view/nsViewManager.cpp
author Gurzau Raul <rgurzau@mozilla.com>
Sat, 25 May 2019 09:07:49 +0300
changeset 475564 af54b2de7028db03f42207598f7a0b4ba81e262f
parent 475534 d98dfc5659273b0984ac10f15c503dc4dc11eea6
child 475624 5440467afab5639d3626dbaeadef000a2953e30e
permissions -rw-r--r--
Backed out 31 changesets (bug 1552643, bug 1550422) for xpcshell crash on a CLOSED TREE. Backed out changeset e30c1aa75529 (bug 1552643) Backed out changeset caadcd7e02d3 (bug 1552643) Backed out changeset aa7086ab09be (bug 1552643) Backed out changeset 0b4029671710 (bug 1550422) Backed out changeset a16295296035 (bug 1550422) Backed out changeset 3b70307c0db5 (bug 1550422) Backed out changeset 69df7818d4a3 (bug 1550422) Backed out changeset d98dfc565927 (bug 1550422) Backed out changeset 6f0997976944 (bug 1550422) Backed out changeset 0edd264464c2 (bug 1550422) Backed out changeset 9ea6da7a74ec (bug 1550422) Backed out changeset f855f9309c8b (bug 1550422) Backed out changeset 1033546224a7 (bug 1550422) Backed out changeset ade7384c6186 (bug 1550422) Backed out changeset 75b04de7e99c (bug 1550422) Backed out changeset 91c3acdb2454 (bug 1550422) Backed out changeset 77d2f80257d1 (bug 1550422) Backed out changeset e0cd10d35327 (bug 1550422) Backed out changeset 097091082423 (bug 1550422) Backed out changeset 2f328853c1ab (bug 1550422) Backed out changeset f92f2cc29cb1 (bug 1550422) Backed out changeset 6dc82f88333d (bug 1550422) Backed out changeset c20f66494d69 (bug 1550422) Backed out changeset 2ba22cddeb6f (bug 1550422) Backed out changeset 3aa72f89e295 (bug 1550422) Backed out changeset ab4c4e806977 (bug 1550422) Backed out changeset 72e5de040dda (bug 1550422) Backed out changeset 7d3c2d486706 (bug 1550422) Backed out changeset 132e0b8d8468 (bug 1550422) Backed out changeset 54c85ac75dd0 (bug 1550422) Backed out changeset d7ba4a18dd54 (bug 1550422)

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

#include "nsViewManager.h"

#include "mozilla/MouseEvents.h"
#include "mozilla/PresShell.h"
#include "mozilla/PresShellInlines.h"
#include "mozilla/Preferences.h"
#include "mozilla/StartupTimeline.h"
#include "mozilla/dom/Document.h"
#include "nsAutoPtr.h"
#include "nsGfxCIID.h"
#include "nsView.h"
#include "nsCOMPtr.h"
#include "nsRegion.h"
#include "nsCOMArray.h"
#include "nsIPluginWidget.h"
#include "nsXULPopupManager.h"
#include "nsPresContext.h"
#include "GeckoProfiler.h"
#include "nsRefreshDriver.h"
#include "nsContentUtils.h"  // for nsAutoScriptBlocker
#include "nsLayoutUtils.h"
#include "Layers.h"
#include "gfxPlatform.h"
#include "gfxPrefs.h"

/**
   XXX TODO XXX

   DeCOMify newly private methods
   Optimize view storage
*/

/**
   A note about platform assumptions:

   We assume that a widget is z-ordered on top of its parent.

   We do NOT assume anything about the relative z-ordering of sibling widgets.
   Even though we ask for a specific z-order, we don't assume that widget
   z-ordering actually works.
*/

using namespace mozilla;
using namespace mozilla::layers;

#define NSCOORD_NONE INT32_MIN

#undef DEBUG_MOUSE_LOCATION

// Weakly held references to all of the view managers
nsTArray<nsViewManager*>* nsViewManager::gViewManagers = nullptr;
uint32_t nsViewManager::gLastUserEventTime = 0;

nsViewManager::nsViewManager()
    : mPresShell(nullptr),
      mDelayedResize(NSCOORD_NONE, NSCOORD_NONE),
      mRootView(nullptr),
      mRootViewManager(this),
      mRefreshDisableCount(0),
      mPainting(false),
      mRecursiveRefreshPending(false),
      mHasPendingWidgetGeometryChanges(false) {
  if (gViewManagers == nullptr) {
    // Create an array to hold a list of view managers
    gViewManagers = new nsTArray<nsViewManager*>;
  }

  gViewManagers->AppendElement(this);
}

nsViewManager::~nsViewManager() {
  if (mRootView) {
    // Destroy any remaining views
    mRootView->Destroy();
    mRootView = nullptr;
  }

  if (!IsRootVM()) {
    // We have a strong ref to mRootViewManager
    NS_RELEASE(mRootViewManager);
  }

  NS_ASSERTION(gViewManagers != nullptr, "About to use null gViewManagers");

