png++  0.2.9
consumer.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_CONSUMER_HPP_INCLUDED
00032 #define PNGPP_CONSUMER_HPP_INCLUDED
00033 
00034 #include <cassert>
00035 #include <stdexcept>
00036 #include <iostream>
00037 #include <istream>
00038 
00039 #include "config.hpp"
00040 #include "error.hpp"
00041 #include "streaming_base.hpp"
00042 #include "reader.hpp"
00043 #include "pixel_buffer.hpp"
00044 
00045 namespace png
00046 {
00047 
00121     template< typename pixel,
00122               class pixcon,
00123               class info_holder = def_image_info_holder,
00124               bool interlacing_supported = false >
00125     class consumer
00126         : public streaming_base< pixel, info_holder >
00127     {
00128     public:
00129         typedef pixel_traits< pixel > traits;
00130 
00134         struct transform_identity
00135         {
00136             void operator()(io_base&) const {}
00137         };
00138 
00143         template< typename istream >
00144         void read(istream& stream)
00145         {
00146             read(stream, transform_identity());
00147         }
00148 
00157         template< typename istream, class transformation >
00158         void read(istream& stream, transformation const& transform)
00159         {
00160             reader< istream > rd(stream);
00161             rd.read_info();
00162             transform(rd);
00163 
00164 #if __BYTE_ORDER == __LITTLE_ENDIAN
00165             if (pixel_traits< pixel >::get_bit_depth() == 16)
00166             {
00167 #ifdef PNG_READ_SWAP_SUPPORTED
00168                 rd.set_swap();
00169 #else
00170                 throw error("Cannot read 16-bit image: recompile with PNG_READ_SWAP_SUPPORTED.");
00171 #endif
00172             }
00173 #endif
00174 
00175             // interlace handling _must_ be set up prior to info update
00176             size_t pass_count;
00177             if (rd.get_interlace_type() != interlace_none)
00178             {
00179 #ifdef PNG_READ_INTERLACING_SUPPORTED
00180                 pass_count = rd.set_interlace_handling();
00181 #else
00182                 throw error("Cannot read interlaced image: interlace handling disabled.");
00183 #endif
00184             }
00185             else
00186             {
00187                 pass_count = 1;
00188             }
00189 
00190             rd.update_info();
00191             if (rd.get_color_type() != traits::get_color_type()
00192                 || rd.get_bit_depth() != traits::get_bit_depth())
00193             {
00194                 throw std::logic_error("color type and/or bit depth mismatch"
00195                                        " in png::consumer::read()");
00196             }
00197 
00198             this->get_info() = rd.get_image_info();
00199 
00200             pixcon* pixel_con = static_cast< pixcon* >(this);
00201             if (pass_count > 1 && !interlacing_supported)
00202             {
00203                 skip_interlaced_rows(rd, pass_count);
00204                 pass_count = 1;
00205             }
00206             read_rows(rd, pass_count, pixel_con);
00207 
00208             rd.read_end_info();
00209         }
00210 
00211     protected:
00212         typedef streaming_base< pixel, info_holder > base;
00213 
00218         explicit consumer(image_info& info)
00219             : base(info)
00220         {
00221         }
00222 
00223     private:
00224         template< typename istream >
00225         void skip_interlaced_rows(reader< istream >& rd, size_t pass_count)
00226         {
00227             typedef std::vector< pixel > row;
00228             typedef row_traits< row > row_traits_type;
00229             row dummy_row(this->get_info().get_width());
00230             for (size_t pass = 1; pass < pass_count; ++pass)
00231             {
00232                 rd.read_row(reinterpret_cast< byte* >
00233                             (row_traits_type::get_data(dummy_row)));
00234             }
00235         }
00236 
00237         template< typename istream >
00238         void read_rows(reader< istream >& rd, size_t pass_count,
00239                        pixcon* pixel_con)
00240         {
00241             for (size_t pass = 0; pass < pass_count; ++pass)
00242             {
00243                 pixel_con->reset(pass);
00244 
00245                 for (uint_32 pos = 0; pos < this->get_info().get_height(); ++pos)
00246                 {
00247                     rd.read_row(pixel_con->get_next_row(pos));
00248                 }
00249             }
00250         }
00251     };
00252 
00253 } // namespace png
00254 
00255 #endif // PNGPP_CONSUMER_HPP_INCLUDED