gecko-dev/layout/generic/nsHTMLContainerFrame.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * Version: NPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.1 (the "License"); you may not use this file except in
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 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is 
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or 
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#include "nsHTMLContainerFrame.h"
#include "nsIRenderingContext.h"
#include "nsIPresContext.h"
#include "nsIPresShell.h"
#include "nsIStyleContext.h"
#include "nsStyleConsts.h"
#include "nsCSSRendering.h"
#include "nsIContent.h"
#include "nsLayoutAtoms.h"
#include "nsCSSAnonBoxes.h"
#include "nsIWidget.h"
#include "nsILinkHandler.h"
#include "nsHTMLValue.h"
#include "nsGUIEvent.h"
#include "nsIDocument.h"
#include "nsIURL.h"
#include "nsPlaceholderFrame.h"
#include "nsIHTMLContent.h"
#include "nsHTMLParts.h"
#include "nsIView.h"
#include "nsIViewManager.h"
#include "nsViewsCID.h"
#include "nsIDOMEvent.h"
#include "nsIScrollableView.h"
#include "nsWidgetsCID.h"
#include "nsIStyleSet.h"
#include "nsCOMPtr.h"
#include "nsIDeviceContext.h"
#include "nsIFontMetrics.h"
#include "nsReflowPath.h"

static NS_DEFINE_CID(kCChildCID, NS_CHILD_CID);

NS_IMETHODIMP
nsHTMLContainerFrame::Paint(nsIPresContext*      aPresContext,
                            nsIRenderingContext& aRenderingContext,
                            const nsRect&        aDirtyRect,
                            nsFramePaintLayer    aWhichLayer,
                            PRUint32             aFlags)
{
  if (NS_FRAME_IS_UNFLOWABLE & mState) {
    return NS_OK;
  }

  // Paint inline element backgrounds in the foreground layer, but
  // others in the background (bug 36710).  (nsInlineFrame::Paint does
  // this differently.)
  if (NS_FRAME_PAINT_LAYER_BACKGROUND == aWhichLayer) {
    PaintSelf(aPresContext, aRenderingContext, aDirtyRect, aFlags);
  }
    
  PaintChildren(aPresContext, aRenderingContext, aDirtyRect, aWhichLayer, aFlags);
  return NS_OK;
}

void
nsHTMLContainerFrame::PaintSelf(nsIPresContext*      aPresContext,
                                nsIRenderingContext& aRenderingContext,
                                const nsRect&        aDirtyRect,
                                PRUint32             aFlags)
{
  // The visibility check belongs here since child elements have the
  // opportunity to override the visibility property and display even if
  // their parent is hidden.

  PRBool isVisible;
  if (NS_FAILED(IsVisibleForPainting(aPresContext, aRenderingContext,
                                     PR_TRUE, &isVisible)) ||
      !isVisible ||
      mRect.width == 0 || mRect.height == 0) {
    return;
  }

  // Paint our background and border
  PRIntn skipSides = GetSkipSides();
  const nsStyleBorder* border;
  ::GetStyleData(mStyleContext, &border);
  const nsStylePadding* padding;
  ::GetStyleData(mStyleContext, &padding);
  const nsStyleOutline* outline;
  ::GetStyleData(mStyleContext, &outline);

  nsRect rect(0, 0, mRect.width, mRect.height);
  nsCSSRendering::PaintBackground(aPresContext, aRenderingContext, this,
                                  aDirtyRect, rect, *border, *padding,
                                  0, 0);
  nsCSSRendering::PaintBorder(aPresContext, aRenderingContext, this,
                              aDirtyRect, rect, *border, mStyleContext,
                              skipSides);
  nsCSSRendering::PaintOutline(aPresContext, aRenderingContext, this,
                               aDirtyRect, rect, *border, *outline,
                               mStyleContext, 0);
}

