Add m-esr52 at 52.6.0

1 files changed, 682 insertions, 0 deletions

diff --git a/editor/libeditor/HTMLAbsPositionEditor.cpp b/editor/libeditor/HTMLAbsPositionEditor.cpp
new file mode 100644
index 000000000..670da78ae
--- /dev/null
+++ b/editor/libeditor/HTMLAbsPositionEditor.cpp
@@ -0,0 +1,682 @@
+/* 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/HTMLEditor.h"
+
+#include <math.h>
+
+#include "HTMLEditorObjectResizerUtils.h"
+#include "HTMLEditRules.h"
+#include "HTMLEditUtils.h"
+#include "TextEditUtils.h"
+#include "mozilla/EditorUtils.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/dom/Selection.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/mozalloc.h"
+#include "nsAString.h"
+#include "nsAlgorithm.h"
+#include "nsCOMPtr.h"
+#include "nsComputedDOMStyle.h"
+#include "nsDebug.h"
+#include "nsError.h"
+#include "nsGkAtoms.h"
+#include "nsIContent.h"
+#include "nsROCSSPrimitiveValue.h"
+#include "nsIDOMCSSStyleDeclaration.h"
+#include "nsIDOMElement.h"
+#include "nsIDOMEventListener.h"
+#include "nsIDOMEventTarget.h"
+#include "nsIDOMNode.h"
+#include "nsDOMCSSRGBColor.h"
+#include "nsIDOMWindow.h"
+#include "nsIEditor.h"
+#include "nsIEditRules.h"
+#include "nsIHTMLEditor.h"
+#include "nsIHTMLObjectResizer.h"
+#include "nsINode.h"
+#include "nsIPresShell.h"
+#include "nsISupportsImpl.h"
+#include "nsISupportsUtils.h"
+#include "nsLiteralString.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+#include "nsStringFwd.h"
+#include "nscore.h"
+#include <algorithm>
+
+namespace mozilla {
+
+using namespace dom;
+
+#define  BLACK_BG_RGB_TRIGGER 0xd0
+
+NS_IMETHODIMP
+HTMLEditor::AbsolutePositionSelection(bool aEnabled)
+{
+  AutoEditBatch beginBatching(this);
+  AutoRules beginRulesSniffing(this,
+                               aEnabled ? EditAction::setAbsolutePosition :
+                                          EditAction::removeAbsolutePosition,
+                               nsIEditor::eNext);
+
+  // the line below does not match the code; should it be removed?
+  // Find out if the selection is collapsed:
+  RefPtr<Selection> selection = GetSelection();
+  NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
+
+  TextRulesInfo ruleInfo(aEnabled ? EditAction::setAbsolutePosition :
+                                    EditAction::removeAbsolutePosition);
+  bool cancel, handled;
+  // Protect the edit rules object from dying
+  nsCOMPtr<nsIEditRules> rules(mRules);
+  nsresult rv = rules->WillDoAction(selection, &ruleInfo, &cancel, &handled);
+  if (NS_FAILED(rv) || cancel) {
+    return rv;
+  }
+
+  return rules->DidDoAction(selection, &ruleInfo, rv);
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetAbsolutelyPositionedSelectionContainer(nsIDOMElement** _retval)
+{
+  nsAutoString positionStr;
+  nsCOMPtr<nsINode> node = GetSelectionContainer();
+  nsCOMPtr<nsIDOMNode> resultNode;
+
+  while (!resultNode && node && !node->IsHTMLElement(nsGkAtoms::html)) {
+    nsresult rv =
+      mCSSEditUtils->GetComputedProperty(*node, *nsGkAtoms::position,
+                                         positionStr);
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (positionStr.EqualsLiteral("absolute"))
+      resultNode = GetAsDOMNode(node);
+    else {
+      node = node->GetParentNode();
+    }
+  }
+
+  nsCOMPtr<nsIDOMElement> element = do_QueryInterface(resultNode);
+  element.forget(_retval);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetSelectionContainerAbsolutelyPositioned(
+              bool* aIsSelectionContainerAbsolutelyPositioned)
+{
+  *aIsSelectionContainerAbsolutelyPositioned = (mAbsolutelyPositionedObject != nullptr);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetAbsolutePositioningEnabled(bool* aIsEnabled)
