widget/TextEventDispatcher.cpp
author Rob Wu <rob@robwu.nl>
Sat, 24 Sep 2016 11:16:32 +0200
changeset 320058 a41f871e2d1b37754bbd1001c36c075511b49342
parent 317446 4e3211aa00ab01a1d81e6af54939d6adbaee5d5f
permissions -rw-r--r--
Bug 1299411 - Decouple Port implementation from API r=aswan Decoupled the API from the implementation. From now on it is possible to create Port instances without generating an API. This allows us to internally use Ports to pass around messages with minimal overhead (in the form of unnecessary clones of messages). This will be used by native messaging. This commit has no behavioral change, it is mostly moving around some code and storing the internal message listener in a set. MozReview-Commit-ID: 4h0LNJvTH9R

/* -*- 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/. */

#include "mozilla/Preferences.h"
#include "mozilla/TextEvents.h"
#include "mozilla/TextEventDispatcher.h"
#include "nsIDocShell.h"
#include "nsIFrame.h"
#include "nsIPresShell.h"
#include "nsIWidget.h"
#include "nsPIDOMWindow.h"
#include "nsView.h"

namespace mozilla {
namespace widget {

/******************************************************************************
 * TextEventDispatcher
 *****************************************************************************/

bool TextEventDispatcher::sDispatchKeyEventsDuringComposition = false;

TextEventDispatcher::TextEventDispatcher(nsIWidget* aWidget)
  : mWidget(aWidget)
  , mDispatchingEvent(0)
  , mInputTransactionType(eNoInputTransaction)
  , mIsComposing(false)
{
  MOZ_RELEASE_ASSERT(mWidget, "aWidget must not be nullptr");

  static bool sInitialized = false;
  if (!sInitialized) {
    Preferences::AddBoolVarCache(
      &sDispatchKeyEventsDuringComposition,
      "dom.keyboardevent.dispatch_during_composition",
      false);
    sInitialized = true;
  }
}

nsresult
TextEventDispatcher::BeginInputTransaction(
                       TextEventDispatcherListener* aListener)
{
  return BeginInputTransactionInternal(aListener,
                                       eSameProcessSyncInputTransaction);
}

nsresult
TextEventDispatcher::BeginTestInputTransaction(
                       TextEventDispatcherListener* aListener,
                       bool aIsAPZAware)
{
  return BeginInputTransactionInternal(aListener,
           aIsAPZAware ? eAsyncTestInputTransaction :
                         eSameProcessSyncTestInputTransaction);
}

nsresult
TextEventDispatcher::BeginNativeInputTransaction()
{
  if (NS_WARN_IF(!mWidget)) {
    return NS_ERROR_FAILURE;
  }
  RefPtr<TextEventDispatcherListener> listener =
    mWidget->GetNativeTextEventDispatcherListener();
  if (NS_WARN_IF(!listener)) {
    return NS_ERROR_FAILURE;
  }
  return BeginInputTransactionInternal(listener, eNativeInputTransaction);
}

nsresult
TextEventDispatcher::BeginInputTransactionInternal(
                       TextEventDispatcherListener* aListener,
                       InputTransactionType aType)
{
  if (NS_WARN_IF(!aListener)) {
    return NS_ERROR_INVALID_ARG;
  }
  nsCOMPtr<TextEventDispatcherListener> listener = do_QueryReferent(mListener);
  if (listener) {
    if (listener == aListener && mInputTransactionType == aType) {
      return NS_OK;
    }
    // If this has composition or is dispatching an event, any other listener
    // can steal ownership.  Especially, if the latter case is allowed,
    // nobody cannot begin input transaction with this if a modal dialog is
    // opened during dispatching an event.
    if (IsComposing() || IsDispatchingEvent()) {
      return NS_ERROR_ALREADY_INITIALIZED;
    }
  }
  mListener = do_GetWeakReference(aListener);
  mInputTransactionType = aType;
  if (listener && listener != aListener) {
    listener->OnRemovedFrom(this);
  }
  return NS_OK;
}

