gecko/widget/nsBaseWidget.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/ArrayUtils.h"
#include "mozilla/TextEventDispatcher.h"

#include "mozilla/layers/CompositorChild.h"
#include "mozilla/layers/CompositorParent.h"
#include "mozilla/layers/ImageBridgeChild.h"
#include "nsBaseWidget.h"
#include "nsDeviceContext.h"
#include "nsCOMPtr.h"
#include "nsGfxCIID.h"
#include "nsWidgetsCID.h"
#include "nsServiceManagerUtils.h"
#include "nsIScreenManager.h"
#include "nsAppDirectoryServiceDefs.h"
#include "nsISimpleEnumerator.h"
#include "nsIContent.h"
#include "nsIDocument.h"
#include "nsIPresShell.h"
#include "nsIServiceManager.h"
#include "mozilla/Preferences.h"
#include "BasicLayers.h"
#include "ClientLayerManager.h"
#include "mozilla/layers/Compositor.h"
#include "nsIXULRuntime.h"
#include "nsIXULWindow.h"
#include "nsIBaseWindow.h"
#include "nsXULPopupManager.h"
#include "nsIWidgetListener.h"
#include "nsIGfxInfo.h"
#include "npapi.h"
#include "base/thread.h"
#include "prdtoa.h"
#include "prenv.h"
#include "mozilla/Attributes.h"
#include "mozilla/unused.h"
#include "nsContentUtils.h"
#include "gfxPrefs.h"
#include "mozilla/gfx/2D.h"
#include "mozilla/MouseEvents.h"
#include "GLConsts.h"
#include "mozilla/unused.h"
#include "mozilla/IMEStateManager.h"
#include "mozilla/VsyncDispatcher.h"
#include "mozilla/layers/APZCTreeManager.h"
#include "mozilla/layers/APZEventState.h"
#include "mozilla/layers/APZThreadUtils.h"
#include "mozilla/layers/ChromeProcessController.h"
#include "mozilla/layers/InputAPZContext.h"
#include "mozilla/layers/APZCCallbackHelper.h"
#include "mozilla/dom/ContentChild.h"
#include "mozilla/dom/TabParent.h"
#include "mozilla/Move.h"
#include "mozilla/Services.h"
#include "mozilla/Snprintf.h"
#include "nsRefPtrHashtable.h"
#include "TouchEvents.h"
#include "WritingModes.h"
#include "InputData.h"
#ifdef ACCESSIBILITY
#include "nsAccessibilityService.h"
#endif

#ifdef DEBUG
#include "nsIObserver.h"

static void debug_RegisterPrefCallbacks();

#endif

#ifdef NOISY_WIDGET_LEAKS
static int32_t gNumWidgets;
#endif

#ifdef XP_MACOSX
#include "nsCocoaFeatures.h"
#endif

#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
static nsRefPtrHashtable<nsVoidPtrHashKey, nsIWidget>* sPluginWidgetList;
#endif

nsIRollupListener* nsBaseWidget::gRollupListener = nullptr;

using namespace mozilla::dom;
using namespace mozilla::layers;
using namespace mozilla::ipc;
using namespace mozilla::widget;
using namespace mozilla;
using base::Thread;

nsIContent* nsBaseWidget::mLastRollup = nullptr;
// Global user preference for disabling native theme. Used
// in NativeWindowTheme.
bool            gDisableNativeTheme               = false;

// Async pump timer during injected long touch taps
#define TOUCH_INJECT_PUMP_TIMER_MSEC 50
#define TOUCH_INJECT_LONG_TAP_DEFAULT_MSEC 1500
int32_t nsIWidget::sPointerIdCounter = 0;

// Some statics from nsIWidget.h
/*static*/ uint64_t AutoObserverNotifier::sObserverId = 0;
/*static*/ nsDataHashtable<nsUint64HashKey, nsCOMPtr<nsIObserver>> AutoObserverNotifier::sSavedObservers;

namespace mozilla {
namespace widget {

void
IMENotification::SelectionChangeDataBase::SetWritingMode(
                                        const WritingMode& aWritingMode)
{
  mWritingMode = aWritingMode.mWritingMode;
}

WritingMode
IMENotification::SelectionChangeDataBase::GetWritingMode() const
{
  return WritingMode(mWritingMode);
}

} // namespace widget
} // namespace mozilla

nsAutoRollup::nsAutoRollup()
{
  // remember if mLastRollup was null, and only clear it upon destruction
  // if so. This prevents recursive usage of nsAutoRollup from clearing
  // mLastRollup when it shouldn't.
  wasClear = !nsBaseWidget::mLastRollup;
}

nsAutoRollup::~nsAutoRollup()
{
  if (nsBaseWidget::mLastRollup && wasClear) {
    NS_RELEASE(nsBaseWidget::mLastRollup);
  }
}

NS_IMPL_ISUPPORTS(nsBaseWidget, nsIWidget, nsISupportsWeakReference)

//-------------------------------------------------------------------------
//
// nsBaseWidget constructor
//
//-------------------------------------------------------------------------

nsBaseWidget::nsBaseWidget()
: mWidgetListener(nullptr)
, mAttachedWidgetListener(nullptr)
, mPreviouslyAttachedWidgetListener(nullptr)
, mLayerManager(nullptr)
, mCompositorVsyncDispatcher(nullptr)
, mCursor(eCursor_standard)
, mBorderStyle(eBorderStyle_none)
, mBounds(0,0,0,0)
, mOriginalBounds(nullptr)
, mClipRectCount(0)
, mSizeMode(nsSizeMode_Normal)
, mPopupLevel(ePopupLevelTop)
, mPopupType(ePopupTypeAny)
, mUpdateCursor(true)
, mUseAttachedEvents(false)
, mIMEHasFocus(false)
{
#ifdef NOISY_WIDGET_LEAKS
  gNumWidgets++;
  printf("WIDGETS+ = %d\n", gNumWidgets);
#endif

#ifdef DEBUG
  debug_RegisterPrefCallbacks();
#endif

#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
  if (!sPluginWidgetList) {
    sPluginWidgetList = new nsRefPtrHashtable<nsVoidPtrHashKey, nsIWidget>();
  }
#endif
  mShutdownObserver = new WidgetShutdownObserver(this);
}

NS_IMPL_ISUPPORTS(WidgetShutdownObserver, nsIObserver)

WidgetShutdownObserver::WidgetShutdownObserver(nsBaseWidget* aWidget) :
  mWidget(aWidget),
  mRegistered(false)
{
  Register();
}

WidgetShutdownObserver::~WidgetShutdownObserver()
{
  // No need to call Unregister(), we can't be destroyed until nsBaseWidget
  // gets torn down. The observer service and nsBaseWidget have a ref on us
  // so nsBaseWidget has to call Unregister and then clear its ref.
}

NS_IMETHODIMP
WidgetShutdownObserver::Observe(nsISupports *aSubject,
                                const char *aTopic,
                                const char16_t *aData)
{
  if (mWidget && !strcmp(aTopic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
    nsCOMPtr<nsIWidget> kungFuDeathGrip(mWidget);
    mWidget->Shutdown();
  }
  return NS_OK;
}

void
WidgetShutdownObserver::Register()
{
  if (!mRegistered) {
    mRegistered = true;
    nsContentUtils::RegisterShutdownObserver(this);
  }
}

void
WidgetShutdownObserver::Unregister()
{
  if (mRegistered) {
    mWidget = nullptr;
    nsContentUtils::UnregisterShutdownObserver(this);
    mRegistered = false;
  }
}

void
nsBaseWidget::Shutdown()
{
  DestroyCompositor();
  FreeShutdownObserver();
#if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
  if (sPluginWidgetList) {
    delete sPluginWidgetList;
    sPluginWidgetList = nullptr;
  }
#endif
}

void nsBaseWidget::DestroyCompositor()
{
  if (mCompositorChild) {
    // XXX CompositorChild and CompositorParent might be re-created in
    // ClientLayerManager destructor. See bug 1133426.
    RefPtr<CompositorChild> compositorChild = mCompositorChild;
    RefPtr<CompositorParent> compositorParent = mCompositorParent;
    mCompositorChild->Destroy();
  }

  // Can have base widgets that are things like tooltips
  // which don't have CompositorVsyncDispatchers
  if (mCompositorVsyncDispatcher) {
    mCompositorVsyncDispatcher->Shutdown();
  }
}

void nsBaseWidget::DestroyLayerManager()
{
  if (mLayerManager) {
    mLayerManager->Destroy();
    mLayerManager = nullptr;
  }
  DestroyCompositor();
}

void
nsBaseWidget::FreeShutdownObserver()
{
  if (mShutdownObserver) {
    mShutdownObserver->Unregister();
  }
  mShutdownObserver = nullptr;
}

//-------------------------------------------------------------------------
//
// nsBaseWidget destructor
//
//-------------------------------------------------------------------------
nsBaseWidget::~nsBaseWidget()
{
  IMEStateManager::WidgetDestroyed(this);

  if (mLayerManager &&
      mLayerManager->GetBackendType() == LayersBackend::LAYERS_BASIC) {
    static_cast<BasicLayerManager*>(mLayerManager.get())->ClearRetainerWidget();
  }

  FreeShutdownObserver();
  DestroyLayerManager();

#ifdef NOISY_WIDGET_LEAKS
  gNumWidgets--;
  printf("WIDGETS- = %d\n", gNumWidgets);
#endif

  delete mOriginalBounds;
}

//-------------------------------------------------------------------------
//
// Basic create.
//
//-------------------------------------------------------------------------
void nsBaseWidget::BaseCreate(nsIWidget* aParent,
                              const LayoutDeviceIntRect& aRect,
                              nsWidgetInitData* aInitData)
{
  static bool gDisableNativeThemeCached = false;
  if (!gDisableNativeThemeCached) {
    Preferences::AddBoolVarCache(&gDisableNativeTheme,
                                 "mozilla.widget.disable-native-theme",
                                 gDisableNativeTheme);
    gDisableNativeThemeCached = true;
  }

  // keep a reference to the device context
  if (nullptr != aInitData) {
    mWindowType = aInitData->mWindowType;
    mBorderStyle = aInitData->mBorderStyle;
    mPopupLevel = aInitData->mPopupLevel;
    mPopupType = aInitData->mPopupHint;
  }

  if (aParent) {
    aParent->AddChild(this);
  }
}

NS_IMETHODIMP nsBaseWidget::CaptureMouse(bool aCapture)
{
  return NS_OK;
}

//-------------------------------------------------------------------------
//
// Accessor functions to get/set the client data
//
//-------------------------------------------------------------------------

nsIWidgetListener* nsBaseWidget::GetWidgetListener()
{
  return mWidgetListener;
}

void nsBaseWidget::SetWidgetListener(nsIWidgetListener* aWidgetListener)
{
  mWidgetListener = aWidgetListener;
}

already_AddRefed<nsIWidget>
nsBaseWidget::CreateChild(const LayoutDeviceIntRect& aRect,
                          nsWidgetInitData* aInitData,
                          bool aForceUseIWidgetParent)
{
  nsIWidget* parent = this;
  nsNativeWidget nativeParent = nullptr;

  if (!aForceUseIWidgetParent) {
    // Use only either parent or nativeParent, not both, to match
    // existing code.  Eventually Create() should be divested of its
    // nativeWidget parameter.
    nativeParent = parent ? parent->GetNativeData(NS_NATIVE_WIDGET) : nullptr;
    parent = nativeParent ? nullptr : parent;
    MOZ_ASSERT(!parent || !nativeParent, "messed up logic");
  }

  nsCOMPtr<nsIWidget> widget;
  if (aInitData && aInitData->mWindowType == eWindowType_popup) {
    widget = AllocateChildPopupWidget();
  } else {
    static NS_DEFINE_IID(kCChildCID, NS_CHILD_CID);
    widget = do_CreateInstance(kCChildCID);
  }

  if (widget &&
      NS_SUCCEEDED(widget->Create(parent, nativeParent, aRect, aInitData))) {
    return widget.forget();
  }

  return nullptr;
}

// Attach a view to our widget which we'll send events to.
NS_IMETHODIMP
nsBaseWidget::AttachViewToTopLevel(bool aUseAttachedEvents)
{
  NS_ASSERTION((mWindowType == eWindowType_toplevel ||
                mWindowType == eWindowType_dialog ||
                mWindowType == eWindowType_invisible ||
                mWindowType == eWindowType_child),
               "Can't attach to window of that type");

  mUseAttachedEvents = aUseAttachedEvents;

  return NS_OK;
}

nsIWidgetListener* nsBaseWidget::GetAttachedWidgetListener()
 {
   return mAttachedWidgetListener;
 }

nsIWidgetListener* nsBaseWidget::GetPreviouslyAttachedWidgetListener()
 {
   return mPreviouslyAttachedWidgetListener;
 }

void nsBaseWidget::SetPreviouslyAttachedWidgetListener(nsIWidgetListener* aListener)
 {
   mPreviouslyAttachedWidgetListener = aListener;
 }

void nsBaseWidget::SetAttachedWidgetListener(nsIWidgetListener* aListener)
 {
   mAttachedWidgetListener = aListener;
 }

