gecko-dev/layout/forms/nsFieldSetFrame.cpp

/* -*- 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 "nsCSSAnonBoxes.h"
#include "nsContainerFrame.h"
#include "nsLegendFrame.h"
#include "nsCSSRendering.h"
#include <algorithm>
#include "nsIFrame.h"
#include "nsPresContext.h"
#include "RestyleManager.h"
#include "nsGkAtoms.h"
#include "nsStyleConsts.h"
#include "nsDisplayList.h"
#include "nsRenderingContext.h"
#include "mozilla/Likely.h"

using namespace mozilla;
using namespace mozilla::layout;

class nsFieldSetFrame MOZ_FINAL : public nsContainerFrame {
public:
  NS_DECL_FRAMEARENA_HELPERS

  nsFieldSetFrame(nsStyleContext* aContext);

  NS_HIDDEN_(nscoord)
    GetIntrinsicWidth(nsRenderingContext* aRenderingContext,
                      nsLayoutUtils::IntrinsicWidthType);
  virtual nscoord GetMinWidth(nsRenderingContext* aRenderingContext);
  virtual nscoord GetPrefWidth(nsRenderingContext* aRenderingContext);
  virtual nsSize ComputeSize(nsRenderingContext *aRenderingContext,
                             nsSize aCBSize, nscoord aAvailableWidth,
                             nsSize aMargin, nsSize aBorder, nsSize aPadding,
                             uint32_t aFlags) MOZ_OVERRIDE;
  virtual nscoord GetBaseline() const;

  /**
   * The area to paint box-shadows around.  It's the border rect except
   * when there's a <legend> we offset the y-position to the center of it.
   */
  virtual nsRect VisualBorderRectRelativeToSelf() const MOZ_OVERRIDE {
    nscoord topBorder = StyleBorder()->GetComputedBorderWidth(NS_SIDE_TOP);
    nsRect r(nsPoint(0,0), GetSize());
    if (topBorder < mLegendRect.height) {
      nscoord yoff = (mLegendRect.height - topBorder) / 2;
      r.y += yoff;
      r.height -= yoff;
    }
    return r;
  }

  NS_IMETHOD Reflow(nsPresContext*           aPresContext,
                    nsHTMLReflowMetrics&     aDesiredSize,
                    const nsHTMLReflowState& aReflowState,
                    nsReflowStatus&          aStatus);
                               
  virtual void BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                const nsRect&           aDirtyRect,
                                const nsDisplayListSet& aLists) MOZ_OVERRIDE;

  void PaintBorderBackground(nsRenderingContext& aRenderingContext,
    nsPoint aPt, const nsRect& aDirtyRect, uint32_t aBGFlags);

  NS_IMETHOD AppendFrames(ChildListID    aListID,
                          nsFrameList&   aFrameList);
  NS_IMETHOD InsertFrames(ChildListID    aListID,
                          nsIFrame*      aPrevFrame,
                          nsFrameList&   aFrameList);
  NS_IMETHOD RemoveFrame(ChildListID    aListID,
                         nsIFrame*      aOldFrame);

  virtual nsIAtom* GetType() const;
  virtual bool IsFrameOfType(uint32_t aFlags) const
  {
    return nsContainerFrame::IsFrameOfType(aFlags &
             ~nsIFrame::eCanContainOverflowContainers);
  }

#ifdef ACCESSIBILITY  
  virtual mozilla::a11y::AccType AccessibleType() MOZ_OVERRIDE;
#endif

#ifdef DEBUG
  NS_IMETHOD SetInitialChildList(ChildListID    aListID,
                                 nsFrameList&   aChildList);

  NS_IMETHOD GetFrameName(nsAString& aResult) const {
    return MakeFrameName(NS_LITERAL_STRING("FieldSet"), aResult);
  }
#endif

protected:

  void ReparentFrameList(const nsFrameList& aFrameList);

  /**
   * Return the anonymous frame that contains all descendants except
   * the legend frame.  This is currently always a block frame with
   * pseudo nsCSSAnonBoxes::fieldsetContent -- this may change in the
   * future when we add support for CSS overflow for <fieldset>.
   */
  nsIFrame* GetInner() const
  {
    nsIFrame* last = mFrames.LastChild();
    if (last &&
        last->StyleContext()->GetPseudo() == nsCSSAnonBoxes::fieldsetContent) {
      return last;
    }
    MOZ_ASSERT(mFrames.LastChild() == mFrames.FirstChild());
    return nullptr;
  }