void
TextEventDispatcher::EndInputTransaction(TextEventDispatcherListener* aListener)
{
  if (NS_WARN_IF(IsComposing()) || NS_WARN_IF(IsDispatchingEvent())) {
    return;
  }

  mInputTransactionType = eNoInputTransaction;

  nsCOMPtr<TextEventDispatcherListener> listener = do_QueryReferent(mListener);
  if (NS_WARN_IF(!listener)) {
    return;
  }

  if (NS_WARN_IF(listener != aListener)) {
    return;
  }

  mListener = nullptr;
  listener->OnRemovedFrom(this);
}

void
TextEventDispatcher::OnDestroyWidget()
{
  mWidget = nullptr;
  mPendingComposition.Clear();
  nsCOMPtr<TextEventDispatcherListener> listener = do_QueryReferent(mListener);
  mListener = nullptr;
  mInputTransactionType = eNoInputTransaction;
  if (listener) {
    listener->OnRemovedFrom(this);
  }
}

nsresult
TextEventDispatcher::GetState() const
{
  nsCOMPtr<TextEventDispatcherListener> listener = do_QueryReferent(mListener);
  if (!listener) {
    return NS_ERROR_NOT_INITIALIZED;
  }
  if (!mWidget || mWidget->Destroyed()) {
    return NS_ERROR_NOT_AVAILABLE;
  }
  return NS_OK;
}

void
TextEventDispatcher::InitEvent(WidgetGUIEvent& aEvent) const
{
  aEvent.mTime = PR_IntervalNow();
  aEvent.mRefPoint = LayoutDeviceIntPoint(0, 0);
  aEvent.mFlags.mIsSynthesizedForTests = IsForTests();
  if (aEvent.mClass != eCompositionEventClass) {
    return;
  }
  void* pseudoIMEContext = GetPseudoIMEContext();
  if (pseudoIMEContext) {
    aEvent.AsCompositionEvent()->mNativeIMEContext.
      InitWithRawNativeIMEContext(pseudoIMEContext);
  }
#ifdef DEBUG
  else {
    MOZ_ASSERT(!XRE_IsContentProcess(),
      "Why did the content process start native event transaction?");
    MOZ_ASSERT(aEvent.AsCompositionEvent()->mNativeIMEContext.IsValid(),
      "Native IME context shouldn't be invalid");
  }
#endif // #ifdef DEBUG
}

nsresult
TextEventDispatcher::DispatchEvent(nsIWidget* aWidget,
                                   WidgetGUIEvent& aEvent,
                                   nsEventStatus& aStatus)
{
  MOZ_ASSERT(!aEvent.AsInputEvent(), "Use DispatchInputEvent()");

  RefPtr<TextEventDispatcher> kungFuDeathGrip(this);
  nsCOMPtr<nsIWidget> widget(aWidget);
  mDispatchingEvent++;
  nsresult rv = widget->DispatchEvent(&aEvent, aStatus);
  mDispatchingEvent--;
  return rv;
}

nsresult
TextEventDispatcher::DispatchInputEvent(nsIWidget* aWidget,
                                        WidgetInputEvent& aEvent,
                                        nsEventStatus& aStatus)
{
  RefPtr<TextEventDispatcher> kungFuDeathGrip(this);
  nsCOMPtr<nsIWidget> widget(aWidget);
  mDispatchingEvent++;

  // If the event is dispatched via nsIWidget::DispatchInputEvent(), it
  // sends the event to the parent process first since APZ needs to handle it
  // first.  However, some callers (e.g., keyboard apps on B2G and tests
  // expecting synchronous dispatch) don't want this to do that.
  nsresult rv = NS_OK;
  if (ShouldSendInputEventToAPZ()) {
    aStatus = widget->DispatchInputEvent(&aEvent);
  } else {
    rv = widget->DispatchEvent(&aEvent, aStatus);
  }

  mDispatchingEvent--;
  return rv;
}

nsresult
TextEventDispatcher::StartComposition(nsEventStatus& aStatus,
                                      const WidgetEventTime* aEventTime)
{
  aStatus = nsEventStatus_eIgnore;

  nsresult rv = GetState();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  if (NS_WARN_IF(mIsComposing)) {
    return NS_ERROR_FAILURE;
  }