//-------------------------------------------------------------------------
//
// Close this nsBaseWidget
//
//-------------------------------------------------------------------------
NS_METHOD nsBaseWidget::Destroy()
{
  // Just in case our parent is the only ref to us
  nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
  // disconnect from the parent
  nsIWidget *parent = GetParent();
  if (parent) {
    parent->RemoveChild(this);
  }

  return NS_OK;
}


//-------------------------------------------------------------------------
//
// Set this nsBaseWidget's parent
//
//-------------------------------------------------------------------------
NS_IMETHODIMP nsBaseWidget::SetParent(nsIWidget* aNewParent)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}


//-------------------------------------------------------------------------
//
// Get this nsBaseWidget parent
//
//-------------------------------------------------------------------------
nsIWidget* nsBaseWidget::GetParent(void)
{
  return nullptr;
}

//-------------------------------------------------------------------------
//
// Get this nsBaseWidget top level widget
//
//-------------------------------------------------------------------------
nsIWidget* nsBaseWidget::GetTopLevelWidget()
{
  nsIWidget *topLevelWidget = nullptr, *widget = this;
  while (widget) {
    topLevelWidget = widget;
    widget = widget->GetParent();
  }
  return topLevelWidget;
}

//-------------------------------------------------------------------------
//
// Get this nsBaseWidget's top (non-sheet) parent (if it's a sheet)
//
//-------------------------------------------------------------------------
nsIWidget* nsBaseWidget::GetSheetWindowParent(void)
{
  return nullptr;
}

float nsBaseWidget::GetDPI()
{
  return 96.0f;
}

CSSToLayoutDeviceScale nsIWidget::GetDefaultScale()
{
  double devPixelsPerCSSPixel = DefaultScaleOverride();

  if (devPixelsPerCSSPixel <= 0.0) {
    devPixelsPerCSSPixel = GetDefaultScaleInternal();
  }

  return CSSToLayoutDeviceScale(devPixelsPerCSSPixel);
}

/* static */
double nsIWidget::DefaultScaleOverride()
{
  // The number of device pixels per CSS pixel. A value <= 0 means choose
  // automatically based on the DPI. A positive value is used as-is. This effectively
  // controls the size of a CSS "px".
  double devPixelsPerCSSPixel = -1.0;

  nsAdoptingCString prefString = Preferences::GetCString("layout.css.devPixelsPerPx");
  if (!prefString.IsEmpty()) {
    devPixelsPerCSSPixel = PR_strtod(prefString, nullptr);
  }

  return devPixelsPerCSSPixel;
}

//-------------------------------------------------------------------------
//
// Add a child to the list of children
//
//-------------------------------------------------------------------------
void nsBaseWidget::AddChild(nsIWidget* aChild)
{
  NS_PRECONDITION(!aChild->GetNextSibling() && !aChild->GetPrevSibling(),
                  "aChild not properly removed from its old child list");

  if (!mFirstChild) {
    mFirstChild = mLastChild = aChild;
  } else {
    // append to the list
    NS_ASSERTION(mLastChild, "Bogus state");
    NS_ASSERTION(!mLastChild->GetNextSibling(), "Bogus state");
    mLastChild->SetNextSibling(aChild);
    aChild->SetPrevSibling(mLastChild);
    mLastChild = aChild;
  }
}


//-------------------------------------------------------------------------
//
// Remove a child from the list of children
//
//-------------------------------------------------------------------------
void nsBaseWidget::RemoveChild(nsIWidget* aChild)
{
#ifdef DEBUG
#ifdef XP_MACOSX
  // nsCocoaWindow doesn't implement GetParent, so in that case parent will be
  // null and we'll just have to do without this assertion.
  nsIWidget* parent = aChild->GetParent();
  NS_ASSERTION(!parent || parent == this, "Not one of our kids!");
#else
  NS_ASSERTION(aChild->GetParent() == this, "Not one of our kids!");
#endif
#endif

  if (mLastChild == aChild) {
    mLastChild = mLastChild->GetPrevSibling();
  }
  if (mFirstChild == aChild) {
    mFirstChild = mFirstChild->GetNextSibling();
  }

  // Now remove from the list.  Make sure that we pass ownership of the tail
  // of the list correctly before we have aChild let go of it.
  nsIWidget* prev = aChild->GetPrevSibling();
  nsIWidget* next = aChild->GetNextSibling();
  if (prev) {
    prev->SetNextSibling(next);
  }
  if (next) {
    next->SetPrevSibling(prev);
  }

  aChild->SetNextSibling(nullptr);
  aChild->SetPrevSibling(nullptr);
}


//-------------------------------------------------------------------------
//
// Sets widget's position within its parent's child list.
//
//-------------------------------------------------------------------------
void nsBaseWidget::SetZIndex(int32_t aZIndex)
{
  // Hold a ref to ourselves just in case, since we're going to remove
  // from our parent.
  nsCOMPtr<nsIWidget> kungFuDeathGrip(this);

  mZIndex = aZIndex;

  // reorder this child in its parent's list.
  nsBaseWidget* parent = static_cast<nsBaseWidget*>(GetParent());
  if (parent) {
    parent->RemoveChild(this);
    // Scope sib outside the for loop so we can check it afterward
    nsIWidget* sib = parent->GetFirstChild();
    for ( ; sib; sib = sib->GetNextSibling()) {
      int32_t childZIndex = GetZIndex();
      if (aZIndex < childZIndex) {
        // Insert ourselves before sib
        nsIWidget* prev = sib->GetPrevSibling();
        mNextSibling = sib;
        mPrevSibling = prev;
        sib->SetPrevSibling(this);
        if (prev) {
          prev->SetNextSibling(this);
        } else {
          NS_ASSERTION(sib == parent->mFirstChild, "Broken child list");
          // We've taken ownership of sib, so it's safe to have parent let
          // go of it
          parent->mFirstChild = this;
        }
        PlaceBehind(eZPlacementBelow, sib, false);
        break;
      }
    }
    // were we added to the list?
    if (!sib) {
      parent->AddChild(this);
    }
  }
}

//-------------------------------------------------------------------------
//
// Places widget behind the given widget (platforms must override)
//
//-------------------------------------------------------------------------
NS_IMETHODIMP nsBaseWidget::PlaceBehind(nsTopLevelWidgetZPlacement aPlacement,
                                        nsIWidget *aWidget, bool aActivate)
{
  return NS_OK;
}

//-------------------------------------------------------------------------
//
// Maximize, minimize or restore the window. The BaseWidget implementation
// merely stores the state.
//
//-------------------------------------------------------------------------
NS_IMETHODIMP
nsBaseWidget::SetSizeMode(nsSizeMode aMode)
{
  MOZ_ASSERT(aMode == nsSizeMode_Normal ||
             aMode == nsSizeMode_Minimized ||
             aMode == nsSizeMode_Maximized ||
             aMode == nsSizeMode_Fullscreen);
  mSizeMode = aMode;
  return NS_OK;
}

//-------------------------------------------------------------------------
//
// Get this component cursor
//
//-------------------------------------------------------------------------
nsCursor nsBaseWidget::GetCursor()
{
  return mCursor;
}

NS_METHOD nsBaseWidget::SetCursor(nsCursor aCursor)
{
  mCursor = aCursor;
  return NS_OK;
}

NS_IMETHODIMP nsBaseWidget::SetCursor(imgIContainer* aCursor,
                                      uint32_t aHotspotX, uint32_t aHotspotY)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

//-------------------------------------------------------------------------
//
// Window transparency methods
//
//-------------------------------------------------------------------------

void nsBaseWidget::SetTransparencyMode(nsTransparencyMode aMode) {
}

nsTransparencyMode nsBaseWidget::GetTransparencyMode() {
  return eTransparencyOpaque;
}

bool
nsBaseWidget::IsWindowClipRegionEqual(const nsTArray<LayoutDeviceIntRect>& aRects)
{
  return mClipRects &&
         mClipRectCount == aRects.Length() &&
         memcmp(mClipRects.get(), aRects.Elements(), sizeof(LayoutDeviceIntRect)*mClipRectCount) == 0;
}

void
nsBaseWidget::StoreWindowClipRegion(const nsTArray<LayoutDeviceIntRect>& aRects)
{
  mClipRectCount = aRects.Length();
  mClipRects = MakeUnique<LayoutDeviceIntRect[]>(mClipRectCount);
  if (mClipRects) {
    memcpy(mClipRects.get(), aRects.Elements(), sizeof(LayoutDeviceIntRect)*mClipRectCount);
  }
}

void
nsBaseWidget::GetWindowClipRegion(nsTArray<LayoutDeviceIntRect>* aRects)
{
  if (mClipRects) {
    aRects->AppendElements(mClipRects.get(), mClipRectCount);
  } else {
    aRects->AppendElement(LayoutDeviceIntRect(0, 0, mBounds.width, mBounds.height));
  }
}

const LayoutDeviceIntRegion
nsBaseWidget::RegionFromArray(const nsTArray<LayoutDeviceIntRect>& aRects)
{
  LayoutDeviceIntRegion region;
  for (uint32_t i = 0; i < aRects.Length(); ++i) {
    region.Or(region, aRects[i]);
  }
  return region;
}

void
nsBaseWidget::ArrayFromRegion(const LayoutDeviceIntRegion& aRegion,
                              nsTArray<LayoutDeviceIntRect>& aRects)
{
  const LayoutDeviceIntRect* r;
  for (LayoutDeviceIntRegion::RectIterator iter(aRegion); (r = iter.Next()); ) {
    aRects.AppendElement(*r);
  }
}

nsresult
nsBaseWidget::SetWindowClipRegion(const nsTArray<LayoutDeviceIntRect>& aRects,
                                  bool aIntersectWithExisting)
{
  if (!aIntersectWithExisting) {
    StoreWindowClipRegion(aRects);
  } else {
    // get current rects
    nsTArray<LayoutDeviceIntRect> currentRects;
    GetWindowClipRegion(&currentRects);
    // create region from them
    LayoutDeviceIntRegion currentRegion = RegionFromArray(currentRects);
    // create region from new rects
    LayoutDeviceIntRegion newRegion = RegionFromArray(aRects);
    // intersect regions
    LayoutDeviceIntRegion intersection;
    intersection.And(currentRegion, newRegion);
    // create int rect array from intersection
    nsTArray<LayoutDeviceIntRect> rects;
    ArrayFromRegion(intersection, rects);
    // store
    StoreWindowClipRegion(rects);
  }
  return NS_OK;
}

//-------------------------------------------------------------------------
//
// Set window shadow style
//
//-------------------------------------------------------------------------

NS_IMETHODIMP nsBaseWidget::SetWindowShadowStyle(int32_t aMode)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

//-------------------------------------------------------------------------
//
// Hide window borders/decorations for this widget
//
//-------------------------------------------------------------------------
NS_IMETHODIMP nsBaseWidget::HideWindowChrome(bool aShouldHide)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

/* virtual */ void
nsBaseWidget::PerformFullscreenTransition(FullscreenTransitionStage aStage,
                                          uint16_t aDuration,
                                          nsISupports* aData,
                                          nsIRunnable* aCallback)
{
  MOZ_ASSERT_UNREACHABLE(
    "Should never call PerformFullscreenTransition on nsBaseWidget");
}

//-------------------------------------------------------------------------
//
// Put the window into full-screen mode
//
//-------------------------------------------------------------------------
NS_IMETHODIMP nsBaseWidget::MakeFullScreen(bool aFullScreen, nsIScreen* aScreen)
{
  HideWindowChrome(aFullScreen);

  if (aFullScreen) {
    if (!mOriginalBounds) {
      mOriginalBounds = new CSSIntRect();
    }
    *mOriginalBounds = GetScaledScreenBounds();

    // Move to top-left corner of screen and size to the screen dimensions
    nsCOMPtr<nsIScreen> screen = aScreen;
    if (!screen) {
      screen = GetWidgetScreen();
    }
    if (screen) {
      int32_t left, top, width, height;
      if (NS_SUCCEEDED(screen->GetRectDisplayPix(&left, &top, &width, &height))) {
        Resize(left, top, width, height, true);
      }
    }
  } else if (mOriginalBounds) {
    Resize(mOriginalBounds->x, mOriginalBounds->y, mOriginalBounds->width,
           mOriginalBounds->height, true);
  }

  return NS_OK;
}

nsBaseWidget::AutoLayerManagerSetup::AutoLayerManagerSetup(
    nsBaseWidget* aWidget, gfxContext* aTarget,
    BufferMode aDoubleBuffering, ScreenRotation aRotation)
  : mWidget(aWidget)
{
  mLayerManager = static_cast<BasicLayerManager*>(mWidget->GetLayerManager());
  if (mLayerManager) {
    NS_ASSERTION(mLayerManager->GetBackendType() == LayersBackend::LAYERS_BASIC,
      "AutoLayerManagerSetup instantiated for non-basic layer backend!");
    mLayerManager->SetDefaultTarget(aTarget);
    mLayerManager->SetDefaultTargetConfiguration(aDoubleBuffering, aRotation);
  }
}

nsBaseWidget::AutoLayerManagerSetup::~AutoLayerManagerSetup()
{
  if (mLayerManager) {
    NS_ASSERTION(mLayerManager->GetBackendType() == LayersBackend::LAYERS_BASIC,
      "AutoLayerManagerSetup instantiated for non-basic layer backend!");
    mLayerManager->SetDefaultTarget(nullptr);
    mLayerManager->SetDefaultTargetConfiguration(mozilla::layers::BufferMode::BUFFER_NONE, ROTATION_0);
  }
}

bool
nsBaseWidget::ComputeShouldAccelerate()
{
  return gfxPlatform::GetPlatform()->ShouldUseLayersAcceleration();
}

