packed_pixel.hpp

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00001 /*
00002  * Copyright (C) 2007   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
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     }
00047 
00053     template< size_t bits >
00054     class packed_pixel
00055         : 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

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