  mIsComposing = true;
  WidgetCompositionEvent compositionStartEvent(true, eCompositionStart,
                                               mWidget);
  InitEvent(compositionStartEvent);
  if (aEventTime) {
    compositionStartEvent.AssignEventTime(*aEventTime);
  }
  rv = DispatchEvent(mWidget, compositionStartEvent, aStatus);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

nsresult
TextEventDispatcher::StartCompositionAutomaticallyIfNecessary(
                       nsEventStatus& aStatus,
                       const WidgetEventTime* aEventTime)
{
  if (IsComposing()) {
    return NS_OK;
  }

  nsresult rv = StartComposition(aStatus, aEventTime);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  // If started composition has already been committed, we shouldn't dispatch
  // the compositionchange event.
  if (!IsComposing()) {
    aStatus = nsEventStatus_eConsumeNoDefault;
    return NS_OK;
  }

  // Note that the widget might be destroyed during a call of
  // StartComposition().  In such case, we shouldn't keep dispatching next
  // event.
  rv = GetState();
  if (NS_FAILED(rv)) {
    MOZ_ASSERT(rv != NS_ERROR_NOT_INITIALIZED,
               "aDispatcher must still be initialized in this case");
    aStatus = nsEventStatus_eConsumeNoDefault;
    return NS_OK; // Don't throw exception in this case
  }

  aStatus = nsEventStatus_eIgnore;
  return NS_OK;
}

nsresult
TextEventDispatcher::CommitComposition(nsEventStatus& aStatus,
                                       const nsAString* aCommitString,
                                       const WidgetEventTime* aEventTime)
{
  aStatus = nsEventStatus_eIgnore;

  nsresult rv = GetState();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  // When there is no composition, caller shouldn't try to commit composition
  // with non-existing composition string nor commit composition with empty
  // string.
  if (NS_WARN_IF(!IsComposing() &&
                 (!aCommitString || aCommitString->IsEmpty()))) {
    return NS_ERROR_FAILURE;
  }

  nsCOMPtr<nsIWidget> widget(mWidget);
  rv = StartCompositionAutomaticallyIfNecessary(aStatus, aEventTime);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }
  if (aStatus == nsEventStatus_eConsumeNoDefault) {
    return NS_OK;
  }

  // End current composition and make this free for other IMEs.
  mIsComposing = false;

  EventMessage message = aCommitString ? eCompositionCommit :
                                         eCompositionCommitAsIs;
  WidgetCompositionEvent compositionCommitEvent(true, message, widget);
  InitEvent(compositionCommitEvent);
  if (aEventTime) {
    compositionCommitEvent.AssignEventTime(*aEventTime);
  }
  if (message == eCompositionCommit) {
    compositionCommitEvent.mData = *aCommitString;
    // Don't send CRLF, replace it with LF here.
    compositionCommitEvent.mData.ReplaceSubstring(NS_LITERAL_STRING("\r\n"),
                                                  NS_LITERAL_STRING("\n"));
  }
  rv = DispatchEvent(widget, compositionCommitEvent, aStatus);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

nsresult
TextEventDispatcher::NotifyIME(const IMENotification& aIMENotification)
{
  nsresult rv = NS_ERROR_NOT_IMPLEMENTED;

  // First, send the notification to current input transaction's listener.
  nsCOMPtr<TextEventDispatcherListener> listener = do_QueryReferent(mListener);
  if (listener) {
    rv = listener->NotifyIME(this, aIMENotification);
  }

  if (mInputTransactionType == eNativeInputTransaction || !mWidget) {
    return rv;
  }