  /**
   * Return the frame that represents the legend if any.  This may be
   * a nsLegendFrame or a nsHTMLScrollFrame with the nsLegendFrame as the
   * scrolled frame (aka content insertion frame).
   */
  nsIFrame* GetLegend() const
  {
    if (mFrames.FirstChild() == GetInner()) {
      MOZ_ASSERT(mFrames.LastChild() == mFrames.FirstChild());
      return nullptr;
    }
    MOZ_ASSERT(mFrames.FirstChild() &&
               mFrames.FirstChild()->GetContentInsertionFrame()->GetType() ==
                 nsGkAtoms::legendFrame);
    return mFrames.FirstChild();
  }

  nsRect    mLegendRect;
  nscoord   mLegendSpace;
};

nsIFrame*
NS_NewFieldSetFrame(nsIPresShell* aPresShell, nsStyleContext* aContext)
{
  return new (aPresShell) nsFieldSetFrame(aContext);
}

NS_IMPL_FRAMEARENA_HELPERS(nsFieldSetFrame)

nsFieldSetFrame::nsFieldSetFrame(nsStyleContext* aContext)
  : nsContainerFrame(aContext)
{
  mLegendSpace  = 0;
}

nsIAtom*
nsFieldSetFrame::GetType() const
{
  return nsGkAtoms::fieldSetFrame;
}

#ifdef DEBUG
NS_IMETHODIMP
nsFieldSetFrame::SetInitialChildList(ChildListID    aListID,
                                     nsFrameList&   aChildList)
{
  nsresult rv = nsContainerFrame::SetInitialChildList(kPrincipalList, aChildList);
  MOZ_ASSERT(GetInner());
  return rv;
}
#endif

class nsDisplayFieldSetBorderBackground : public nsDisplayItem {
public:
  nsDisplayFieldSetBorderBackground(nsDisplayListBuilder* aBuilder,
                                    nsFieldSetFrame* aFrame)
    : nsDisplayItem(aBuilder, aFrame) {
    MOZ_COUNT_CTOR(nsDisplayFieldSetBorderBackground);
  }
#ifdef NS_BUILD_REFCNT_LOGGING
  virtual ~nsDisplayFieldSetBorderBackground() {
    MOZ_COUNT_DTOR(nsDisplayFieldSetBorderBackground);
  }
#endif

  virtual void HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
                       HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames);
  virtual void Paint(nsDisplayListBuilder* aBuilder,
                     nsRenderingContext* aCtx);
  virtual void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
                                         const nsDisplayItemGeometry* aGeometry,
                                         nsRegion *aInvalidRegion) MOZ_OVERRIDE;
  NS_DISPLAY_DECL_NAME("FieldSetBorderBackground", TYPE_FIELDSET_BORDER_BACKGROUND)
};

void nsDisplayFieldSetBorderBackground::HitTest(nsDisplayListBuilder* aBuilder, const nsRect& aRect,
                                                HitTestState* aState, nsTArray<nsIFrame*> *aOutFrames)
{
  // aPt is guaranteed to be in this item's bounds. We do the hit test based on the
  // frame bounds even though our background doesn't cover the whole frame.
  // It's not clear whether this is correct.
  aOutFrames->AppendElement(mFrame);
}

void
nsDisplayFieldSetBorderBackground::Paint(nsDisplayListBuilder* aBuilder,
                                         nsRenderingContext* aCtx)
{
  static_cast<nsFieldSetFrame*>(mFrame)->
    PaintBorderBackground(*aCtx, ToReferenceFrame(),
                          mVisibleRect, aBuilder->GetBackgroundPaintFlags());
}

void
nsDisplayFieldSetBorderBackground::ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
                                                             const nsDisplayItemGeometry* aGeometry,
                                                             nsRegion *aInvalidRegion)
{
  AddInvalidRegionForSyncDecodeBackgroundImages(aBuilder, aGeometry, aInvalidRegion);

  nsDisplayItem::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
}

void
nsFieldSetFrame::BuildDisplayList(nsDisplayListBuilder*   aBuilder,
                                  const nsRect&           aDirtyRect,
                                  const nsDisplayListSet& aLists) {
  // Paint our background and border in a special way.
  // REVIEW: We don't really need to check frame emptiness here; if it's empty,
  // the background/border display item won't do anything, and if it isn't empty,
  // we need to paint the outline
  if (!(GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER) &&
      IsVisibleForPainting(aBuilder)) {
    if (StyleBorder()->mBoxShadow) {
      aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
        nsDisplayBoxShadowOuter(aBuilder, this));
    }

