/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * The contents of this file are subject to the Netscape Public License
 * Version 1.0 (the "License"); you may not use this file except in
 * compliance with the License.  You may obtain a copy of the License at
 * http://www.mozilla.org/NPL/
 *
 * 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 Communicator client code.
 *
 * The Initial Developer of the Original Code is Netscape Communications
 * Corporation.  Portions created by Netscape are Copyright (C) 1998
 * Netscape Communications Corporation.  All Rights Reserved.
 */
#ifndef nsILineIterator_h___
#define nsILineIterator_h___

#include "nsISupports.h"

/* a6cf90ff-15b3-11d2-932e-00805f8add32 */
#define NS_ILINE_ITERATOR_IID \
 { 0xa6cf90ff, 0x15b3, 0x11d2,{0x93, 0x2e, 0x00, 0x80, 0x5f, 0x8a, 0xdd, 0x32}}

// Line iterator API.
//
// Lines are numbered from 0 to N, where 0 is the top line and N is
// the bottom line.
//
// NOTE: while you can get this interface by doing a slezy hacky
// QueryInterface on block frames, it isn't like a normal com
// interface: its not reflexive (you can't query back to the block
// frame) and unlike other frames, it *IS* reference counted so don't
// forget to NS_RELEASE it when you are done with it!

class nsILineIterator : public nsISupports {
public:
  NS_DEFINE_STATIC_IID_ACCESSOR(NS_ILINE_ITERATOR_IID)

  // Return the number of lines in the block.
  NS_IMETHOD GetNumLines(PRInt32* aResult) = 0;

  // Return the prevailing direction for the line. aIsRightToLeft will
  // be set to PR_TRUE if the CSS direction property for the block is
  // "rtl", otherwise aIsRightToLeft will be set to PR_FALSE.
  NS_IMETHOD GetDirection(PRBool* aIsRightToLeft) = 0;

  // Return structural information about a line. aFirstFrameOnLine is
  // the first frame on the line and aNumFramesOnLine is the number of
  // frames that are on the line. If the line-number is invalid then
  // aFirstFrameOnLine will be nsnull and aNumFramesOnLine will be
  // zero. For valid line numbers, aLineBounds is set to the bounding
  // box of the line (which is based on the in-flow position of the
  // frames on the line; if a frame was moved because of relative
  // positioning then its coordinates may be outside the line bounds).
  NS_IMETHOD GetLine(PRInt32 aLineNumber,
                     nsIFrame** aFirstFrameOnLine,
                     PRInt32* aNumFramesOnLine,
                     nsRect& aLineBounds) = 0;

  // Given a frame thats a child of the block, find which line its on
  // and return that line index into aIndexResult. aIndexResult will
  // be set to -1 if the frame cannot be found.
  NS_IMETHOD FindLineContaining(nsIFrame* aFrame,
                                PRInt32* aLineNumberResult) = 0;

  // Given a Y coordinate relative to the block that provided this
  // line iterator, find the line that contains the Y
  // coordinate. Returns -1 in aLineNumberResult if the Y coordinate
  // is above the first line. Returns N (where N is the number of
  // lines) if the Y coordinate is below the last line.
  NS_IMETHOD FindLineAt(nscoord aY,
                        PRInt32* aLineNumberResult) = 0;

  // Given a line number and an X coordinate, find the frame on the
  // line that is nearest to the X coordinate. The
  // aXIsBeforeFirstFrame and aXIsAfterLastFrame flags are updated
  // appropriately.
  NS_IMETHOD FindFrameAt(PRInt32 aLineNumber,
                         nscoord aX,
                         nsIFrame** aFrameFound,
                         PRBool* aXIsBeforeFirstFrame,
                         PRBool* aXIsAfterLastFrame) = 0;
};

#endif /* nsILineIterator_h___ */