  // If current input transaction isn't for native event handler, we should
  // send the notification to the native text event dispatcher listener
  // since native event handler may need to do something from
  // TextEventDispatcherListener::NotifyIME() even before there is no
  // input transaction yet.  For example, native IME handler may need to
  // create new context at receiving NOTIFY_IME_OF_FOCUS.  In this case,
  // mListener may not be initialized since input transaction should be
  // initialized immediately before dispatching every WidgetKeyboardEvent
  // and WidgetCompositionEvent (dispatching events always occurs after
  // focus move).
  nsCOMPtr<TextEventDispatcherListener> nativeListener =
    mWidget->GetNativeTextEventDispatcherListener();
  if (!nativeListener) {
    return rv;
  }
  switch (aIMENotification.mMessage) {
    case REQUEST_TO_COMMIT_COMPOSITION:
    case REQUEST_TO_CANCEL_COMPOSITION:
      // It's not necessary to notify native IME of requests.
      return rv;
    default: {
      // Even if current input transaction's listener returns NS_OK or
      // something, we need to notify native IME of notifications because
      // when user typing after TIP does something, the changed information
      // is necessary for them.
      nsresult rv2 =
        nativeListener->NotifyIME(this, aIMENotification);
      // But return the result from current listener except when the
      // notification isn't handled.
      return rv == NS_ERROR_NOT_IMPLEMENTED ? rv2 : rv;
    }
  }
}

bool
TextEventDispatcher::DispatchKeyboardEvent(
                       EventMessage aMessage,
                       const WidgetKeyboardEvent& aKeyboardEvent,
                       nsEventStatus& aStatus,
                       void* aData)
{
  return DispatchKeyboardEventInternal(aMessage, aKeyboardEvent, aStatus,
                                       aData);
}

bool
TextEventDispatcher::DispatchKeyboardEventInternal(
                       EventMessage aMessage,
                       const WidgetKeyboardEvent& aKeyboardEvent,
                       nsEventStatus& aStatus,
                       void* aData,
                       uint32_t aIndexOfKeypress,
                       bool aNeedsCallback)
{
  // Note that this method is also used for dispatching key events on a plugin
  // because key events on a plugin should be dispatched same as normal key
  // events.  Then, only some handlers which need to intercept key events
  // before the focused plugin (e.g., reserved shortcut key handlers) can
  // consume the events.
  MOZ_ASSERT(WidgetKeyboardEvent::IsKeyDownOrKeyDownOnPlugin(aMessage) ||
             WidgetKeyboardEvent::IsKeyUpOrKeyUpOnPlugin(aMessage) ||
             aMessage == eKeyPress, "Invalid aMessage value");
  nsresult rv = GetState();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return false;
  }

  // If the key shouldn't cause keypress events, don't this patch them.
  if (aMessage == eKeyPress && !aKeyboardEvent.ShouldCauseKeypressEvents()) {
    return false;
  }

  // Basically, key events shouldn't be dispatched during composition.
  // Note that plugin process has different IME context.  Therefore, we don't
  // need to check our composition state when the key event is fired on a
  // plugin.
  if (IsComposing() && !WidgetKeyboardEvent::IsKeyEventOnPlugin(aMessage)) {
    // However, if we need to behave like other browsers, we need the keydown
    // and keyup events.  Note that this behavior is also allowed by D3E spec.
    // FYI: keypress events must not be fired during composition.
    if (!sDispatchKeyEventsDuringComposition || aMessage == eKeyPress) {
      return false;
    }
    // XXX If there was mOnlyContentDispatch for this case, it might be useful
    //     because our chrome doesn't assume that key events are fired during
    //     composition.
  }

  WidgetKeyboardEvent keyEvent(true, aMessage, mWidget);
  InitEvent(keyEvent);
  keyEvent.AssignKeyEventData(aKeyboardEvent, false);

  if (aStatus == nsEventStatus_eConsumeNoDefault) {
    // If the key event should be dispatched as consumed event, marking it here.
    // This is useful to prevent double action.  E.g., when the key was already
    // handled by system, our chrome shouldn't handle it.
    keyEvent.PreventDefaultBeforeDispatch();
  }

