gecko-dev/layout/base/public/nsIFrameTraversal.h

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#ifndef NSIFRAMETRAVERSAL_H
#define NSIFRAMETRAVERSAL_H

#include "nsISupports.h"
#include "nsIEnumerator.h"
#include "nsIFrame.h"

/* Brief explanation of frame traversal types:
 *
 * LEAF:
 *  Iterate over only the leaf frames in the tree, in depth-first order.
 *
 * EXTENSIVE:
 *  Iterate over all frames in the tree, including non-leaf frames.
 *  Child frames are traversed before their parents going both forward
 *  and backward.
 *
 * FOCUS:
 *  Traverse frames in "focus" order, which is like extensive but
 *  does a strict preorder traversal in both directions.  This type of
 *  traversal also handles placeholder frames transparently, meaning that
 *  it will never stop on one - going down will get the real frame, going
 *  back up will go on past the placeholder, so the placeholders are logically
 *  part of the frame tree.
 *
 * FASTEST:
 *  XXX not implemented
 *
 * VISUAL:
 *  Traverse frames in "visual" order (left-to-right, top-to-bottom).
 */

enum nsTraversalType{
  LEAF,
  EXTENSIVE,
  FOCUS,
  FASTEST
#ifdef IBMBIDI // Simon
   , VISUAL
#endif
}; 

// {1691E1F3-EE41-11d4-9885-00C04FA0CF4B}
#define NS_IFRAMETRAVERSAL_IID \
{ 0x1691e1f3, 0xee41, 0x11d4, { 0x98, 0x85, 0x0, 0xc0, 0x4f, 0xa0, 0xcf, 0x4b } }

class nsIFrameTraversal : public nsISupports
{
public:
  NS_DEFINE_STATIC_IID_ACCESSOR(NS_IFRAMETRAVERSAL_IID)

  NS_IMETHOD NewFrameTraversal(nsIBidirectionalEnumerator **aEnumerator,
                              PRUint32 aType,
                              nsIPresContext* aPresContext,
                              nsIFrame *aStart) = 0;
};


#endif //NSIFRAMETRAVERSAL_H