/*
* CVS identifier:
*
* $Id: LayersInfo.java,v 1.7 2001/04/15 14:31:22 grosbois Exp $
*
* Class:                   LayersInfo
*
* Description:             Specification of a layer
*
*
*
* COPYRIGHT:
* 
* This software module was originally developed by Raphaël Grosbois and
* Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
* Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
* Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
* Centre France S.A) in the course of development of the JPEG2000
* standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
* software module is an implementation of a part of the JPEG 2000
* Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
* Systems AB and Canon Research Centre France S.A (collectively JJ2000
* Partners) agree not to assert against ISO/IEC and users of the JPEG
* 2000 Standard (Users) any of their rights under the copyright, not
* including other intellectual property rights, for this software module
* with respect to the usage by ISO/IEC and Users of this software module
* or modifications thereof for use in hardware or software products
* claiming conformance to the JPEG 2000 Standard. Those intending to use
* this software module in hardware or software products are advised that
* their use may infringe existing patents. The original developers of
* this software module, JJ2000 Partners and ISO/IEC assume no liability
* for use of this software module or modifications thereof. No license
* or right to this software module is granted for non JPEG 2000 Standard
* conforming products. JJ2000 Partners have full right to use this
* software module for his/her own purpose, assign or donate this
* software module to any third party and to inhibit third parties from
* using this software module for non JPEG 2000 Standard conforming
* products. This copyright notice must be included in all copies or
* derivative works of this software module.
* 
* Copyright (c) 1999/2000 JJ2000 Partners.
* */
using System;
namespace CSJ2K.j2k.entropy.encoder
{
	
	/// <summary> This class stores the specification of a layer distribution in the bit
	/// stream. The specification is made of optimization points and a number of
	/// extra layers to add between the optimization points. Each optimization
	/// point creates a layer which is optimized by the rate allocator to the
	/// specified target bitrate. The extra layers are added by the rate allocator
	/// between the optimized layers, with the difference that they are not
	/// optimized (i.e. they have no precise target bitrate).
	/// 
	/// <p>The overall target bitrate for the bit stream is always added as the
	/// last optimization point without any extra layers after it. If there are
	/// some optimization points whose target bitrate is larger than the overall
	/// target bitrate, the overall target bitrate will still appear as the last
	/// optimization point, even though it does not follow the increasing target
	/// bitrate order of the other optimization points. The rate allocator is
	/// responsible for eliminating layers that have target bitrates larger than
	/// the overall target bitrate.</p>
	/// 
	/// <p>Optimization points can be added with the addOptPoint() method. It takes
	/// the target bitrate for the optimized layer and the number of extra layers
	/// to add after it.</p>
	/// 
	/// <p>Information about the total number of layers, total number of
	/// optimization points, target bitrates, etc. can be obtained with the other
	/// methods.</p>
	/// 
	/// </summary>
	public class LayersInfo
	{
		/// <summary> Returns the overall target bitrate for the entire bit stream.
		/// 
		/// </summary>
		/// <returns> The overall target bitrate
		/// 
		/// </returns>
		virtual public float TotBitrate
		{
			get
			{
				return totbrate;
			}
			
		}
		/// <summary> Returns the total number of layers, according to the layer
		/// specification of this object and the overall target bitrate.
		/// 
		/// </summary>
		/// <returns> The total number of layers, according to the layer spec.
		/// 
		/// </returns>
		virtual public int TotNumLayers
		{
			get
			{
				return totlyrs;
			}
			
		}
		/// <summary> Returns the number of layers to optimize, or optimization points, as
		/// specified by this object.
		/// 
		/// </summary>
		/// <returns> The number of optimization points
		/// 
		/// </returns>
		virtual public int NOptPoints
		{
			get
			{
				// overall target bitrate is counted as extra
				return nopt + 1;
			}
			
		}
		
		/// <summary>The initial size for the arrays: 10 </summary>
		private const int SZ_INIT = 10;
		
		/// <summary>The size increment for the arrays </summary>
		private const int SZ_INCR = 5;
		
		/// <summary>The total number of layers </summary>
		// Starts at 1: overall target bitrate is always an extra optimized layer
		internal int totlyrs = 1;
		