void
nsHTMLContainerFrame::PaintDecorationsAndChildren(
                                       nsIPresContext*      aPresContext,
                                       nsIRenderingContext& aRenderingContext,
                                       const nsRect&        aDirtyRect,
                                       nsFramePaintLayer    aWhichLayer,
                                       PRBool               aIsBlock,
                                       PRUint32             aFlags)
{
  // Do standards mode painting of 'text-decoration's: under+overline
  // behind children, line-through in front.  For Quirks mode, see
  // nsTextFrame::PaintTextDecorations.  (See bug 1777.)
  nscolor underColor, overColor, strikeColor;
  PRUint8 decorations = NS_STYLE_TEXT_DECORATION_NONE;
  nsCOMPtr<nsIFontMetrics> fm;
  nsCompatibility mode;
  aPresContext->GetCompatibilityMode(&mode);

  if (eCompatibility_NavQuirks != mode && 
      NS_FRAME_PAINT_LAYER_FOREGROUND == aWhichLayer) {
    GetTextDecorations(aPresContext, aIsBlock, decorations, underColor, 
                       overColor, strikeColor);
    if (decorations & (NS_STYLE_TEXT_DECORATION_UNDERLINE |
                       NS_STYLE_TEXT_DECORATION_OVERLINE |
                       NS_STYLE_TEXT_DECORATION_LINE_THROUGH)) {
      const nsStyleFont* font;
      ::GetStyleData(this, &font);
      NS_ASSERTION(font->mFont.decorations == NS_FONT_DECORATION_NONE,
                   "fonts on style structs shouldn't have decorations");

      // XXX This is relatively slow and shouldn't need to be used here.
      nsCOMPtr<nsIDeviceContext> deviceContext;
      aRenderingContext.GetDeviceContext(*getter_AddRefs(deviceContext));
      nsCOMPtr<nsIFontMetrics> normalFont;
      deviceContext->GetMetricsFor(font->mFont, *getter_AddRefs(fm));
    }
    if (decorations & NS_STYLE_TEXT_DECORATION_UNDERLINE) {
      PaintTextDecorations(aRenderingContext, fm,
                           NS_STYLE_TEXT_DECORATION_UNDERLINE, underColor);
    }
    if (decorations & NS_STYLE_TEXT_DECORATION_OVERLINE) {
      PaintTextDecorations(aRenderingContext, fm,
                           NS_STYLE_TEXT_DECORATION_OVERLINE, overColor);
    }
  }

  PaintChildren(aPresContext, aRenderingContext, aDirtyRect,
                aWhichLayer, aFlags);

  if (decorations & NS_STYLE_TEXT_DECORATION_LINE_THROUGH) {
    PaintTextDecorations(aRenderingContext, fm,
                         NS_STYLE_TEXT_DECORATION_LINE_THROUGH, strikeColor);
  }
}

static PRBool 
HasTextFrameDescendant(nsIPresContext* aPresContext, nsIFrame* parent);

void
nsHTMLContainerFrame::GetTextDecorations(nsIPresContext* aPresContext, 
                                         PRBool aIsBlock,
                                         PRUint8& aDecorations,
                                         nscolor& aUnderColor, 
                                         nscolor& aOverColor, 
                                         nscolor& aStrikeColor)
{
  aDecorations = NS_STYLE_TEXT_DECORATION_NONE;
  if (!mStyleContext->HasTextDecorations()) {
    // This is a neccessary, but not sufficient, condition for text
    // decorations.
    return; 
  }