    // don't bother checking to see if we really have a border or background.
    // we usually will have a border.
    aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
      nsDisplayFieldSetBorderBackground(aBuilder, this));
  
    DisplayOutlineUnconditional(aBuilder, aLists);

    DO_GLOBAL_REFLOW_COUNT_DSP("nsFieldSetFrame");
  }

  if (GetPrevInFlow()) {
    DisplayOverflowContainers(aBuilder, aDirtyRect, aLists);
  }

  nsDisplayListCollection contentDisplayItems;
  if (nsIFrame* inner = GetInner()) {
    // Collect the inner frame's display items into their own collection.
    // We need to be calling BuildDisplayList on it before the legend in
    // case it contains out-of-flow frames whose placeholders are in the
    // legend. However, we want the inner frame's display items to be
    // after the legend's display items in z-order, so we need to save them
    // and append them later.
    BuildDisplayListForChild(aBuilder, inner, aDirtyRect, contentDisplayItems);
  }
  if (nsIFrame* legend = GetLegend()) {
    // The legend's background goes on our BlockBorderBackgrounds list because
    // it's a block child.
    nsDisplayListSet set(aLists, aLists.BlockBorderBackgrounds());
    BuildDisplayListForChild(aBuilder, legend, aDirtyRect, set);
  }
  // Put the inner frame's display items on the master list. Note that this
  // moves its border/background display items to our BorderBackground() list,
  // which isn't really correct, but it's OK because the inner frame is
  // anonymous and can't have its own border and background.
  contentDisplayItems.MoveTo(aLists);
}

void
nsFieldSetFrame::PaintBorderBackground(nsRenderingContext& aRenderingContext,
    nsPoint aPt, const nsRect& aDirtyRect, uint32_t aBGFlags)
{
  // if the border is smaller than the legend. Move the border down
  // to be centered on the legend. 
  // FIXME: This means border-radius clamping is incorrect; we should
  // override nsIFrame::GetBorderRadii.
  nsRect rect = VisualBorderRectRelativeToSelf();
  nscoord yoff = rect.y;
  rect += aPt;
  nsPresContext* presContext = PresContext();

  nsCSSRendering::PaintBackground(presContext, aRenderingContext, this,
                                  aDirtyRect, rect, aBGFlags);

  nsCSSRendering::PaintBoxShadowInner(presContext, aRenderingContext,
                                      this, rect, aDirtyRect);

   if (nsIFrame* legend = GetLegend()) {
     nscoord topBorder = StyleBorder()->GetComputedBorderWidth(NS_SIDE_TOP);

    // Use the rect of the legend frame, not mLegendRect, so we draw our
    // border under the legend's left and right margins.
    nsRect legendRect = legend->GetRect() + aPt;
    
    // we should probably use PaintBorderEdges to do this but for now just use clipping
    // to achieve the same effect.

    // draw left side
    nsRect clipRect(rect);
    clipRect.width = legendRect.x - rect.x;
    clipRect.height = topBorder;

    aRenderingContext.PushState();
    aRenderingContext.IntersectClip(clipRect);
    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
                                aDirtyRect, rect, mStyleContext);

    aRenderingContext.PopState();


    // draw right side
    clipRect = rect;
    clipRect.x = legendRect.XMost();
    clipRect.width = rect.XMost() - legendRect.XMost();
    clipRect.height = topBorder;

    aRenderingContext.PushState();
    aRenderingContext.IntersectClip(clipRect);
    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
                                aDirtyRect, rect, mStyleContext);

    aRenderingContext.PopState();

    
    // draw bottom
    clipRect = rect;
    clipRect.y += topBorder;
    clipRect.height = mRect.height - (yoff + topBorder);
    
    aRenderingContext.PushState();
    aRenderingContext.IntersectClip(clipRect);
    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
                                aDirtyRect, rect, mStyleContext);

    aRenderingContext.PopState();
  } else {

    nsCSSRendering::PaintBorder(presContext, aRenderingContext, this,
                                aDirtyRect,
                                nsRect(aPt, mRect.Size()),
                                mStyleContext);
  }
}

nscoord
nsFieldSetFrame::GetIntrinsicWidth(nsRenderingContext* aRenderingContext,
                                   nsLayoutUtils::IntrinsicWidthType aType)
{
  nscoord legendWidth = 0;
  nscoord contentWidth = 0;
  if (nsIFrame* legend = GetLegend()) {
    legendWidth =
      nsLayoutUtils::IntrinsicForContainer(aRenderingContext, legend, aType);
  }

