCharMessage(aMessage));
  }
  bool IsDeadCharMessage(const MSG& aMSG) const
  {
    return IsDeadCharMessage(aMSG.message);
  }
  bool IsDeadCharMessage(UINT aMessage) const
  {
    return (aMessage == WM_DEADCHAR || aMessage == WM_SYSDEADCHAR);
  }
  bool IsSysCharMessage(const MSG& aMSG) const
  {
    return IsSysCharMessage(aMSG.message);
  }
  bool IsSysCharMessage(UINT aMessage) const
  {
    return (aMessage == WM_SYSCHAR || aMessage == WM_SYSDEADCHAR);
  }
  bool MayBeSameCharMessage(const MSG& aCharMsg1, const MSG& aCharMsg2) const;
  bool IsFollowedByNonControlCharMessage() const;
  bool IsFollowedByDeadCharMessage() const;
  bool IsKeyMessageOnPlugin() const
  {
    return (mMsg.message == MOZ_WM_KEYDOWN ||
            mMsg.message == MOZ_WM_KEYUP);
  }

  /**
   * GetFollowingCharMessage() returns following char message of handling
   * keydown event.  If the message is found, this method returns true.
   * Otherwise, returns false.
   *
   * WARNING: Even if this returns true, aCharMsg may be WM_NULL or its
   *          hwnd may be different window.
   *
   * @param aRemove     true if the found message should be removed from the
   *                    queue.  Otherwise, false.
   */
  bool GetFollowingCharMessage(MSG& aCharMsg, bool aRemove = true) const;

  /**
   * Whether the key event can compute virtual keycode from the scancode value.
   */
  bool CanComputeVirtualKeyCodeFromScanCode() const;

  /**
   * Wraps MapVirtualKeyEx() with MAPVK_VSC_TO_VK.
   */
  uint8_t ComputeVirtualKeyCodeFromScanCode() const;

  /**
   * Wraps MapVirtualKeyEx() with MAPVK_VSC_TO_VK_EX.
   */
  uint8_t ComputeVirtualKeyCodeFromScanCodeEx() const;

  /**
   * Wraps MapVirtualKeyEx() with MAPVK_VK_TO_VSC_EX or MAPVK_VK_TO_VSC.
   */
  uint16_t ComputeScanCodeExFromVirtualKeyCode(UINT aVirtualKeyCode) const;

  /**
   * Wraps MapVirtualKeyEx() with MAPVK_VSC_TO_VK and MAPVK_VK_TO_CHAR.
   */
  char16_t ComputeUnicharFromScanCode() const;

  /**
   * Initializes the aKeyEvent with the information stored in the instance.
   */
  nsEventStatus InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
                             const ModifierKeyState& aModKeyState,
                             const MSG* aMsgSentToPlugin = nullptr) const;
  nsEventStatus InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
                             const MSG* aMsgSentToPlugin = nullptr) const;

  /**
   * Dispatches a command event for aEventCommand.
   * Returns true if the event is consumed.  Otherwise, false.
   */
  bool DispatchCommandEvent(uint32_t aEventCommand) const;

  /**
   * DispatchKeyPressEventsWithoutCharMessage() dispatches keypress event(s)
   * without char messages.  So, this should be used only when there are no
   * following char messages.
   */
  bool DispatchKeyPressEventsWithoutCharMessage() const;

  /**
   * Remove all following WM_CHAR, WM_SYSCHAR and WM_DEADCHAR messages for the
   * WM_KEYDOWN or WM_SYSKEYDOWN message.  Additionally, dispatches plugin
   * events if it's necessary.
   * Returns true if the widget is destroyed.  Otherwise, false.
   */
  bool DispatchPluginEventsAndDiscardsCharMessages() const;

  /**
   * DispatchKeyPressEventForFollowingCharMessage() dispatches keypress event
   * for following WM_*CHAR message which is removed and set to aCharMsg.
   * Returns true if the event is consumed.  Otherwise, false.
   */
  bool DispatchKeyPressEventForFollowingCharMessage(const MSG& aCharMsg) const;

  /**
   * Checkes whether the key event down message is handled without following
   * WM_CHAR messages.  For example, if following WM_CHAR message indicates
   * control character input, the WM_CHAR message is unclear whether it's
   * caused by a printable key with Ctrl or just a function key such as Enter
   * or Backspace.
   */
  bool NeedsToHandleWithoutFollowingCharMessages() const;

