common/rfb/TightPalette.cxx

/* Copyright (C) 2000-2005 Constantin Kaplinsky.  All Rights Reserved.
 *    
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 * USA.
 */

//
// TightPalette class implementation.
//

#include <rfb/TightPalette.h>

using namespace rfb;

TightPalette::TightPalette(int maxColors)
{
  setMaxColors(maxColors);
  reset();
}

void TightPalette::reset()
{
  m_numColors = 0;
  memset(m_hash, 0, 256 * sizeof(TightColorList *));
}

void TightPalette::setMaxColors(int maxColors)
{
  m_maxColors = maxColors;
  if (m_maxColors < 0) {
    m_maxColors = 0;
  } else if (m_maxColors > 254) {
    m_maxColors = 254;
  }
}

int TightPalette::insert(rdr::U32 rgb, int numPixels)
{
  TightColorList *pnode;
  TightColorList *prev_pnode = NULL;
  int hash_key, idx, new_idx, count;

  hash_key = hashFunc(rgb);

  pnode = m_hash[hash_key];

  while (pnode != NULL) {
    if (pnode->rgb == rgb) {
      // Such palette entry already exists.
      new_idx = idx = pnode->idx;
      count = m_entry[idx].numPixels + numPixels;
      if (new_idx && m_entry[new_idx-1].numPixels < count) {
        do {
          m_entry[new_idx] = m_entry[new_idx-1];
          m_entry[new_idx].listNode->idx = new_idx;
          new_idx--;
        }
        while (new_idx && m_entry[new_idx-1].numPixels < count);

        m_entry[new_idx].listNode = pnode;
        pnode->idx = new_idx;
      }
      m_entry[new_idx].numPixels = count;
      return m_numColors;
    }
    prev_pnode = pnode;
    pnode = pnode->next;
  }

  // Check if the palette is full.
  if (m_numColors == 256 || m_numColors == m_maxColors) {
    m_numColors = 0;
    return 0;
  }

  // Move palette entries with lesser pixel counts.
  for ( idx = m_numColors;
        idx > 0 && m_entry[idx-1].numPixels < numPixels;
        idx-- ) {
    m_entry[idx] = m_entry[idx-1];
    m_entry[idx].listNode->idx = idx;
  }

  // Add new palette entry into the freed slot.
  pnode = &m_list[m_numColors];
  if (prev_pnode != NULL) {
    prev_pnode->next = pnode;
  } else {
    m_hash[hash_key] = pnode;
  }
  pnode->next = NULL;
  pnode->idx = idx;
  pnode->rgb = rgb;
  m_entry[idx].listNode = pnode;
  m_entry[idx].numPixels = numPixels;

  return ++m_numColors;
}