#ifdef DEBUG
  bool removed =
#endif
      gViewManagers->RemoveElement(this);
  NS_ASSERTION(
      removed,
      "Viewmanager instance was not in the global list of viewmanagers");

  if (gViewManagers->IsEmpty()) {
    // There aren't any more view managers so
    // release the global array of view managers
    delete gViewManagers;
    gViewManagers = nullptr;
  }

  MOZ_RELEASE_ASSERT(!mPresShell,
                     "Releasing nsViewManager without having called Destroy on "
                     "the PresShell!");
}

// We don't hold a reference to the presentation context because it
// holds a reference to us.
nsresult nsViewManager::Init(nsDeviceContext* aContext) {
  MOZ_ASSERT(nullptr != aContext, "null ptr");

  if (nullptr == aContext) {
    return NS_ERROR_NULL_POINTER;
  }
  if (nullptr != mContext) {
    return NS_ERROR_ALREADY_INITIALIZED;
  }
  mContext = aContext;

  return NS_OK;
}

nsView* nsViewManager::CreateView(const nsRect& aBounds, nsView* aParent,
                                  nsViewVisibility aVisibilityFlag) {
  auto* v = new nsView(this, aVisibilityFlag);
  v->SetParent(aParent);
  v->SetPosition(aBounds.X(), aBounds.Y());
  nsRect dim(0, 0, aBounds.Width(), aBounds.Height());
  v->SetDimensions(dim, false);
  return v;
}

void nsViewManager::SetRootView(nsView* aView) {
  MOZ_ASSERT(!aView || aView->GetViewManager() == this,
             "Unexpected viewmanager on root view");

  // Do NOT destroy the current root view. It's the caller's responsibility
  // to destroy it
  mRootView = aView;

  if (mRootView) {
    nsView* parent = mRootView->GetParent();
    if (parent) {
      // Calling InsertChild on |parent| will InvalidateHierarchy() on us, so
      // no need to set mRootViewManager ourselves here.
      parent->InsertChild(mRootView, nullptr);
    } else {
      InvalidateHierarchy();
    }

    mRootView->SetZIndex(false, 0);
  }
  // Else don't touch mRootViewManager
}

void nsViewManager::GetWindowDimensions(nscoord* aWidth, nscoord* aHeight) {
  if (nullptr != mRootView) {
    if (mDelayedResize == nsSize(NSCOORD_NONE, NSCOORD_NONE)) {
      nsRect dim = mRootView->GetDimensions();
      *aWidth = dim.Width();
      *aHeight = dim.Height();
    } else {
      *aWidth = mDelayedResize.width;
      *aHeight = mDelayedResize.height;
    }
  } else {
    *aWidth = 0;
    *aHeight = 0;
  }
}

void nsViewManager::DoSetWindowDimensions(nscoord aWidth, nscoord aHeight) {
  nsRect oldDim = mRootView->GetDimensions();
  nsRect newDim(0, 0, aWidth, aHeight);
  // We care about resizes even when one dimension is already zero.
  if (!oldDim.IsEqualEdges(newDim)) {
    // Don't resize the widget. It is already being set elsewhere.
    mRootView->SetDimensions(newDim, true, false);
    if (RefPtr<PresShell> presShell = mPresShell) {
      presShell->ResizeReflow(aWidth, aHeight, oldDim.Width(), oldDim.Height());
    }
  }
}

bool nsViewManager::ShouldDelayResize() const {
  MOZ_ASSERT(mRootView);
  if (!mRootView->IsEffectivelyVisible() || !mPresShell ||
      !mPresShell->IsVisible()) {
    return true;
  }
  if (nsRefreshDriver* rd = mPresShell->GetRefreshDriver()) {
    if (rd->IsResizeSuppressed()) {
      return true;
    }
  }
  return false;
}

void nsViewManager::SetWindowDimensions(nscoord aWidth, nscoord aHeight,
                                        bool aDelayResize) {
  if (mRootView) {
    if (!ShouldDelayResize() && !aDelayResize) {
      if (mDelayedResize != nsSize(NSCOORD_NONE, NSCOORD_NONE) &&
          mDelayedResize != nsSize(aWidth, aHeight)) {
        // We have a delayed resize; that now obsolete size may already have
        // been flushed to the PresContext so we need to update the PresContext
        // with the new size because if the new size is exactly the same as the
        // root view's current size then DoSetWindowDimensions will not
        // request a resize reflow (which would correct it). See bug 617076.
        mDelayedResize = nsSize(aWidth, aHeight);
        FlushDelayedResize(false);
      }
      mDelayedResize.SizeTo(NSCOORD_NONE, NSCOORD_NONE);
      DoSetWindowDimensions(aWidth, aHeight);
    } else {
      mDelayedResize.SizeTo(aWidth, aHeight);
      if (mPresShell) {
        mPresShell->SetNeedStyleFlush();
        mPresShell->SetNeedLayoutFlush();
      }
    }
  }
}

void nsViewManager::FlushDelayedResize(bool aDoReflow) {
  if (mDelayedResize != nsSize(NSCOORD_NONE, NSCOORD_NONE)) {
    if (aDoReflow) {
      DoSetWindowDimensions(mDelayedResize.width, mDelayedResize.height);
      mDelayedResize.SizeTo(NSCOORD_NONE, NSCOORD_NONE);
    } else if (mPresShell && !mPresShell->GetIsViewportOverridden()) {
      nsPresContext* presContext = mPresShell->GetPresContext();
      if (presContext) {
        presContext->SetVisibleArea(nsRect(nsPoint(0, 0), mDelayedResize));
      }
    }
  }
}