  // A mask of all possible decorations.
  PRUint8 decorMask = NS_STYLE_TEXT_DECORATION_UNDERLINE |
                      NS_STYLE_TEXT_DECORATION_OVERLINE |
                      NS_STYLE_TEXT_DECORATION_LINE_THROUGH; 

  const nsStyleTextReset* styleText;
  ::GetStyleData(mStyleContext, &styleText);

  if (!aIsBlock) {
    aDecorations = styleText->mTextDecoration  & decorMask;
    if (aDecorations) {
      const nsStyleColor* styleColor;
      ::GetStyleData(mStyleContext, &styleColor);
      aUnderColor = styleColor->mColor;
      aOverColor = styleColor->mColor;
      aStrikeColor = styleColor->mColor;
    }
  }
  else {
    // walk tree
    for (nsIFrame *frame = this; frame && decorMask; frame->GetParent(&frame)) {
      // find text-decorations.  "Inherit" from parent *block* frames

      nsCOMPtr<nsIStyleContext> styleContext;
      frame->GetStyleContext(getter_AddRefs(styleContext));
      const nsStyleDisplay* styleDisplay;
      ::GetStyleData(styleContext.get(), &styleDisplay);
      if (!styleDisplay->IsBlockLevel()) {
        // If an inline frame is discovered while walking up the tree,
        // we should stop according to CSS3 draft. CSS2 is rather vague
        // about this.
        break;
      }

      ::GetStyleData(styleContext.get(), &styleText);
      PRUint8 decors = decorMask & styleText->mTextDecoration;
      if (decors) {
        // A *new* text-decoration is found.
        const nsStyleColor* styleColor;
        ::GetStyleData(styleContext.get(), &styleColor);

        if (NS_STYLE_TEXT_DECORATION_UNDERLINE & decors) {
          aUnderColor = styleColor->mColor;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_UNDERLINE;
          aDecorations |= NS_STYLE_TEXT_DECORATION_UNDERLINE;
        }
        if (NS_STYLE_TEXT_DECORATION_OVERLINE & decors) {
          aOverColor = styleColor->mColor;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_OVERLINE;
          aDecorations |= NS_STYLE_TEXT_DECORATION_OVERLINE;
        }
        if (NS_STYLE_TEXT_DECORATION_LINE_THROUGH & decors) {
          aStrikeColor = styleColor->mColor;
          decorMask &= ~NS_STYLE_TEXT_DECORATION_LINE_THROUGH;
          aDecorations |= NS_STYLE_TEXT_DECORATION_LINE_THROUGH;
        }
      }
    }
  }
  
  if (aDecorations) {
    // If this frame contains no text, we're required to ignore this property
    if (!HasTextFrameDescendant(aPresContext, this)) {
      aDecorations = NS_STYLE_TEXT_DECORATION_NONE;
    }
  }
}

static PRBool 
HasTextFrameDescendant(nsIPresContext* aPresContext, nsIFrame* aParent)
{
  nsIFrame* kid = nsnull;
  nsCOMPtr<nsIAtom> frameType;
    
  for (aParent->FirstChild(aPresContext, nsnull, &kid); kid; 
       kid->GetNextSibling(&kid))
  {
    kid->GetFrameType(getter_AddRefs(frameType));
    if (frameType == nsLayoutAtoms::textFrame) {
      // This is only a candidate. We need to determine if this text
      // frame is empty, as in containing only (non-pre) whitespace.
      // See bug 20163.
      nsCompatibility mode;
      aPresContext->GetCompatibilityMode(&mode);
      const nsStyleText* styleText; 
      ::GetStyleData(kid, &styleText);
      // XXXldb This is the wrong way to set |isPre|.
      PRBool isPre = NS_STYLE_WHITESPACE_PRE == styleText->mWhiteSpace ||
            NS_STYLE_WHITESPACE_MOZ_PRE_WRAP == styleText->mWhiteSpace;
      PRBool isEmpty;
      kid->IsEmpty(mode, isPre, &isEmpty);
      if (!isEmpty) {
        return PR_TRUE;
      }
    }
    if (HasTextFrameDescendant(aPresContext, kid)) {
      return PR_TRUE;
    }
  }
  return PR_FALSE;
}

