From 2aa4a82499d4becd2284cdb482213d541b8804dd Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 28 Apr 2024 16:29:10 +0200
Subject: Adding upstream version 86.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 widget/gtk/IMContextWrapper.h | 685 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 685 insertions(+)
 create mode 100644 widget/gtk/IMContextWrapper.h

(limited to 'widget/gtk/IMContextWrapper.h')

diff --git a/widget/gtk/IMContextWrapper.h b/widget/gtk/IMContextWrapper.h
new file mode 100644
index 0000000000..9ebb22fc3d
--- /dev/null
+++ b/widget/gtk/IMContextWrapper.h
@@ -0,0 +1,685 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:expandtab:shiftwidth=4:tabstop=4:
+ */
+/* 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 IMContextWrapper_h_
+#define IMContextWrapper_h_
+
+#include <gdk/gdk.h>
+#include <gtk/gtk.h>
+
+#include "nsString.h"
+#include "nsCOMPtr.h"
+#include "nsTArray.h"
+#include "nsIWidget.h"
+#include "mozilla/CheckedInt.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/TextEventDispatcherListener.h"
+#include "WritingModes.h"
+
+class nsWindow;
+
+namespace mozilla {
+namespace widget {
+
+/**
+ * KeyHandlingState is result of IMContextWrapper::OnKeyEvent().
+ */
+enum class KeyHandlingState {
+  // The native key event has not been handled by IMContextWrapper.
+  eNotHandled,
+  // The native key event was handled by IMContextWrapper.
+  eHandled,
+  // The native key event has not been handled by IMContextWrapper,
+  // but eKeyDown or eKeyUp event has been dispatched.
+  eNotHandledButEventDispatched,
+  // The native key event has not been handled by IMContextWrapper,
+  // but eKeyDown or eKeyUp event has been dispatched and consumed.
+  eNotHandledButEventConsumed,
+};
+
+class IMContextWrapper final : public TextEventDispatcherListener {
+ public:
+  // TextEventDispatcherListener implementation
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD NotifyIME(TextEventDispatcher* aTextEventDispatcher,
+                       const IMENotification& aNotification) override;
+  NS_IMETHOD_(IMENotificationRequests) GetIMENotificationRequests() override;
+  NS_IMETHOD_(void)
+  OnRemovedFrom(TextEventDispatcher* aTextEventDispatcher) override;
+  NS_IMETHOD_(void)
+  WillDispatchKeyboardEvent(TextEventDispatcher* aTextEventDispatcher,
+                            WidgetKeyboardEvent& aKeyboardEvent,
+                            uint32_t aIndexOfKeypress, void* aData) override;
+
+ public:
+  // aOwnerWindow is a pointer of the owner window.  When aOwnerWindow is
+  // destroyed, the related IME contexts are released (i.e., IME cannot be
+  // used with the instance after that).
+  explicit IMContextWrapper(nsWindow* aOwnerWindow);
+
+  // Called when the process is being shut down.
+  static void Shutdown();
+
+  // "Enabled" means the users can use all IMEs.
+  // I.e., the focus is in the normal editors.
+  bool IsEnabled() const;
+
+  // OnFocusWindow is a notification that aWindow is going to be focused.
+  void OnFocusWindow(nsWindow* aWindow);
+  // OnBlurWindow is a notification that aWindow is going to be unfocused.
+  void OnBlurWindow(nsWindow* aWindow);
+  // OnDestroyWindow is a notification that aWindow is going to be destroyed.
+  void OnDestroyWindow(nsWindow* aWindow);
+  // OnFocusChangeInGecko is a notification that an editor gets focus.
+  void OnFocusChangeInGecko(bool aFocus);
+  // OnSelectionChange is a notification that selection (caret) is changed
+  // in the focused editor.
+  void OnSelectionChange(nsWindow* aCaller,
+                         const IMENotification& aIMENotification);
+  // OnThemeChanged is called when desktop theme is changed.
+  static void OnThemeChanged();
+
+  /**
+   * OnKeyEvent() is called when aWindow gets a native key press event or a
+   * native key release event.  If this returns true, the key event was
+   * filtered by IME.  Otherwise, this returns false.