+{
+  *aIsEnabled = mIsAbsolutelyPositioningEnabled;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::SetAbsolutePositioningEnabled(bool aIsEnabled)
+{
+  mIsAbsolutelyPositioningEnabled = aIsEnabled;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::RelativeChangeElementZIndex(nsIDOMElement* aElement,
+                                          int32_t aChange,
+                                          int32_t* aReturn)
+{
+  NS_ENSURE_ARG_POINTER(aElement);
+  NS_ENSURE_ARG_POINTER(aReturn);
+  if (!aChange) // early way out, no change
+    return NS_OK;
+
+  int32_t zIndex;
+  nsresult rv = GetElementZIndex(aElement, &zIndex);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  zIndex = std::max(zIndex + aChange, 0);
+  SetElementZIndex(aElement, zIndex);
+  *aReturn = zIndex;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::SetElementZIndex(nsIDOMElement* aElement,
+                             int32_t aZindex)
+{
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_ARG_POINTER(element);
+
+  nsAutoString zIndexStr;
+  zIndexStr.AppendInt(aZindex);
+
+  mCSSEditUtils->SetCSSProperty(*element, *nsGkAtoms::z_index, zIndexStr);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::RelativeChangeZIndex(int32_t aChange)
+{
+  AutoEditBatch beginBatching(this);
+  AutoRules beginRulesSniffing(this,
+                               (aChange < 0) ? EditAction::decreaseZIndex :
+                                               EditAction::increaseZIndex,
+                               nsIEditor::eNext);
+
+  // brade: can we get rid of this comment?
+  // Find out if the selection is collapsed:
+  RefPtr<Selection> selection = GetSelection();
+  NS_ENSURE_TRUE(selection, NS_ERROR_NULL_POINTER);
+  TextRulesInfo ruleInfo(aChange < 0 ? EditAction::decreaseZIndex :
+                                       EditAction::increaseZIndex);
+  bool cancel, handled;
+  // Protect the edit rules object from dying
+  nsCOMPtr<nsIEditRules> rules(mRules);
+  nsresult rv = rules->WillDoAction(selection, &ruleInfo, &cancel, &handled);
+  if (cancel || NS_FAILED(rv)) {
+    return rv;
+  }
+
+  return rules->DidDoAction(selection, &ruleInfo, rv);
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetElementZIndex(nsIDOMElement* aElement,
+                             int32_t* aZindex)
+{
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_STATE(element || !aElement);
+  nsAutoString zIndexStr;
+  *aZindex = 0;
+
+  nsresult rv =
+    mCSSEditUtils->GetSpecifiedProperty(*element, *nsGkAtoms::z_index,
+                                        zIndexStr);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (zIndexStr.EqualsLiteral("auto")) {
+    // we have to look at the positioned ancestors
+    // cf. CSS 2 spec section 9.9.1
+    nsCOMPtr<nsIDOMNode> parentNode;
+    rv = aElement->GetParentNode(getter_AddRefs(parentNode));
+    NS_ENSURE_SUCCESS(rv, rv);
+    nsCOMPtr<nsINode> node = do_QueryInterface(parentNode);
+    nsAutoString positionStr;
+    while (node && zIndexStr.EqualsLiteral("auto") &&
+           !node->IsHTMLElement(nsGkAtoms::body)) {
+      rv = mCSSEditUtils->GetComputedProperty(*node, *nsGkAtoms::position,
+                                              positionStr);
+      NS_ENSURE_SUCCESS(rv, rv);
+      if (positionStr.EqualsLiteral("absolute")) {
+        // ah, we found one, what's its z-index ? If its z-index is auto,
+        // we have to continue climbing the document's tree
+        rv = mCSSEditUtils->GetComputedProperty(*node, *nsGkAtoms::z_index,