  if (nsIFrame* inner = GetInner()) {
    contentWidth =
      nsLayoutUtils::IntrinsicForContainer(aRenderingContext, inner, aType);
  }
      
  return std::max(legendWidth, contentWidth);
}


nscoord
nsFieldSetFrame::GetMinWidth(nsRenderingContext* aRenderingContext)
{
  nscoord result = 0;
  DISPLAY_MIN_WIDTH(this, result);

  result = GetIntrinsicWidth(aRenderingContext, nsLayoutUtils::MIN_WIDTH);
  return result;
}

nscoord
nsFieldSetFrame::GetPrefWidth(nsRenderingContext* aRenderingContext)
{
  nscoord result = 0;
  DISPLAY_PREF_WIDTH(this, result);

  result = GetIntrinsicWidth(aRenderingContext, nsLayoutUtils::PREF_WIDTH);
  return result;
}

/* virtual */ nsSize
nsFieldSetFrame::ComputeSize(nsRenderingContext *aRenderingContext,
                             nsSize aCBSize, nscoord aAvailableWidth,
                             nsSize aMargin, nsSize aBorder, nsSize aPadding,
                             uint32_t aFlags)
{
  nsSize result =
    nsContainerFrame::ComputeSize(aRenderingContext, aCBSize, aAvailableWidth,
                                  aMargin, aBorder, aPadding, aFlags);

  // Fieldsets never shrink below their min width.

  // If we're a container for font size inflation, then shrink
  // wrapping inside of us should not apply font size inflation.
  AutoMaybeDisableFontInflation an(this);

  nscoord minWidth = GetMinWidth(aRenderingContext);
  if (minWidth > result.width)
    result.width = minWidth;

  return result;
}

NS_IMETHODIMP 
nsFieldSetFrame::Reflow(nsPresContext*           aPresContext,
                        nsHTMLReflowMetrics&     aDesiredSize,
                        const nsHTMLReflowState& aReflowState,
                        nsReflowStatus&          aStatus)
{
  DO_GLOBAL_REFLOW_COUNT("nsFieldSetFrame");
  DISPLAY_REFLOW(aPresContext, this, aReflowState, aDesiredSize, aStatus);

  NS_PRECONDITION(aReflowState.ComputedWidth() != NS_INTRINSICSIZE,
                  "Should have a precomputed width!");      
  
  // Initialize OUT parameter
  aStatus = NS_FRAME_COMPLETE;

  nsOverflowAreas ocBounds;
  nsReflowStatus ocStatus = NS_FRAME_COMPLETE;
  if (GetPrevInFlow()) {
    ReflowOverflowContainerChildren(aPresContext, aReflowState, ocBounds, 0,
                                    ocStatus);
  }

  //------------ Handle Incremental Reflow -----------------
  bool reflowInner;
  bool reflowLegend;
  nsIFrame* legend = GetLegend();
  nsIFrame* inner = GetInner();
  if (aReflowState.ShouldReflowAllKids()) {
    reflowInner = inner != nullptr;
    reflowLegend = legend != nullptr;
  } else {
    reflowInner = inner && NS_SUBTREE_DIRTY(inner);
    reflowLegend = legend && NS_SUBTREE_DIRTY(legend);
  }

  // We don't allow fieldsets to break vertically. If we did, we'd
  // need logic here to push and pull overflow frames.
  nsSize availSize(aReflowState.ComputedWidth(), NS_UNCONSTRAINEDSIZE);
  NS_ASSERTION(!inner ||
      nsLayoutUtils::IntrinsicForContainer(aReflowState.rendContext,
                                           inner,
                                           nsLayoutUtils::MIN_WIDTH) <=
               availSize.width,
               "Bogus availSize.width; should be bigger");
  NS_ASSERTION(!legend ||
      nsLayoutUtils::IntrinsicForContainer(aReflowState.rendContext,
                                           legend,
                                           nsLayoutUtils::MIN_WIDTH) <=
               availSize.width,
               "Bogus availSize.width; should be bigger");

  // get our border and padding
  const nsMargin &borderPadding = aReflowState.mComputedBorderPadding;
  nsMargin border = borderPadding - aReflowState.mComputedPadding;  

  // Figure out how big the legend is if there is one. 
  // get the legend's margin
  nsMargin legendMargin(0,0,0,0);
  // reflow the legend only if needed
  if (reflowLegend) {
    nsHTMLReflowState legendReflowState(aPresContext, aReflowState,
                                        legend, availSize);

    nsHTMLReflowMetrics legendDesiredSize;