+   * NOTE: When the native key press event starts composition, this returns
+   *       true but dispatches an eKeyDown event or eKeyUp event before
+   *       dispatching composition events or content command event.
+   *
+   * @param aWindow                       A window on which user operate the
+   *                                      key.
+   * @param aEvent                        A native key press or release
+   *                                      event.
+   * @param aKeyboardEventWasDispatched   true if eKeyDown or eKeyUp event
+   *                                      for aEvent has already been
+   *                                      dispatched.  In this case,
+   *                                      this class doesn't dispatch
+   *                                      keyboard event anymore.
+   */
+  KeyHandlingState OnKeyEvent(nsWindow* aWindow, GdkEventKey* aEvent,
+                              bool aKeyboardEventWasDispatched = false);
+
+  // IME related nsIWidget methods.
+  nsresult EndIMEComposition(nsWindow* aCaller);
+  void SetInputContext(nsWindow* aCaller, const InputContext* aContext,
+                       const InputContextAction* aAction);
+  InputContext GetInputContext();
+  void OnUpdateComposition();
+  void OnLayoutChange();
+
+  TextEventDispatcher* GetTextEventDispatcher();
+
+  // TODO: Typically, new IM comes every several years.  And now, our code
+  //       becomes really IM behavior dependent.  So, perhaps, we need prefs
+  //       to control related flags for IM developers.
+  enum class IMContextID : uint8_t {
+    Fcitx,  // 4.x or earlier
+    Fcitx5,
+    IBus,
+    IIIMF,
+    Scim,
+    Uim,
+    Wayland,
+    Unknown,
+  };
+
+  friend std::ostream& operator<<(std::ostream& aStream,
+                                  const IMContextID& aIMContextID) {
+    switch (aIMContextID) {
+      case IMContextID::Fcitx:
+        return aStream << "Fcitx";
+      case IMContextID::Fcitx5:
+        return aStream << "Fcitx5";
+      case IMContextID::IBus:
+        return aStream << "IBus";
+      case IMContextID::IIIMF:
+        return aStream << "IIIMF";
+      case IMContextID::Scim:
+        return aStream << "Scim";
+      case IMContextID::Uim:
+        return aStream << "Uim";
+      case IMContextID::Wayland:
+        return aStream << "Wayland";
+      case IMContextID::Unknown:
+        return aStream << "Unknown";
+    }
+    MOZ_ASSERT_UNREACHABLE("Add new case for the new IM support");
+    return aStream << "Unknown";
+  }
+
+  /**
+   * GetIMName() returns IM name associated with mContext.  If the context is
+   * xim, this look for actual engine from XMODIFIERS environment variable.
+   */
+  nsDependentCSubstring GetIMName() const;
+
+  /**
+   * GetWaitingSynthesizedKeyPressHardwareKeyCode() returns hardware_keycode
+   * value of last handled GDK_KEY_PRESS event which is probable handled by
+   * IME asynchronously and we have not received synthesized GDK_KEY_PRESS
+   * event yet.
+   */
+  static guint16 GetWaitingSynthesizedKeyPressHardwareKeyCode() {
+    return sWaitingSynthesizedKeyPressHardwareKeyCode;
+  }
+
+ protected:
+  ~IMContextWrapper();
+
+  // Owner of an instance of this class. This should be top level window.
+  // The owner window must release the contexts when it's destroyed because
+  // the IME contexts need the native window.  If OnDestroyWindow() is called
+  // with the owner window, it'll release IME contexts.  Otherwise, it'll
+  // just clean up any existing composition if it's related to the destroying
+  // child window.
+  nsWindow* mOwnerWindow;
+
+  // A last focused window in this class's context.
+  nsWindow* mLastFocusedWindow;
+
+  // Actual context. This is used for handling the user's input.
+  GtkIMContext* mContext;
+
+  // mSimpleContext is used for the password field and
+  // the |ime-mode: disabled;| editors if sUseSimpleContext is true.