CompositorParent* nsBaseWidget::NewCompositorParent(int aSurfaceWidth,
                                                    int aSurfaceHeight)
{
  return new CompositorParent(this, false, aSurfaceWidth, aSurfaceHeight);
}

void nsBaseWidget::CreateCompositor()
{
  LayoutDeviceIntRect rect;
  GetBounds(rect);
  CreateCompositor(rect.width, rect.height);
}

already_AddRefed<GeckoContentController>
nsBaseWidget::CreateRootContentController()
{
  RefPtr<GeckoContentController> controller = new ChromeProcessController(this, mAPZEventState, mAPZC);
  return controller.forget();
}

void nsBaseWidget::ConfigureAPZCTreeManager()
{
  MOZ_ASSERT(mAPZC);

  ConfigureAPZControllerThread();

  mAPZC->SetDPI(GetDPI());

  RefPtr<APZCTreeManager> treeManager = mAPZC;  // for capture by the lambdas

  ContentReceivedInputBlockCallback callback(
      [treeManager](const ScrollableLayerGuid& aGuid,
                    uint64_t aInputBlockId,
                    bool aPreventDefault)
      {
        MOZ_ASSERT(NS_IsMainThread());
        APZThreadUtils::RunOnControllerThread(NewRunnableMethod(
            treeManager.get(), &APZCTreeManager::ContentReceivedInputBlock,
            aInputBlockId, aPreventDefault));
      });
  mAPZEventState = new APZEventState(this, mozilla::Move(callback));

  mSetAllowedTouchBehaviorCallback = [treeManager](uint64_t aInputBlockId,
                                                   const nsTArray<TouchBehaviorFlags>& aFlags)
  {
    MOZ_ASSERT(NS_IsMainThread());
    APZThreadUtils::RunOnControllerThread(NewRunnableMethod(
        treeManager.get(), &APZCTreeManager::SetAllowedTouchBehavior,
        aInputBlockId, aFlags));
  };

  RefPtr<GeckoContentController> controller = CreateRootContentController();
  if (controller) {
    uint64_t rootLayerTreeId = mCompositorParent->RootLayerTreeId();
    CompositorParent::SetControllerForLayerTree(rootLayerTreeId, controller);
  }

  // When APZ is enabled, we can actually enable raw touch events because we
  // have code that can deal with them properly. If APZ is not enabled, this
  // function doesn't get called.
  if (Preferences::GetInt("dom.w3c_touch_events.enabled", 0) ||
      Preferences::GetBool("dom.w3c_pointer_events.enabled", false)) {
    RegisterTouchWindow();
  }
}

void nsBaseWidget::ConfigureAPZControllerThread()
{
  // By default the controller thread is the main thread.
  APZThreadUtils::SetControllerThread(MessageLoop::current());
}

void
nsBaseWidget::SetConfirmedTargetAPZC(uint64_t aInputBlockId,
                                     const nsTArray<ScrollableLayerGuid>& aTargets) const
{
  // Need to specifically bind this since it's overloaded.
  void (APZCTreeManager::*setTargetApzcFunc)(uint64_t, const nsTArray<ScrollableLayerGuid>&)
          = &APZCTreeManager::SetTargetAPZC;
  APZThreadUtils::RunOnControllerThread(NewRunnableMethod(
    mAPZC.get(), setTargetApzcFunc, aInputBlockId, aTargets));
}

void
nsBaseWidget::UpdateZoomConstraints(const uint32_t& aPresShellId,
                                    const FrameMetrics::ViewID& aViewId,
                                    const Maybe<ZoomConstraints>& aConstraints)
{
  if (!mCompositorParent || !mAPZC) {
    if (mInitialZoomConstraints) {
      MOZ_ASSERT(mInitialZoomConstraints->mPresShellID == aPresShellId);
      MOZ_ASSERT(mInitialZoomConstraints->mViewID == aViewId);
      if (!aConstraints) {
        mInitialZoomConstraints.reset();
      }
    }

    if (aConstraints) {
      // We have some constraints, but the compositor and APZC aren't created yet.
      // Save these so we can use them later.
      mInitialZoomConstraints = Some(InitialZoomConstraints(aPresShellId, aViewId, aConstraints.ref()));
    }
    return;
  }
  uint64_t layersId = mCompositorParent->RootLayerTreeId();
  mAPZC->UpdateZoomConstraints(ScrollableLayerGuid(layersId, aPresShellId, aViewId),
                               aConstraints);
}

bool
nsBaseWidget::AsyncPanZoomEnabled() const
{
  return !!mAPZC;
}

nsEventStatus
nsBaseWidget::ProcessUntransformedAPZEvent(WidgetInputEvent* aEvent,
                                           const ScrollableLayerGuid& aGuid,
                                           uint64_t aInputBlockId,
                                           nsEventStatus aApzResponse)
{
  MOZ_ASSERT(NS_IsMainThread());
  InputAPZContext context(aGuid, aInputBlockId, aApzResponse);

  // If this is a touch event and APZ has targeted it to an APZC in the root
  // process, apply that APZC's callback-transform before dispatching the
  // event. If the event is instead targeted to an APZC in the child process,
  // the transform will be applied in the child process before dispatching
  // the event there (see e.g. TabChild::RecvRealTouchEvent()).
  // TODO: Do other types of events (than touch) need this?
  if (aEvent->AsTouchEvent() && aGuid.mLayersId == mCompositorParent->RootLayerTreeId()) {
    APZCCallbackHelper::ApplyCallbackTransform(*aEvent->AsTouchEvent(), aGuid,
        GetDefaultScale());
  }

  // Make a copy of the original event for the APZCCallbackHelper helpers that
  // we call later, because the event passed to DispatchEvent can get mutated in
  // ways that we don't want (i.e. touch points can get stripped out).
  nsEventStatus status;
  UniquePtr<WidgetEvent> original(aEvent->Duplicate());
  DispatchEvent(aEvent, status);

  if (mAPZC && !context.WasRoutedToChildProcess()) {
    // EventStateManager did not route the event into the child process.
    // It's safe to communicate to APZ that the event has been processed.
    // TODO: Eventually we'll be able to move the SendSetTargetAPZCNotification
    // call into APZEventState::Process*Event() as well.
    if (WidgetTouchEvent* touchEvent = aEvent->AsTouchEvent()) {
      if (touchEvent->mMessage == eTouchStart) {
        if (gfxPrefs::TouchActionEnabled()) {
          APZCCallbackHelper::SendSetAllowedTouchBehaviorNotification(this,
              *(original->AsTouchEvent()), aInputBlockId,
              mSetAllowedTouchBehaviorCallback);
        }
        APZCCallbackHelper::SendSetTargetAPZCNotification(this, GetDocument(),
            *(original->AsTouchEvent()), aGuid, aInputBlockId);
      }
      mAPZEventState->ProcessTouchEvent(*touchEvent, aGuid, aInputBlockId,
          aApzResponse, status);
    } else if (WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent()) {
      if (wheelEvent->mFlags.mHandledByAPZ) {
        APZCCallbackHelper::SendSetTargetAPZCNotification(this, GetDocument(),
            *(original->AsWheelEvent()), aGuid, aInputBlockId);
        if (wheelEvent->mCanTriggerSwipe) {
          ReportSwipeStarted(aInputBlockId, wheelEvent->TriggersSwipe());
        }
        mAPZEventState->ProcessWheelEvent(*wheelEvent, aGuid, aInputBlockId);
      }
    } else if (WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent()) {
      mAPZEventState->ProcessMouseEvent(*mouseEvent, aGuid, aInputBlockId);
    }
  }

  return status;
}

nsEventStatus
nsBaseWidget::DispatchInputEvent(WidgetInputEvent* aEvent)
{
  if (mAPZC) {
    nsEventStatus result = mAPZC->ReceiveInputEvent(*aEvent, nullptr, nullptr);
    if (result == nsEventStatus_eConsumeNoDefault) {
      return result;
    }
  }

  nsEventStatus status;
  DispatchEvent(aEvent, status);
  return status;
}

class DispatchWheelEventOnMainThread : public Task
{
public:
  DispatchWheelEventOnMainThread(const ScrollWheelInput& aWheelInput,
                                 nsBaseWidget* aWidget,
                                 nsEventStatus aAPZResult,
                                 uint64_t aInputBlockId,
                                 ScrollableLayerGuid aGuid)
    : mWheelInput(aWheelInput)
    , mWidget(aWidget)
    , mAPZResult(aAPZResult)
    , mInputBlockId(aInputBlockId)
    , mGuid(aGuid)
  {
  }

  void Run()
  {
    WidgetWheelEvent wheelEvent = mWheelInput.ToWidgetWheelEvent(mWidget);
    mWidget->ProcessUntransformedAPZEvent(&wheelEvent, mGuid, mInputBlockId, mAPZResult);
    return;
  }

private:
  ScrollWheelInput mWheelInput;
  nsBaseWidget* mWidget;
  nsEventStatus mAPZResult;
  uint64_t mInputBlockId;
  ScrollableLayerGuid mGuid;
};

class DispatchWheelInputOnControllerThread : public Task
{
public:
  DispatchWheelInputOnControllerThread(const WidgetWheelEvent& aWheelEvent,
                                       APZCTreeManager* aAPZC,
                                       nsBaseWidget* aWidget)
    : mMainMessageLoop(MessageLoop::current())
    , mWheelInput(aWheelEvent)
    , mAPZC(aAPZC)
    , mWidget(aWidget)
    , mInputBlockId(0)
  {
  }

  void Run()
  {
    mAPZResult = mAPZC->ReceiveInputEvent(mWheelInput, &mGuid, &mInputBlockId);
    if (mAPZResult == nsEventStatus_eConsumeNoDefault) {
      return;
    }
    mMainMessageLoop->PostTask(FROM_HERE,
                               new DispatchWheelEventOnMainThread(mWheelInput, mWidget, mAPZResult, mInputBlockId, mGuid));
    return;
  }

private:
  MessageLoop* mMainMessageLoop;
  ScrollWheelInput mWheelInput;
  RefPtr<APZCTreeManager> mAPZC;
  nsBaseWidget* mWidget;
  nsEventStatus mAPZResult;
  uint64_t mInputBlockId;
  ScrollableLayerGuid mGuid;
};

nsEventStatus
nsBaseWidget::DispatchAPZAwareEvent(WidgetInputEvent* aEvent)
{
  MOZ_ASSERT(NS_IsMainThread());
  if (mAPZC) {
    if (APZThreadUtils::IsControllerThread()) {
      uint64_t inputBlockId = 0;
      ScrollableLayerGuid guid;

      nsEventStatus result = mAPZC->ReceiveInputEvent(*aEvent, &guid, &inputBlockId);
      if (result == nsEventStatus_eConsumeNoDefault) {
          return result;
      }
      return ProcessUntransformedAPZEvent(aEvent, guid, inputBlockId, result);
    } else {
      WidgetWheelEvent* wheelEvent = aEvent->AsWheelEvent();
      if (wheelEvent) {
        APZThreadUtils::RunOnControllerThread(new DispatchWheelInputOnControllerThread(*wheelEvent, mAPZC, this));
        return nsEventStatus_eConsumeDoDefault;
      }
      MOZ_CRASH();
    }
  }

  nsEventStatus status;
  DispatchEvent(aEvent, status);
  return status;
}

nsIDocument*
nsBaseWidget::GetDocument() const
{
  if (mWidgetListener) {
    if (nsIPresShell* presShell = mWidgetListener->GetPresShell()) {
      return presShell->GetDocument();
    }
  }
  return nullptr;
}

void nsBaseWidget::CreateCompositorVsyncDispatcher()
{
  // Parent directly listens to the vsync source whereas
  // child process communicate via IPC
  // Should be called AFTER gfxPlatform is initialized
  if (XRE_IsParentProcess()) {
    mCompositorVsyncDispatcher = new CompositorVsyncDispatcher();
  }
}

CompositorVsyncDispatcher*
nsBaseWidget::GetCompositorVsyncDispatcher()
{
  return mCompositorVsyncDispatcher;
}

void nsBaseWidget::CreateCompositor(int aWidth, int aHeight)
{
  // This makes sure that gfxPlatforms gets initialized if it hasn't by now.
  gfxPlatform::GetPlatform();

  MOZ_ASSERT(gfxPlatform::UsesOffMainThreadCompositing(),
             "This function assumes OMTC");

  MOZ_ASSERT(!mCompositorParent && !mCompositorChild,
    "Should have properly cleaned up the previous PCompositor pair beforehand");

  if (mCompositorChild) {
    mCompositorChild->Destroy();
  }

  // Recreating this is tricky, as we may still have an old and we need
  // to make sure it's properly destroyed by calling DestroyCompositor!