// Convert aIn from being relative to and in appunits of aFromView, to being
// relative to and in appunits of aToView.
static nsRegion ConvertRegionBetweenViews(const nsRegion& aIn,
                                          nsView* aFromView, nsView* aToView) {
  nsRegion out = aIn;
  out.MoveBy(aFromView->GetOffsetTo(aToView));
  out = out.ScaleToOtherAppUnitsRoundOut(
      aFromView->GetViewManager()->AppUnitsPerDevPixel(),
      aToView->GetViewManager()->AppUnitsPerDevPixel());
  return out;
}

nsView* nsViewManager::GetDisplayRootFor(nsView* aView) {
  nsView* displayRoot = aView;
  for (;;) {
    nsView* displayParent = displayRoot->GetParent();
    if (!displayParent) return displayRoot;

    if (displayRoot->GetFloating() && !displayParent->GetFloating())
      return displayRoot;

    // If we have a combobox dropdown popup within a panel popup, both the view
    // for the dropdown popup and its parent will be floating, so we need to
    // distinguish this situation. We do this by looking for a widget. Any view
    // with a widget is a display root, except for plugins.
    nsIWidget* widget = displayRoot->GetWidget();
    if (widget && widget->WindowType() == eWindowType_popup) {
      NS_ASSERTION(displayRoot->GetFloating() && displayParent->GetFloating(),
                   "this should only happen with floating views that have "
                   "floating parents");
      return displayRoot;
    }

    displayRoot = displayParent;
  }
}

/**
   aRegion is given in device coordinates!!
   aContext may be null, in which case layers should be used for
   rendering.
*/
void nsViewManager::Refresh(nsView* aView,
                            const LayoutDeviceIntRegion& aRegion) {
  NS_ASSERTION(aView->GetViewManager() == this, "wrong view manager");

  if (mPresShell && mPresShell->IsNeverPainting()) {
    return;
  }

  // damageRegion is the damaged area, in twips, relative to the view origin
  nsRegion damageRegion = aRegion.ToAppUnits(AppUnitsPerDevPixel());

  // move region from widget coordinates into view coordinates
  damageRegion.MoveBy(-aView->ViewToWidgetOffset());

  if (damageRegion.IsEmpty()) {
#ifdef DEBUG_roc
    nsRect viewRect = aView->GetDimensions();
    nsRect damageRect = damageRegion.GetBounds();
    printf_stderr(
        "XXX Damage rectangle (%d,%d,%d,%d) does not intersect the widget's "
        "view (%d,%d,%d,%d)!\n",
        damageRect.x, damageRect.y, damageRect.width, damageRect.height,
        viewRect.x, viewRect.y, viewRect.width, viewRect.height);
#endif
    return;
  }

  nsIWidget* widget = aView->GetWidget();
  if (!widget) {
    return;
  }

  NS_ASSERTION(!IsPainting(), "recursive painting not permitted");
  if (IsPainting()) {
    RootViewManager()->mRecursiveRefreshPending = true;
    return;
  }

  {
    nsAutoScriptBlocker scriptBlocker;
    SetPainting(true);

    NS_ASSERTION(GetDisplayRootFor(aView) == aView,
                 "Widgets that we paint must all be display roots");

    if (RefPtr<PresShell> presShell = mPresShell) {
#ifdef MOZ_DUMP_PAINTING
      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
        printf_stderr("--COMPOSITE-- %p\n", presShell.get());
      }
#endif
      LayerManager* manager = widget->GetLayerManager();
      if (!manager->NeedsWidgetInvalidation()) {
        manager->FlushRendering();
      } else {
        presShell->Paint(aView, damageRegion, PaintFlags::PaintComposite);
      }
#ifdef MOZ_DUMP_PAINTING
      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
        printf_stderr("--ENDCOMPOSITE--\n");
      }
#endif
      mozilla::StartupTimeline::RecordOnce(
          mozilla::StartupTimeline::FIRST_PAINT);
    }

    SetPainting(false);
  }

  if (RootViewManager()->mRecursiveRefreshPending) {
    RootViewManager()->mRecursiveRefreshPending = false;
    InvalidateAllViews();
  }
}

void nsViewManager::ProcessPendingUpdatesForView(nsView* aView,
                                                 bool aFlushDirtyRegion) {
  NS_ASSERTION(IsRootVM(), "Updates will be missed");
  if (!aView) {
    return;
  }

