pjs/layout/base/public/nsLayoutUtils.h

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#ifndef nsLayoutUtils_h__
#define nsLayoutUtils_h__

class nsIFrame;
class nsIPresContext;

/**
 * nsLayoutUtils is a namespace class used for various helper
 * functions that are useful in multiple places in layout.  The goal
 * is not to define multiple copies of the same static helper.
 */
class nsLayoutUtils
{
public:
  /**
   * GetBeforeFrame returns the :before frame of the given frame, if
   * one exists.  This is typically O(1).  The frame passed in must be
   * the first-in-flow.   
   *
   * @param aFrame the frame whose :before is wanted
   * @param aPresContext the prescontext
   * @return the :before frame or nsnull if there isn't one
   */
  static nsIFrame* GetBeforeFrame(nsIFrame* aFrame, nsIPresContext* aPresContext);

  /**
   * GetAfterFrame returns the :after frame of the given frame, if one
   * exists.  This will walk the in-flow chain to the last-in-flow if
   * needed.  This function is typically O(N) in the number of child
   * frames, following in-flows, etc.
   *
   * @param aFrame the frame whose :after is wanted
   * @param aPresContext the prescontext
   * @return the :after frame or nsnull if there isn't one
   */
  static nsIFrame* GetAfterFrame(nsIFrame* aFrame, nsIPresContext* aPresContext);

  /** ---------------------------------------------------
   *  Giving a child frame it searches "up" the tree until it
   *  finds a "Page" frame.
   */
  static nsIFrame* GetPageFrame(nsIFrame* aFrame);
};

#endif // nsLayoutUtils_h__