  // If we've already received a shutdown notification, don't try
  // create a new compositor.
  if (!mShutdownObserver) {
    return;
  }

  CreateCompositorVsyncDispatcher();
  mCompositorParent = NewCompositorParent(aWidth, aHeight);
  RefPtr<ClientLayerManager> lm = new ClientLayerManager(this);
  mCompositorChild = new CompositorChild(lm);
  mCompositorChild->OpenSameProcess(mCompositorParent);

  // Make sure the parent knows it is same process.
  mCompositorParent->SetOtherProcessId(base::GetCurrentProcId());

  uint64_t rootLayerTreeId = mCompositorParent->RootLayerTreeId();
  mAPZC = CompositorParent::GetAPZCTreeManager(rootLayerTreeId);
  if (mAPZC) {
    ConfigureAPZCTreeManager();
  }

  if (mInitialZoomConstraints) {
    UpdateZoomConstraints(mInitialZoomConstraints->mPresShellID,
                          mInitialZoomConstraints->mViewID,
                          Some(mInitialZoomConstraints->mConstraints));
    mInitialZoomConstraints.reset();
  }

  TextureFactoryIdentifier textureFactoryIdentifier;
  PLayerTransactionChild* shadowManager = nullptr;

  nsTArray<LayersBackend> backendHints;
  gfxPlatform::GetPlatform()->GetCompositorBackends(ComputeShouldAccelerate(), backendHints);

  bool success = false;
  if (!backendHints.IsEmpty()) {
    shadowManager = mCompositorChild->SendPLayerTransactionConstructor(
      backendHints, 0, &textureFactoryIdentifier, &success);
  }

  ShadowLayerForwarder* lf = lm->AsShadowForwarder();

  if (!success || !lf) {
    NS_WARNING("Failed to create an OMT compositor.");
    DestroyCompositor();
    mLayerManager = nullptr;
    mCompositorChild = nullptr;
    mCompositorParent = nullptr;
    mCompositorVsyncDispatcher = nullptr;
    return;
  }

  lf->SetShadowManager(shadowManager);
  lf->IdentifyTextureHost(textureFactoryIdentifier);
  ImageBridgeChild::IdentifyCompositorTextureHost(textureFactoryIdentifier);
  WindowUsesOMTC();

  mLayerManager = lm.forget();

  if (mWindowType == eWindowType_toplevel) {
    // Only track compositors for top-level windows, since other window types
    // may use the basic compositor.
    gfxPlatform::GetPlatform()->NotifyCompositorCreated(mLayerManager->GetCompositorBackendType());
  }
}

bool nsBaseWidget::ShouldUseOffMainThreadCompositing()
{
  return gfxPlatform::UsesOffMainThreadCompositing();
}

LayerManager* nsBaseWidget::GetLayerManager(PLayerTransactionChild* aShadowManager,
                                            LayersBackend aBackendHint,
                                            LayerManagerPersistence aPersistence,
                                            bool* aAllowRetaining)
{
  if (!mLayerManager) {
    if (!mShutdownObserver) {
      // We are shutting down, do not try to re-create a LayerManager
      return nullptr;
    }
    // Try to use an async compositor first, if possible
    if (ShouldUseOffMainThreadCompositing()) {
      // e10s uses the parameter to pass in the shadow manager from the TabChild
      // so we don't expect to see it there since this doesn't support e10s.
      NS_ASSERTION(aShadowManager == nullptr, "Async Compositor not supported with e10s");
      CreateCompositor();
    }

    if (!mLayerManager) {
      mLayerManager = CreateBasicLayerManager();
    }
  }
  if (aAllowRetaining) {
    *aAllowRetaining = true;
  }
  return mLayerManager;
}

LayerManager* nsBaseWidget::CreateBasicLayerManager()
{
  return new BasicLayerManager(this);
}

CompositorChild* nsBaseWidget::GetRemoteRenderer()
{
  return mCompositorChild;
}

already_AddRefed<mozilla::gfx::DrawTarget> nsBaseWidget::StartRemoteDrawing()
{
  return nullptr;
}

//-------------------------------------------------------------------------
//
// Destroy the window
//
//-------------------------------------------------------------------------
void nsBaseWidget::OnDestroy()
{
  if (mTextEventDispatcher) {
    mTextEventDispatcher->OnDestroyWidget();
    // Don't release it until this widget actually released because after this
    // is called, TextEventDispatcher() may create it again.
  }
}

NS_METHOD nsBaseWidget::SetWindowClass(const nsAString& xulWinType)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_METHOD nsBaseWidget::MoveClient(double aX, double aY)
{
  LayoutDeviceIntPoint clientOffset(GetClientOffset());

  // GetClientOffset returns device pixels; scale back to display pixels
  // if that's what this widget uses for the Move/Resize APIs
  CSSToLayoutDeviceScale scale = BoundsUseDisplayPixels()
                                    ? GetDefaultScale()
                                    : CSSToLayoutDeviceScale(1.0);
  aX -= clientOffset.x * 1.0 / scale.scale;
  aY -= clientOffset.y * 1.0 / scale.scale;

  return Move(aX, aY);
}

NS_METHOD nsBaseWidget::ResizeClient(double aWidth,
                                     double aHeight,
                                     bool aRepaint)
{
  NS_ASSERTION((aWidth >=0) , "Negative width passed to ResizeClient");
  NS_ASSERTION((aHeight >=0), "Negative height passed to ResizeClient");

  LayoutDeviceIntRect clientBounds;
  GetClientBounds(clientBounds);

  // GetClientBounds and mBounds are device pixels; scale back to display pixels
  // if that's what this widget uses for the Move/Resize APIs
  CSSToLayoutDeviceScale scale = BoundsUseDisplayPixels()
                                    ? GetDefaultScale()
                                    : CSSToLayoutDeviceScale(1.0);
  double invScale = 1.0 / scale.scale;
  aWidth = mBounds.width * invScale + (aWidth - clientBounds.width * invScale);
  aHeight = mBounds.height * invScale + (aHeight - clientBounds.height * invScale);

  return Resize(aWidth, aHeight, aRepaint);
}

NS_METHOD nsBaseWidget::ResizeClient(double aX,
                                     double aY,
                                     double aWidth,
                                     double aHeight,
                                     bool aRepaint)
{
  NS_ASSERTION((aWidth >=0) , "Negative width passed to ResizeClient");
  NS_ASSERTION((aHeight >=0), "Negative height passed to ResizeClient");

  LayoutDeviceIntRect clientBounds;
  GetClientBounds(clientBounds);

  double scale = BoundsUseDisplayPixels() ? 1.0 / GetDefaultScale().scale : 1.0;
  aWidth = mBounds.width * scale + (aWidth - clientBounds.width * scale);
  aHeight = mBounds.height * scale + (aHeight - clientBounds.height * scale);

  LayoutDeviceIntPoint clientOffset(GetClientOffset());
  aX -= clientOffset.x * scale;
  aY -= clientOffset.y * scale;

  return Resize(aX, aY, aWidth, aHeight, aRepaint);
}

//-------------------------------------------------------------------------
//
// Bounds
//
//-------------------------------------------------------------------------

/**
* If the implementation of nsWindow supports borders this method MUST be overridden
*
**/
NS_METHOD nsBaseWidget::GetClientBounds(LayoutDeviceIntRect &aRect)
{
  return GetBounds(aRect);
}

/**
* If the implementation of nsWindow supports borders this method MUST be overridden
*
**/
NS_METHOD nsBaseWidget::GetBounds(LayoutDeviceIntRect &aRect)
{
  aRect = LayoutDeviceIntRect::FromUnknownRect(mBounds);
  return NS_OK;
}

/**
* If the implementation of nsWindow uses a local coordinate system within the window,
* this method must be overridden
*
**/
NS_METHOD nsBaseWidget::GetScreenBounds(LayoutDeviceIntRect& aRect)
{
  return GetBounds(aRect);
}

NS_METHOD nsBaseWidget::GetRestoredBounds(LayoutDeviceIntRect& aRect)
{
  if (SizeMode() != nsSizeMode_Normal) {
    return NS_ERROR_FAILURE;
  }
  return GetScreenBounds(aRect);
}

LayoutDeviceIntPoint
nsBaseWidget::GetClientOffset()
{
  return LayoutDeviceIntPoint(0, 0);
}

NS_IMETHODIMP
nsBaseWidget::GetNonClientMargins(LayoutDeviceIntMargin &margins)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsBaseWidget::SetNonClientMargins(LayoutDeviceIntMargin &margins)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_METHOD nsBaseWidget::EnableDragDrop(bool aEnable)
{
  return NS_OK;
}

uint32_t nsBaseWidget::GetMaxTouchPoints() const
{
  return 0;
}

NS_METHOD nsBaseWidget::SetModal(bool aModal)
{
  return NS_ERROR_FAILURE;
}

NS_IMETHODIMP
nsBaseWidget::GetAttention(int32_t aCycleCount) {
    return NS_OK;
}

bool
nsBaseWidget::HasPendingInputEvent()
{
  return false;
}

NS_IMETHODIMP
nsBaseWidget::SetIcon(const nsAString&)
{
  return NS_OK;
}

NS_IMETHODIMP
nsBaseWidget::SetWindowTitlebarColor(nscolor aColor, bool aActive)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

bool
nsBaseWidget::ShowsResizeIndicator(LayoutDeviceIntRect* aResizerRect)
{
  return false;
}

NS_IMETHODIMP
nsBaseWidget::OverrideSystemMouseScrollSpeed(double aOriginalDeltaX,
                                             double aOriginalDeltaY,
                                             double& aOverriddenDeltaX,
                                             double& aOverriddenDeltaY)
{
  aOverriddenDeltaX = aOriginalDeltaX;
  aOverriddenDeltaY = aOriginalDeltaY;

  static bool sInitialized = false;
  static bool sIsOverrideEnabled = false;
  static int32_t sIntFactorX = 0;
  static int32_t sIntFactorY = 0;

  if (!sInitialized) {
    Preferences::AddBoolVarCache(&sIsOverrideEnabled,
      "mousewheel.system_scroll_override_on_root_content.enabled", false);
    Preferences::AddIntVarCache(&sIntFactorX,
      "mousewheel.system_scroll_override_on_root_content.horizontal.factor", 0);
    Preferences::AddIntVarCache(&sIntFactorY,
      "mousewheel.system_scroll_override_on_root_content.vertical.factor", 0);
    sIntFactorX = std::max(sIntFactorX, 0);
    sIntFactorY = std::max(sIntFactorY, 0);
    sInitialized = true;
  }

  if (!sIsOverrideEnabled) {
    return NS_OK;
  }

  // The pref value must be larger than 100, otherwise, we don't override the
  // delta value.
  if (sIntFactorX > 100) {
    double factor = static_cast<double>(sIntFactorX) / 100;
    aOverriddenDeltaX *= factor;
  }
  if (sIntFactorY > 100) {
    double factor = static_cast<double>(sIntFactorY) / 100;
    aOverriddenDeltaY *= factor;
  }

  return NS_OK;
}


/**
 * Modifies aFile to point at an icon file with the given name and suffix.  The
 * suffix may correspond to a file extension with leading '.' if appropriate.
 * Returns true if the icon file exists and can be read.
 */
static bool
ResolveIconNameHelper(nsIFile *aFile,
                      const nsAString &aIconName,
                      const nsAString &aIconSuffix)
{
  aFile->Append(NS_LITERAL_STRING("icons"));
  aFile->Append(NS_LITERAL_STRING("default"));
  aFile->Append(aIconName + aIconSuffix);

  bool readable;
  return NS_SUCCEEDED(aFile->IsReadable(&readable)) && readable;
}

/**
 * Resolve the given icon name into a local file object.  This method is
 * intended to be called by subclasses of nsBaseWidget.  aIconSuffix is a
 * platform specific icon file suffix (e.g., ".ico" under Win32).
 *
 * If no file is found matching the given parameters, then null is returned.
 */
void
nsBaseWidget::ResolveIconName(const nsAString &aIconName,
                              const nsAString &aIconSuffix,
                              nsIFile **aResult)
{
  *aResult = nullptr;

  nsCOMPtr<nsIProperties> dirSvc = do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID);
  if (!dirSvc)
    return;

  // first check auxilary chrome directories

  nsCOMPtr<nsISimpleEnumerator> dirs;
  dirSvc->Get(NS_APP_CHROME_DIR_LIST, NS_GET_IID(nsISimpleEnumerator),
              getter_AddRefs(dirs));
  if (dirs) {
    bool hasMore;
    while (NS_SUCCEEDED(dirs->HasMoreElements(&hasMore)) && hasMore) {
      nsCOMPtr<nsISupports> element;
      dirs->GetNext(getter_AddRefs(element));
      if (!element)
        continue;
      nsCOMPtr<nsIFile> file = do_QueryInterface(element);
      if (!file)
        continue;
      if (ResolveIconNameHelper(file, aIconName, aIconSuffix)) {
        NS_ADDREF(*aResult = file);
        return;
      }
    }
  }

  // then check the main app chrome directory

  nsCOMPtr<nsIFile> file;
  dirSvc->Get(NS_APP_CHROME_DIR, NS_GET_IID(nsIFile),
              getter_AddRefs(file));
  if (file && ResolveIconNameHelper(file, aIconName, aIconSuffix))
    NS_ADDREF(*aResult = file);
}