  /**
   * ComputeInputtingStringWithKeyboardLayout() computes string to be inputted
   * with the key and the modifier state, without shift state and with shift
   * state.
   */
  void ComputeInputtingStringWithKeyboardLayout();
};

class KeyboardLayout
{
  friend class NativeKey;

private:
  KeyboardLayout();
  ~KeyboardLayout();

  static KeyboardLayout* sInstance;
  static nsIIdleServiceInternal* sIdleService;

  struct DeadKeyTableListEntry
  {
    DeadKeyTableListEntry* next;
    uint8_t data[1];
  };

  HKL mKeyboardLayout;

  VirtualKey mVirtualKeys[NS_NUM_OF_KEYS];
  DeadKeyTableListEntry* mDeadKeyTableListHead;
  int32_t mActiveDeadKey;                 // -1 = no active dead-key
  VirtualKey::ShiftState mDeadKeyShiftState;

  bool mIsOverridden : 1;
  bool mIsPendingToRestoreKeyboardLayout : 1;

  static inline int32_t GetKeyIndex(uint8_t aVirtualKey);
  static int CompareDeadKeyEntries(const void* aArg1, const void* aArg2,
                                   void* aData);
  static bool AddDeadKeyEntry(char16_t aBaseChar, char16_t aCompositeChar,
                                DeadKeyEntry* aDeadKeyArray, uint32_t aEntries);
  bool EnsureDeadKeyActive(bool aIsActive, uint8_t aDeadKey,
                             const PBYTE aDeadKeyKbdState);
  uint32_t GetDeadKeyCombinations(uint8_t aDeadKey,
                                  const PBYTE aDeadKeyKbdState,
                                  uint16_t aShiftStatesWithBaseChars,
                                  DeadKeyEntry* aDeadKeyArray,
                                  uint32_t aMaxEntries);
  void DeactivateDeadKeyState();
  const DeadKeyTable* AddDeadKeyTable(const DeadKeyEntry* aDeadKeyArray,
                                      uint32_t aEntries);
  void ReleaseDeadKeyTables();

  /**
   * Loads the specified keyboard layout. This method always clear the dead key
   * state.
   */
  void LoadLayout(HKL aLayout);

  /**
   * InitNativeKey() must be called when actually widget receives WM_KEYDOWN or
   * WM_KEYUP.  This method is stateful.  This saves current dead key state at
   * WM_KEYDOWN.  Additionally, computes current inputted character(s) and set
   * them to the aNativeKey.
   */
  void InitNativeKey(NativeKey& aNativeKey,
                     const ModifierKeyState& aModKeyState);

public:
  static KeyboardLayout* GetInstance();
  static void Shutdown();
  static void NotifyIdleServiceOfUserActivity();

  static bool IsPrintableCharKey(uint8_t aVirtualKey);

  /**
   * IsDeadKey() returns true if aVirtualKey is a dead key with aModKeyState.
   * This method isn't stateful.
   */
  bool IsDeadKey(uint8_t aVirtualKey,
                 const ModifierKeyState& aModKeyState) const;

  /**
   * IsSysKey() returns true if aVirtualKey with aModKeyState causes WM_SYSKEY*
   * or WM_SYS*CHAR messages.
   */
  bool IsSysKey(uint8_t aVirtualKey,
                const ModifierKeyState& aModKeyState) const;

  /**
   * MaybeInitNativeKeyWithCompositeChar() may initialize aNativeKey with
   * proper composite character when dead key produces a composite character.
   * Otherwise, just returns false.
   */
  bool MaybeInitNativeKeyWithCompositeChar(
         NativeKey& aNativeKey,
         const ModifierKeyState& aModKeyState);

  /**
   * GetUniCharsAndModifiers() returns characters which is inputted by the
   * aVirtualKey with aModKeyState.  This method isn't stateful.
   */
  UniCharsAndModifiers GetUniCharsAndModifiers(
                         uint8_t aVirtualKey,
                         const ModifierKeyState& aModKeyState) const;

  /**
   * OnLayoutChange() must be called before the first keydown message is
   * received.  LoadLayout() changes the keyboard state, that causes breaking
   * dead key state.  Therefore, we need to load the layout before the first
   * keydown message.
   */
  void OnLayoutChange(HKL aKeyboardLayout)
  {
    MOZ_ASSERT(!mIsOverridden);
    LoadLayout(aKeyboardLayout);
  }

  /**
   * OverrideLayout() loads the specified keyboard layout.
   */
  void OverrideLayout(HKL aLayout)
  {
    mIsOverridden = true;
    LoadLayout(aLayout);
  }

  /**
   * RestoreLayout() loads the current keyboard layout of the thread.
   */
  void RestoreLayout()
  {
    mIsOverridden = false;
    mIsPendingToRestoreKeyboardLayout = true;
  }

  uint32_t ConvertNativeKeyCodeToDOMKeyCode(UINT aNativeKeyCode) const;

