gecko-dev/layout/base/nsFrameTraversal.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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#include "nsCOMPtr.h"
#include "nsGkAtoms.h"

#include "nsFrameTraversal.h"
#include "nsFrameList.h"
#include "nsPlaceholderFrame.h"


class nsFrameIterator: public nsIBidirectionalEnumerator
{
public:
  NS_DECL_ISUPPORTS

  NS_IMETHOD First();

  NS_IMETHOD Last();
  
  NS_IMETHOD Next();

  NS_IMETHOD Prev();

  NS_IMETHOD CurrentItem(nsISupports **aItem);

  NS_IMETHOD IsDone();//what does this mean??off edge? yes

  nsFrameIterator(nsPresContext* aPresContext, nsIFrame *aStart,
                  nsIteratorType aType, PRBool aLockScroll, PRBool aFollowOOFs);

protected:
  void      setCurrent(nsIFrame *aFrame){mCurrent = aFrame;}
  nsIFrame *getCurrent(){return mCurrent;}
  void      setStart(nsIFrame *aFrame){mStart = aFrame;}
  nsIFrame *getStart(){return mStart;}
  nsIFrame *getLast(){return mLast;}
  void      setLast(nsIFrame *aFrame){mLast = aFrame;}
  PRInt8    getOffEdge(){return mOffEdge;}
  void      setOffEdge(PRInt8 aOffEdge){mOffEdge = aOffEdge;}
  void      SetLockInScrollView(PRBool aLockScroll){mLockScroll = aLockScroll;}

  /*
   Our own versions of the standard frame tree navigation
   methods, which, if the iterator is following out-of-flows,
   apply the following rules for placeholder frames:
   
   - If a frame HAS a placeholder frame, getting its parent
   gets the placeholder's parent.
   
   - If a frame's first child or next/prev sibling IS a
   placeholder frame, then we instead return the real frame.
   
   - If a frame HAS a placeholder frame, getting its next/prev
   sibling gets the placeholder frame's next/prev sibling.
   
   These are all applied recursively to support multiple levels of
   placeholders.
   */  
  
  nsIFrame* GetParentFrame(nsIFrame* aFrame);
  // like GetParentFrame but returns null once a popup frame is reached
  nsIFrame* GetParentFrameNotPopup(nsIFrame* aFrame);

  nsIFrame* GetFirstChild(nsIFrame* aFrame);
  nsIFrame* GetLastChild(nsIFrame* aFrame);

  nsIFrame* GetNextSibling(nsIFrame* aFrame);
  nsIFrame* GetPrevSibling(nsIFrame* aFrame);

  /*
   These methods are overridden by the bidi visual iterator to have the
   semantics of "get first child in visual order", "get last child in visual
   order", "get next sibling in visual order" and "get previous sibling in visual
   order".
  */
  
  virtual nsIFrame* GetFirstChildInner(nsIFrame* aFrame);
  virtual nsIFrame* GetLastChildInner(nsIFrame* aFrame);  

  virtual nsIFrame* GetNextSiblingInner(nsIFrame* aFrame);
  virtual nsIFrame* GetPrevSiblingInner(nsIFrame* aFrame);

  nsIFrame* GetPlaceholderFrame(nsIFrame* aFrame);
  PRBool    IsPopupFrame(nsIFrame* aFrame);

  nsPresContext* mPresContext;
  PRPackedBool mLockScroll;
  PRPackedBool mFollowOOFs;
  nsIteratorType mType;

private:
  nsIFrame *mStart;
  nsIFrame *mCurrent;
  nsIFrame *mLast; //the last one that was in current;
  PRInt8    mOffEdge; //0= no -1 to far prev, 1 to far next;
};



// Bidi visual iterator
class nsVisualIterator: public nsFrameIterator
{
public:
  nsVisualIterator(nsPresContext* aPresContext, nsIFrame *aStart,
                   nsIteratorType aType, PRBool aLockScroll, PRBool aFollowOOFs) :
  nsFrameIterator(aPresContext, aStart, aType, aLockScroll, aFollowOOFs) {}

protected:
  nsIFrame* GetFirstChildInner(nsIFrame* aFrame);
  nsIFrame* GetLastChildInner(nsIFrame* aFrame);  
  
  nsIFrame* GetNextSiblingInner(nsIFrame* aFrame);
  nsIFrame* GetPrevSiblingInner(nsIFrame* aFrame);  
};