NS_IMETHODIMP
nsBaseWidget::BeginResizeDrag(WidgetGUIEvent* aEvent,
                              int32_t aHorizontal,
                              int32_t aVertical)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsBaseWidget::BeginMoveDrag(WidgetMouseEvent* aEvent)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

uint32_t
nsBaseWidget::GetGLFrameBufferFormat()
{
  return LOCAL_GL_RGBA;
}

void nsBaseWidget::SetSizeConstraints(const SizeConstraints& aConstraints)
{
  mSizeConstraints = aConstraints;
  // We can't ensure that the size is honored at this point because we're
  // probably in the middle of a reflow.
}

const widget::SizeConstraints& nsBaseWidget::GetSizeConstraints() const
{
  return mSizeConstraints;
}

// static
nsIRollupListener*
nsBaseWidget::GetActiveRollupListener()
{
  // If set, then this is likely an <html:select> dropdown.
  if (gRollupListener)
    return gRollupListener;

  return nsXULPopupManager::GetInstance();
}

void
nsBaseWidget::NotifyWindowDestroyed()
{
  if (!mWidgetListener)
    return;

  nsCOMPtr<nsIXULWindow> window = mWidgetListener->GetXULWindow();
  nsCOMPtr<nsIBaseWindow> xulWindow(do_QueryInterface(window));
  if (xulWindow) {
    xulWindow->Destroy();
  }
}

void
nsBaseWidget::NotifySizeMoveDone()
{
  if (!mWidgetListener || mWidgetListener->GetXULWindow())
    return;

  nsIPresShell* presShell = mWidgetListener->GetPresShell();
  if (presShell) {
    presShell->WindowSizeMoveDone();
  }
}

void
nsBaseWidget::NotifyWindowMoved(int32_t aX, int32_t aY)
{
  if (mWidgetListener) {
    mWidgetListener->WindowMoved(this, aX, aY);
  }

  if (mIMEHasFocus && GetIMEUpdatePreference().WantPositionChanged()) {
    NotifyIME(IMENotification(IMEMessage::NOTIFY_IME_OF_POSITION_CHANGE));
  }
}

void
nsBaseWidget::NotifySysColorChanged()
{
  if (!mWidgetListener || mWidgetListener->GetXULWindow())
    return;

  nsIPresShell* presShell = mWidgetListener->GetPresShell();
  if (presShell) {
    presShell->SysColorChanged();
  }
}

void
nsBaseWidget::NotifyThemeChanged()
{
  if (!mWidgetListener || mWidgetListener->GetXULWindow())
    return;

  nsIPresShell* presShell = mWidgetListener->GetPresShell();
  if (presShell) {
    presShell->ThemeChanged();
  }
}

void
nsBaseWidget::NotifyUIStateChanged(UIStateChangeType aShowAccelerators,
                                   UIStateChangeType aShowFocusRings)
{
  if (nsIDocument* doc = GetDocument()) {
    nsPIDOMWindow* win = doc->GetWindow();
    if (win) {
      win->SetKeyboardIndicators(aShowAccelerators, aShowFocusRings);
    }
  }
}

NS_IMETHODIMP
nsBaseWidget::NotifyIME(const IMENotification& aIMENotification)
{
  switch (aIMENotification.mMessage) {
    case REQUEST_TO_COMMIT_COMPOSITION:
    case REQUEST_TO_CANCEL_COMPOSITION:
      // Currently, if native IME handler doesn't use TextEventDispatcher,
      // the request may be notified to mTextEventDispatcher or native IME
      // directly.  Therefore, if mTextEventDispatcher has a composition,
      // the request should be handled by the mTextEventDispatcher.
      if (mTextEventDispatcher && mTextEventDispatcher->IsComposing()) {
        return mTextEventDispatcher->NotifyIME(aIMENotification);
      }
      // Otherwise, it should be handled by native IME.
      return NotifyIMEInternal(aIMENotification);
    case NOTIFY_IME_OF_FOCUS:
      mIMEHasFocus = true;
      // We should notify TextEventDispatcher of focus notification, first.
      // After that, notify native IME too.
      if (mTextEventDispatcher) {
        mTextEventDispatcher->NotifyIME(aIMENotification);
      }
      return NotifyIMEInternal(aIMENotification);
    case NOTIFY_IME_OF_BLUR: {
      // We should notify TextEventDispatcher of blur notification, first.
      // After that, notify native IME too.
      if (mTextEventDispatcher) {
        mTextEventDispatcher->NotifyIME(aIMENotification);
      }
      nsresult rv = NotifyIMEInternal(aIMENotification);
      mIMEHasFocus = false;
      return rv;
    }
    default:
      // Otherwise, notify only native IME for now.
      return NotifyIMEInternal(aIMENotification);
  }
}

NS_IMETHODIMP_(nsIWidget::TextEventDispatcher*)
nsBaseWidget::GetTextEventDispatcher()
{
  if (!mTextEventDispatcher) {
    mTextEventDispatcher = new TextEventDispatcher(this);
  }
  return mTextEventDispatcher;
}

#ifdef ACCESSIBILITY

#ifdef XP_WIN
// defined in nsAppRunner.cpp
extern const char* kAccessibilityLastRunDatePref;

static inline uint32_t
PRTimeToSeconds(PRTime t_usec)
{
  PRTime usec_per_sec = PR_USEC_PER_SEC;
  return uint32_t(t_usec /= usec_per_sec);
}
#endif

a11y::Accessible*
nsBaseWidget::GetRootAccessible()
{
  NS_ENSURE_TRUE(mWidgetListener, nullptr);

  nsIPresShell* presShell = mWidgetListener->GetPresShell();
  NS_ENSURE_TRUE(presShell, nullptr);

  // If container is null then the presshell is not active. This often happens
  // when a preshell is being held onto for fastback.
  nsPresContext* presContext = presShell->GetPresContext();
  NS_ENSURE_TRUE(presContext->GetContainerWeak(), nullptr);

  // Accessible creation might be not safe so use IsSafeToRunScript to
  // make sure it's not created at unsafe times.
  nsCOMPtr<nsIAccessibilityService> accService =
    services::GetAccessibilityService();
  if (accService) {
#ifdef XP_WIN
    uint32_t now = PRTimeToSeconds(PR_Now());
    Preferences::SetInt(kAccessibilityLastRunDatePref, now);
#endif
    return accService->GetRootDocumentAccessible(presShell, nsContentUtils::IsSafeToRunScript());
  }

  return nullptr;
}

#endif // ACCESSIBILITY

void
nsBaseWidget::StartAsyncScrollbarDrag(const AsyncDragMetrics& aDragMetrics)
{
  if (!AsyncPanZoomEnabled()) {
    return;
  }

  MOZ_ASSERT(XRE_IsParentProcess() && mCompositorParent);

  int layersId = mCompositorParent->RootLayerTreeId();;
  ScrollableLayerGuid guid(layersId, aDragMetrics.mPresShellId, aDragMetrics.mViewId);

  APZThreadUtils::RunOnControllerThread(
    NewRunnableMethod(mAPZC.get(), &APZCTreeManager::StartScrollbarDrag, guid, aDragMetrics));
}

CSSIntRect
nsBaseWidget::GetScaledScreenBounds()
{
  LayoutDeviceIntRect bounds;
  GetScreenBounds(bounds);

  // *Dividing* a LayoutDeviceIntRect by a CSSToLayoutDeviceScale gives a
  // CSSIntRect.
  CSSToLayoutDeviceScale scale = GetDefaultScale();
  return RoundedToInt(bounds / scale);
}

already_AddRefed<nsIScreen>
nsBaseWidget::GetWidgetScreen()
{
  nsCOMPtr<nsIScreenManager> screenManager;
  screenManager = do_GetService("@mozilla.org/gfx/screenmanager;1");
  if (!screenManager) {
    return nullptr;
  }

  CSSIntRect bounds = GetScaledScreenBounds();
  nsCOMPtr<nsIScreen> screen;
  screenManager->ScreenForRect(bounds.x, bounds.y,
                               bounds.width, bounds.height,
                               getter_AddRefs(screen));
  return screen.forget();
}

nsresult
nsIWidget::SynthesizeNativeTouchTap(ScreenIntPoint aPointerScreenPoint, bool aLongTap,
                                    nsIObserver* aObserver)
{
  AutoObserverNotifier notifier(aObserver, "touchtap");

  if (sPointerIdCounter > TOUCH_INJECT_MAX_POINTS) {
    sPointerIdCounter = 0;
  }
  int pointerId = sPointerIdCounter;
  sPointerIdCounter++;
  nsresult rv = SynthesizeNativeTouchPoint(pointerId, TOUCH_CONTACT,
                                           aPointerScreenPoint, 1.0, 90, nullptr);
  if (NS_FAILED(rv)) {
    return rv;
  }

  if (!aLongTap) {
    nsresult rv = SynthesizeNativeTouchPoint(pointerId, TOUCH_REMOVE,
                                             aPointerScreenPoint, 0, 0, nullptr);
    return rv;
  }

  // initiate a long tap
  int elapse = Preferences::GetInt("ui.click_hold_context_menus.delay",
                                   TOUCH_INJECT_LONG_TAP_DEFAULT_MSEC);
  if (!mLongTapTimer) {
    mLongTapTimer = do_CreateInstance(NS_TIMER_CONTRACTID, &rv);
    if (NS_FAILED(rv)) {
      SynthesizeNativeTouchPoint(pointerId, TOUCH_CANCEL,
                                 aPointerScreenPoint, 0, 0, nullptr);
      return NS_ERROR_UNEXPECTED;
    }
    // Windows requires recuring events, so we set this to a smaller window
    // than the pref value.
    int timeout = elapse;
    if (timeout > TOUCH_INJECT_PUMP_TIMER_MSEC) {
      timeout = TOUCH_INJECT_PUMP_TIMER_MSEC;
    }
    mLongTapTimer->InitWithFuncCallback(OnLongTapTimerCallback, this,
                                        timeout,
                                        nsITimer::TYPE_REPEATING_SLACK);
  }

  // If we already have a long tap pending, cancel it. We only allow one long
  // tap to be active at a time.
  if (mLongTapTouchPoint) {
    SynthesizeNativeTouchPoint(mLongTapTouchPoint->mPointerId, TOUCH_CANCEL,
                               mLongTapTouchPoint->mPosition, 0, 0, nullptr);
  }

  mLongTapTouchPoint = new LongTapInfo(pointerId, aPointerScreenPoint,
                                       TimeDuration::FromMilliseconds(elapse),
                                       aObserver);
  notifier.SkipNotification();  // we'll do it in the long-tap callback
  return NS_OK;
}

// static
void
nsIWidget::OnLongTapTimerCallback(nsITimer* aTimer, void* aClosure)
{
  nsIWidget *self = static_cast<nsIWidget *>(aClosure);

  if ((self->mLongTapTouchPoint->mStamp + self->mLongTapTouchPoint->mDuration) >
      TimeStamp::Now()) {
#ifdef XP_WIN
    // Windows needs us to keep pumping feedback to the digitizer, so update
    // the pointer id with the same position.
    self->SynthesizeNativeTouchPoint(self->mLongTapTouchPoint->mPointerId,
                                     TOUCH_CONTACT,
                                     self->mLongTapTouchPoint->mPosition,
                                     1.0, 90, nullptr);
#endif
    return;
  }

  AutoObserverNotifier notifier(self->mLongTapTouchPoint->mObserver, "touchtap");

  // finished, remove the touch point
  self->mLongTapTimer->Cancel();
  self->mLongTapTimer = nullptr;
  self->SynthesizeNativeTouchPoint(self->mLongTapTouchPoint->mPointerId,
                                   TOUCH_REMOVE,
                                   self->mLongTapTouchPoint->mPosition,
                                   0, 0, nullptr);
  self->mLongTapTouchPoint = nullptr;
}

nsresult
nsIWidget::ClearNativeTouchSequence(nsIObserver* aObserver)
{
  AutoObserverNotifier notifier(aObserver, "cleartouch");

  if (!mLongTapTimer) {
    return NS_OK;
  }
  mLongTapTimer->Cancel();
  mLongTapTimer = nullptr;
  SynthesizeNativeTouchPoint(mLongTapTouchPoint->mPointerId, TOUCH_CANCEL,
                             mLongTapTouchPoint->mPosition, 0, 0, nullptr);
  mLongTapTouchPoint = nullptr;
  return NS_OK;
}

void
nsBaseWidget::RegisterPluginWindowForRemoteUpdates()
{
#if !defined(XP_WIN) && !defined(MOZ_WIDGET_GTK)
  NS_NOTREACHED("nsBaseWidget::RegisterPluginWindowForRemoteUpdates not implemented!");
  return;
#else
  MOZ_ASSERT(NS_IsMainThread());
  void* id = GetNativeData(NS_NATIVE_PLUGIN_ID);
  if (!id) {
    NS_WARNING("This is not a valid native widget!");
    return;
  }
  MOZ_ASSERT(sPluginWidgetList);
  sPluginWidgetList->Put(id, this);
#endif
}

void
nsBaseWidget::UnregisterPluginWindowForRemoteUpdates()
{
#if !defined(XP_WIN) && !defined(MOZ_WIDGET_GTK)
  NS_NOTREACHED("nsBaseWidget::UnregisterPluginWindowForRemoteUpdates not implemented!");
  return;
#else
  MOZ_ASSERT(NS_IsMainThread());
  void* id = GetNativeData(NS_NATIVE_PLUGIN_ID);
  if (!id) {
    NS_WARNING("This is not a valid native widget!");
    return;
  }
  MOZ_ASSERT(sPluginWidgetList);
  sPluginWidgetList->Remove(id);
#endif
}