  RefPtr<PresShell> rootPresShell = mPresShell;
  AutoTArray<nsCOMPtr<nsIWidget>, 1> widgets;
  aView->GetViewManager()->ProcessPendingUpdatesRecurse(aView, widgets);
  for (uint32_t i = 0; i < widgets.Length(); ++i) {
    nsView* view = nsView::GetViewFor(widgets[i]);
    if (view) {
      if (view->mNeedsWindowPropertiesSync) {
        view->mNeedsWindowPropertiesSync = false;
        if (nsViewManager* vm = view->GetViewManager()) {
          if (PresShell* presShell = vm->GetPresShell()) {
            presShell->SyncWindowProperties(view);
          }
        }
      }
    }
    view = nsView::GetViewFor(widgets[i]);
    if (view) {
      view->ResetWidgetBounds(false, true);
    }
  }
  if (rootPresShell->GetViewManager() != this) {
    return;  // presentation might have been torn down
  }
  if (aFlushDirtyRegion) {
    nsAutoScriptBlocker scriptBlocker;
    SetPainting(true);
    for (uint32_t i = 0; i < widgets.Length(); ++i) {
      nsIWidget* widget = widgets[i];
      nsView* view = nsView::GetViewFor(widget);
      if (view) {
        RefPtr<nsViewManager> viewManager = view->GetViewManager();
        viewManager->ProcessPendingUpdatesPaint(MOZ_KnownLive(widget));
      }
    }
    SetPainting(false);
  }
}

void nsViewManager::ProcessPendingUpdatesRecurse(
    nsView* aView, AutoTArray<nsCOMPtr<nsIWidget>, 1>& aWidgets) {
  if (mPresShell && mPresShell->IsNeverPainting()) {
    return;
  }

  for (nsView* childView = aView->GetFirstChild(); childView;
       childView = childView->GetNextSibling()) {
    childView->GetViewManager()->ProcessPendingUpdatesRecurse(childView,
                                                              aWidgets);
  }

  nsIWidget* widget = aView->GetWidget();
  if (widget) {
    aWidgets.AppendElement(widget);
  } else {
    FlushDirtyRegionToWidget(aView);
  }
}

void nsViewManager::ProcessPendingUpdatesPaint(nsIWidget* aWidget) {
  if (aWidget->NeedsPaint()) {
    // If an ancestor widget was hidden and then shown, we could
    // have a delayed resize to handle.
    for (RefPtr<nsViewManager> vm = this; vm;
         vm = vm->mRootView->GetParent()
                  ? vm->mRootView->GetParent()->GetViewManager()
                  : nullptr) {
      if (vm->mDelayedResize != nsSize(NSCOORD_NONE, NSCOORD_NONE) &&
          vm->mRootView->IsEffectivelyVisible() && vm->mPresShell &&
          vm->mPresShell->IsVisible()) {
        vm->FlushDelayedResize(true);
      }
    }
    nsView* view = nsView::GetViewFor(aWidget);

    if (!view) {
      NS_ERROR("FlushDelayedResize destroyed the nsView?");
      return;
    }

    nsIWidgetListener* previousListener =
        aWidget->GetPreviouslyAttachedWidgetListener();

    if (previousListener && previousListener != view &&
        view->IsPrimaryFramePaintSuppressed()) {
      return;
    }

    if (RefPtr<PresShell> presShell = mPresShell) {
#ifdef MOZ_DUMP_PAINTING
      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
        printf_stderr(
            "---- PAINT START ----PresShell(%p), nsView(%p), nsIWidget(%p)\n",
            presShell.get(), view, aWidget);
      }
#endif

      presShell->Paint(view, nsRegion(), PaintFlags::PaintLayers);
      view->SetForcedRepaint(false);

#ifdef MOZ_DUMP_PAINTING
      if (nsLayoutUtils::InvalidationDebuggingIsEnabled()) {
        printf_stderr("---- PAINT END ----\n");
      }
#endif
    }
  }
  FlushDirtyRegionToWidget(nsView::GetViewFor(aWidget));
}

void nsViewManager::FlushDirtyRegionToWidget(nsView* aView) {
  NS_ASSERTION(aView->GetViewManager() == this,
               "FlushDirtyRegionToWidget called on view we don't own");

  if (!aView->HasNonEmptyDirtyRegion()) return;

  nsRegion* dirtyRegion = aView->GetDirtyRegion();
  nsView* nearestViewWithWidget = aView;
  while (!nearestViewWithWidget->HasWidget() &&
         nearestViewWithWidget->GetParent()) {
    nearestViewWithWidget = nearestViewWithWidget->GetParent();
  }
  nsRegion r =
      ConvertRegionBetweenViews(*dirtyRegion, aView, nearestViewWithWidget);

  nsViewManager* widgetVM = nearestViewWithWidget->GetViewManager();
  widgetVM->InvalidateWidgetArea(nearestViewWithWidget, r);
  dirtyRegion->SetEmpty();
}

void nsViewManager::InvalidateView(nsView* aView) {
  // Mark the entire view as damaged
  InvalidateView(aView, aView->GetDimensions());
}

static void AddDirtyRegion(nsView* aView, const nsRegion& aDamagedRegion) {
  nsRegion* dirtyRegion = aView->GetDirtyRegion();
  if (!dirtyRegion) return;

  dirtyRegion->Or(*dirtyRegion, aDamagedRegion);
  dirtyRegion->SimplifyOutward(8);
}

void nsViewManager::PostPendingUpdate() {
  nsViewManager* rootVM = RootViewManager();
  rootVM->mHasPendingWidgetGeometryChanges = true;
  if (rootVM->mPresShell) {
    rootVM->mPresShell->ScheduleViewManagerFlush();
  }
}