+  // These editors disable IME.  But dead keys should work.  Fortunately,
+  // the simple IM context of GTK2 support only them.
+  GtkIMContext* mSimpleContext;
+
+  // mDummyContext is a dummy context and will be used in Focus()
+  // when the state of mEnabled means disabled.  This context's IME state is
+  // always "closed", so it closes IME forcedly.
+  GtkIMContext* mDummyContext;
+
+  // mComposingContext is not nullptr while one of mContext, mSimpleContext
+  // and mDummyContext has composition.
+  // XXX: We don't assume that two or more context have composition same time.
+  GtkIMContext* mComposingContext;
+
+  // IME enabled state and other things defined in InputContext.
+  // Use following helper methods if you don't need the detail of the status.
+  InputContext mInputContext;
+
+  // mCompositionStart is the start offset of the composition string in the
+  // current content.  When <textarea> or <input> have focus, it means offset
+  // from the first character of them.  When a HTML editor has focus, it
+  // means offset from the first character of the root element of the editor.
+  uint32_t mCompositionStart;
+
+  // mDispatchedCompositionString is the latest composition string which
+  // was dispatched by compositionupdate event.
+  nsString mDispatchedCompositionString;
+
+  // mSelectedStringRemovedByComposition is the selected string which was
+  // removed by first compositionchange event.
+  nsString mSelectedStringRemovedByComposition;
+
+  // OnKeyEvent() temporarily sets mProcessingKeyEvent to the given native
+  // event.
+  GdkEventKey* mProcessingKeyEvent;
+
+  /**
+   * GdkEventKeyQueue stores *copy* of GdkEventKey instances.  However, this
+   * must be safe to our usecase since it has |time| and the value should not
+   * be same as older event.
+   */
+  class GdkEventKeyQueue final {
+   public:
+    ~GdkEventKeyQueue() { Clear(); }
+
+    void Clear() {
+      if (!mEvents.IsEmpty()) {
+        RemoveEventsAt(0, mEvents.Length());
+      }
+    }
+
+    /**
+     * PutEvent() puts new event into the queue.
+     */
+    void PutEvent(const GdkEventKey* aEvent) {
+      GdkEventKey* newEvent = reinterpret_cast<GdkEventKey*>(
+          gdk_event_copy(reinterpret_cast<const GdkEvent*>(aEvent)));
+      newEvent->state &= GDK_MODIFIER_MASK;
+      mEvents.AppendElement(newEvent);
+    }
+
+    /**
+     * RemoveEvent() removes oldest same event and its preceding events
+     * from the queue.
+     */
+    void RemoveEvent(const GdkEventKey* aEvent) {
+      size_t index = IndexOf(aEvent);
+      if (NS_WARN_IF(index == GdkEventKeyQueue::NoIndex())) {
+        return;
+      }
+      RemoveEventsAt(0, index + 1);
+    }
+
+    /**
+     * FirstEvent() returns oldest event in the queue.
+     */
+    GdkEventKey* GetFirstEvent() const {
+      if (mEvents.IsEmpty()) {
+        return nullptr;
+      }
+      return mEvents[0];
+    }
+
+    bool IsEmpty() const { return mEvents.IsEmpty(); }
+
+    static size_t NoIndex() { return nsTArray<GdkEventKey*>::NoIndex; }
+    size_t Length() const { return mEvents.Length(); }
+    size_t IndexOf(const GdkEventKey* aEvent) const {
+      static_assert(!(GDK_MODIFIER_MASK & (1 << 24)),
+                    "We assumes 25th bit is used by some IM, but used by GDK");
+      static_assert(!(GDK_MODIFIER_MASK & (1 << 25)),
+                    "We assumes 26th bit is used by some IM, but used by GDK");
+      for (size_t i = 0; i < mEvents.Length(); i++) {
+        GdkEventKey* event = mEvents[i];
+        // It must be enough to compare only type, time, keyval and
+        // part of state.   Note that we cannot compaire two events
+        // simply since IME may have changed unused bits of state.
