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/* -*- 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 */
#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.
// The native key event was handled by IMContextWrapper.
// The native key event has not been handled by IMContextWrapper,
// but eKeyDown or eKeyUp event has been dispatched.
// The native key event has not been handled by IMContextWrapper,
// but eKeyDown or eKeyUp event has been dispatched and consumed.
class IMContextWrapper final : public TextEventDispatcherListener {
// TextEventDispatcherListener implementation
NS_IMETHOD NotifyIME(TextEventDispatcher* aTextEventDispatcher,
const IMENotification& aNotification) override;
NS_IMETHOD_(IMENotificationRequests) GetIMENotificationRequests() override;
OnRemovedFrom(TextEventDispatcher* aTextEventDispatcher) override;
WillDispatchKeyboardEvent(TextEventDispatcher* aTextEventDispatcher,
WidgetKeyboardEvent& aKeyboardEvent,
uint32_t aIndexOfKeypress, void* aData) override;
// 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
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;
// 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 {
~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;
* 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())) {
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))) {
return i;
return GdkEventKeyQueue::NoIndex();
nsTArray<GdkEventKey*> mEvents;
void RemoveEventsAt(size_t aStart, size_t aCount) {
for (size_t i = aStart; i < aStart + aCount; 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 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 ==
* 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";
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() {
mOffset = UINT32_MAX;
mWritingMode = WritingMode();
void CollapseTo(uint32_t aOffset, const WritingMode& aWritingMode) {
mWritingMode = aWritingMode;
mOffset = aOffset;
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.
* 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);
* 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_