/*virtual*/ void
nsHTMLContainerFrame::PaintTextDecorationLines(
                   nsIRenderingContext& aRenderingContext, 
                   nscolor aColor, 
                   nscoord aOffset, 
                   nscoord aAscent, 
                   nscoord aSize) 
{
  nsMargin bp;
  CalcBorderPadding(bp);
  aRenderingContext.SetColor(aColor);
  nscoord innerWidth = mRect.width - bp.left - bp.right;
  aRenderingContext.FillRect(bp.left, 
                             bp.top + aAscent - aOffset, innerWidth, aSize);
}

void
nsHTMLContainerFrame::PaintTextDecorations(
                            nsIRenderingContext& aRenderingContext,
                            nsIFontMetrics* aFontMetrics,
                            PRUint8 aDecoration,
                            nscolor aColor)
{
  nscoord ascent, offset, size;
  aFontMetrics->GetMaxAscent(ascent);
  if (aDecoration & 
      (NS_STYLE_TEXT_DECORATION_UNDERLINE 
       | NS_STYLE_TEXT_DECORATION_OVERLINE)) {
    aFontMetrics->GetUnderline(offset, size);
    if (NS_STYLE_TEXT_DECORATION_UNDERLINE & aDecoration) {
      PaintTextDecorationLines(aRenderingContext, aColor, offset, ascent, size);
    }
    else if (NS_STYLE_TEXT_DECORATION_OVERLINE & aDecoration) {
      PaintTextDecorationLines(aRenderingContext, aColor, ascent, ascent, size);
    }
  }
  else if (NS_STYLE_TEXT_DECORATION_LINE_THROUGH & aDecoration) {
    aFontMetrics->GetStrikeout(offset, size);
    PaintTextDecorationLines(aRenderingContext, aColor, offset, ascent, size);
  }
}

/**
 * Create a next-in-flow for aFrame. Will return the newly created
 * frame in aNextInFlowResult <b>if and only if</b> a new frame is
 * created; otherwise nsnull is returned in aNextInFlowResult.
 */
nsresult
nsHTMLContainerFrame::CreateNextInFlow(nsIPresContext* aPresContext,
                                       nsIFrame*       aOuterFrame,
                                       nsIFrame*       aFrame,
                                       nsIFrame*&      aNextInFlowResult)
{
  aNextInFlowResult = nsnull;

  nsIFrame* nextInFlow;
  aFrame->GetNextInFlow(&nextInFlow);
  if (nsnull == nextInFlow) {
    // Create a continuation frame for the child frame and insert it
    // into our lines child list.
    nsIFrame* nextFrame;
    aFrame->GetNextSibling(&nextFrame);

    nsIPresShell* presShell;
    nsIStyleSet*  styleSet;
    aPresContext->GetShell(&presShell);
    presShell->GetStyleSet(&styleSet);
    NS_RELEASE(presShell);
    styleSet->CreateContinuingFrame(aPresContext, aFrame, aOuterFrame, &nextInFlow);
    NS_RELEASE(styleSet);

    if (nsnull == nextInFlow) {
      return NS_ERROR_OUT_OF_MEMORY;
    }
    aFrame->SetNextSibling(nextInFlow);
    nextInFlow->SetNextSibling(nextFrame);

    NS_FRAME_LOG(NS_FRAME_TRACE_NEW_FRAMES,
       ("nsHTMLContainerFrame::MaybeCreateNextInFlow: frame=%p nextInFlow=%p",
        aFrame, nextInFlow));

    aNextInFlowResult = nextInFlow;
  }
  return NS_OK;
}

static nsresult
ReparentFrameViewTo(nsIPresContext* aPresContext,
                    nsIFrame*       aFrame,
                    nsIViewManager* aViewManager,
                    nsIView*        aNewParentView,
                    nsIView*        aOldParentView)
{
  nsIView*  view;

  // XXX What to do about placeholder views for "position: fixed" elements?
  // They should be reparented too.

