FasTC/PVRTCEncoder/src/Pixel.h

/* FasTC
 * Copyright (c) 2013 University of North Carolina at Chapel Hill.
 * All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for educational, research, and non-profit purposes, without
 * fee, and without a written agreement is hereby granted, provided that the
 * above copyright notice, this paragraph, and the following four paragraphs
 * appear in all copies.
 *
 * Permission to incorporate this software into commercial products may be
 * obtained by contacting the authors or the Office of Technology Development
 * at the University of North Carolina at Chapel Hill <otd@unc.edu>.
 *
 * This software program and documentation are copyrighted by the University of
 * North Carolina at Chapel Hill. The software program and documentation are
 * supplied "as is," without any accompanying services from the University of
 * North Carolina at Chapel Hill or the authors. The University of North
 * Carolina at Chapel Hill and the authors do not warrant that the operation of
 * the program will be uninterrupted or error-free. The end-user understands
 * that the program was developed for research purposes and is advised not to
 * rely exclusively on the program for any reason.
 *
 * IN NO EVENT SHALL THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL OR THE
 * AUTHORS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL,
 * OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF
 * THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF NORTH CAROLINA
 * AT CHAPEL HILL OR THE AUTHORS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL AND THE AUTHORS SPECIFICALLY
 * DISCLAIM ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND ANY 
 * STATUTORY WARRANTY OF NON-INFRINGEMENT. THE SOFTWARE PROVIDED HEREUNDER IS ON
 * AN "AS IS" BASIS, AND THE UNIVERSITY  OF NORTH CAROLINA AT CHAPEL HILL AND
 * THE AUTHORS HAVE NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, 
 * ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Please send all BUG REPORTS to <pavel@cs.unc.edu>.
 *
 * The authors may be contacted via:
 *
 * Pavel Krajcevski
 * Dept of Computer Science
 * 201 S Columbia St
 * Frederick P. Brooks, Jr. Computer Science Bldg
 * Chapel Hill, NC 27599-3175
 * USA
 * 
 * <http://gamma.cs.unc.edu/FasTC/>
 */

#ifndef PVRTCENCODER_SRC_PIXEL_H_
#define PVRTCENCODER_SRC_PIXEL_H_

#include "Core/include/TexCompTypes.h"

namespace PVRTCC {

class Pixel {
 public:
  Pixel(): m_A(0), m_R(0), m_G(0), m_B(0) {
    for(int i = 0; i < 4; i++) m_BitDepth[i] = 8;
  }

  explicit Pixel(uint32 rgba) {
    for(int i = 0; i < 4; i++) m_BitDepth[i] = 8;
    UnpackRGBA(rgba);
  }

  Pixel(const uint8 *bits,
        const uint8 channelDepth[4] = static_cast<uint8 *>(0),
        uint8 bitOffset = 0) {
    FromBits(bits, channelDepth, bitOffset);
  }

  // Reads a pixel from memory given the bit depth. If NULL then
  // it is assumed to be 8 bit RGBA. The bit offset is the offset
  // from the least significant bit from which we start reading
  // the pixel values.
  void FromBits(const uint8 *bits,
                const uint8 channelDepth[4] = static_cast<uint8 *>(0),
                uint8 bitOffset = 0);

  // Changes the depth of each pixel. This scales the values to
  // the appropriate bit depth by either truncating the least
  // significant bits when going from larger to smaller bit depth
  // or by repeating the most significant bits when going from
  // smaller to larger bit depths.
  void ChangeBitDepth(const uint8 (&newDepth)[4]);

  // Changes the bit depth of a single component. See the comment
  // above for how we do this.
  static uint8 ChangeBitDepth(uint8 val, uint8 oldDepth, uint8 newDepth);

  const uint8 &A() const { return m_A; }
  uint8 &A() { return m_A; }
  const uint8 &R() const { return m_R; }
  uint8 &R() { return m_R; }
  const uint8 &G() const { return m_G; }
  uint8 &G() { return m_G; }
  const uint8 &B() const { return m_B; }
  uint8 &B() { return m_B; }
  const uint8 &Component(uint32 idx) const { return m_Component[idx]; }
  uint8 &Component(uint32 idx) { return m_Component[idx]; }

  void GetBitDepth(uint8 (&outDepth)[4]) const {
    for(int i = 0; i < 4; i++) {
      outDepth[i] = m_BitDepth[i];
    }
  }

  // Take all of the components, transform them to their 8-bit variants,
  // and then pack each channel into an R8G8B8A8 32-bit integer. We assume
  // that the architecture is little-endian, so the alpha channel will end
  // up in the most-significant byte.
  uint32 PackRGBA() const;
  void UnpackRGBA(uint32 rgba);

  // Tests for equality by comparing the values and the bit depths.
  bool operator==(const Pixel &) const;

 private:
  union {
    struct {
      uint8 m_A;
      uint8 m_R;
      uint8 m_G;
      uint8 m_B;
    };
    uint8 m_Component[4];
  };

  // This contains the number of bits that each pixel has.
  uint8 m_BitDepth[4];
};

}  // namespace PVRTCC

#endif  // PVRTCENCODER_SRC_PIXEL_H_