  // Corrects each member for the specific key event type.
  if (keyEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING) {
    MOZ_ASSERT(!aIndexOfKeypress,
      "aIndexOfKeypress must be 0 for non-printable key");
    // If the keyboard event isn't caused by printable key, its charCode should
    // be 0.
    keyEvent.SetCharCode(0);
  } else {
    if (WidgetKeyboardEvent::IsKeyDownOrKeyDownOnPlugin(aMessage) ||
        WidgetKeyboardEvent::IsKeyUpOrKeyUpOnPlugin(aMessage)) {
      MOZ_RELEASE_ASSERT(!aIndexOfKeypress,
        "aIndexOfKeypress must be 0 for either eKeyDown or eKeyUp");
    } else {
      MOZ_RELEASE_ASSERT(
        !aIndexOfKeypress || aIndexOfKeypress < keyEvent.mKeyValue.Length(),
        "aIndexOfKeypress must be 0 - mKeyValue.Length() - 1");
    }
    wchar_t ch =
      keyEvent.mKeyValue.IsEmpty() ? 0 : keyEvent.mKeyValue[aIndexOfKeypress];
    keyEvent.SetCharCode(static_cast<uint32_t>(ch));
    if (aMessage == eKeyPress) {
      // keyCode of eKeyPress events of printable keys should be always 0.
      keyEvent.mKeyCode = 0;
      // eKeyPress events are dispatched for every character.
      // So, each key value of eKeyPress events should be a character.
      if (ch) {
        keyEvent.mKeyValue.Assign(ch);
      } else {
        keyEvent.mKeyValue.Truncate();
      }
    }
  }
  if (WidgetKeyboardEvent::IsKeyUpOrKeyUpOnPlugin(aMessage)) {
    // mIsRepeat of keyup event must be false.
    keyEvent.mIsRepeat = false;
  }
  // mIsComposing should be initialized later.
  keyEvent.mIsComposing = false;
  if (mInputTransactionType == eNativeInputTransaction) {
    // Copy mNativeKeyEvent here because for safety for other users of
    // AssignKeyEventData(), it doesn't copy this.
    keyEvent.mNativeKeyEvent = aKeyboardEvent.mNativeKeyEvent;
  } else {
    // If it's not a keyboard event for native key event, we should ensure that
    // mNativeKeyEvent and mPluginEvent are null/empty.
    keyEvent.mNativeKeyEvent = nullptr;
    keyEvent.mPluginEvent.Clear();
  }
  // TODO: Manage mUniqueId here.

  // Request the alternative char codes for the key event.
  // eKeyDown also needs alternative char codes because nsXBLWindowKeyHandler
  // needs to check if a following keypress event is reserved by chrome for
  // stopping propagation of its preceding keydown event.
  keyEvent.mAlternativeCharCodes.Clear();
  if ((WidgetKeyboardEvent::IsKeyDownOrKeyDownOnPlugin(aMessage) ||
       aMessage == eKeyPress) &&
      (aNeedsCallback || keyEvent.IsControl() || keyEvent.IsAlt() ||
       keyEvent.IsMeta() || keyEvent.IsOS())) {
    nsCOMPtr<TextEventDispatcherListener> listener =
      do_QueryReferent(mListener);
    if (listener) {
      DebugOnly<WidgetKeyboardEvent> original(keyEvent);
      listener->WillDispatchKeyboardEvent(this, keyEvent, aIndexOfKeypress,
                                          aData);
      MOZ_ASSERT(keyEvent.mMessage ==
                   static_cast<WidgetKeyboardEvent&>(original).mMessage);
      MOZ_ASSERT(keyEvent.mKeyCode ==
                   static_cast<WidgetKeyboardEvent&>(original).mKeyCode);
      MOZ_ASSERT(keyEvent.mLocation ==
                   static_cast<WidgetKeyboardEvent&>(original).mLocation);
      MOZ_ASSERT(keyEvent.mIsRepeat ==
                   static_cast<WidgetKeyboardEvent&>(original).mIsRepeat);
      MOZ_ASSERT(keyEvent.mIsComposing ==
                   static_cast<WidgetKeyboardEvent&>(original).mIsComposing);
      MOZ_ASSERT(keyEvent.mKeyNameIndex ==
                   static_cast<WidgetKeyboardEvent&>(original).mKeyNameIndex);
      MOZ_ASSERT(keyEvent.mCodeNameIndex ==
                   static_cast<WidgetKeyboardEvent&>(original).mCodeNameIndex);
      MOZ_ASSERT(keyEvent.mKeyValue ==
                   static_cast<WidgetKeyboardEvent&>(original).mKeyValue);
      MOZ_ASSERT(keyEvent.mCodeValue ==
                   static_cast<WidgetKeyboardEvent&>(original).mCodeValue);
    }
  }