  // Does aFrame have a view?
  aFrame->GetView(aPresContext, &view);
  if (view) {
    // Verify that the current parent view is what we think it is
    //nsIView*  parentView;
    //NS_ASSERTION(parentView == aOldParentView, "unexpected parent view");

    aViewManager->RemoveChild(view);
    
    // The view will remember the Z-order and other attributes that have been set on it.
    // XXX Pretend this view is last of the parent's views in document order
    aViewManager->InsertChild(aNewParentView, view, nsnull, PR_TRUE);
  } else {
    // Iterate the child frames, and check each child frame to see if it has
    // a view
    nsIFrame* childFrame;
    aFrame->FirstChild(aPresContext, nsnull, &childFrame);
    while (childFrame) {
      ReparentFrameViewTo(aPresContext, childFrame, aViewManager, aNewParentView, aOldParentView);
      childFrame->GetNextSibling(&childFrame);
    }

    // Also check the overflow-list
    aFrame->FirstChild(aPresContext, nsLayoutAtoms::overflowList, &childFrame);
    while (childFrame) {
      ReparentFrameViewTo(aPresContext, childFrame, aViewManager, aNewParentView, aOldParentView);
      childFrame->GetNextSibling(&childFrame);
    }

      // Also check the floater-list
    aFrame->FirstChild(aPresContext, nsLayoutAtoms::floaterList, &childFrame);
    while (childFrame) {
      ReparentFrameViewTo(aPresContext, childFrame, aViewManager, aNewParentView, aOldParentView);
      childFrame->GetNextSibling(&childFrame);
    }

  }

  return NS_OK;
}

// Helper function that returns the nearest view to this frame. Checks
// this frame, its parent frame, its parent frame, ...
static nsIView*
GetClosestViewFor(nsIPresContext* aPresContext, nsIFrame* aFrame)
{
  NS_PRECONDITION(aFrame, "null frame pointer");
  nsIView*  view;

  do {
    aFrame->GetView(aPresContext, &view);
    if (view) {
      break;
    }
    aFrame->GetParent(&aFrame);
  } while (aFrame);

  NS_POSTCONDITION(view, "no containing view");
  return view;
}

nsresult
nsHTMLContainerFrame::ReparentFrameView(nsIPresContext* aPresContext,
                                        nsIFrame*       aChildFrame,
                                        nsIFrame*       aOldParentFrame,
                                        nsIFrame*       aNewParentFrame)
{
  NS_PRECONDITION(aChildFrame, "null child frame pointer");
  NS_PRECONDITION(aOldParentFrame, "null old parent frame pointer");
  NS_PRECONDITION(aNewParentFrame, "null new parent frame pointer");
  NS_PRECONDITION(aOldParentFrame != aNewParentFrame, "same old and new parent frame");

  nsIView*  childView;
  nsIView*  oldParentView;
  nsIView*  newParentView;
  
  // This code is called often and we need it to be as fast as possible, so
  // see if we can trivially detect that no work needs to be done
  aChildFrame->GetView(aPresContext, &childView);
  if (!childView) {
    // Child frame doesn't have a view. See if it has any child frames
    nsIFrame* firstChild;
    aChildFrame->FirstChild(aPresContext, nsnull, &firstChild);
    if (!firstChild) {
      return NS_OK;
    }
  }

  // See if either the old parent frame or the new parent frame have a view
  aOldParentFrame->GetView(aPresContext, &oldParentView);
  aNewParentFrame->GetView(aPresContext, &newParentView);

  if (!oldParentView && !newParentView) {
    // Walk up both the old parent frame and the new parent frame nodes
    // stopping when we either find a common parent or views for one
    // or both of the frames.
    //
    // This works well in the common case where we push/pull and the old parent
    // frame and the new parent frame are part of the same flow. They will
    // typically be the same distance (height wise) from the
    do {
      aOldParentFrame->GetParent(&aOldParentFrame);
      aNewParentFrame->GetParent(&aNewParentFrame);
      
      // We should never walk all the way to the root frame without finding
      // a view
      NS_ASSERTION(aOldParentFrame && aNewParentFrame, "didn't find view");