+                                                zIndexStr);
+        NS_ENSURE_SUCCESS(rv, rv);
+      }
+      node = node->GetParentNode();
+    }
+  }
+
+  if (!zIndexStr.EqualsLiteral("auto")) {
+    nsresult errorCode;
+    *aZindex = zIndexStr.ToInteger(&errorCode);
+  }
+
+  return NS_OK;
+}
+
+already_AddRefed<Element>
+HTMLEditor::CreateGrabber(nsINode* aParentNode)
+{
+  // let's create a grabber through the element factory
+  nsCOMPtr<nsIDOMElement> retDOM;
+  CreateAnonymousElement(NS_LITERAL_STRING("span"), GetAsDOMNode(aParentNode),
+                         NS_LITERAL_STRING("mozGrabber"), false,
+                         getter_AddRefs(retDOM));
+
+  NS_ENSURE_TRUE(retDOM, nullptr);
+
+  // add the mouse listener so we can detect a click on a resizer
+  nsCOMPtr<nsIDOMEventTarget> evtTarget(do_QueryInterface(retDOM));
+  evtTarget->AddEventListener(NS_LITERAL_STRING("mousedown"),
+                              mEventListener, false);
+
+  nsCOMPtr<Element> ret = do_QueryInterface(retDOM);
+  return ret.forget();
+}
+
+NS_IMETHODIMP
+HTMLEditor::RefreshGrabber()
+{
+  NS_ENSURE_TRUE(mAbsolutelyPositionedObject, NS_ERROR_NULL_POINTER);
+
+  nsresult rv =
+    GetPositionAndDimensions(
+      static_cast<nsIDOMElement*>(GetAsDOMNode(mAbsolutelyPositionedObject)),
+      mPositionedObjectX,
+      mPositionedObjectY,
+      mPositionedObjectWidth,
+      mPositionedObjectHeight,
+      mPositionedObjectBorderLeft,
+      mPositionedObjectBorderTop,
+      mPositionedObjectMarginLeft,
+      mPositionedObjectMarginTop);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  SetAnonymousElementPosition(mPositionedObjectX+12,
+                              mPositionedObjectY-14,
+                              static_cast<nsIDOMElement*>(GetAsDOMNode(mGrabber)));
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::HideGrabber()
+{
+  nsresult rv = mAbsolutelyPositionedObject->UnsetAttr(kNameSpaceID_None,
+                                                       nsGkAtoms::_moz_abspos,
+                                                       true);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  mAbsolutelyPositionedObject = nullptr;
+  NS_ENSURE_TRUE(mGrabber, NS_ERROR_NULL_POINTER);
+
+  // get the presshell's document observer interface.
+  nsCOMPtr<nsIPresShell> ps = GetPresShell();
+  // We allow the pres shell to be null; when it is, we presume there
+  // are no document observers to notify, but we still want to
+  // UnbindFromTree.
+
+  nsCOMPtr<nsIContent> parentContent = mGrabber->GetParent();
+  NS_ENSURE_TRUE(parentContent, NS_ERROR_NULL_POINTER);
+
+  DeleteRefToAnonymousNode(static_cast<nsIDOMElement*>(GetAsDOMNode(mGrabber)), parentContent, ps);
+  mGrabber = nullptr;
+  DeleteRefToAnonymousNode(static_cast<nsIDOMElement*>(GetAsDOMNode(mPositioningShadow)), parentContent, ps);
+  mPositioningShadow = nullptr;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::ShowGrabberOnElement(nsIDOMElement* aElement)
+{
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_ARG_POINTER(element);
+
+  if (NS_WARN_IF(!IsDescendantOfEditorRoot(element))) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  if (mGrabber) {
+    NS_ERROR("call HideGrabber first");
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  nsAutoString classValue;
+  nsresult rv = CheckPositionedElementBGandFG(aElement, classValue);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = element->SetAttr(kNameSpaceID_None, nsGkAtoms::_moz_abspos,
+                        classValue, true);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // first, let's keep track of that element...
