reader.hpp
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/*
* Copyright (C) 2007,2008 Alex Shulgin
*
* This file is part of png++ the C++ wrapper for libpng. PNG++ is free
* software; the exact copying conditions are as follows:
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef PNGPP_READER_HPP_INCLUDED
#define PNGPP_READER_HPP_INCLUDED
#include <cassert>
#include "io_base.hpp"
namespace png
{
template< class istream >
class reader
: public io_base
{
public:
explicit reader(istream& stream)
: io_base(png_create_read_struct(PNG_LIBPNG_VER_STRING,
static_cast< io_base* >(this),
raise_error,
0))
{
png_set_read_fn(m_png, & stream, read_data);
}
~reader()
{
png_destroy_read_struct(& m_png,
m_info.get_png_info_ptr(),
m_end_info.get_png_info_ptr());
}
void read_png()
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
png_read_png(m_png,
m_info.get_png_info(),
/* transforms = */ 0,
/* params = */ 0);
}
void read_info()
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
m_info.read();
}
void read_row(byte* bytes)
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
png_read_row(m_png, bytes, 0);
}
void read_end_info()
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
m_end_info.read();
}
void update_info()
{
m_info.update();
}
private:
static void read_data(png_struct* png, byte* data, png_size_t length)
{
io_base* io = static_cast< io_base* >(png_get_error_ptr(png));
reader* rd = static_cast< reader* >(io);
rd->reset_error();
istream* stream = reinterpret_cast< istream* >(png_get_io_ptr(png));
try
{
stream->read(reinterpret_cast< char* >(data), length);
if (!stream->good())
{
rd->set_error("istream::read() failed");
}
}
catch (std::exception const& error)
{
rd->set_error(error.what());
}
catch (...)
{
assert(!"read_data: caught something wrong");
rd->set_error("read_data: caught something wrong");
}
if (rd->is_error())
{
rd->raise_error();
}
}
};
} // namespace png
#endif // PNGPP_READER_HPP_INCLUDED
png::io_base::m_end_info
end_info m_end_info
Definition: io_base.hpp:461
io_base.hpp
png::io_base
Base class for PNG reader/writer classes.
Definition: io_base.hpp:62
png::reader::read_info
void read_info()
Reads info about PNG image.
Definition: reader.hpp:108
png::info::read
void read()
Definition: info.hpp:55
png::io_base::is_error
bool is_error() const
Definition: io_base.hpp:442
png::io_base::m_info
info m_info
Definition: io_base.hpp:460
png::info::update
void update()
Definition: info.hpp:160
png::reader
The PNG reader class template. This is the low-level reading interface–use image class or consumer c...
Definition: reader.hpp:65
png::io_base::m_error
std::string m_error
Definition: io_base.hpp:462
png::io_base::raise_error
void raise_error()
Definition: io_base.hpp:447
png::reader::read_row
void read_row(byte *bytes)
Reads a row of image data at a time.
Definition: reader.hpp:120
png::reader::read_end_info
void read_end_info()
Reads ending info about PNG image.
Definition: reader.hpp:132
png::io_base::m_png
png_struct * m_png
Definition: io_base.hpp:459
png::info_base::get_png_info
png_info * get_png_info() const
Definition: info_base.hpp:59
png::info_base::get_png_info_ptr
png_info ** get_png_info_ptr()
Definition: info_base.hpp:64
png::byte
png_byte byte
Definition: types.hpp:39
png::reader::read_png
void read_png()
Reads the whole PNG data stream into memory. Not particularly useful.
Definition: reader.hpp:93
png::reader::update_info
void update_info()
Definition: reader.hpp:141
png::io_base::reset_error
void reset_error()
Definition: io_base.hpp:430
png::reader::reader
reader(istream &stream)
Constructs a reader prepared to read PNG image from a stream.
Definition: reader.hpp:73
png::reader::~reader
~reader()
Definition: reader.hpp:82
png::end_info::read
void read()
Definition: end_info.hpp:59
png
Definition: color.hpp:36
png::error
Exception class to represent runtime errors related to png++ operation.
Definition: error.hpp:57
png::io_base::set_error
void set_error(char const *message)
Definition: io_base.hpp:424