		/// <summary>The overall target bitrate, for the whole bit stream </summary>
		internal float totbrate;
		
		/// <summary>The number of optimized layers, or optimization points, without
		/// counting the extra one coming from the overall target bitrate 
		/// </summary>
		internal int nopt;
		
		/// <summary>The target bitrate to which specified layers should be optimized. </summary>
		internal float[] optbrate = new float[SZ_INIT];
		
		/// <summary>The number of extra layers to be added after an optimized layer. After
		/// the layer that is optimized to optbrate[i], extralyrs[i] extra layers
		/// should be added. These layers are allocated between the bitrate
		/// optbrate[i] and the next optimized bitrate optbrate[i+1] or, if it does
		/// not exist, the overall target bitrate. 
		/// </summary>
		internal int[] extralyrs = new int[SZ_INIT];
		
		/// <summary> Creates a new LayersInfo object. The overall target bitrate 'brate' is
		/// always an extra optimization point, with no extra layers are after
		/// it. Note that any optimization points that are added with addOptPoint()
		/// are always added before the overall target bitrate.
		/// 
		/// </summary>
		/// <param name="brate">The overall target bitrate for the bit stream
		/// 
		/// </param>
		public LayersInfo(float brate)
		{
			if (brate <= 0)
			{
				throw new System.ArgumentException("Overall target bitrate must " + "be a positive number");
			}
			totbrate = brate;
		}
		
		/// <summary> Returns the target bitrate of the optmimization point 'n'.
		/// 
		/// </summary>
		/// <param name="n">The optimization point index (starts at 0).
		/// 
		/// </param>
		/// <returns> The target bitrate (in bpp) for the optimization point 'n'.
		/// 
		/// </returns>
		public virtual float getTargetBitrate(int n)
		{
			// overall target bitrate is counted as extra
			return (n < nopt)?optbrate[n]:totbrate;
		}
		
		/// <summary> Returns the number of extra layers to add after the optimization point
		/// 'n', but before optimization point 'n+1'. If there is no optimization
		/// point 'n+1' then they should be added before the overall target
		/// bitrate.
		/// 
		/// </summary>
		/// <param name="n">The optimization point index (starts at 0).
		/// 
		/// </param>
		/// <returns> The number of extra (unoptimized) layers to add after the
		/// optimization point 'n'
		/// 
		/// </returns>
		public virtual int getExtraLayers(int n)
		{
			// overall target bitrate is counted as extra
			return (n < nopt)?extralyrs[n]:0;
		}
		
		/// <summary> Adds a new optimization point, with target bitrate 'brate' and with
		/// 'elyrs' (unoptimized) extra layers after it. The target bitrate 'brate'
		/// must be larger than the previous optimization point. The arguments are
		/// checked and IllegalArgumentException is thrown if they are not correct.
		/// 
		/// </summary>
		/// <param name="brate">The target bitrate for the optimized layer.
		/// 
		/// </param>
		/// <param name="elyrs">The number of extra (unoptimized) layers to add after the
		/// optimized layer.
		/// 
		/// </param>
		public virtual void  addOptPoint(float brate, int elyrs)
		{
			// Check validity of arguments
			if (brate <= 0)
			{
				throw new System.ArgumentException("Target bitrate must be positive");
			}
			if (elyrs < 0)
			{
				throw new System.ArgumentException("The number of extra layers " + "must be 0 or more");
			}
			if (nopt > 0 && optbrate[nopt - 1] >= brate)
			{
				throw new System.ArgumentException("New optimization point must have " + "a target bitrate higher than the " + "preceding one");
			}
			// Check room for new optimization point
			if (optbrate.Length == nopt)
			{
				// Need more room
				float[] tbr = optbrate;
				int[] tel = extralyrs;
				// both arrays always have same size
				optbrate = new float[optbrate.Length + SZ_INCR];
				extralyrs = new int[extralyrs.Length + SZ_INCR];
				Array.Copy(tbr, 0, optbrate, 0, nopt);
				Array.Copy(tel, 0, extralyrs, 0, nopt);
			}
			// Add new optimization point
			optbrate[nopt] = brate;
			extralyrs[nopt] = elyrs;
			nopt++;
			// Update total number of layers
			totlyrs += 1 + elyrs;
		}
	}
}