• Main Page
  • Namespaces
  • Classes
  • Files
  • File List

consumer.hpp

Go to the documentation of this file.
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:"
00171                             " recompile with PNG_READ_SWAP_SUPPORTED.");
00172 #endif
00173             }
00174 #endif
00175 
00176             // interlace handling _must_ be set up prior to info update
00177             size_t pass_count;
00178             if (rd.get_interlace_type() != interlace_none)
00179             {
00180 #ifdef PNG_READ_INTERLACING_SUPPORTED
00181                 pass_count = rd.set_interlace_handling();
00182 #else
00183                 throw error("Cannot read interlaced image:"
00184                             " interlace handling disabled.");
00185 #endif
00186             }
00187             else
00188             {
00189                 pass_count = 1;
00190             }
00191 
00192             rd.update_info();
00193             if (rd.get_color_type() != traits::get_color_type()
00194                 || rd.get_bit_depth() != traits::get_bit_depth())
00195             {
00196                 throw std::logic_error("color type and/or bit depth mismatch"
00197                                        " in png::consumer::read()");
00198             }
00199 
00200             this->get_info() = rd.get_image_info();
00201 
00202             pixcon* pixel_con = static_cast< pixcon* >(this);
00203             if (pass_count > 1 && !interlacing_supported)
00204             {
00205                 skip_interlaced_rows(rd, pass_count);
00206                 pass_count = 1;
00207             }
00208             read_rows(rd, pass_count, pixel_con);
00209 
00210             rd.read_end_info();
00211         }
00212 
00213     protected:
00214         typedef streaming_base< pixel, info_holder > base;
00215 
00220         explicit consumer(image_info& info)
00221             : base(info)
00222         {
00223         }
00224 
00225     private:
00226         template< typename istream >
00227         void skip_interlaced_rows(reader< istream >& rd, size_t pass_count)
00228         {
00229             typedef std::vector< pixel > row;
00230             typedef row_traits< row > row_traits_type;
00231             row dummy_row(this->get_info().get_width());
00232             for (size_t pass = 1; pass < pass_count; ++pass)
00233             {
00234                 rd.read_row(reinterpret_cast< byte* >
00235                             (row_traits_type::get_data(dummy_row)));
00236             }
00237         }
00238 
00239         template< typename istream >
00240         void read_rows(reader< istream >& rd, size_t pass_count,
00241                        pixcon* pixel_con)
00242         {
00243             for (size_t pass = 0; pass < pass_count; ++pass)
00244             {
00245                 pixel_con->reset(pass);
00246 
00247                 for (size_t pos = 0; pos < this->get_info().get_height(); ++pos)
00248                 {
00249                     rd.read_row(pixel_con->get_next_row(pos));
00250                 }
00251             }
00252         }
00253     };
00254 
00255 } // namespace png
00256 
00257 #endif // PNGPP_CONSUMER_HPP_INCLUDED

Generated on Mon Sep 6 2010 13:31:06 for png++ by  doxygen 1.7.1