      // See if we reached a common parent
      if (aOldParentFrame == aNewParentFrame) {
        break;
      }

      // Get the views
      aOldParentFrame->GetView(aPresContext, &oldParentView);
      aNewParentFrame->GetView(aPresContext, &newParentView);
    } while (!(oldParentView || newParentView));
  }


  // See if we found a common parent frame
  if (aOldParentFrame == aNewParentFrame) {
    // We found a common parent and there are no views between the old parent
    // and the common parent or the new parent frame and the common parent.
    // Because neither the old parent frame nor the new parent frame have views,
    // then any child views don't need reparenting
    return NS_OK;
  }

  // We found views for one or both of the parent frames before we found a
  // common parent
  NS_ASSERTION(oldParentView || newParentView, "internal error");
  if (!oldParentView) {
    oldParentView = GetClosestViewFor(aPresContext, aOldParentFrame);
  }
  if (!newParentView) {
    newParentView = GetClosestViewFor(aPresContext, aNewParentFrame);
  }
  
  // See if the old parent frame and the new parent frame are in the
  // same view sub-hierarchy. If they are then we don't have to do
  // anything
  if (oldParentView != newParentView) {
    nsCOMPtr<nsIViewManager>  viewManager;
    oldParentView->GetViewManager(*getter_AddRefs(viewManager));

    // They're not so we need to reparent any child views
    return ReparentFrameViewTo(aPresContext, aChildFrame, viewManager, newParentView,
                               oldParentView);
  }

  return NS_OK;
}

nsresult
nsHTMLContainerFrame::ReparentFrameViewList(nsIPresContext* aPresContext,
                                            nsIFrame*       aChildFrameList,
                                            nsIFrame*       aOldParentFrame,
                                            nsIFrame*       aNewParentFrame)
{
  NS_PRECONDITION(aChildFrameList, "null child frame list");
  NS_PRECONDITION(aOldParentFrame, "null old parent frame pointer");
  NS_PRECONDITION(aNewParentFrame, "null new parent frame pointer");
  NS_PRECONDITION(aOldParentFrame != aNewParentFrame, "same old and new parent frame");

  nsIView*  oldParentView;
  nsIView*  newParentView;
  
  // See if either the old parent frame or the new parent frame have a view
  aOldParentFrame->GetView(aPresContext, &oldParentView);
  aNewParentFrame->GetView(aPresContext, &newParentView);

  if (!oldParentView && !newParentView) {
    // Walk up both the old parent frame and the new parent frame nodes
    // stopping when we either find a common parent or views for one
    // or both of the frames.
    //
    // This works well in the common case where we push/pull and the old parent
    // frame and the new parent frame are part of the same flow. They will
    // typically be the same distance (height wise) from the
    do {
      aOldParentFrame->GetParent(&aOldParentFrame);
      aNewParentFrame->GetParent(&aNewParentFrame);
      
      // We should never walk all the way to the root frame without finding
      // a view
      NS_ASSERTION(aOldParentFrame && aNewParentFrame, "didn't find view");

      // See if we reached a common parent
      if (aOldParentFrame == aNewParentFrame) {
        break;
      }

      // Get the views
      aOldParentFrame->GetView(aPresContext, &oldParentView);
      aNewParentFrame->GetView(aPresContext, &newParentView);
    } while (!(oldParentView || newParentView));
  }


  // See if we found a common parent frame
  if (aOldParentFrame == aNewParentFrame) {
    // We found a common parent and there are no views between the old parent
    // and the common parent or the new parent frame and the common parent.
    // Because neither the old parent frame nor the new parent frame have views,
    // then any child views don't need reparenting
    return NS_OK;
  }