// static
nsIWidget*
nsIWidget::LookupRegisteredPluginWindow(uintptr_t aWindowID)
{
#if !defined(XP_WIN) && !defined(MOZ_WIDGET_GTK)
  NS_NOTREACHED("nsBaseWidget::LookupRegisteredPluginWindow not implemented!");
  return nullptr;
#else
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(sPluginWidgetList);
  return sPluginWidgetList->GetWeak((void*)aWindowID);
#endif
}

// static
void
nsIWidget::UpdateRegisteredPluginWindowVisibility(uintptr_t aOwnerWidget,
                                                  nsTArray<uintptr_t>& aPluginIds)
{
#if !defined(XP_WIN) && !defined(MOZ_WIDGET_GTK)
  NS_NOTREACHED("nsBaseWidget::UpdateRegisteredPluginWindowVisibility not implemented!");
  return;
#else
  MOZ_ASSERT(NS_IsMainThread());
  MOZ_ASSERT(sPluginWidgetList);

  // Our visible list is associated with a compositor which is associated with
  // a specific top level window. We use the parent widget during iteration
  // to skip the plugin widgets owned by other top level windows.
  for (auto iter = sPluginWidgetList->Iter(); !iter.Done(); iter.Next()) {
    const void* windowId = iter.Key();
    nsIWidget* widget = iter.UserData();

    MOZ_ASSERT(windowId);
    MOZ_ASSERT(widget);

    if (!widget->Destroyed()) {
      if ((uintptr_t)widget->GetParent() == aOwnerWidget) {
        widget->Show(aPluginIds.Contains((uintptr_t)windowId));
      }
    }
  }
#endif
}

already_AddRefed<mozilla::gfx::SourceSurface>
nsIWidget::SnapshotWidgetOnScreen()
{
  // This is only supported on a widget with a compositor.
  LayerManager* layerManager = GetLayerManager();
  if (!layerManager) {
    return nullptr;
  }

  ClientLayerManager* lm = layerManager->AsClientLayerManager();
  if (!lm) {
    return nullptr;
  }

  CompositorChild* cc = lm->GetRemoteRenderer();
  if (!cc) {
    return nullptr;
  }

  LayoutDeviceIntRect bounds;
  GetBounds(bounds);
  if (bounds.IsEmpty()) {
    return nullptr;
  }

  gfx::IntSize size(bounds.width, bounds.height);

  ShadowLayerForwarder* forwarder = lm->AsShadowForwarder();
  SurfaceDescriptor surface;
  if (!forwarder->AllocSurfaceDescriptor(size, gfxContentType::COLOR_ALPHA, &surface)) {
    return nullptr;
  }

  if (!cc->SendMakeWidgetSnapshot(surface)) {
    return nullptr;
  }

  RefPtr<gfx::DataSourceSurface> snapshot = GetSurfaceForDescriptor(surface);
  RefPtr<gfx::DrawTarget> dt =
    gfxPlatform::GetPlatform()->CreateOffscreenContentDrawTarget(size, gfx::SurfaceFormat::B8G8R8A8);
  if (!snapshot || !dt) {
    forwarder->DestroySharedSurface(&surface);
    return nullptr;
  }

  dt->DrawSurface(snapshot,
                  gfx::Rect(gfx::Point(), gfx::Size(size)),
                  gfx::Rect(gfx::Point(), gfx::Size(size)),
                  gfx::DrawSurfaceOptions(gfx::Filter::POINT));

  forwarder->DestroySharedSurface(&surface);
  return dt->Snapshot();
}

NS_IMETHODIMP_(nsIWidget::NativeIMEContext)
nsIWidget::GetNativeIMEContext()
{
  return NativeIMEContext(this);
}

namespace mozilla {
namespace widget {

void
NativeIMEContext::Init(nsIWidget* aWidget)
{
  if (!aWidget) {
    mRawNativeIMEContext = reinterpret_cast<uintptr_t>(nullptr);
    mOriginProcessID = static_cast<uint64_t>(-1);
    return;
  }
  if (!XRE_IsContentProcess()) {
    mRawNativeIMEContext = reinterpret_cast<uintptr_t>(
      aWidget->GetNativeData(NS_RAW_NATIVE_IME_CONTEXT));
    mOriginProcessID = 0;
    return;
  }
  // If this is created in a child process, aWidget is an instance of
  // PuppetWidget which doesn't support NS_RAW_NATIVE_IME_CONTEXT.
  // Instead of that PuppetWidget::GetNativeIMEContext() returns cached
  // native IME context of the parent process.
  *this = aWidget->GetNativeIMEContext();
}

void
NativeIMEContext::InitWithRawNativeIMEContext(void* aRawNativeIMEContext)
{
  if (NS_WARN_IF(!aRawNativeIMEContext)) {
    mRawNativeIMEContext = reinterpret_cast<uintptr_t>(nullptr);
    mOriginProcessID = static_cast<uint64_t>(-1);
    return;
  }
  mRawNativeIMEContext = reinterpret_cast<uintptr_t>(aRawNativeIMEContext);
  mOriginProcessID =
    XRE_IsContentProcess() ? ContentChild::GetSingleton()->GetID() : 0;
}

void
IMENotification::TextChangeDataBase::MergeWith(
                   const IMENotification::TextChangeDataBase& aOther)
{
  MOZ_ASSERT(aOther.IsValid(),
             "Merging data must store valid data");
  MOZ_ASSERT(aOther.mStartOffset <= aOther.mRemovedEndOffset,
             "end of removed text must be same or larger than start");
  MOZ_ASSERT(aOther.mStartOffset <= aOther.mAddedEndOffset,
             "end of added text must be same or larger than start");

  if (!IsValid()) {
    *this = aOther;
    return;
  }

  // |mStartOffset| and |mRemovedEndOffset| represent all replaced or removed
  // text ranges.  I.e., mStartOffset should be the smallest offset of all
  // modified text ranges in old text.  |mRemovedEndOffset| should be the
  // largest end offset in old text of all modified text ranges.
  // |mAddedEndOffset| represents the end offset of all inserted text ranges.
  // I.e., only this is an offset in new text.
  // In other words, between mStartOffset and |mRemovedEndOffset| of the
  // premodified text was already removed.  And some text whose length is
  // |mAddedEndOffset - mStartOffset| is inserted to |mStartOffset|.  I.e.,
  // this allows IME to mark dirty the modified text range with |mStartOffset|
  // and |mRemovedEndOffset| if IME stores all text of the focused editor and
  // to compute new text length with |mAddedEndOffset| and |mRemovedEndOffset|.
  // Additionally, IME can retrieve only the text between |mStartOffset| and
  // |mAddedEndOffset| for updating stored text.

  // For comparing new and old |mStartOffset|/|mRemovedEndOffset| values, they
  // should be adjusted to be in same text. The |newData.mStartOffset| and
  // |newData.mRemovedEndOffset| should be computed as in old text because
  // |mStartOffset| and |mRemovedEndOffset| represent the modified text range
  // in the old text but even if some text before the values of the newData
  // has already been modified, the values don't include the changes.

  // For comparing new and old |mAddedEndOffset| values, they should be
  // adjusted to be in same text.  The |oldData.mAddedEndOffset| should be
  // computed as in the new text because |mAddedEndOffset| indicates the end
  // offset of inserted text in the new text but |oldData.mAddedEndOffset|
  // doesn't include any changes of the text before |newData.mAddedEndOffset|.

  const TextChangeDataBase& newData = aOther;
  const TextChangeDataBase oldData = *this;

  // mCausedByComposition should be true only when all changes are caused by
  // composition.
  mCausedByComposition =
    newData.mCausedByComposition && oldData.mCausedByComposition;
  // mOccurredDuringComposition should be true only when all changes occurred
  // during composition.
  mOccurredDuringComposition =
    newData.mOccurredDuringComposition && oldData.mOccurredDuringComposition;

  if (newData.mStartOffset >= oldData.mAddedEndOffset) {
    // Case 1:
    // If new start is after old end offset of added text, it means that text
    // after the modified range is modified.  Like:
    // added range of old change:             +----------+
    // removed range of new change:                           +----------+
    // So, the old start offset is always the smaller offset.
    mStartOffset = oldData.mStartOffset;
    // The new end offset of removed text is moved by the old change and we
    // need to cancel the move of the old change for comparing the offsets in
    // same text because it doesn't make sensce to compare offsets in different
    // text.
    uint32_t newRemovedEndOffsetInOldText =
      newData.mRemovedEndOffset - oldData.Difference();
    mRemovedEndOffset =
      std::max(newRemovedEndOffsetInOldText, oldData.mRemovedEndOffset);
    // The new end offset of added text is always the larger offset.
    mAddedEndOffset = newData.mAddedEndOffset;
    return;
  }

  if (newData.mStartOffset >= oldData.mStartOffset) {
    // If new start is in the modified range, it means that new data changes
    // a part or all of the range.
    mStartOffset = oldData.mStartOffset;
    if (newData.mRemovedEndOffset >= oldData.mAddedEndOffset) {
      // Case 2:
      // If new end of removed text is greater than old end of added text, it
      // means that all or a part of modified range modified again and text
      // after the modified range is also modified.  Like:
      // added range of old change:             +----------+
      // removed range of new change:                   +----------+
      // So, the new removed end offset is moved by the old change and we need
      // to cancel the move of the old change for comparing the offsets in the
      // same text because it doesn't make sense to compare the offsets in
      // different text.
      uint32_t newRemovedEndOffsetInOldText =
        newData.mRemovedEndOffset - oldData.Difference();
      mRemovedEndOffset =
        std::max(newRemovedEndOffsetInOldText, oldData.mRemovedEndOffset);
      // The old end of added text is replaced by new change. So, it should be
      // same as the new start.  On the other hand, the new added end offset is
      // always same or larger.  Therefore, the merged end offset of added
      // text should be the new end offset of added text.
      mAddedEndOffset = newData.mAddedEndOffset;
      return;
    }

    // Case 3:
    // If new end of removed text is less than old end of added text, it means
    // that only a part of the modified range is modified again.  Like:
    // added range of old change:             +------------+
    // removed range of new change:               +-----+
    // So, the new end offset of removed text should be same as the old end
    // offset of removed text.  Therefore, the merged end offset of removed
    // text should be the old text change's |mRemovedEndOffset|.
    mRemovedEndOffset = oldData.mRemovedEndOffset;
    // The old end of added text is moved by new change.  So, we need to cancel
    // the move of the new change for comparing the offsets in same text.
    uint32_t oldAddedEndOffsetInNewText =
      oldData.mAddedEndOffset + newData.Difference();
    mAddedEndOffset =
      std::max(newData.mAddedEndOffset, oldAddedEndOffsetInNewText);
    return;
  }

  if (newData.mRemovedEndOffset >= oldData.mStartOffset) {
    // If new end of removed text is greater than old start (and new start is
    // less than old start), it means that a part of modified range is modified
    // again and some new text before the modified range is also modified.
    MOZ_ASSERT(newData.mStartOffset < oldData.mStartOffset,
      "new start offset should be less than old one here");
    mStartOffset = newData.mStartOffset;
    if (newData.mRemovedEndOffset >= oldData.mAddedEndOffset) {
      // Case 4:
      // If new end of removed text is greater than old end of added text, it
      // means that all modified text and text after the modified range is
      // modified.  Like:
      // added range of old change:             +----------+
      // removed range of new change:        +------------------+
      // So, the new end of removed text is moved by the old change.  Therefore,
      // we need to cancel the move of the old change for comparing the offsets
      // in same text because it doesn't make sense to compare the offsets in
      // different text.
      uint32_t newRemovedEndOffsetInOldText =
        newData.mRemovedEndOffset - oldData.Difference();
      mRemovedEndOffset =
        std::max(newRemovedEndOffsetInOldText, oldData.mRemovedEndOffset);
      // The old end of added text is replaced by new change.  So, the old end
      // offset of added text is same as new text change's start offset.  Then,
      // new change's end offset of added text is always same or larger than
      // it.  Therefore, merged end offset of added text is always the new end
      // offset of added text.
      mAddedEndOffset = newData.mAddedEndOffset;
      return;
    }