+        if (event->time == aEvent->time) {
+          if (NS_WARN_IF(event->type != aEvent->type) ||
+              NS_WARN_IF(event->keyval != aEvent->keyval) ||
+              NS_WARN_IF(event->state != (aEvent->state & GDK_MODIFIER_MASK))) {
+            continue;
+          }
+        }
+        return i;
+      }
+      return GdkEventKeyQueue::NoIndex();
+    }
+
+   private:
+    nsTArray<GdkEventKey*> mEvents;
+
+    void RemoveEventsAt(size_t aStart, size_t aCount) {
+      for (size_t i = aStart; i < aStart + aCount; i++) {
+        gdk_event_free(reinterpret_cast<GdkEvent*>(mEvents[i]));
+      }
+      mEvents.RemoveElementsAt(aStart, aCount);
+    }
+  };
+  // OnKeyEvent() append mPostingKeyEvents when it believes that a key event
+  // is posted to other IME process.
+  GdkEventKeyQueue mPostingKeyEvents;
+
+  static guint16 sWaitingSynthesizedKeyPressHardwareKeyCode;
+
+  struct Range {
+    uint32_t mOffset;
+    uint32_t mLength;
+
+    Range() : mOffset(UINT32_MAX), mLength(UINT32_MAX) {}
+
+    bool IsValid() const { return mOffset != UINT32_MAX; }
+    void Clear() {
+      mOffset = UINT32_MAX;
+      mLength = UINT32_MAX;
+    }
+  };
+
+  // current target offset and length of IME composition
+  Range mCompositionTargetRange;
+
+  // mCompositionState indicates current status of composition.
+  enum eCompositionState : uint8_t {
+    eCompositionState_NotComposing,
+    eCompositionState_CompositionStartDispatched,
+    eCompositionState_CompositionChangeEventDispatched
+  };
+  eCompositionState mCompositionState;
+
+  bool IsComposing() const {
+    return (mCompositionState != eCompositionState_NotComposing);
+  }
+
+  bool IsComposingOn(GtkIMContext* aContext) const {
+    return IsComposing() && mComposingContext == aContext;
+  }
+
+  bool IsComposingOnCurrentContext() const {
+    return IsComposingOn(GetCurrentContext());
+  }
+
+  bool EditorHasCompositionString() {
+    return (mCompositionState ==
+            eCompositionState_CompositionChangeEventDispatched);
+  }
+
+  /**
+   * Checks if aContext is valid context for handling composition.
+   *
+   * @param aContext          An IM context which is specified by native
+   *                          composition events.
+   * @return                  true if the context is valid context for
+   *                          handling composition.  Otherwise, false.
+   */
+  bool IsValidContext(GtkIMContext* aContext) const;
+
+  const char* GetCompositionStateName() {
+    switch (mCompositionState) {
+      case eCompositionState_NotComposing:
+        return "NotComposing";
+      case eCompositionState_CompositionStartDispatched:
+        return "CompositionStartDispatched";
+      case eCompositionState_CompositionChangeEventDispatched:
+        return "CompositionChangeEventDispatched";
+      default:
+        return "InvaildState";
+    }
+  }
+
+  // mIMContextID indicates the ID of mContext.  This is actually indicates
+  // IM which user selected.
+  IMContextID mIMContextID;
+
+  struct Selection final {
+    nsString mString;
+    uint32_t mOffset;
+    WritingMode mWritingMode;
+
+    Selection() : mOffset(UINT32_MAX) {}
+
+    void Clear() {
+      mString.Truncate();
+      mOffset = UINT32_MAX;
+      mWritingMode = WritingMode();
+    }
+    void CollapseTo(uint32_t aOffset, const WritingMode& aWritingMode) {
+      mWritingMode = aWritingMode;
+      mOffset = aOffset;
+      mString.Truncate();
+    }
+
+    void Assign(const IMENotification& aIMENotification);
+    void Assign(const WidgetQueryContentEvent& aSelectedTextEvent);
+
+    bool IsValid() const { return mOffset != UINT32_MAX; }
+    bool Collapsed() const { return mString.IsEmpty(); }
+    uint32_t Length() const { return mString.Length(); }
+    uint32_t EndOffset() const {
+      if (NS_WARN_IF(!IsValid())) {
+        return UINT32_MAX;
+      }
+      CheckedInt<uint32_t> endOffset =
+          CheckedInt<uint32_t>(mOffset) + mString.Length();
+      if (NS_WARN_IF(!endOffset.isValid())) {
+        return UINT32_MAX;
+      }
+      return endOffset.value();
+    }
+  } mSelection;
+  bool EnsureToCacheSelection(nsAString* aSelectedString = nullptr);
+
+  // mIsIMFocused is set to TRUE when we call gtk_im_context_focus_in(). And
+  // it's set to FALSE when we call gtk_im_context_focus_out().