    ReflowChild(legend, aPresContext, legendDesiredSize, legendReflowState,
                0, 0, NS_FRAME_NO_MOVE_FRAME, aStatus);
#ifdef NOISY_REFLOW
    printf("  returned (%d, %d)\n", legendDesiredSize.width, legendDesiredSize.height);
#endif
    // figure out the legend's rectangle
    legendMargin = legend->GetUsedMargin();
    mLegendRect.width  = legendDesiredSize.width + legendMargin.left + legendMargin.right;
    mLegendRect.height = legendDesiredSize.height + legendMargin.top + legendMargin.bottom;
    mLegendRect.x = borderPadding.left;
    mLegendRect.y = 0;

    nscoord oldSpace = mLegendSpace;
    mLegendSpace = 0;
    if (mLegendRect.height > border.top) {
      // center the border on the legend
      mLegendSpace = mLegendRect.height - border.top;
    } else {
      mLegendRect.y = (border.top - mLegendRect.height)/2;
    }

    // if the legend space changes then we need to reflow the 
    // content area as well.
    if (mLegendSpace != oldSpace && inner) {
      reflowInner = true;
    }

    FinishReflowChild(legend, aPresContext, &legendReflowState, 
                      legendDesiredSize, 0, 0, NS_FRAME_NO_MOVE_FRAME);    
  } else if (!legend) {
    mLegendRect.SetEmpty();
    mLegendSpace = 0;
  } else {
    // mLegendSpace and mLegendRect haven't changed, but we need
    // the used margin when placing the legend.
    legendMargin = legend->GetUsedMargin();
  }

  // reflow the content frame only if needed
  if (reflowInner) {
    nsHTMLReflowState kidReflowState(aPresContext, aReflowState, inner,
                                     availSize);
    // Our child is "height:100%" but we actually want its height to be reduced
    // by the amount of content-height the legend is eating up, unless our
    // height is unconstrained (in which case the child's will be too).
    if (aReflowState.ComputedHeight() != NS_UNCONSTRAINEDSIZE) {
      kidReflowState.SetComputedHeight(std::max(0, aReflowState.ComputedHeight() - mLegendSpace));
    }

    kidReflowState.mComputedMinHeight =
      std::max(0, aReflowState.mComputedMinHeight - mLegendSpace);

    if (aReflowState.mComputedMaxHeight != NS_UNCONSTRAINEDSIZE) {
      kidReflowState.mComputedMaxHeight =
        std::max(0, aReflowState.mComputedMaxHeight - mLegendSpace);
    }

    nsHTMLReflowMetrics kidDesiredSize(aDesiredSize.mFlags);
    // Reflow the frame
    NS_ASSERTION(kidReflowState.mComputedMargin == nsMargin(0,0,0,0),
                 "Margins on anonymous fieldset child not supported!");
    nsPoint pt(borderPadding.left, borderPadding.top + mLegendSpace);
    ReflowChild(inner, aPresContext, kidDesiredSize, kidReflowState,
                pt.x, pt.y, 0, aStatus);

    FinishReflowChild(inner, aPresContext, &kidReflowState, 
                      kidDesiredSize, pt.x, pt.y, 0);
    NS_FRAME_TRACE_REFLOW_OUT("FieldSet::Reflow", aStatus);
  }

  nsRect contentRect(0,0,0,0);
  if (inner) {
    // We don't support margins on inner, so our "content rect" is just
    // its rect.
    contentRect = inner->GetRect();
  }

  // use the computed width if the inner content does not fill it
  if (aReflowState.ComputedWidth() > contentRect.width) {
    contentRect.width = aReflowState.ComputedWidth();
  }

  if (legend) {
    // if the content rect is larger then the  legend we can align the legend
    if (contentRect.width > mLegendRect.width) {
      int32_t align = static_cast<nsLegendFrame*>
        (legend->GetContentInsertionFrame())->GetAlign();

      switch(align) {
        case NS_STYLE_TEXT_ALIGN_RIGHT:
          mLegendRect.x = contentRect.width - mLegendRect.width + borderPadding.left;
          break;
        case NS_STYLE_TEXT_ALIGN_CENTER:
          // Note: rounding removed; there doesn't seem to be any need
          mLegendRect.x = contentRect.width / 2 - mLegendRect.width / 2 + borderPadding.left;
          break;
      }
  