+  mAbsolutelyPositionedObject = element;
+
+  mGrabber = CreateGrabber(element->GetParentNode());
+  NS_ENSURE_TRUE(mGrabber, NS_ERROR_FAILURE);
+
+  // and set its position
+  return RefreshGrabber();
+}
+
+nsresult
+HTMLEditor::StartMoving(nsIDOMElement* aHandle)
+{
+  nsCOMPtr<nsINode> parentNode = mGrabber->GetParentNode();
+
+  // now, let's create the resizing shadow
+  mPositioningShadow = CreateShadow(GetAsDOMNode(parentNode),
+      static_cast<nsIDOMElement*>(GetAsDOMNode(mAbsolutelyPositionedObject)));
+  NS_ENSURE_TRUE(mPositioningShadow, NS_ERROR_FAILURE);
+  nsresult rv = SetShadowPosition(mPositioningShadow,
+                                  mAbsolutelyPositionedObject,
+                                  mPositionedObjectX, mPositionedObjectY);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // make the shadow appear
+  mPositioningShadow->UnsetAttr(kNameSpaceID_None, nsGkAtoms::_class, true);
+
+  // position it
+  mCSSEditUtils->SetCSSPropertyPixels(*mPositioningShadow, *nsGkAtoms::width,
+                                      mPositionedObjectWidth);
+  mCSSEditUtils->SetCSSPropertyPixels(*mPositioningShadow, *nsGkAtoms::height,
+                                      mPositionedObjectHeight);
+
+  mIsMoving = true;
+  return NS_OK; // XXX Looks like nobody refers this result
+}
+
+void
+HTMLEditor::SnapToGrid(int32_t& newX, int32_t& newY)
+{
+  if (mSnapToGridEnabled && mGridSize) {
+    newX = (int32_t) floor( ((float)newX / (float)mGridSize) + 0.5f ) * mGridSize;
+    newY = (int32_t) floor( ((float)newY / (float)mGridSize) + 0.5f ) * mGridSize;
+  }
+}
+
+nsresult
+HTMLEditor::GrabberClicked()
+{
+  // add a mouse move listener to the editor
+  nsresult rv = NS_OK;
+  if (!mMouseMotionListenerP) {
+    mMouseMotionListenerP = new ResizerMouseMotionListener(this);
+    if (!mMouseMotionListenerP) {return NS_ERROR_NULL_POINTER;}
+
+    nsCOMPtr<nsIDOMEventTarget> piTarget = GetDOMEventTarget();
+    NS_ENSURE_TRUE(piTarget, NS_ERROR_FAILURE);
+
+    rv = piTarget->AddEventListener(NS_LITERAL_STRING("mousemove"),
+                                     mMouseMotionListenerP,
+                                     false, false);
+    NS_ASSERTION(NS_SUCCEEDED(rv),
+                 "failed to register mouse motion listener");
+  }
+  mGrabberClicked = true;
+  return rv;
+}
+
+nsresult
+HTMLEditor::EndMoving()
+{
+  if (mPositioningShadow) {
+    nsCOMPtr<nsIPresShell> ps = GetPresShell();
+    NS_ENSURE_TRUE(ps, NS_ERROR_NOT_INITIALIZED);
+
+    nsCOMPtr<nsIContent> parentContent = mGrabber->GetParent();
+    NS_ENSURE_TRUE(parentContent, NS_ERROR_FAILURE);
+
+    DeleteRefToAnonymousNode(static_cast<nsIDOMElement*>(GetAsDOMNode(mPositioningShadow)),
+                             parentContent, ps);
+
+    mPositioningShadow = nullptr;
+  }
+  nsCOMPtr<nsIDOMEventTarget> piTarget = GetDOMEventTarget();
+
+  if (piTarget && mMouseMotionListenerP) {
+    DebugOnly<nsresult> rv =
+      piTarget->RemoveEventListener(NS_LITERAL_STRING("mousemove"),
+                                    mMouseMotionListenerP,
+                                    false);
+    NS_ASSERTION(NS_SUCCEEDED(rv), "failed to remove mouse motion listener");
+  }
+  mMouseMotionListenerP = nullptr;
+
+  mGrabberClicked = false;
+  mIsMoving = false;
+  RefPtr<Selection> selection = GetSelection();
+  if (!selection) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+  return CheckSelectionStateForAnonymousButtons(selection);
+}
+nsresult
+HTMLEditor::SetFinalPosition(int32_t aX,
+                             int32_t aY)
+{
+  nsresult rv = EndMoving();
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  // we have now to set the new width and height of the resized object
+  // we don't set the x and y position because we don't control that in
+  // a normal HTML layout
+  int32_t newX = mPositionedObjectX + aX - mOriginalX - (mPositionedObjectBorderLeft+mPositionedObjectMarginLeft);
+  int32_t newY = mPositionedObjectY + aY - mOriginalY - (mPositionedObjectBorderTop+mPositionedObjectMarginTop);
+
+  SnapToGrid(newX, newY);
+
+  nsAutoString x, y;
+  x.AppendInt(newX);
+  y.AppendInt(newY);
+
+  // we want one transaction only from a user's point of view
+  AutoEditBatch batchIt(this);
+
+  nsCOMPtr<Element> absolutelyPositionedObject =
+    do_QueryInterface(mAbsolutelyPositionedObject);
+  NS_ENSURE_STATE(absolutelyPositionedObject);
+  mCSSEditUtils->SetCSSPropertyPixels(*absolutelyPositionedObject,
+                                      *nsGkAtoms::top, newY);
+  mCSSEditUtils->SetCSSPropertyPixels(*absolutelyPositionedObject,
+                                      *nsGkAtoms::left, newX);
+  // keep track of that size
+  mPositionedObjectX  = newX;
+  mPositionedObjectY  = newY;
+