+  bool mIsIMFocused;
+  // mFallbackToKeyEvent is set to false when this class starts to handle
+  // a native key event (at that time, mProcessingKeyEvent is set to the
+  // native event).  If active IME just commits composition with a character
+  // which is produced by the key with current keyboard layout, this is set
+  // to true.
+  bool mFallbackToKeyEvent;
+  // mKeyboardEventWasDispatched is used by OnKeyEvent() and
+  // MaybeDispatchKeyEventAsProcessedByIME().
+  // MaybeDispatchKeyEventAsProcessedByIME() dispatches an eKeyDown or
+  // eKeyUp event event if the composition is caused by a native
+  // key press event.  If this is true, a keyboard event has been dispatched
+  // for the native event.  If so, MaybeDispatchKeyEventAsProcessedByIME()
+  // won't dispatch keyboard event anymore.
+  bool mKeyboardEventWasDispatched;
+  // Whether the keyboard event which as dispatched at setting
+  // mKeyboardEventWasDispatched to true was consumed or not.
+  bool mKeyboardEventWasConsumed;
+  // mIsDeletingSurrounding is true while OnDeleteSurroundingNative() is
+  // trying to delete the surrounding text.
+  bool mIsDeletingSurrounding;
+  // mLayoutChanged is true after OnLayoutChange() is called.  This is reset
+  // when eCompositionChange is being dispatched.
+  bool mLayoutChanged;
+  // mSetCursorPositionOnKeyEvent true when caret rect or position is updated
+  // with no composition.  If true, we update candidate window position
+  // before key down
+  bool mSetCursorPositionOnKeyEvent;
+  // mPendingResettingIMContext becomes true if selection change notification
+  // is received during composition but the selection change occurred before
+  // starting the composition.  In such case, we cannot notify IME of
+  // selection change during composition because we don't want to commit
+  // the composition in such case.  However, we should notify IME of the
+  // selection change after the composition is committed.
+  bool mPendingResettingIMContext;
+  // mRetrieveSurroundingSignalReceived is true after "retrieve_surrounding"
+  // signal is received until selection is changed in Gecko.
+  bool mRetrieveSurroundingSignalReceived;
+  // mMaybeInDeadKeySequence is set to true when we detect a dead key press
+  // and set to false when we're sure dead key sequence has been finished.
+  // Note that we cannot detect which key event causes ending a dead key
+  // sequence.  For example, when you press dead key grave with ibus Spanish
+  // keyboard layout, it just consumes the key event when we call
+  // gtk_im_context_filter_keypress().  Then, pressing "Escape" key cancels
+  // the dead key sequence but we don't receive any signal and it's consumed
+  // by gtk_im_context_filter_keypress() normally.  On the other hand, when
+  // pressing "Shift" key causes exactly same behavior but dead key sequence
+  // isn't finished yet.
+  bool mMaybeInDeadKeySequence;
+  // mIsIMInAsyncKeyHandlingMode is set to true if we know that IM handles
+  // key events asynchronously.  I.e., filtered key event may come again
+  // later.
+  bool mIsIMInAsyncKeyHandlingMode;
+  // mIsKeySnooped is set to true if IM uses key snooper to listen key events.
+  // In such case, we won't receive key events if IME consumes the event.