    } else {
      // otherwise make place for the legend
      contentRect.width = mLegendRect.width;
    }
    // place the legend
    nsRect actualLegendRect(mLegendRect);
    actualLegendRect.Deflate(legendMargin);

    nsPoint curOrigin = legend->GetPosition();

    // only if the origin changed
    if ((curOrigin.x != actualLegendRect.x) || (curOrigin.y != actualLegendRect.y)) {
      legend->SetPosition(nsPoint(actualLegendRect.x , actualLegendRect.y));
      nsContainerFrame::PositionFrameView(legend);

      // We need to recursively process the legend frame's
      // children since we're moving the frame after Reflow.
      nsContainerFrame::PositionChildViews(legend);
    }
  }

  // Return our size and our result
  if (aReflowState.ComputedHeight() == NS_INTRINSICSIZE) {
    aDesiredSize.height = mLegendSpace + 
                          borderPadding.TopBottom() +
                          contentRect.height;
  } else {
    nscoord min = borderPadding.TopBottom() + mLegendRect.height;
    aDesiredSize.height =
      aReflowState.ComputedHeight() + borderPadding.TopBottom();
    if (aDesiredSize.height < min)
      aDesiredSize.height = min;
  }
  aDesiredSize.width = contentRect.width + borderPadding.LeftRight();
  aDesiredSize.SetOverflowAreasToDesiredBounds();
  if (legend)
    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, legend);
  if (inner)
    ConsiderChildOverflow(aDesiredSize.mOverflowAreas, inner);

  // Merge overflow container bounds and status.
  aDesiredSize.mOverflowAreas.UnionWith(ocBounds);
  NS_MergeReflowStatusInto(&aStatus, ocStatus);

  FinishReflowWithAbsoluteFrames(aPresContext, aDesiredSize, aReflowState, aStatus);

  InvalidateFrame();

  NS_FRAME_SET_TRUNCATION(aStatus, aReflowState, aDesiredSize);
  return NS_OK;
}

NS_IMETHODIMP
nsFieldSetFrame::AppendFrames(ChildListID    aListID,
                              nsFrameList&   aFrameList)
{
  // aFrameList is not allowed to contain "the legend" for this fieldset
  ReparentFrameList(aFrameList);
  return GetInner()->AppendFrames(aListID, aFrameList);
}

NS_IMETHODIMP
nsFieldSetFrame::InsertFrames(ChildListID    aListID,
                              nsIFrame*      aPrevFrame,
                              nsFrameList&   aFrameList)
{
  NS_ASSERTION(!aPrevFrame || aPrevFrame->GetParent() == this ||
               aPrevFrame->GetParent() == GetInner(),
               "inserting after sibling frame with different parent");

  // aFrameList is not allowed to contain "the legend" for this fieldset
  ReparentFrameList(aFrameList);
  if (MOZ_UNLIKELY(aPrevFrame == GetLegend())) {
    aPrevFrame = nullptr;
  }
  return GetInner()->InsertFrames(aListID, aPrevFrame, aFrameList);
}

NS_IMETHODIMP
nsFieldSetFrame::RemoveFrame(ChildListID    aListID,
                             nsIFrame*      aOldFrame)
{
  // For reference, see bug 70648, bug 276104 and bug 236071.
  NS_ASSERTION(aOldFrame != GetLegend(), "Cannot remove legend here");
  return GetInner()->RemoveFrame(aListID, aOldFrame);
}

#ifdef ACCESSIBILITY
a11y::AccType
nsFieldSetFrame::AccessibleType()
{
  return a11y::eHTMLGroupboxType;
}
#endif

void
nsFieldSetFrame::ReparentFrameList(const nsFrameList& aFrameList)
{
  RestyleManager* restyleManager = PresContext()->RestyleManager();
  nsIFrame* inner = GetInner();
  for (nsFrameList::Enumerator e(aFrameList); !e.AtEnd(); e.Next()) {
    NS_ASSERTION(GetLegend() || e.get()->GetType() != nsGkAtoms::legendFrame,
                 "The fieldset's legend is not allowed in this list");
    e.get()->SetParent(inner);
    restyleManager->ReparentStyleContext(e.get());
  }
}

nscoord
nsFieldSetFrame::GetBaseline() const
{
  // We know inner is a block, so calling GetBaseline() on it will do
  // the right thing (that being to return the baseline of the last line).
  nsIFrame* inner = GetInner();
  NS_ASSERTION(nsLayoutUtils::GetAsBlock(inner), "Unexpected inner");
  return inner->GetPosition().y + inner->GetBaseline();
}