+  return RefreshResizers();
+}
+
+void
+HTMLEditor::AddPositioningOffset(int32_t& aX,
+                                 int32_t& aY)
+{
+  // Get the positioning offset
+  int32_t positioningOffset =
+    Preferences::GetInt("editor.positioning.offset", 0);
+
+  aX += positioningOffset;
+  aY += positioningOffset;
+}
+
+NS_IMETHODIMP
+HTMLEditor::AbsolutelyPositionElement(nsIDOMElement* aElement,
+                                      bool aEnabled)
+{
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_ARG_POINTER(element);
+
+  nsAutoString positionStr;
+  mCSSEditUtils->GetComputedProperty(*element, *nsGkAtoms::position,
+                                     positionStr);
+  bool isPositioned = (positionStr.EqualsLiteral("absolute"));
+
+  // nothing to do if the element is already in the state we want
+  if (isPositioned == aEnabled)
+    return NS_OK;
+
+  AutoEditBatch batchIt(this);
+
+  if (aEnabled) {
+    int32_t x, y;
+    GetElementOrigin(aElement, x, y);
+
+    mCSSEditUtils->SetCSSProperty(*element, *nsGkAtoms::position,
+                                  NS_LITERAL_STRING("absolute"));
+
+    AddPositioningOffset(x, y);
+    SnapToGrid(x, y);
+    SetElementPosition(*element, x, y);
+
+    // we may need to create a br if the positioned element is alone in its
+    // container
+    nsCOMPtr<nsINode> element = do_QueryInterface(aElement);
+    NS_ENSURE_STATE(element);
+
+    nsINode* parentNode = element->GetParentNode();
+    if (parentNode->GetChildCount() == 1) {
+      nsCOMPtr<nsIDOMNode> brNode;
+      nsresult rv = CreateBR(parentNode->AsDOMNode(), 0, address_of(brNode));
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+  else {
+    mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::position,
+                                     EmptyString());
+    mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::top,
+                                     EmptyString());
+    mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::left,
+                                     EmptyString());
+    mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::z_index,
+                                     EmptyString());
+
+    if (!HTMLEditUtils::IsImage(aElement)) {
+      mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::width,
+                                       EmptyString());
+      mCSSEditUtils->RemoveCSSProperty(*element, *nsGkAtoms::height,
+                                       EmptyString());
+    }
+
+    nsCOMPtr<dom::Element> element = do_QueryInterface(aElement);
+    if (element && element->IsHTMLElement(nsGkAtoms::div) &&
+        !HasStyleOrIdOrClass(element)) {
+      RefPtr<HTMLEditRules> htmlRules =
+        static_cast<HTMLEditRules*>(mRules.get());
+      NS_ENSURE_TRUE(htmlRules, NS_ERROR_FAILURE);
+      nsresult rv = htmlRules->MakeSureElemStartsOrEndsOnCR(aElement);
+      NS_ENSURE_SUCCESS(rv, rv);
+      rv = RemoveContainer(element);
+      NS_ENSURE_SUCCESS(rv, rv);
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::SetSnapToGridEnabled(bool aEnabled)
+{
+  mSnapToGridEnabled = aEnabled;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetSnapToGridEnabled(bool* aIsEnabled)
+{
+  *aIsEnabled = mSnapToGridEnabled;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::SetGridSize(uint32_t aSize)
+{
+  mGridSize = aSize;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+HTMLEditor::GetGridSize(uint32_t* aSize)
+{
+  *aSize = mGridSize;
+  return NS_OK;
+}
+
+// self-explanatory
+NS_IMETHODIMP
+HTMLEditor::SetElementPosition(nsIDOMElement* aElement,
+                               int32_t aX,
+                               int32_t aY)
+{
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_STATE(element);
+
+  SetElementPosition(*element, aX, aY);
+  return NS_OK;
+}
+
+void
+HTMLEditor::SetElementPosition(Element& aElement,
+                               int32_t aX,
+                               int32_t aY)
+{
+  AutoEditBatch batchIt(this);
+  mCSSEditUtils->SetCSSPropertyPixels(aElement, *nsGkAtoms::left, aX);
+  mCSSEditUtils->SetCSSPropertyPixels(aElement, *nsGkAtoms::top, aY);
+}
+
+// self-explanatory
+NS_IMETHODIMP
+HTMLEditor::GetPositionedElement(nsIDOMElement** aReturn)
+{
+  nsCOMPtr<nsIDOMElement> ret =
+    static_cast<nsIDOMElement*>(GetAsDOMNode(mAbsolutelyPositionedObject));
+  ret.forget(aReturn);
+  return NS_OK;
+}
+
+nsresult
+HTMLEditor::CheckPositionedElementBGandFG(nsIDOMElement* aElement,
+                                          nsAString& aReturn)
+{
+  // we are going to outline the positioned element and bring it to the
+  // front to overlap any other element intersecting with it. But
+  // first, let's see what's the background and foreground colors of the
+  // positioned element.