+  bool mIsKeySnooped;
+
+  // sLastFocusedContext is a pointer to the last focused instance of this
+  // class.  When a instance is destroyed and sLastFocusedContext refers it,
+  // this is cleared.  So, this refers valid pointer always.
+  static IMContextWrapper* sLastFocusedContext;
+
+  // sUseSimpleContext indeicates if password editors and editors with
+  // |ime-mode: disabled;| should use GtkIMContextSimple.
+  // If true, they use GtkIMContextSimple.  Otherwise, not.
+  static bool sUseSimpleContext;
+
+  // Callback methods for native IME events.  These methods should call
+  // the related instance methods simply.
+  static gboolean OnRetrieveSurroundingCallback(GtkIMContext* aContext,
+                                                IMContextWrapper* aModule);
+  static gboolean OnDeleteSurroundingCallback(GtkIMContext* aContext,
+                                              gint aOffset, gint aNChars,
+                                              IMContextWrapper* aModule);
+  static void OnCommitCompositionCallback(GtkIMContext* aContext,
+                                          const gchar* aString,
+                                          IMContextWrapper* aModule);
+  static void OnChangeCompositionCallback(GtkIMContext* aContext,
+                                          IMContextWrapper* aModule);
+  static void OnStartCompositionCallback(GtkIMContext* aContext,
+                                         IMContextWrapper* aModule);
+  static void OnEndCompositionCallback(GtkIMContext* aContext,
+                                       IMContextWrapper* aModule);
+
+  // The instance methods for the native IME events.
+  gboolean OnRetrieveSurroundingNative(GtkIMContext* aContext);
+  gboolean OnDeleteSurroundingNative(GtkIMContext* aContext, gint aOffset,
+                                     gint aNChars);
+  void OnCommitCompositionNative(GtkIMContext* aContext, const gchar* aString);
+  void OnChangeCompositionNative(GtkIMContext* aContext);
+  void OnStartCompositionNative(GtkIMContext* aContext);
+  void OnEndCompositionNative(GtkIMContext* aContext);
+
+  /**
+   * GetCurrentContext() returns current IM context which is chosen with the
+   * enabled state.
+   * WARNING:
+   *     When this class receives some signals for a composition after focus
+   *     is moved in Gecko, the result of this may be different from given
+   *     context by the signals.
+   */
+  GtkIMContext* GetCurrentContext() const;
+
+  /**
+   * GetActiveContext() returns a composing context or current context.
+   */
+  GtkIMContext* GetActiveContext() const {
+    return mComposingContext ? mComposingContext : GetCurrentContext();
+  }
+
+  // If the owner window and IM context have been destroyed, returns TRUE.
+  bool IsDestroyed() { return !mOwnerWindow; }
+
+  // Sets focus to the instance of this class.
+  void Focus();
+
+  // Steals focus from the instance of this class.
+  void Blur();
+
+  // Initializes the instance.
+  void Init();
+
+  /**
+   * Reset the active context, i.e., if there is mComposingContext, reset it.
+   * Otherwise, reset current context.  Note that all native composition
+   * events during calling this will be ignored.
+   */
+  void ResetIME();
+
+  // Gets the current composition string by the native APIs.
+  void GetCompositionString(GtkIMContext* aContext,
+                            nsAString& aCompositionString);
+
+  /**
+   * Generates our text range array from current composition string.
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   * @param aCompositionString    The data to be dispatched with
+   *                              compositionchange event.
+   */
+  already_AddRefed<TextRangeArray> CreateTextRangeArray(
+      GtkIMContext* aContext, const nsAString& aCompositionString);
+
+  /**
+   * SetTextRange() initializes aTextRange with aPangoAttrIter.
+   *
+   * @param aPangoAttrIter            An iter which represents a clause of the
+   *                                  composition string.
+   * @param aUTF8CompositionString    The whole composition string (UTF-8).
+   * @param aUTF16CaretOffset         The caret offset in the composition
+   *                                  string encoded as UTF-16.
+   * @param aTextRange                The result.
+   * @return                          true if this initializes aTextRange.
+   *                                  Otherwise, false.
