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# packed_pixel.hpp

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    00001 /*
    00002  * Copyright (C) 2007,2008   Alex Shulgin
    00003  *
    00004  * This file is part of png++ the C++ wrapper for libpng.  PNG++ is free
    00005  * software; the exact copying conditions are as follows:
    00006  *
    00007  * Redistribution and use in source and binary forms, with or without
    00008  * modification, are permitted provided that the following conditions are met:
    00009  *
    00010  * 1. Redistributions of source code must retain the above copyright notice,
    00011  * this list of conditions and the following disclaimer.
    00012  *
    00013  * 2. Redistributions in binary form must reproduce the above copyright
    00014  * notice, this list of conditions and the following disclaimer in the
    00015  * documentation and/or other materials provided with the distribution.
    00016  *
    00017  * 3. The name of the author may not be used to endorse or promote products
    00018  * derived from this software without specific prior written permission.
    00019  *
    00020  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
    00021  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    00022  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
    00023  * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    00024  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
    00025  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
    00026  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
    00027  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
    00028  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
    00029  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    00030  */
    00031 #ifndef PNGPP_PACKED_PIXEL_HPP_INCLUDED
    00032 #define PNGPP_PACKED_PIXEL_HPP_INCLUDED
    00033
    00034 #include "types.hpp"
    00035
    00036 namespace png
    00037 {
    00038
    00039     namespace detail
    00040     {
    00041         template< size_t bits > class allowed_bit_depth;
    00042
    00043         template<> class allowed_bit_depth< 1 > {};
    00044         template<> class allowed_bit_depth< 2 > {};
    00045         template<> class allowed_bit_depth< 4 > {};
    00046     } // namespace detail
    00047
    00053     template< size_t bits >
    00054     class packed_pixel
    00055         : detail::allowed_bit_depth< bits >
    00056     {
    00057     public:
    00058         packed_pixel(byte value = 0)
    00059             : m_value(value & get_bit_mask())
    00060         {
    00061         }
    00062
    00063         operator byte() const
    00064         {
    00065             return m_value;
    00066         }
    00067
    00068         static size_t const get_bit_depth()
    00069         {
    00070             return bits;
    00071         }
    00072
    00073         static byte const get_bit_mask()
    00074         {
    00075             return (1 << bits) - 1;
    00076         }
    00077
    00078     private:
    00079         byte m_value;
    00080     };
    00081
    00082 } // namespace png
    00083
    00084 #endif // PNGPP_PACKED_PIXEL_HPP_INCLUDED