/**
 * @param aDamagedRegion this region, relative to aWidgetView, is invalidated in
 * every widget child of aWidgetView, plus aWidgetView's own widget
 */
void nsViewManager::InvalidateWidgetArea(nsView* aWidgetView,
                                         const nsRegion& aDamagedRegion) {
  NS_ASSERTION(aWidgetView->GetViewManager() == this,
               "InvalidateWidgetArea called on view we don't own");
  nsIWidget* widget = aWidgetView->GetWidget();

#if 0
  nsRect dbgBounds = aDamagedRegion.GetBounds();
  printf("InvalidateWidgetArea view:%X (%d) widget:%X region: %d, %d, %d, %d\n",
    aWidgetView, aWidgetView->IsAttachedToTopLevel(),
    widget, dbgBounds.x, dbgBounds.y, dbgBounds.width, dbgBounds.height);
#endif

  // If the widget is hidden, it don't cover nothing
  if (widget && !widget->IsVisible()) {
    return;
  }

  if (!widget) {
    // The root view or a scrolling view might not have a widget
    // (for example, during printing). We get here when we scroll
    // during printing to show selected options in a listbox, for example.
    return;
  }

  // Update all child widgets with the damage. In the process,
  // accumulate the union of all the child widget areas, or at least
  // some subset of that.
  nsRegion children;
  if (widget->GetTransparencyMode() != eTransparencyTransparent) {
    for (nsIWidget* childWidget = widget->GetFirstChild(); childWidget;
         childWidget = childWidget->GetNextSibling()) {
      nsView* view = nsView::GetViewFor(childWidget);
      NS_ASSERTION(view != aWidgetView, "will recur infinitely");
      nsWindowType type = childWidget->WindowType();
      if (view && childWidget->IsVisible() && type != eWindowType_popup) {
        NS_ASSERTION(childWidget->IsPlugin(),
                     "Only plugin or popup widgets can be children!");

        // We do not need to invalidate in plugin widgets, but we should
        // exclude them from the invalidation region IF we're not on
        // Mac. On Mac we need to draw under plugin widgets, because
        // plugin widgets are basically invisible
#ifndef XP_MACOSX
        // GetBounds should compensate for chrome on a toplevel widget
        LayoutDeviceIntRect bounds = childWidget->GetBounds();

        nsTArray<LayoutDeviceIntRect> clipRects;
        childWidget->GetWindowClipRegion(&clipRects);
        for (uint32_t i = 0; i < clipRects.Length(); ++i) {
          nsRect rr = LayoutDeviceIntRect::ToAppUnits(
              clipRects[i] + bounds.TopLeft(), AppUnitsPerDevPixel());
          children.Or(children, rr - aWidgetView->ViewToWidgetOffset());
          children.SimplifyInward(20);
        }
#endif
      }
    }
  }

  nsRegion leftOver;
  leftOver.Sub(aDamagedRegion, children);

  if (!leftOver.IsEmpty()) {
    for (auto iter = leftOver.RectIter(); !iter.Done(); iter.Next()) {
      LayoutDeviceIntRect bounds = ViewToWidget(aWidgetView, iter.Get());
      widget->Invalidate(bounds);
    }
  }
}

static bool ShouldIgnoreInvalidation(nsViewManager* aVM) {
  while (aVM) {
    PresShell* presShell = aVM->GetPresShell();
    if (!presShell || presShell->ShouldIgnoreInvalidation()) {
      return true;
    }
    nsView* view = aVM->GetRootView()->GetParent();
    aVM = view ? view->GetViewManager() : nullptr;
  }
  return false;
}

void nsViewManager::InvalidateView(nsView* aView, const nsRect& aRect) {
  // If painting is suppressed in the presshell or an ancestor drop all
  // invalidates, it will invalidate everything when it unsuppresses.
  if (ShouldIgnoreInvalidation(this)) {
    return;
  }

  InvalidateViewNoSuppression(aView, aRect);
}

void nsViewManager::InvalidateViewNoSuppression(nsView* aView,
                                                const nsRect& aRect) {
  MOZ_ASSERT(nullptr != aView, "null view");

  NS_ASSERTION(aView->GetViewManager() == this,
               "InvalidateViewNoSuppression called on view we don't own");

  nsRect damagedRect(aRect);
  if (damagedRect.IsEmpty()) {
    return;
  }

  nsView* displayRoot = GetDisplayRootFor(aView);
  nsViewManager* displayRootVM = displayRoot->GetViewManager();
  // Propagate the update to the displayRoot, since iframes, for example,
  // can overlap each other and be translucent.  So we have to possibly
  // invalidate our rect in each of the widgets we have lying about.
  damagedRect.MoveBy(aView->GetOffsetTo(displayRoot));
  int32_t rootAPD = displayRootVM->AppUnitsPerDevPixel();
  int32_t APD = AppUnitsPerDevPixel();
  damagedRect = damagedRect.ScaleToOtherAppUnitsRoundOut(APD, rootAPD);