+   */
+  bool SetTextRange(PangoAttrIterator* aPangoAttrIter,
+                    const gchar* aUTF8CompositionString,
+                    uint32_t aUTF16CaretOffset, TextRange& aTextRange) const;
+
+  /**
+   * ToNscolor() converts the PangoColor in aPangoAttrColor to nscolor.
+   */
+  static nscolor ToNscolor(PangoAttrColor* aPangoAttrColor);
+
+  /**
+   * Move the candidate window with "fake" cursor position.
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   */
+  void SetCursorPosition(GtkIMContext* aContext);
+
+  // Queries the current selection offset of the window.
+  uint32_t GetSelectionOffset(nsWindow* aWindow);
+
+  // Get current paragraph text content and cursor position
+  nsresult GetCurrentParagraph(nsAString& aText, uint32_t& aCursorPos);
+
+  /**
+   * Delete text portion
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   * @param aOffset               Start offset of the range to delete.
+   * @param aNChars               Count of characters to delete.  It depends
+   *                              on |g_utf8_strlen()| what is one character.
+   */
+  nsresult DeleteText(GtkIMContext* aContext, int32_t aOffset,
+                      uint32_t aNChars);
+
+  // Initializes the GUI event.
+  void InitEvent(WidgetGUIEvent& aEvent);
+
+  // Called before destroying the context to work around some platform bugs.
+  void PrepareToDestroyContext(GtkIMContext* aContext);
+
+  /**
+   *  WARNING:
+   *    Following methods dispatch gecko events.  Then, the focused widget
+   *    can be destroyed, and also it can be stolen focus.  If they returns
+   *    FALSE, callers cannot continue the composition.
+   *      - MaybeDispatchKeyEventAsProcessedByIME
+   *      - DispatchCompositionStart
+   *      - DispatchCompositionChangeEvent
+   *      - DispatchCompositionCommitEvent
+   */
+
+  /**
+   * Dispatch an eKeyDown or eKeyUp event whose mKeyCode value is
+   * NS_VK_PROCESSKEY and mKeyNameIndex is KEY_NAME_INDEX_Process if
+   * we're not in a dead key sequence, mProcessingKeyEvent is nullptr
+   * but mPostingKeyEvents is not empty or mProcessingKeyEvent is not
+   * nullptr and mKeyboardEventWasDispatched is still false.  If this
+   * dispatches a keyboard event, this sets mKeyboardEventWasDispatched
+   * to true.
+   *
+   * @param aFollowingEvent       The following event message.
+   * @return                      If the caller can continue to handle
+   *                              composition, returns true.  Otherwise,
+   *                              false.  For example, if focus is moved
+   *                              by dispatched keyboard event, returns
+   *                              false.
+   */
+  bool MaybeDispatchKeyEventAsProcessedByIME(EventMessage aFollowingEvent);
+
+  /**
+   * Dispatches a composition start event.
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   * @return                      true if the focused widget is neither
+   *                              destroyed nor changed.  Otherwise, false.
+   */
+  bool DispatchCompositionStart(GtkIMContext* aContext);
+
+  /**
+   * Dispatches a compositionchange event.
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   * @param aCompositionString    New composition string.
+   * @return                      true if the focused widget is neither
+   *                              destroyed nor changed.  Otherwise, false.
+   */
+  bool DispatchCompositionChangeEvent(GtkIMContext* aContext,
+                                      const nsAString& aCompositionString);
+
+  /**
+   * Dispatches a compositioncommit event or compositioncommitasis event.
+   *
+   * @param aContext              A GtkIMContext which is being handled.
+   * @param aCommitString         If this is nullptr, the composition will
+   *                              be committed with last dispatched data.
+   *                              Otherwise, the composition will be
+   *                              committed with this value.
+   * @return                      true if the focused widget is neither
+   *                              destroyed nor changed.  Otherwise, false.
+   */
+  bool DispatchCompositionCommitEvent(GtkIMContext* aContext,
+                                      const nsAString* aCommitString = nullptr);
+};
+
+}  // namespace widget
+}  // namespace mozilla
+
+#endif  // #ifndef IMContextWrapper_h_
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