  // We found views for one or both of the parent frames before we found a
  // common parent
  NS_ASSERTION(oldParentView || newParentView, "internal error");
  if (!oldParentView) {
    oldParentView = GetClosestViewFor(aPresContext, aOldParentFrame);
  }
  if (!newParentView) {
    newParentView = GetClosestViewFor(aPresContext, aNewParentFrame);
  }
  
  // See if the old parent frame and the new parent frame are in the
  // same view sub-hierarchy. If they are then we don't have to do
  // anything
  if (oldParentView != newParentView) {
    nsCOMPtr<nsIViewManager>  viewManager;
    oldParentView->GetViewManager(*getter_AddRefs(viewManager));

    // They're not so we need to reparent any child views
    for (nsIFrame* f = aChildFrameList; f; f->GetNextSibling(&f)) {
      ReparentFrameViewTo(aPresContext, f, viewManager, newParentView,
                          oldParentView);
    }
  }

  return NS_OK;
}

nsresult
nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
                                         nsIFrame* aFrame,
                                         nsIStyleContext* aStyleContext,
                                         nsIFrame* aContentParentFrame,
                                         PRBool aForce)
{
  nsIView* view;
  aFrame->GetView(aPresContext, &view);
  if (nsnull != view) {
    return NS_OK;
  }

  // If we don't yet have a view, see if we need a view
  if (!(aForce || FrameNeedsView(aPresContext, aFrame, aStyleContext))) {
    // don't need a view
    return NS_OK;
  }

  // Create a view
  nsIFrame* parent = nsnull;
  aFrame->GetParentWithView(aPresContext, &parent);
  NS_ASSERTION(parent, "GetParentWithView failed");

  nsIView* parentView = nsnull;
  parent->GetView(aPresContext, &parentView);
  NS_ASSERTION(parentView, "no parent with view");

  // Create a view
  static NS_DEFINE_CID(kViewCID, NS_VIEW_CID);
  nsresult result = CallCreateInstance(kViewCID, &view);
  if (NS_FAILED(result)) {
    return result;
  }
    
  nsCOMPtr<nsIViewManager> viewManager;
  parentView->GetViewManager(*getter_AddRefs(viewManager));
  NS_ASSERTION(nsnull != viewManager, "null view manager");
    
  // Initialize the view
  nsRect bounds;
  aFrame->GetRect(bounds);
  view->Init(viewManager, bounds, parentView);

  SyncFrameViewProperties(aPresContext, aFrame, aStyleContext, view);

  // Insert the view into the view hierarchy. If the parent view is a
  // scrolling view we need to do this differently
  nsIScrollableView*  scrollingView;
  if (NS_SUCCEEDED(CallQueryInterface(parentView, &scrollingView))) {
    scrollingView->SetScrolledView(view);
  } else {
    // XXX Drop it at the end of the document order until we can do better
    viewManager->InsertChild(parentView, view, nsnull, PR_TRUE);

    if (nsnull != aContentParentFrame) {
      // If, for some reason, GetView below fails to initialize zParentView,
      // then ensure that we completely bypass InsertZPlaceholder below.
      // The effect will be as if we never knew about aContentParentFrame
      // in the first place, so at least this code won't be doing any damage.
      nsIView* zParentView = parentView;
      
      aContentParentFrame->GetView(aPresContext, &zParentView);
      
      if (nsnull == zParentView) {
        nsIFrame* zParentFrame = nsnull;
        
        aContentParentFrame->GetParentWithView(aPresContext, &zParentFrame);
        NS_ASSERTION(zParentFrame, "GetParentWithView failed");
        zParentFrame->GetView(aPresContext, &zParentView);
        NS_ASSERTION(zParentView, "no parent with view");
      }
      
      if (zParentView != parentView) {
        viewManager->InsertZPlaceholder(zParentView, view, nsnull, PR_TRUE);
      }
    }
  }

  // XXX If it's fixed positioned, then create a widget so it floats
  // above the scrolling area
  const nsStyleDisplay* display;
  ::GetStyleData(aStyleContext, &display);
  if (NS_STYLE_POSITION_FIXED == display->mPosition) {
    view->CreateWidget(kCChildCID);
  }