    // Case 5:
    // If new end of removed text is less than old end of added text, it
    // means that only a part of the modified range is modified again.  Like:
    // added range of old change:             +----------+
    // removed range of new change:      +----------+
    // So, the new end of removed text should be same as old end of removed
    // text for preventing end of removed text to be modified.  Therefore,
    // merged end offset of removed text is always the old end offset of removed
    // text.
    mRemovedEndOffset = oldData.mRemovedEndOffset;
    // The old end of added text is moved by this change.  So, we need to
    // cancel the move of the new change for comparing the offsets in same text
    // because it doesn't make sense to compare the offsets in different text.
    uint32_t oldAddedEndOffsetInNewText =
      oldData.mAddedEndOffset + newData.Difference();
    mAddedEndOffset =
      std::max(newData.mAddedEndOffset, oldAddedEndOffsetInNewText);
    return;
  }

  // Case 6:
  // Otherwise, i.e., both new end of added text and new start are less than
  // old start, text before the modified range is modified.  Like:
  // added range of old change:                  +----------+
  // removed range of new change: +----------+
  MOZ_ASSERT(newData.mStartOffset < oldData.mStartOffset,
    "new start offset should be less than old one here");
  mStartOffset = newData.mStartOffset;
  MOZ_ASSERT(newData.mRemovedEndOffset < oldData.mRemovedEndOffset,
     "new removed end offset should be less than old one here");
  mRemovedEndOffset = oldData.mRemovedEndOffset;
  // The end of added text should be adjusted with the new difference.
  uint32_t oldAddedEndOffsetInNewText =
    oldData.mAddedEndOffset + newData.Difference();
  mAddedEndOffset =
    std::max(newData.mAddedEndOffset, oldAddedEndOffsetInNewText);
}

#ifdef DEBUG

// Let's test the code of merging multiple text change data in debug build
// and crash if one of them fails because this feature is very complex but
// cannot be tested with mochitest.
void
IMENotification::TextChangeDataBase::Test()
{
  static bool gTestTextChangeEvent = true;
  if (!gTestTextChangeEvent) {
    return;
  }
  gTestTextChangeEvent = false;

  /****************************************************************************
   * Case 1
   ****************************************************************************/

  // Appending text
  MergeWith(TextChangeData(10, 10, 20, false, false));
  MergeWith(TextChangeData(20, 20, 35, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 1-1-1: mStartOffset should be the first offset");
  MOZ_ASSERT(mRemovedEndOffset == 10, // 20 - (20 - 10)
    "Test 1-1-2: mRemovedEndOffset should be the first end of removed text");
  MOZ_ASSERT(mAddedEndOffset == 35,
    "Test 1-1-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Removing text (longer line -> shorter line)
  MergeWith(TextChangeData(10, 20, 10, false, false));
  MergeWith(TextChangeData(10, 30, 10, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 1-2-1: mStartOffset should be the first offset");
  MOZ_ASSERT(mRemovedEndOffset == 40, // 30 + (10 - 20)
    "Test 1-2-2: mRemovedEndOffset should be the the last end of removed text "
    "with already removed length");
  MOZ_ASSERT(mAddedEndOffset == 10,
    "Test 1-2-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Removing text (shorter line -> longer line)
  MergeWith(TextChangeData(10, 20, 10, false, false));
  MergeWith(TextChangeData(10, 15, 10, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 1-3-1: mStartOffset should be the first offset");
  MOZ_ASSERT(mRemovedEndOffset == 25, // 15 + (10 - 20)
    "Test 1-3-2: mRemovedEndOffset should be the the last end of removed text "
    "with already removed length");
  MOZ_ASSERT(mAddedEndOffset == 10,
    "Test 1-3-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Appending text at different point (not sure if actually occurs)
  MergeWith(TextChangeData(10, 10, 20, false, false));
  MergeWith(TextChangeData(55, 55, 60, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 1-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 45, // 55 - (10 - 20)
    "Test 1-4-2: mRemovedEndOffset should be the the largest end of removed "
    "text without already added length");
  MOZ_ASSERT(mAddedEndOffset == 60,
    "Test 1-4-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Removing text at different point (not sure if actually occurs)
  MergeWith(TextChangeData(10, 20, 10, false, false));
  MergeWith(TextChangeData(55, 68, 55, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 1-5-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 78, // 68 - (10 - 20)
    "Test 1-5-2: mRemovedEndOffset should be the the largest end of removed "
    "text with already removed length");
  MOZ_ASSERT(mAddedEndOffset == 55,
    "Test 1-5-3: mAddedEndOffset should be the largest end of added text");
  Clear();

  // Replacing text and append text (becomes longer)
  MergeWith(TextChangeData(30, 35, 32, false, false));
  MergeWith(TextChangeData(32, 32, 40, false, false));
  MOZ_ASSERT(mStartOffset == 30,
    "Test 1-6-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 35, // 32 - (32 - 35)
    "Test 1-6-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 40,
    "Test 1-6-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text and append text (becomes shorter)
  MergeWith(TextChangeData(30, 35, 32, false, false));
  MergeWith(TextChangeData(32, 32, 33, false, false));
  MOZ_ASSERT(mStartOffset == 30,
    "Test 1-7-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 35, // 32 - (32 - 35)
    "Test 1-7-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 33,
    "Test 1-7-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Removing text and replacing text after first range (not sure if actually
  // occurs)
  MergeWith(TextChangeData(30, 35, 30, false, false));
  MergeWith(TextChangeData(32, 34, 48, false, false));
  MOZ_ASSERT(mStartOffset == 30,
    "Test 1-8-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 39, // 34 - (30 - 35)
    "Test 1-8-2: mRemovedEndOffset should be the the first end of removed text "
    "without already removed text");
  MOZ_ASSERT(mAddedEndOffset == 48,
    "Test 1-8-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Removing text and replacing text after first range (not sure if actually
  // occurs)
  MergeWith(TextChangeData(30, 35, 30, false, false));
  MergeWith(TextChangeData(32, 38, 36, false, false));
  MOZ_ASSERT(mStartOffset == 30,
    "Test 1-9-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 43, // 38 - (30 - 35)
    "Test 1-9-2: mRemovedEndOffset should be the the first end of removed text "
    "without already removed text");
  MOZ_ASSERT(mAddedEndOffset == 36,
    "Test 1-9-3: mAddedEndOffset should be the last end of added text");
  Clear();

  /****************************************************************************
   * Case 2
   ****************************************************************************/

  // Replacing text in around end of added text (becomes shorter) (not sure
  // if actually occurs)
  MergeWith(TextChangeData(50, 50, 55, false, false));
  MergeWith(TextChangeData(53, 60, 54, false, false));
  MOZ_ASSERT(mStartOffset == 50,
    "Test 2-1-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 55, // 60 - (55 - 50)
    "Test 2-1-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 54,
    "Test 2-1-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text around end of added text (becomes longer) (not sure
  // if actually occurs)
  MergeWith(TextChangeData(50, 50, 55, false, false));
  MergeWith(TextChangeData(54, 62, 68, false, false));
  MOZ_ASSERT(mStartOffset == 50,
    "Test 2-2-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 57, // 62 - (55 - 50)
    "Test 2-2-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 68,
    "Test 2-2-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text around end of replaced text (became shorter) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(36, 48, 45, false, false));
  MergeWith(TextChangeData(43, 50, 49, false, false));
  MOZ_ASSERT(mStartOffset == 36,
    "Test 2-3-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 53, // 50 - (45 - 48)
    "Test 2-3-2: mRemovedEndOffset should be the the last end of removed text "
    "without already removed text length");
  MOZ_ASSERT(mAddedEndOffset == 49,
    "Test 2-3-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text around end of replaced text (became longer) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(36, 52, 53, false, false));
  MergeWith(TextChangeData(43, 68, 61, false, false));
  MOZ_ASSERT(mStartOffset == 36,
    "Test 2-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 67, // 68 - (53 - 52)
    "Test 2-4-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 61,
    "Test 2-4-3: mAddedEndOffset should be the last end of added text");
  Clear();

  /****************************************************************************
   * Case 3
   ****************************************************************************/

  // Appending text in already added text (not sure if actually occurs)
  MergeWith(TextChangeData(10, 10, 20, false, false));
  MergeWith(TextChangeData(15, 15, 30, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 3-1-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 10,
    "Test 3-1-2: mRemovedEndOffset should be the the first end of removed text");
  MOZ_ASSERT(mAddedEndOffset == 35, // 20 + (30 - 15)
    "Test 3-1-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text in added text (not sure if actually occurs)
  MergeWith(TextChangeData(50, 50, 55, false, false));
  MergeWith(TextChangeData(52, 53, 56, false, false));
  MOZ_ASSERT(mStartOffset == 50,
    "Test 3-2-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 50,
    "Test 3-2-2: mRemovedEndOffset should be the the first end of removed text");
  MOZ_ASSERT(mAddedEndOffset == 58, // 55 + (56 - 53)
    "Test 3-2-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text in replaced text (became shorter) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(36, 48, 45, false, false));
  MergeWith(TextChangeData(37, 38, 50, false, false));
  MOZ_ASSERT(mStartOffset == 36,
    "Test 3-3-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 48,
    "Test 3-3-2: mRemovedEndOffset should be the the first end of removed text");
  MOZ_ASSERT(mAddedEndOffset == 57, // 45 + (50 - 38)
    "Test 3-3-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text in replaced text (became longer) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(32, 48, 53, false, false));
  MergeWith(TextChangeData(43, 50, 52, false, false));
  MOZ_ASSERT(mStartOffset == 32,
    "Test 3-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 48,
    "Test 3-4-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 55, // 53 + (52 - 50)
    "Test 3-4-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text in replaced text (became shorter) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(36, 48, 50, false, false));
  MergeWith(TextChangeData(37, 49, 47, false, false));
  MOZ_ASSERT(mStartOffset == 36,
    "Test 3-5-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 48,
    "Test 3-5-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 48, // 50 + (47 - 49)
    "Test 3-5-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();

  // Replacing text in replaced text (became longer) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(32, 48, 53, false, false));
  MergeWith(TextChangeData(43, 50, 47, false, false));
  MOZ_ASSERT(mStartOffset == 32,
    "Test 3-6-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 48,
    "Test 3-6-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 50, // 53 + (47 - 50)
    "Test 3-6-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();

  /****************************************************************************
   * Case 4
   ****************************************************************************/

  // Replacing text all of already append text (not sure if actually occurs)
  MergeWith(TextChangeData(50, 50, 55, false, false));
  MergeWith(TextChangeData(44, 66, 68, false, false));
  MOZ_ASSERT(mStartOffset == 44,
    "Test 4-1-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 61, // 66 - (55 - 50)
    "Test 4-1-2: mRemovedEndOffset should be the the last end of removed text "
    "without already added text length");
  MOZ_ASSERT(mAddedEndOffset == 68,
    "Test 4-1-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text around a point in which text was removed (not sure if
  // actually occurs)
  MergeWith(TextChangeData(50, 62, 50, false, false));
  MergeWith(TextChangeData(44, 66, 68, false, false));
  MOZ_ASSERT(mStartOffset == 44,
    "Test 4-2-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 78, // 66 - (50 - 62)
    "Test 4-2-2: mRemovedEndOffset should be the the last end of removed text "
    "without already removed text length");
  MOZ_ASSERT(mAddedEndOffset == 68,
    "Test 4-2-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text all replaced text (became shorter) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(50, 62, 60, false, false));
  MergeWith(TextChangeData(49, 128, 130, false, false));
  MOZ_ASSERT(mStartOffset == 49,
    "Test 4-3-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 130, // 128 - (60 - 62)
    "Test 4-3-2: mRemovedEndOffset should be the the last end of removed text "
    "without already removed text length");
  MOZ_ASSERT(mAddedEndOffset == 130,
    "Test 4-3-3: mAddedEndOffset should be the last end of added text");
  Clear();

  // Replacing text all replaced text (became longer) (not sure if actually
  // occurs)
  MergeWith(TextChangeData(50, 61, 73, false, false));
  MergeWith(TextChangeData(44, 100, 50, false, false));
  MOZ_ASSERT(mStartOffset == 44,
    "Test 4-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 88, // 100 - (73 - 61)
    "Test 4-4-2: mRemovedEndOffset should be the the last end of removed text "
    "with already added text length");
  MOZ_ASSERT(mAddedEndOffset == 50,
    "Test 4-4-3: mAddedEndOffset should be the last end of added text");
  Clear();

  /****************************************************************************
   * Case 5
   ****************************************************************************/

  // Replacing text around start of added text (not sure if actually occurs)
  MergeWith(TextChangeData(50, 50, 55, false, false));
  MergeWith(TextChangeData(48, 52, 49, false, false));
  MOZ_ASSERT(mStartOffset == 48,
    "Test 5-1-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 50,
    "Test 5-1-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 52, // 55 + (52 - 49)
    "Test 5-1-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text around start of replaced text (became shorter) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(50, 60, 58, false, false));
  MergeWith(TextChangeData(43, 50, 48, false, false));
  MOZ_ASSERT(mStartOffset == 43,
    "Test 5-2-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 60,
    "Test 5-2-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 56, // 58 + (48 - 50)
    "Test 5-2-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();

  // Replacing text around start of replaced text (became longer) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(50, 60, 68, false, false));
  MergeWith(TextChangeData(43, 55, 53, false, false));
  MOZ_ASSERT(mStartOffset == 43,
    "Test 5-3-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 60,
    "Test 5-3-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 66, // 68 + (53 - 55)
    "Test 5-3-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();