/************IMPLEMENTATIONS**************/

nsresult NS_CreateFrameTraversal(nsIFrameTraversal** aResult)
{
  NS_ENSURE_ARG_POINTER(aResult);
  *aResult = nsnull;

  nsCOMPtr<nsIFrameTraversal> t(new nsFrameTraversal());
  if (!t)
    return NS_ERROR_OUT_OF_MEMORY;

  *aResult = t;
  NS_ADDREF(*aResult);

  return NS_OK;
}

nsresult
NS_NewFrameTraversal(nsIBidirectionalEnumerator **aEnumerator,
                     nsPresContext* aPresContext,
                     nsIFrame *aStart,
                     nsIteratorType aType,
                     PRBool aVisual,
                     PRBool aLockInScrollView,
                     PRBool aFollowOOFs)
{
  if (!aEnumerator || !aStart)
    return NS_ERROR_NULL_POINTER;
  nsFrameIterator *trav;
  if (aVisual) {
    trav = new nsVisualIterator(aPresContext, aStart, aType,
                                aLockInScrollView, aFollowOOFs);
  } else {
    trav = new nsFrameIterator(aPresContext, aStart, aType,
                               aLockInScrollView, aFollowOOFs);
  }
  if (!trav)
    return NS_ERROR_OUT_OF_MEMORY;
  *aEnumerator = static_cast<nsIBidirectionalEnumerator*>(trav);
  NS_ADDREF(trav);
  return NS_OK;
}


nsFrameTraversal::nsFrameTraversal()
{
}

nsFrameTraversal::~nsFrameTraversal()
{
}

NS_IMPL_ISUPPORTS1(nsFrameTraversal,nsIFrameTraversal)

NS_IMETHODIMP 
 nsFrameTraversal::NewFrameTraversal(nsIBidirectionalEnumerator **aEnumerator,
                                     nsPresContext* aPresContext,
                                     nsIFrame *aStart,
                                     PRInt32 aType,
                                     PRBool aVisual,
                                     PRBool aLockInScrollView,
                                     PRBool aFollowOOFs)
{
  return NS_NewFrameTraversal(aEnumerator, aPresContext, aStart,
                              static_cast<nsIteratorType>(aType),
                              aVisual, aLockInScrollView, aFollowOOFs);  
}

// nsFrameIterator implementation

NS_IMPL_ISUPPORTS2(nsFrameIterator, nsIEnumerator, nsIBidirectionalEnumerator)

nsFrameIterator::nsFrameIterator(nsPresContext* aPresContext, nsIFrame *aStart,
                                 nsIteratorType aType, PRBool aLockInScrollView,
                                 PRBool aFollowOOFs)
{
  mOffEdge = 0;
  mPresContext = aPresContext;
  if (aFollowOOFs && aStart)
    aStart = nsPlaceholderFrame::GetRealFrameFor(aStart);
  setStart(aStart);
  setCurrent(aStart);
  setLast(aStart);
  mType = aType;
  SetLockInScrollView(aLockInScrollView);
  mFollowOOFs = aFollowOOFs;
}



NS_IMETHODIMP
nsFrameIterator::CurrentItem(nsISupports **aItem)
{
  if (!aItem)
    return NS_ERROR_NULL_POINTER;
  *aItem = mCurrent;
  if (mOffEdge)
    return NS_ENUMERATOR_FALSE;
  return NS_OK;
}



NS_IMETHODIMP
nsFrameIterator::IsDone()//what does this mean??off edge? yes
{
  if (mOffEdge != 0)
    return NS_OK;
  return NS_ENUMERATOR_FALSE;
}



NS_IMETHODIMP
nsFrameIterator::First()
{
  mCurrent = mStart;
  return NS_OK;
}

static PRBool
IsRootFrame(nsIFrame* aFrame)
{
  nsIAtom* atom = aFrame->GetType();
  return (atom == nsGkAtoms::canvasFrame) ||
         (atom == nsGkAtoms::rootFrame);
}