  /**
   * ConvertNativeKeyCodeToKeyNameIndex() returns KeyNameIndex value for
   * non-printable keys (except some special keys like space key).
   */
  KeyNameIndex ConvertNativeKeyCodeToKeyNameIndex(uint8_t aVirtualKey) const;

  /**
   * ConvertScanCodeToCodeNameIndex() returns CodeNameIndex value for
   * the given scan code.  aScanCode can be over 0xE000 since this method
   * doesn't use Windows API.
   */
  static CodeNameIndex ConvertScanCodeToCodeNameIndex(UINT aScanCode);

  HKL GetLayout() const
  {
    return mIsPendingToRestoreKeyboardLayout ? ::GetKeyboardLayout(0) :
                                               mKeyboardLayout;
  }

  /**
   * This wraps MapVirtualKeyEx() API with MAPVK_VK_TO_VSC.
   */
  WORD ComputeScanCodeForVirtualKeyCode(uint8_t aVirtualKeyCode) const;

  /**
   * Implementation of nsIWidget::SynthesizeNativeKeyEvent().
   */
  nsresult SynthesizeNativeKeyEvent(nsWindowBase* aWidget,
                                    int32_t aNativeKeyboardLayout,
                                    int32_t aNativeKeyCode,
                                    uint32_t aModifierFlags,
                                    const nsAString& aCharacters,
                                    const nsAString& aUnmodifiedCharacters);
};

class RedirectedKeyDownMessageManager
{
public:
  /*
   * If a window receives WM_KEYDOWN message or WM_SYSKEYDOWM message which is
   * a redirected message, NativeKey::DispatchKeyDownAndKeyPressEvent()
   * prevents to dispatch eKeyDown event because it has been dispatched
   * before the message was redirected.  However, in some cases, WM_*KEYDOWN
   * message handler may not handle actually.  Then, the message handler needs
   * to forget the redirected message and remove WM_CHAR message or WM_SYSCHAR
   * message for the redirected keydown message.  AutoFlusher class is a helper
   * class for doing it.  This must be created in the stack.
   */
  class MOZ_STACK_CLASS AutoFlusher final
  {
  public:
    AutoFlusher(nsWindowBase* aWidget, const MSG &aMsg) :
      mCancel(!RedirectedKeyDownMessageManager::IsRedirectedMessage(aMsg)),
      mWidget(aWidget), mMsg(aMsg)
    {
    }

    ~AutoFlusher()
    {
      if (mCancel) {
        return;
      }
      // Prevent unnecessary keypress event
      if (!mWidget->Destroyed()) {
        RedirectedKeyDownMessageManager::RemoveNextCharMessage(mMsg.hwnd);
      }
      // Foreget the redirected message
      RedirectedKeyDownMessageManager::Forget();
    }

    void Cancel() { mCancel = true; }

  private:
    bool mCancel;
    RefPtr<nsWindowBase> mWidget;
    const MSG &mMsg;
  };

  static void WillRedirect(const MSG& aMsg, bool aDefualtPrevented)
  {
    sRedirectedKeyDownMsg = aMsg;
    sDefaultPreventedOfRedirectedMsg = aDefualtPrevented;
  }

  static void Forget()
  {
    sRedirectedKeyDownMsg.message = WM_NULL;
  }

  static void PreventDefault() { sDefaultPreventedOfRedirectedMsg = true; }
  static bool DefaultPrevented() { return sDefaultPreventedOfRedirectedMsg; }

  static bool IsRedirectedMessage(const MSG& aMsg);

  /**
   * RemoveNextCharMessage() should be called by WM_KEYDOWN or WM_SYSKEYDOWM
   * message handler.  If there is no WM_(SYS)CHAR message for it, this
   * method does nothing.
   * NOTE: WM_(SYS)CHAR message is posted by TranslateMessage() API which is
   * called in message loop.  So, WM_(SYS)KEYDOWN message should have
   * WM_(SYS)CHAR message in the queue if the keydown event causes character
   * input.
   */
  static void RemoveNextCharMessage(HWND aWnd);

private:
  // sRedirectedKeyDownMsg is WM_KEYDOWN message or WM_SYSKEYDOWN message which
  // is reirected with SendInput() API by
  // widget::NativeKey::DispatchKeyDownAndKeyPressEvent()
  static MSG sRedirectedKeyDownMsg;
  static bool sDefaultPreventedOfRedirectedMsg;
};

} // namespace widget
} // namespace mozilla

#endif