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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_WRITER_HPP_INCLUDED
#define PNGPP_WRITER_HPP_INCLUDED
#include <cassert>
#include "io_base.hpp"
namespace png
{
/**
* \brief PNG writer class template. This is the low-level
* writing interface--use image class or generator class to
* actually write images.
*
* The \c ostream template parameter specifies the type of output
* stream to work with. The \c ostream class should implement the
* minimum of the following interface:
*
* \code
* class my_ostream
* {
* public:
* void write(char const*, size_t);
* void flush();
* bool good();
* };
* \endcode
*
* With the semantics similar to the \c std::ostream. Naturally,
* \c std::ostream fits this requirement and can be used with the
* writer class as is.
*
* \see image, reader, generator, io_base
*/
template< class ostream >
class writer
: public io_base
{
public:
/**
* \brief Constructs a writer prepared to write PNG image into
* a \a stream.
*/
explicit writer(ostream& stream)
: io_base(png_create_write_struct(PNG_LIBPNG_VER_STRING,
static_cast< io_base* >(this),
raise_error,
0))
{
png_set_write_fn(m_png, & stream, write_data, flush_data);
}
~writer()
{
m_end_info.destroy();
png_destroy_write_struct(& m_png, m_info.get_png_info_ptr());
}
void write_png() const
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
png_write_png(m_png,
m_info.get_png_info(),
/* transforms = */ 0,
/* params = */ 0);
}
/**
* \brief Write info about PNG image.
*/
void write_info() const
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
m_info.write();
}
/**
* \brief Writes a row of image data at a time.
*/
void write_row(byte* bytes)
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
png_write_row(m_png, bytes);
}
/**
* \brief Reads ending info about PNG image.
*/
void write_end_info() const
{
if (setjmp(png_jmpbuf(m_png)))
{
throw error(m_error);
}
m_end_info.write();
}
private:
static void write_data(png_struct* png, byte* data, png_size_t length)
{
io_base* io = static_cast< io_base* >(png_get_error_ptr(png));
writer* wr = static_cast< writer* >(io);
wr->reset_error();
ostream* stream = reinterpret_cast< ostream* >(png_get_io_ptr(png));
try
{
stream->write(reinterpret_cast< char* >(data), length);
if (!stream->good())
{
wr->set_error("ostream::write() failed");
}
}
catch (std::exception const& error)
{
wr->set_error(error.what());
}
catch (...)
{
assert(!"caught something wrong");
wr->set_error("write_data: caught something wrong");
}
if (wr->is_error())
{
wr->raise_error();
}
}
static void flush_data(png_struct* png)
{
io_base* io = static_cast< io_base* >(png_get_error_ptr(png));
writer* wr = static_cast< writer* >(io);
wr->reset_error();
ostream* stream = reinterpret_cast< ostream* >(png_get_io_ptr(png));
try
{
stream->flush();
if (!stream->good())
{
wr->set_error("ostream::flush() failed");
}
}
catch (std::exception const& error)
{
wr->set_error(error.what());
}
catch (...)
{
assert(!"caught something wrong");
wr->set_error("flush_data: caught something wrong");
}
if (wr->is_error())
{
wr->raise_error();
}
}
};
} // namespace png
#endif // PNGPP_WRITER_HPP_INCLUDED
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