  DispatchInputEvent(mWidget, keyEvent, aStatus);
  return true;
}

bool
TextEventDispatcher::MaybeDispatchKeypressEvents(
                       const WidgetKeyboardEvent& aKeyboardEvent,
                       nsEventStatus& aStatus,
                       void* aData,
                       bool aNeedsCallback)
{
  // If the key event was consumed, keypress event shouldn't be fired.
  if (aStatus == nsEventStatus_eConsumeNoDefault) {
    return false;
  }

  // If the key shouldn't cause keypress events, don't fire them.
  if (!aKeyboardEvent.ShouldCauseKeypressEvents()) {
    return false;
  }

  // If the key isn't a printable key or just inputting one character or
  // no character, we should dispatch only one keypress.  Otherwise, i.e.,
  // if the key is a printable key and inputs multiple characters, keypress
  // event should be dispatched the count of inputting characters times.
  size_t keypressCount =
    aKeyboardEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING ?
      1 : std::max(static_cast<nsAString::size_type>(1),
                   aKeyboardEvent.mKeyValue.Length());
  bool isDispatched = false;
  bool consumed = false;
  for (size_t i = 0; i < keypressCount; i++) {
    aStatus = nsEventStatus_eIgnore;
    if (!DispatchKeyboardEventInternal(eKeyPress, aKeyboardEvent,
                                       aStatus, aData, i, aNeedsCallback)) {
      // The widget must have been gone.
      break;
    }
    isDispatched = true;
    if (!consumed) {
      consumed = (aStatus == nsEventStatus_eConsumeNoDefault);
    }
  }

  // If one of the keypress event was consumed, return ConsumeNoDefault.
  if (consumed) {
    aStatus = nsEventStatus_eConsumeNoDefault;
  }

  return isDispatched;
}

/******************************************************************************
 * TextEventDispatcher::PendingComposition
 *****************************************************************************/

TextEventDispatcher::PendingComposition::PendingComposition()
{
  Clear();
}

void
TextEventDispatcher::PendingComposition::Clear()
{
  mString.Truncate();
  mClauses = nullptr;
  mCaret.mRangeType = TextRangeType::eUninitialized;
}

void
TextEventDispatcher::PendingComposition::EnsureClauseArray()
{
  if (mClauses) {
    return;
  }
  mClauses = new TextRangeArray();
}

nsresult
TextEventDispatcher::PendingComposition::SetString(const nsAString& aString)
{
  mString = aString;
  return NS_OK;
}

nsresult
TextEventDispatcher::PendingComposition::AppendClause(
                                           uint32_t aLength,
                                           TextRangeType aTextRangeType)
{
  if (NS_WARN_IF(!aLength)) {
    return NS_ERROR_INVALID_ARG;
  }

  switch (aTextRangeType) {
    case TextRangeType::eRawClause:
    case TextRangeType::eSelectedRawClause:
    case TextRangeType::eConvertedClause:
    case TextRangeType::eSelectedClause: {
      EnsureClauseArray();
      TextRange textRange;
      textRange.mStartOffset =
        mClauses->IsEmpty() ? 0 : mClauses->LastElement().mEndOffset;
      textRange.mEndOffset = textRange.mStartOffset + aLength;
      textRange.mRangeType = aTextRangeType;
      mClauses->AppendElement(textRange);
      return NS_OK;
    }
    default:
      return NS_ERROR_INVALID_ARG;
  }
}

nsresult
TextEventDispatcher::PendingComposition::SetCaret(uint32_t aOffset,
                                                  uint32_t aLength)
{
  mCaret.mStartOffset = aOffset;
  mCaret.mEndOffset = mCaret.mStartOffset + aLength;
  mCaret.mRangeType = TextRangeType::eCaret;
  return NS_OK;
}

nsresult
TextEventDispatcher::PendingComposition::Set(const nsAString& aString,
                                             const TextRangeArray* aRanges)
{
  Clear();

  nsAutoString str(aString);
  // Don't expose CRLF to web contents, instead, use LF.
  str.ReplaceSubstring(NS_LITERAL_STRING("\r\n"), NS_LITERAL_STRING("\n"));
  nsresult rv = SetString(str);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  if (!aRanges || aRanges->IsEmpty()) {
    // Create dummy range if aString isn't empty.
    if (!aString.IsEmpty()) {
      rv = AppendClause(str.Length(), TextRangeType::eRawClause);
      if (NS_WARN_IF(NS_FAILED(rv))) {
        return rv;
      }
    }
    return NS_OK;
  }