  // accumulate this rectangle in the view's dirty region, so we can
  // process it later.
  AddDirtyRegion(displayRoot, nsRegion(damagedRect));
}

void nsViewManager::InvalidateAllViews() {
  if (RootViewManager() != this) {
    return RootViewManager()->InvalidateAllViews();
  }

  InvalidateViews(mRootView);
}

void nsViewManager::InvalidateViews(nsView* aView) {
  // Invalidate this view.
  InvalidateView(aView);

  // Invalidate all children as well.
  nsView* childView = aView->GetFirstChild();
  while (nullptr != childView) {
    childView->GetViewManager()->InvalidateViews(childView);
    childView = childView->GetNextSibling();
  }
}

void nsViewManager::WillPaintWindow(nsIWidget* aWidget) {
  if (aWidget) {
    nsView* view = nsView::GetViewFor(aWidget);
    LayerManager* manager = aWidget->GetLayerManager();
    if (view &&
        (view->ForcedRepaint() || !manager->NeedsWidgetInvalidation())) {
      ProcessPendingUpdates();
      // Re-get the view pointer here since the ProcessPendingUpdates might have
      // destroyed it during CallWillPaintOnObservers.
      view = nsView::GetViewFor(aWidget);
      if (view) {
        view->SetForcedRepaint(false);
      }
    }
  }

  if (RefPtr<PresShell> presShell = mPresShell) {
    presShell->WillPaintWindow();
  }
}

bool nsViewManager::PaintWindow(nsIWidget* aWidget,
                                const LayoutDeviceIntRegion& aRegion) {
  if (!aWidget || !mContext) return false;

  NS_ASSERTION(
      IsPaintingAllowed(),
      "shouldn't be receiving paint events while painting is disallowed!");

  // Get the view pointer here since NS_WILL_PAINT might have
  // destroyed it during CallWillPaintOnObservers (bug 378273).
  nsView* view = nsView::GetViewFor(aWidget);
  if (view && !aRegion.IsEmpty()) {
    Refresh(view, aRegion);
  }

  return true;
}

void nsViewManager::DidPaintWindow() {
  if (RefPtr<PresShell> presShell = mPresShell) {
    presShell->DidPaintWindow();
  }
}

void nsViewManager::DispatchEvent(WidgetGUIEvent* aEvent, nsView* aView,
                                  nsEventStatus* aStatus) {
  AUTO_PROFILER_LABEL("nsViewManager::DispatchEvent", OTHER);

  WidgetMouseEvent* mouseEvent = aEvent->AsMouseEvent();
  if ((mouseEvent &&
       // Ignore mouse events that we synthesize.
       mouseEvent->mReason == WidgetMouseEvent::eReal &&
       // Ignore mouse exit and enter (we'll get moves if the user
       // is really moving the mouse) since we get them when we
       // create and destroy widgets.
       mouseEvent->mMessage != eMouseExitFromWidget &&
       mouseEvent->mMessage != eMouseEnterIntoWidget) ||
      aEvent->HasKeyEventMessage() || aEvent->HasIMEEventMessage() ||
      aEvent->mMessage == ePluginInputEvent) {
    gLastUserEventTime = PR_IntervalToMicroseconds(PR_IntervalNow());
  }

  // Find the view whose coordinates system we're in.
  nsView* view = aView;
  bool dispatchUsingCoordinates = aEvent->IsUsingCoordinates();
  if (dispatchUsingCoordinates) {
    // Will dispatch using coordinates. Pretty bogus but it's consistent
    // with what presshell does.
    view = GetDisplayRootFor(view);
  }

  // If the view has no frame, look for a view that does.
  nsIFrame* frame = view->GetFrame();
  if (!frame && (dispatchUsingCoordinates || aEvent->HasKeyEventMessage() ||
                 aEvent->IsIMERelatedEvent() ||
                 aEvent->IsNonRetargetedNativeEventDelivererForPlugin() ||
                 aEvent->HasPluginActivationEventMessage())) {
    while (view && !view->GetFrame()) {
      view = view->GetParent();
    }

    if (view) {
      frame = view->GetFrame();
    }
  }

  if (nullptr != frame) {
    // Hold a refcount to the presshell. The continued existence of the
    // presshell will delay deletion of this view hierarchy should the event
    // want to cause its destruction in, say, some JavaScript event handler.
    if (RefPtr<PresShell> presShell = view->GetViewManager()->GetPresShell()) {
      presShell->HandleEvent(frame, aEvent, false, aStatus);
      return;
    }
  }

  *aStatus = nsEventStatus_eIgnore;
}

// Recursively reparent widgets if necessary

void nsViewManager::ReparentChildWidgets(nsView* aView, nsIWidget* aNewWidget) {
  MOZ_ASSERT(aNewWidget, "null widget");

  if (aView->HasWidget()) {
    // Check to see if the parent widget is the
    // same as the new parent. If not then reparent
    // the widget, otherwise there is nothing more
    // to do for the view and its descendants
    nsIWidget* widget = aView->GetWidget();
    nsIWidget* parentWidget = widget->GetParent();
    if (parentWidget) {
      // Child widget
      if (parentWidget != aNewWidget) {
        widget->SetParent(aNewWidget);
      }
    } else {
      // Toplevel widget (popup, dialog, etc)
      widget->ReparentNativeWidget(aNewWidget);
    }
    return;
  }