NS_IMETHODIMP
nsFrameIterator::Last()
{
  nsIFrame* result;
  nsIFrame* parent = getCurrent();
  // If the current frame is a popup, don't move farther up the tree.
  // Otherwise, get the nearest root frame or popup.
  if (parent->GetType() != nsGkAtoms::menuPopupFrame) {
    while (!IsRootFrame(parent) && (result = GetParentFrameNotPopup(parent)))
      parent = result;
  }

  while ((result = GetLastChild(parent))) {
    parent = result;
  }
  
  setCurrent(parent);
  if (!parent)
    setOffEdge(1);
  return NS_OK;
}

NS_IMETHODIMP
nsFrameIterator::Next()
{
  // recursive-oid method to get next frame
  nsIFrame *result = nsnull;
  nsIFrame *parent = getCurrent();
  if (!parent)
    parent = getLast();

  if (mType == eLeaf) {
    // Drill down to first leaf
    while ((result = GetFirstChild(parent))) {
      parent = result;
    }
  } else if (mType == ePreOrder) {
    result = GetFirstChild(parent);
    if (result)
      parent = result;
  }

  if (parent != getCurrent()) {
    result = parent;
  } else {
    while (parent) {
      result = GetNextSibling(parent);
      if (result) {
        if (mType != ePreOrder) {
          parent = result;
          while ((result = GetFirstChild(parent))) {
            parent = result;
          }
          result = parent;
        }
        break;
      }
      else {
        result = GetParentFrameNotPopup(parent);
        if (!result || IsRootFrame(result) ||
            (mLockScroll && result->GetType() == nsGkAtoms::scrollFrame)) {
          result = nsnull;
          break;
        }
        if (mType == ePostOrder)
          break;
        parent = result;
      }
    }
  }

  setCurrent(result);
  if (!result) {
    setOffEdge(1);
    setLast(parent);
  }
  return NS_OK;
}

NS_IMETHODIMP
nsFrameIterator::Prev()
{
  // recursive-oid method to get prev frame
  nsIFrame *result = nsnull;
  nsIFrame *parent = getCurrent();
  if (!parent)
    parent = getLast();

  if (mType == eLeaf) {
    // Drill down to last leaf
    while ((result = GetLastChild(parent))) {
      parent = result;
    }
  } else if (mType == ePostOrder) {
    result = GetLastChild(parent);
    if (result)
      parent = result;
  }
  
  if (parent != getCurrent()) {
    result = parent;
  } else {
    while (parent) {
      result = GetPrevSibling(parent);
      if (result) {
        if (mType != ePostOrder) {
          parent = result;
          while ((result = GetLastChild(parent))) {
            parent = result;
          }
          result = parent;
        }
        break;
      } else {
        result = GetParentFrameNotPopup(parent);
        if (!result || IsRootFrame(result) ||
            (mLockScroll && result->GetType() == nsGkAtoms::scrollFrame)) {
          result = nsnull;
          break;
        }
        if (mType == ePreOrder)
          break;
        parent = result;
      }
    }
  }

  setCurrent(result);
  if (!result) {
    setOffEdge(-1);
    setLast(parent);
  }
  return NS_OK;
}

nsIFrame*
nsFrameIterator::GetParentFrame(nsIFrame* aFrame)
{
  if (mFollowOOFs)
    aFrame = GetPlaceholderFrame(aFrame);
  if (aFrame)
    return aFrame->GetParent();
  
  return nsnull;
}

nsIFrame*
nsFrameIterator::GetParentFrameNotPopup(nsIFrame* aFrame)
{
  if (mFollowOOFs)
    aFrame = GetPlaceholderFrame(aFrame);
  if (aFrame) {
    nsIFrame* parent = aFrame->GetParent();
    if (!IsPopupFrame(parent))
      return parent;
  }
    
  return nsnull;
}

nsIFrame*
nsFrameIterator::GetFirstChild(nsIFrame* aFrame)
{
  nsIFrame* result = GetFirstChildInner(aFrame);
  if (result && mFollowOOFs) {
    result = nsPlaceholderFrame::GetRealFrameFor(result);
    
    if (IsPopupFrame(result))
      result = GetNextSibling(result);
  }
  return result;
}

nsIFrame*
nsFrameIterator::GetLastChild(nsIFrame* aFrame)
{
  nsIFrame* result = GetLastChildInner(aFrame);
  if (result && mFollowOOFs) {
    result = nsPlaceholderFrame::GetRealFrameFor(result);
    