  // Replacing text around start of replaced text (became shorter) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(50, 60, 58, false, false));
  MergeWith(TextChangeData(43, 50, 128, false, false));
  MOZ_ASSERT(mStartOffset == 43,
    "Test 5-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 60,
    "Test 5-4-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 136, // 58 + (128 - 50)
    "Test 5-4-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Replacing text around start of replaced text (became longer) (not sure if
  // actually occurs)
  MergeWith(TextChangeData(50, 60, 68, false, false));
  MergeWith(TextChangeData(43, 55, 65, false, false));
  MOZ_ASSERT(mStartOffset == 43,
    "Test 5-5-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 60,
    "Test 5-5-2: mRemovedEndOffset should be the the first end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 78, // 68 + (65 - 55)
    "Test 5-5-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  /****************************************************************************
   * Case 6
   ****************************************************************************/

  // Appending text before already added text (not sure if actually occurs)
  MergeWith(TextChangeData(30, 30, 45, false, false));
  MergeWith(TextChangeData(10, 10, 20, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 6-1-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 30,
    "Test 6-1-2: mRemovedEndOffset should be the the largest end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 55, // 45 + (20 - 10)
    "Test 6-1-3: mAddedEndOffset should be the first end of added text with "
    "added text length by the new change");
  Clear();

  // Removing text before already removed text (not sure if actually occurs)
  MergeWith(TextChangeData(30, 35, 30, false, false));
  MergeWith(TextChangeData(10, 25, 10, false, false));
  MOZ_ASSERT(mStartOffset == 10,
    "Test 6-2-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 35,
    "Test 6-2-2: mRemovedEndOffset should be the the largest end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 15, // 30 - (25 - 10)
    "Test 6-2-3: mAddedEndOffset should be the first end of added text with "
    "removed text length by the new change");
  Clear();

  // Replacing text before already replaced text (not sure if actually occurs)
  MergeWith(TextChangeData(50, 65, 70, false, false));
  MergeWith(TextChangeData(13, 24, 15, false, false));
  MOZ_ASSERT(mStartOffset == 13,
    "Test 6-3-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 65,
    "Test 6-3-2: mRemovedEndOffset should be the the largest end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 61, // 70 + (15 - 24)
    "Test 6-3-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();

  // Replacing text before already replaced text (not sure if actually occurs)
  MergeWith(TextChangeData(50, 65, 70, false, false));
  MergeWith(TextChangeData(13, 24, 36, false, false));
  MOZ_ASSERT(mStartOffset == 13,
    "Test 6-4-1: mStartOffset should be the smallest offset");
  MOZ_ASSERT(mRemovedEndOffset == 65,
    "Test 6-4-2: mRemovedEndOffset should be the the largest end of removed "
    "text");
  MOZ_ASSERT(mAddedEndOffset == 82, // 70 + (36 - 24)
    "Test 6-4-3: mAddedEndOffset should be the first end of added text without "
    "removed text length by the new change");
  Clear();
}

#endif // #ifdef DEBUG

} // namespace widget
} // namespace mozilla

#ifdef DEBUG
//////////////////////////////////////////////////////////////
//
// Convert a GUI event message code to a string.
// Makes it a lot easier to debug events.
//
// See gtk/nsWidget.cpp and windows/nsWindow.cpp
// for a DebugPrintEvent() function that uses
// this.
//
//////////////////////////////////////////////////////////////
/* static */ nsAutoString
nsBaseWidget::debug_GuiEventToString(WidgetGUIEvent* aGuiEvent)
{
  NS_ASSERTION(nullptr != aGuiEvent,"cmon, null gui event.");

  nsAutoString eventName(NS_LITERAL_STRING("UNKNOWN"));

#define _ASSIGN_eventName(_value,_name)\
case _value: eventName.AssignLiteral(_name) ; break

  switch(aGuiEvent->mMessage)
  {
    _ASSIGN_eventName(eBlur,"eBlur");
    _ASSIGN_eventName(eLegacyDragGesture,"eLegacyDragGesture");
    _ASSIGN_eventName(eDrop,"eDrop");
    _ASSIGN_eventName(eDragEnter,"eDragEnter");
    _ASSIGN_eventName(eDragExit,"eDragExit");
    _ASSIGN_eventName(eDragOver,"eDragOver");
    _ASSIGN_eventName(eEditorInput,"eEditorInput");
    _ASSIGN_eventName(eFocus,"eFocus");
    _ASSIGN_eventName(eFormSelect,"eFormSelect");
    _ASSIGN_eventName(eFormChange,"eFormChange");
    _ASSIGN_eventName(eFormReset,"eFormReset");
    _ASSIGN_eventName(eFormSubmit,"eFormSubmit");
    _ASSIGN_eventName(eImageAbort,"eImageAbort");
    _ASSIGN_eventName(eLoadError,"eLoadError");
    _ASSIGN_eventName(eKeyDown,"eKeyDown");
    _ASSIGN_eventName(eKeyPress,"eKeyPress");
    _ASSIGN_eventName(eKeyUp,"eKeyUp");
    _ASSIGN_eventName(eMouseEnterIntoWidget,"eMouseEnterIntoWidget");
    _ASSIGN_eventName(eMouseExitFromWidget,"eMouseExitFromWidget");
    _ASSIGN_eventName(eMouseDown,"eMouseDown");
    _ASSIGN_eventName(eMouseUp,"eMouseUp");
    _ASSIGN_eventName(eMouseClick,"eMouseClick");
    _ASSIGN_eventName(eMouseDoubleClick,"eMouseDoubleClick");
    _ASSIGN_eventName(eMouseMove,"eMouseMove");
    _ASSIGN_eventName(eLoad,"eLoad");
    _ASSIGN_eventName(ePopState,"ePopState");
    _ASSIGN_eventName(eBeforeScriptExecute,"eBeforeScriptExecute");
    _ASSIGN_eventName(eAfterScriptExecute,"eAfterScriptExecute");
    _ASSIGN_eventName(eUnload,"eUnload");
    _ASSIGN_eventName(eHashChange,"eHashChange");
    _ASSIGN_eventName(eReadyStateChange,"eReadyStateChange");
    _ASSIGN_eventName(eXULBroadcast, "eXULBroadcast");
    _ASSIGN_eventName(eXULCommandUpdate, "eXULCommandUpdate");

#undef _ASSIGN_eventName

  default:
    {
      char buf[32];

      snprintf_literal(buf,"UNKNOWN: %d",aGuiEvent->mMessage);

      CopyASCIItoUTF16(buf, eventName);
    }
    break;
  }

  return nsAutoString(eventName);
}
//////////////////////////////////////////////////////////////
//
// Code to deal with paint and event debug prefs.
//
//////////////////////////////////////////////////////////////
struct PrefPair
{
  const char * name;
  bool value;
};

static PrefPair debug_PrefValues[] =
{
  { "nglayout.debug.crossing_event_dumping", false },
  { "nglayout.debug.event_dumping", false },
  { "nglayout.debug.invalidate_dumping", false },
  { "nglayout.debug.motion_event_dumping", false },
  { "nglayout.debug.paint_dumping", false },
  { "nglayout.debug.paint_flashing", false }
};

//////////////////////////////////////////////////////////////
bool
nsBaseWidget::debug_GetCachedBoolPref(const char * aPrefName)
{
  NS_ASSERTION(nullptr != aPrefName,"cmon, pref name is null.");

  for (uint32_t i = 0; i < ArrayLength(debug_PrefValues); i++)
  {
    if (strcmp(debug_PrefValues[i].name, aPrefName) == 0)
    {
      return debug_PrefValues[i].value;
    }
  }

  return false;
}
//////////////////////////////////////////////////////////////
static void debug_SetCachedBoolPref(const char * aPrefName,bool aValue)
{
  NS_ASSERTION(nullptr != aPrefName,"cmon, pref name is null.");

  for (uint32_t i = 0; i < ArrayLength(debug_PrefValues); i++)
  {
    if (strcmp(debug_PrefValues[i].name, aPrefName) == 0)
    {
      debug_PrefValues[i].value = aValue;

      return;
    }
  }

  NS_ASSERTION(false, "cmon, this code is not reached dude.");
}

//////////////////////////////////////////////////////////////
class Debug_PrefObserver final : public nsIObserver {
    ~Debug_PrefObserver() {}

  public:
    NS_DECL_ISUPPORTS
    NS_DECL_NSIOBSERVER
};

NS_IMPL_ISUPPORTS(Debug_PrefObserver, nsIObserver)

NS_IMETHODIMP
Debug_PrefObserver::Observe(nsISupports* subject, const char* topic,
                            const char16_t* data)
{
  NS_ConvertUTF16toUTF8 prefName(data);

  bool value = Preferences::GetBool(prefName.get(), false);
  debug_SetCachedBoolPref(prefName.get(), value);
  return NS_OK;
}

//////////////////////////////////////////////////////////////
/* static */ void
debug_RegisterPrefCallbacks()
{
  static bool once = true;

  if (!once) {
    return;
  }

  once = false;

  nsCOMPtr<nsIObserver> obs(new Debug_PrefObserver());
  for (uint32_t i = 0; i < ArrayLength(debug_PrefValues); i++) {
    // Initialize the pref values
    debug_PrefValues[i].value =
      Preferences::GetBool(debug_PrefValues[i].name, false);

    if (obs) {
      // Register callbacks for when these change
      Preferences::AddStrongObserver(obs, debug_PrefValues[i].name);
    }
  }
}
//////////////////////////////////////////////////////////////
static int32_t
_GetPrintCount()
{
  static int32_t sCount = 0;

  return ++sCount;
}
//////////////////////////////////////////////////////////////
/* static */ bool
nsBaseWidget::debug_WantPaintFlashing()
{
  return debug_GetCachedBoolPref("nglayout.debug.paint_flashing");
}
//////////////////////////////////////////////////////////////
/* static */ void
nsBaseWidget::debug_DumpEvent(FILE *                aFileOut,
                              nsIWidget *           aWidget,
                              WidgetGUIEvent*       aGuiEvent,
                              const nsAutoCString & aWidgetName,
                              int32_t               aWindowID)
{
  if (aGuiEvent->mMessage == eMouseMove) {
    if (!debug_GetCachedBoolPref("nglayout.debug.motion_event_dumping"))
      return;
  }

  if (aGuiEvent->mMessage == eMouseEnterIntoWidget ||
      aGuiEvent->mMessage == eMouseExitFromWidget) {
    if (!debug_GetCachedBoolPref("nglayout.debug.crossing_event_dumping"))
      return;
  }

  if (!debug_GetCachedBoolPref("nglayout.debug.event_dumping"))
    return;

  NS_LossyConvertUTF16toASCII tempString(debug_GuiEventToString(aGuiEvent).get());

  fprintf(aFileOut,
          "%4d %-26s widget=%-8p name=%-12s id=0x%-6x refpt=%d,%d\n",
          _GetPrintCount(),
          tempString.get(),
          (void *) aWidget,
          aWidgetName.get(),
          aWindowID,
          aGuiEvent->refPoint.x,
          aGuiEvent->refPoint.y);
}
//////////////////////////////////////////////////////////////
/* static */ void
nsBaseWidget::debug_DumpPaintEvent(FILE *                aFileOut,
                                   nsIWidget *           aWidget,
                                   const nsIntRegion &   aRegion,
                                   const nsAutoCString & aWidgetName,
                                   int32_t               aWindowID)
{
  NS_ASSERTION(nullptr != aFileOut,"cmon, null output FILE");
  NS_ASSERTION(nullptr != aWidget,"cmon, the widget is null");

  if (!debug_GetCachedBoolPref("nglayout.debug.paint_dumping"))
    return;

  nsIntRect rect = aRegion.GetBounds();
  fprintf(aFileOut,
          "%4d PAINT      widget=%p name=%-12s id=0x%-6x bounds-rect=%3d,%-3d %3d,%-3d",
          _GetPrintCount(),
          (void *) aWidget,
          aWidgetName.get(),
          aWindowID,
          rect.x, rect.y, rect.width, rect.height
    );

  fprintf(aFileOut,"\n");
}
//////////////////////////////////////////////////////////////
/* static */ void
nsBaseWidget::debug_DumpInvalidate(FILE* aFileOut,
                                   nsIWidget* aWidget,
                                   const LayoutDeviceIntRect* aRect,
                                   const nsAutoCString& aWidgetName,
                                   int32_t aWindowID)
{
  if (!debug_GetCachedBoolPref("nglayout.debug.invalidate_dumping"))
    return;

  NS_ASSERTION(nullptr != aFileOut,"cmon, null output FILE");
  NS_ASSERTION(nullptr != aWidget,"cmon, the widget is null");

  fprintf(aFileOut,
          "%4d Invalidate widget=%p name=%-12s id=0x%-6x",
          _GetPrintCount(),
          (void *) aWidget,
          aWidgetName.get(),
          aWindowID);

  if (aRect) {
    fprintf(aFileOut,
            " rect=%3d,%-3d %3d,%-3d",
            aRect->x, aRect->y, aRect->width, aRect->height);
  } else {
    fprintf(aFileOut,
            " rect=%-15s",
            "none");
  }

  fprintf(aFileOut, "\n");
}
//////////////////////////////////////////////////////////////

#endif // DEBUG