  // Need to check each of the views children to see
  // if they have a widget and reparent it.

  for (nsView* kid = aView->GetFirstChild(); kid; kid = kid->GetNextSibling()) {
    ReparentChildWidgets(kid, aNewWidget);
  }
}

// Reparent a view and its descendant views widgets if necessary

void nsViewManager::ReparentWidgets(nsView* aView, nsView* aParent) {
  MOZ_ASSERT(aParent, "Must have a parent");
  MOZ_ASSERT(aView, "Must have a view");

  // Quickly determine whether the view has pre-existing children or a
  // widget. In most cases the view will not have any pre-existing
  // children when this is called.  Only in the case
  // where a view has been reparented by removing it from
  // a reinserting it into a new location in the view hierarchy do we
  // have to consider reparenting the existing widgets for the view and
  // it's descendants.
  if (aView->HasWidget() || aView->GetFirstChild()) {
    nsIWidget* parentWidget = aParent->GetNearestWidget(nullptr);
    if (parentWidget) {
      ReparentChildWidgets(aView, parentWidget);
      return;
    }
    NS_WARNING("Can not find a widget for the parent view");
  }
}

void nsViewManager::InsertChild(nsView* aParent, nsView* aChild,
                                nsView* aSibling, bool aAfter) {
  MOZ_ASSERT(nullptr != aParent, "null ptr");
  MOZ_ASSERT(nullptr != aChild, "null ptr");
  NS_ASSERTION(aSibling == nullptr || aSibling->GetParent() == aParent,
               "tried to insert view with invalid sibling");
  NS_ASSERTION(!IsViewInserted(aChild),
               "tried to insert an already-inserted view");

  if ((nullptr != aParent) && (nullptr != aChild)) {
    // if aAfter is set, we will insert the child after 'prev' (i.e. after 'kid'
    // in document order, otherwise after 'kid' (i.e. before 'kid' in document
    // order).

    if (nullptr == aSibling) {
      if (aAfter) {
        // insert at end of document order, i.e., before first view
        // this is the common case, by far
        aParent->InsertChild(aChild, nullptr);
        ReparentWidgets(aChild, aParent);
      } else {
        // insert at beginning of document order, i.e., after last view
        nsView* kid = aParent->GetFirstChild();
        nsView* prev = nullptr;
        while (kid) {
          prev = kid;
          kid = kid->GetNextSibling();
        }
        // prev is last view or null if there are no children
        aParent->InsertChild(aChild, prev);
        ReparentWidgets(aChild, aParent);
      }
    } else {
      nsView* kid = aParent->GetFirstChild();
      nsView* prev = nullptr;
      while (kid && aSibling != kid) {
        // get the next sibling view
        prev = kid;
        kid = kid->GetNextSibling();
      }
      NS_ASSERTION(kid != nullptr, "couldn't find sibling in child list");
      if (aAfter) {
        // insert after 'kid' in document order, i.e. before in view order
        aParent->InsertChild(aChild, prev);
        ReparentWidgets(aChild, aParent);
      } else {
        // insert before 'kid' in document order, i.e. after in view order
        aParent->InsertChild(aChild, kid);
        ReparentWidgets(aChild, aParent);
      }
    }

    // if the parent view is marked as "floating", make the newly added view
    // float as well.
    if (aParent->GetFloating()) aChild->SetFloating(true);
  }
}

void nsViewManager::RemoveChild(nsView* aChild) {
  NS_ASSERTION(aChild, "aChild must not be null");

  nsView* parent = aChild->GetParent();

  if (nullptr != parent) {
    NS_ASSERTION(
        aChild->GetViewManager() == this || parent->GetViewManager() == this,
        "wrong view manager");
    parent->RemoveChild(aChild);
  }
}

void nsViewManager::MoveViewTo(nsView* aView, nscoord aX, nscoord aY) {
  NS_ASSERTION(aView->GetViewManager() == this, "wrong view manager");
  aView->SetPosition(aX, aY);
}

void nsViewManager::ResizeView(nsView* aView, const nsRect& aRect,
                               bool aRepaintExposedAreaOnly) {
  NS_ASSERTION(aView->GetViewManager() == this, "wrong view manager");

  nsRect oldDimensions = aView->GetDimensions();
  if (!oldDimensions.IsEqualEdges(aRect)) {
    aView->SetDimensions(aRect, true);
  }