    if (IsPopupFrame(result))
      result = GetPrevSibling(result);
  }
  return result;
}

nsIFrame*
nsFrameIterator::GetNextSibling(nsIFrame* aFrame)
{
  nsIFrame* result = nsnull;
  if (mFollowOOFs)
    aFrame = GetPlaceholderFrame(aFrame);
  if (aFrame) {
    result = GetNextSiblingInner(aFrame);
    if (result && mFollowOOFs)
      result = nsPlaceholderFrame::GetRealFrameFor(result);
  }

  if (mFollowOOFs && IsPopupFrame(result))
    result = GetNextSibling(result);

  return result;
}

nsIFrame*
nsFrameIterator::GetPrevSibling(nsIFrame* aFrame)
{
  nsIFrame* result = nsnull;
  if (mFollowOOFs)
    aFrame = GetPlaceholderFrame(aFrame);
  if (aFrame) {
    result = GetPrevSiblingInner(aFrame);
    if (result && mFollowOOFs)
      result = nsPlaceholderFrame::GetRealFrameFor(result);
  }

  if (mFollowOOFs && IsPopupFrame(result))
    result = GetPrevSibling(result);

  return result;
}

nsIFrame*
nsFrameIterator::GetFirstChildInner(nsIFrame* aFrame) {
  return aFrame->GetFirstChild(nsnull);
}

nsIFrame*
nsFrameIterator::GetLastChildInner(nsIFrame* aFrame) {
  nsIFrame* child = aFrame->GetFirstChild(nsnull);
  if (!child)
    return nsnull;
  nsFrameList list(child);
  return list.LastChild();
}

nsIFrame*
nsFrameIterator::GetNextSiblingInner(nsIFrame* aFrame) {
  return aFrame->GetNextSibling();
}

nsIFrame*
nsFrameIterator::GetPrevSiblingInner(nsIFrame* aFrame) {
  nsIFrame* parent = GetParentFrame(aFrame);
  if (!parent)
    return nsnull;
  nsFrameList list(parent->GetFirstChild(nsnull));
  return list.GetPrevSiblingFor(aFrame);
}


nsIFrame*
nsFrameIterator::GetPlaceholderFrame(nsIFrame* aFrame)
{
  nsIFrame* result = aFrame;
  nsIPresShell *presShell = mPresContext->GetPresShell();
  if (presShell) {
    nsIFrame* placeholder = 0;
    presShell->GetPlaceholderFrameFor(aFrame, &placeholder);
    if (placeholder)
      result = placeholder;
  }

  if (result != aFrame)
    result = GetPlaceholderFrame(result);

  return result;
}

PRBool
nsFrameIterator::IsPopupFrame(nsIFrame* aFrame)
{
  return (aFrame &&
          aFrame->GetStyleDisplay()->mDisplay == NS_STYLE_DISPLAY_POPUP);
}

// nsVisualIterator implementation

nsIFrame*
nsVisualIterator::GetFirstChildInner(nsIFrame* aFrame) {
  nsIFrame* child = aFrame->GetFirstChild(nsnull);
  if (!child)
    return nsnull;
  nsFrameList list(child);
  return list.GetNextVisualFor(nsnull);
}

nsIFrame*
nsVisualIterator::GetLastChildInner(nsIFrame* aFrame) {
  nsIFrame* child = aFrame->GetFirstChild(nsnull);
  if (!child)
    return nsnull;
  nsFrameList list(child);
  return list.GetPrevVisualFor(nsnull);
}

nsIFrame*
nsVisualIterator::GetNextSiblingInner(nsIFrame* aFrame) {
  nsIFrame* parent = GetParentFrame(aFrame);
  if (!parent)
    return nsnull;
  nsFrameList list(parent->GetFirstChild(nsnull));
  return list.GetNextVisualFor(aFrame);
}

nsIFrame*
nsVisualIterator::GetPrevSiblingInner(nsIFrame* aFrame) {
  nsIFrame* parent = GetParentFrame(aFrame);
  if (!parent)
    return nsnull;
  nsFrameList list(parent->GetFirstChild(nsnull));
  return list.GetPrevVisualFor(aFrame);
}