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/*
 * interface for rendering objects that manually create subtrees of
 * anonymous content
 */

#ifndef nsIAnonymousContentCreator_h___
#define nsIAnonymousContentCreator_h___

#include "nsISupports.h"
#include "nsIContent.h"

class nsPresContext;
class nsIFrame;
template <class T> class nsTArray;

// {7568a516-3831-4db4-88a7-a42578acc136}
#define NS_IANONYMOUS_CONTENT_CREATOR_IID \
{ 0x7568a516, 0x3831, 0x4db4, \
  { 0x88, 0xa7, 0xa4, 0x25, 0x78, 0xac, 0xc1, 0x36 } }


/**
 * Any source for anonymous content can implement this interface to provide it.
 * HTML frames like nsFileControlFrame currently use this as well as XUL frames
 * like nsScrollbarFrame and nsSliderFrame.
 *
 * @see nsCSSFrameConstructor
 */
class nsIAnonymousContentCreator : public nsISupports {
public:
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IANONYMOUS_CONTENT_CREATOR_IID)

  /**
   * Creates "native" anonymous content and adds the created content to
   * the aElements array. None of the returned elements can be nsnull.
   *
   * @note The returned elements are owned by this object. This object is
   *       responsible for calling UnbindFromTree on the elements it returned
   *       from CreateAnonymousContent when appropriate (i.e. before releasing
   *       them).
   */
  virtual nsresult CreateAnonymousContent(nsTArray<nsIContent*>& aElements)=0;

  /**
   * Implementations can override this method to create special frames for the
   * anonymous content returned from CreateAnonymousContent.
   * By default this method returns nsnull, which means the default frame
   * is created.
   */
  virtual nsIFrame* CreateFrameFor(nsIContent* aContent) { return nsnull; }

  /**
   * This gets called after the frames for the anonymous content have been
   * created and added to the frame tree. By default it does nothing.
   */
  virtual void PostCreateFrames() {}
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIAnonymousContentCreator,
                              NS_IANONYMOUS_CONTENT_CREATOR_IID)

#endif