  // Remember our view
  aFrame->SetView(aPresContext, view);

  NS_FRAME_LOG(NS_FRAME_TRACE_CALLS,
               ("nsHTMLContainerFrame::CreateViewForFrame: frame=%p view=%p",
                aFrame));
  return NS_OK;
}

void
nsHTMLContainerFrame::CheckInvalidateBorder(nsIPresContext* aPresContext,
                                            nsHTMLReflowMetrics& aDesiredSize,
                                            const nsHTMLReflowState& aReflowState)
{
  // XXX This method ought to deal with padding as well
  // If this is a style change reflow targeted at this frame, we must repaint
  // everything (well, we really just have to repaint the borders but we're
  // a bunch of lazybones).
  if (aReflowState.reason == eReflowReason_Incremental) {
    nsHTMLReflowCommand *command = aReflowState.path->mReflowCommand;
    if (command) {
      nsReflowType type;
      command->GetType(type);
      if (type == eReflowType_StyleChanged) {

#ifdef NOISY_BLOCK_INVALIDATE
        printf("%p invalidate 1 (%d, %d, %d, %d)\n",
               this, 0, 0, mRect.width, mRect.height);
#endif

        // Lots of things could have changed so damage our entire bounds
        nsRect damageRect(0, 0, mRect.width, mRect.height);
        if (!damageRect.IsEmpty()) {
          Invalidate(aPresContext,damageRect);
        }

        return;
      }
    }
  }

  // If we changed size, we must invalidate the parts of us that have changed
  // to make the border show up.
  if ((aReflowState.reason == eReflowReason_Incremental ||
       aReflowState.reason == eReflowReason_Dirty)) {
    nsMargin border = aReflowState.mComputedBorderPadding -
                      aReflowState.mComputedPadding;

    // See if our width changed
    if ((aDesiredSize.width != mRect.width) && (border.right > 0)) {
      nsRect damageRect;

      if (aDesiredSize.width < mRect.width) {
        // Our new width is smaller, so we need to make sure that
        // we paint our border in its new position
        damageRect.x = aDesiredSize.width - border.right;
        damageRect.width = border.right;
        damageRect.y = 0;
        damageRect.height = aDesiredSize.height;
      } else {
        // Our new width is larger, so we need to erase our border in its
        // old position
        damageRect.x = mRect.width - border.right;
        damageRect.width = border.right;
        damageRect.y = 0;
        damageRect.height = mRect.height;
      }

#ifdef NOISY_BLOCK_INVALIDATE
      printf("%p invalidate 2 (%d, %d, %d, %d)\n",
             this, damageRect.x, damageRect.y, damageRect.width, damageRect.height);
#endif
      if (!damageRect.IsEmpty()) {
        Invalidate(aPresContext, damageRect);
      }
    }

    // See if our height changed
    if ((aDesiredSize.height != mRect.height) && (border.bottom > 0)) {
      nsRect  damageRect;

      if (aDesiredSize.height < mRect.height) {
        // Our new height is smaller, so we need to make sure that
        // we paint our border in its new position
        damageRect.x = 0;
        damageRect.width = aDesiredSize.width;
        damageRect.y = aDesiredSize.height - border.bottom;
        damageRect.height = border.bottom;

      } else {
        // Our new height is larger, so we need to erase our border in its
        // old position
        damageRect.x = 0;
        damageRect.width = mRect.width;
        damageRect.y = mRect.height - border.bottom;
        damageRect.height = border.bottom;
      }
#ifdef NOISY_BLOCK_INVALIDATE
      printf("%p invalidate 3 (%d, %d, %d, %d)\n",
             this, damageRect.x, damageRect.y, damageRect.width, damageRect.height);
#endif
      if (!damageRect.IsEmpty()) {
        Invalidate(aPresContext, damageRect);
      }
    }
  }
}