  // Adjust offsets in the ranges for XP linefeed character (only \n).
  // XXX Following code is the safest approach.  However, it wastes performance.
  //     For ensuring the clauses do not overlap each other, we should redesign
  //     TextRange later.
  for (uint32_t i = 0; i < aRanges->Length(); ++i) {
    TextRange range = aRanges->ElementAt(i);
    TextRange nativeRange = range;
    if (nativeRange.mStartOffset > 0) {
      nsAutoString preText(Substring(aString, 0, nativeRange.mStartOffset));
      preText.ReplaceSubstring(NS_LITERAL_STRING("\r\n"),
                               NS_LITERAL_STRING("\n"));
      range.mStartOffset = preText.Length();
    }
    if (nativeRange.Length() == 0) {
      range.mEndOffset = range.mStartOffset;
    } else {
      nsAutoString clause(
        Substring(aString, nativeRange.mStartOffset, nativeRange.Length()));
      clause.ReplaceSubstring(NS_LITERAL_STRING("\r\n"),
                              NS_LITERAL_STRING("\n"));
      range.mEndOffset = range.mStartOffset + clause.Length();
    }
    if (range.mRangeType == TextRangeType::eCaret) {
      mCaret = range;
    } else {
      EnsureClauseArray();
      mClauses->AppendElement(range);
    }
  }
  return NS_OK;
}

nsresult
TextEventDispatcher::PendingComposition::Flush(
                                           TextEventDispatcher* aDispatcher,
                                           nsEventStatus& aStatus,
                                           const WidgetEventTime* aEventTime)
{
  aStatus = nsEventStatus_eIgnore;

  nsresult rv = aDispatcher->GetState();
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  if (mClauses && !mClauses->IsEmpty() &&
      mClauses->LastElement().mEndOffset != mString.Length()) {
    NS_WARNING("Sum of length of the all clauses must be same as the string "
               "length");
    Clear();
    return NS_ERROR_ILLEGAL_VALUE;
  }
  if (mCaret.mRangeType == TextRangeType::eCaret) {
    if (mCaret.mEndOffset > mString.Length()) {
      NS_WARNING("Caret position is out of the composition string");
      Clear();
      return NS_ERROR_ILLEGAL_VALUE;
    }
    EnsureClauseArray();
    mClauses->AppendElement(mCaret);
  }

  RefPtr<TextEventDispatcher> kungFuDeathGrip(aDispatcher);
  nsCOMPtr<nsIWidget> widget(aDispatcher->mWidget);
  WidgetCompositionEvent compChangeEvent(true, eCompositionChange, widget);
  aDispatcher->InitEvent(compChangeEvent);
  if (aEventTime) {
    compChangeEvent.AssignEventTime(*aEventTime);
  }
  compChangeEvent.mData = mString;
  if (mClauses) {
    MOZ_ASSERT(!mClauses->IsEmpty(),
               "mClauses must be non-empty array when it's not nullptr");
    compChangeEvent.mRanges = mClauses;
  }

  // While this method dispatches a composition event, some other event handler
  // cause more clauses to be added.  So, we should clear pending composition
  // before dispatching the event.
  Clear();

  rv = aDispatcher->StartCompositionAutomaticallyIfNecessary(aStatus,
                                                             aEventTime);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }
  if (aStatus == nsEventStatus_eConsumeNoDefault) {
    return NS_OK;
  }
  rv = aDispatcher->DispatchEvent(widget, compChangeEvent, aStatus);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  return NS_OK;
}

} // namespace widget
} // namespace mozilla