  // Note that if layout resizes the view and the view has a custom clip
  // region set, then we expect layout to update the clip region too. Thus
  // in the case where mClipRect has been optimized away to just be a null
  // pointer, and this resize is implicitly changing the clip rect, it's OK
  // because layout will change it back again if necessary.
}

void nsViewManager::SetViewFloating(nsView* aView, bool aFloating) {
  NS_ASSERTION(!(nullptr == aView), "no view");

  aView->SetFloating(aFloating);
}

void nsViewManager::SetViewVisibility(nsView* aView,
                                      nsViewVisibility aVisible) {
  NS_ASSERTION(aView->GetViewManager() == this, "wrong view manager");

  if (aVisible != aView->GetVisibility()) {
    aView->SetVisibility(aVisible);
  }
}

bool nsViewManager::IsViewInserted(nsView* aView) {
  if (mRootView == aView) {
    return true;
  }
  if (aView->GetParent() == nullptr) {
    return false;
  }
  nsView* view = aView->GetParent()->GetFirstChild();
  while (view != nullptr) {
    if (view == aView) {
      return true;
    }
    view = view->GetNextSibling();
  }
  return false;
}

void nsViewManager::SetViewZIndex(nsView* aView, bool aAutoZIndex,
                                  int32_t aZIndex) {
  NS_ASSERTION((aView != nullptr), "no view");

  // don't allow the root view's z-index to be changed. It should always be
  // zero. This could be removed and replaced with a style rule, or just removed
  // altogether, with interesting consequences
  if (aView == mRootView) {
    return;
  }

  if (aAutoZIndex) {
    aZIndex = 0;
  }

  aView->SetZIndex(aAutoZIndex, aZIndex);
}

nsViewManager* nsViewManager::IncrementDisableRefreshCount() {
  if (!IsRootVM()) {
    return RootViewManager()->IncrementDisableRefreshCount();
  }

  ++mRefreshDisableCount;

  return this;
}

void nsViewManager::DecrementDisableRefreshCount() {
  NS_ASSERTION(IsRootVM(), "Should only be called on root");
  --mRefreshDisableCount;
  NS_ASSERTION(mRefreshDisableCount >= 0, "Invalid refresh disable count!");
}

void nsViewManager::GetRootWidget(nsIWidget** aWidget) {
  if (!mRootView) {
    *aWidget = nullptr;
    return;
  }
  if (mRootView->HasWidget()) {
    *aWidget = mRootView->GetWidget();
    NS_ADDREF(*aWidget);
    return;
  }
  if (mRootView->GetParent()) {
    mRootView->GetParent()->GetViewManager()->GetRootWidget(aWidget);
    return;
  }
  *aWidget = nullptr;
}

LayoutDeviceIntRect nsViewManager::ViewToWidget(nsView* aView,
                                                const nsRect& aRect) const {
  NS_ASSERTION(aView->GetViewManager() == this, "wrong view manager");

  // account for the view's origin not lining up with the widget's
  nsRect rect = aRect + aView->ViewToWidgetOffset();

  // finally, convert to device coordinates.
  return LayoutDeviceIntRect::FromUnknownRect(
      rect.ToOutsidePixels(AppUnitsPerDevPixel()));
}

void nsViewManager::IsPainting(bool& aIsPainting) {
  aIsPainting = IsPainting();
}

void nsViewManager::ProcessPendingUpdates() {
  if (!IsRootVM()) {
    RefPtr<nsViewManager> rootViewManager = RootViewManager();
    rootViewManager->ProcessPendingUpdates();
    return;
  }

  // Flush things like reflows by calling WillPaint on observer presShells.
  if (mPresShell) {
    mPresShell->GetPresContext()->RefreshDriver()->RevokeViewManagerFlush();

    RefPtr<nsViewManager> strongThis(this);
    CallWillPaintOnObservers();

    ProcessPendingUpdatesForView(mRootView, true);
  }
}

void nsViewManager::UpdateWidgetGeometry() {
  if (!IsRootVM()) {
    RefPtr<nsViewManager> rootViewManager = RootViewManager();
    rootViewManager->UpdateWidgetGeometry();
    return;
  }

  if (mHasPendingWidgetGeometryChanges) {
    mHasPendingWidgetGeometryChanges = false;
    ProcessPendingUpdatesForView(mRootView, false);
  }
}

void nsViewManager::CallWillPaintOnObservers() {
  MOZ_ASSERT(IsRootVM(), "Must be root VM for this to be called!");

  if (NS_WARN_IF(!gViewManagers)) {
    return;
  }

  uint32_t index;
  for (index = 0; index < gViewManagers->Length(); index++) {
    nsViewManager* vm = gViewManagers->ElementAt(index);
    if (vm->RootViewManager() == this) {
      // One of our kids.
      if (vm->mRootView && vm->mRootView->IsEffectivelyVisible()) {
        if (RefPtr<PresShell> presShell = vm->GetPresShell()) {
          presShell->WillPaint();
        }
      }
    }
  }
}

void nsViewManager::GetLastUserEventTime(uint32_t& aTime) {
  aTime = gLastUserEventTime;
}

void nsViewManager::InvalidateHierarchy() {
  if (mRootView) {
    if (!IsRootVM()) {
      NS_RELEASE(mRootViewManager);
    }
    nsView* parent = mRootView->GetParent();
    if (parent) {
      mRootViewManager = parent->GetViewManager()->RootViewManager();
      NS_ADDREF(mRootViewManager);
      NS_ASSERTION(mRootViewManager != this,
                   "Root view had a parent, but it has the same view manager");
    } else {
      mRootViewManager = this;
    }
  }
}