+  // if background-image computed value is 'none,
+  //   If the background color is 'auto' and R G B values of the foreground are
+  //       each above #d0, use a black background
+  //   If the background color is 'auto' and at least one of R G B values of
+  //       the foreground is below #d0, use a white background
+  // Otherwise don't change background/foreground
+  nsCOMPtr<Element> element = do_QueryInterface(aElement);
+  NS_ENSURE_STATE(element || !aElement);
+
+  aReturn.Truncate();
+
+  nsAutoString bgImageStr;
+  nsresult rv =
+    mCSSEditUtils->GetComputedProperty(*element, *nsGkAtoms::background_image,
+                                       bgImageStr);
+  NS_ENSURE_SUCCESS(rv, rv);
+  if (bgImageStr.EqualsLiteral("none")) {
+    nsAutoString bgColorStr;
+    rv =
+      mCSSEditUtils->GetComputedProperty(*element, *nsGkAtoms::backgroundColor,
+                                         bgColorStr);
+    NS_ENSURE_SUCCESS(rv, rv);
+    if (bgColorStr.EqualsLiteral("transparent")) {
+      RefPtr<nsComputedDOMStyle> cssDecl =
+        mCSSEditUtils->GetComputedStyle(element);
+      NS_ENSURE_STATE(cssDecl);
+
+      // from these declarations, get the one we want and that one only
+      ErrorResult error;
+      RefPtr<dom::CSSValue> cssVal = cssDecl->GetPropertyCSSValue(NS_LITERAL_STRING("color"), error);
+      NS_ENSURE_TRUE(!error.Failed(), error.StealNSResult());
+
+      nsROCSSPrimitiveValue* val = cssVal->AsPrimitiveValue();
+      NS_ENSURE_TRUE(val, NS_ERROR_FAILURE);
+
+      if (nsIDOMCSSPrimitiveValue::CSS_RGBCOLOR == val->PrimitiveType()) {
+        nsDOMCSSRGBColor* rgbVal = val->GetRGBColorValue(error);
+        NS_ENSURE_TRUE(!error.Failed(), error.StealNSResult());
+        float r = rgbVal->Red()->
+          GetFloatValue(nsIDOMCSSPrimitiveValue::CSS_NUMBER, error);
+        NS_ENSURE_TRUE(!error.Failed(), error.StealNSResult());
+        float g = rgbVal->Green()->
+          GetFloatValue(nsIDOMCSSPrimitiveValue::CSS_NUMBER, error);
+        NS_ENSURE_TRUE(!error.Failed(), error.StealNSResult());
+        float b = rgbVal->Blue()->
+          GetFloatValue(nsIDOMCSSPrimitiveValue::CSS_NUMBER, error);
+        NS_ENSURE_TRUE(!error.Failed(), error.StealNSResult());
+        if (r >= BLACK_BG_RGB_TRIGGER &&
+            g >= BLACK_BG_RGB_TRIGGER &&
+            b >= BLACK_BG_RGB_TRIGGER)
+          aReturn.AssignLiteral("black");
+        else
+          aReturn.AssignLiteral("white");
+        return NS_OK;
+      }
+    }
+  }
+
+  return NS_OK;
+}
+
+} // namespace mozilla