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// pngstream.cc -- image streams producing PNG files
// Copyright (C) 2008, 2009, 2016 SEIKO EPSON CORPORATION
//
// This file is part of the 'iscan' program.
//
// The 'iscan' program is free-ish software.
// You can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation;
// either version 2 of the License or at your option any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of FITNESS
// FOR A PARTICULAR PURPOSE or MERCHANTABILITY.
// See the GNU General Public License for more details.
//
// You should have received a verbatim copy of the GNU General Public
// License along with this program; if not, write to:
//
// Free Software Foundation, Inc.
// 59 Temple Place, Suite 330
// Boston, MA 02111-1307 USA
//
// As a special exception, the copyright holders give permission
// to link the code of this program with the esmod library and
// distribute linked combinations including the two. You must obey
// the GNU General Public License in all respects for all of the
// code used other then esmod.
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "pngstream.hh"
#include <iostream>
namespace iscan
{
pngstream::pngstream (FILE *fp, const string& name)
: _stream (fp), _header (false), _footer (false)
{
if (!_stream) throw std::invalid_argument ("invalid file handle");
#if HAVE_PNG_H
init ();
#endif
}
pngstream::~pngstream (void)
{
try
{
flush ();
}
catch (const std::exception& oops)
{
std::cerr << oops.what ();
}
#if HAVE_PNG_H
lib->destroy_write_struct (&_png, &_info);
#endif
}
basic_imgstream&
pngstream::write (const byte_type *line, size_type n)
{
if (!line || 0 == n) return *this;
#if HAVE_PNG_H
if (!_header)
{
write_header ();
}
set_error_handler (_png, _info);
lib->write_row (_png, (png_byte *) line);
#endif
return *this;
}
basic_imgstream&
pngstream::flush (void)
{
#if HAVE_PNG_H
set_error_handler (_png, _info);
lib->write_flush (_png);
if (_header && !_footer)
{
lib->write_end (_png, _info);
_footer = true;
}
#endif
fflush (_stream);
return *this;
}
bool
pngstream::is_usable (void)
{
if (lib)
{
return lib->is_usable;
}
lib = new (std::nothrow) png_lib_handle ();
if (!lib)
{
return false;
}
lib->is_usable = false;
lib->message = string ();
lib->lib = NULL;
#if HAVE_PNG_H
try
{
// Some PNG libraries are *not* linked with libz which leads
// to a "file not found" error when calling dlopen. We just
// dlopen the libz library explicitly to work around this.
basic_imgstream::dlopen ("libz");
basic_imgstream::dlopen ("libpng16", validate);
}
catch (std::runtime_error& e)
{
lib->message = e.what ();
return lib->is_usable;
}
#endif /* HAVE_PNG_H */
return lib->is_usable;
}
#if HAVE_PNG_H
#define funcsym(name) \
lib->name \
= ((pngstream::png_lib_handle::name##_f) \
basic_imgstream::dlsym (lib->lib, "png_"#name));
#endif
bool
pngstream::validate (lt_dlhandle h)
{
if (!h) return false;
#if HAVE_PNG_H
lib->lib = h;
funcsym (access_version_number);
funcsym (create_write_struct);
funcsym (create_info_struct);
funcsym (destroy_write_struct);
funcsym (init_io);
funcsym (set_IHDR);
funcsym (set_pHYs);
funcsym (set_invert_mono);
funcsym (write_info);
funcsym (write_row);
funcsym (write_flush);
funcsym (write_end);
if (lib->access_version_number
&& lib->create_write_struct
&& lib->create_info_struct
&& lib->destroy_write_struct
&& lib->init_io
&& lib->set_IHDR
&& lib->set_pHYs
&& lib->set_invert_mono
&& lib->write_info
&& lib->write_row
&& lib->write_flush
&& lib->write_end)
{
lib->is_usable = (PNG_LIBPNG_VER <= lib->access_version_number ());
}
#endif /* HAVE_PNG_H */
return lib->is_usable;
}
#if HAVE_PNG_H
#undef funcsym
#endif
basic_imgstream&
pngstream::write_header (void)
{
check_consistency ();
#if HAVE_PNG_H
set_error_handler (_png, _info);
if (mono == _cspc)
{
_bits = 1;
lib->set_invert_mono (_png);
}
lib->init_io (_png, _stream);
lib->set_IHDR (_png, _info, _h_sz, _v_sz, _bits,
(RGB == _cspc
? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_GRAY),
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
size_type hres = size_type (100 / 2.54 * _hres + 0.5);
size_type vres = size_type (100 / 2.54 * _vres + 0.5);
lib->set_pHYs (_png, _info, hres, vres, PNG_RESOLUTION_METER);
lib->write_info (_png, _info);
#endif /* HAVE_PNG_H */
_header = true;
return *this;
}
void
pngstream::check_consistency (void) const
{
if (!(mono == _cspc || grey == _cspc || RGB == _cspc))
{
throw std::logic_error ("unsupported colour space");
}
}
void
pngstream::init (void)
{
if (!is_usable ())
{
throw std::runtime_error (lib->message);
}
#if HAVE_PNG_H
_png = lib->create_write_struct (version_string,
NULL, NULL, NULL);
_info = NULL;
if (!_png) throw std::bad_alloc ();
_info = lib->create_info_struct (_png);
if (!_info)
{
lib->destroy_write_struct (&_png, NULL);
throw std::bad_alloc ();
}
#endif /* HAVE_PNG_H */
}
pngstream::png_lib_handle *pngstream::lib = NULL;
#if HAVE_PNG_H
png_const_charp pngstream::version_string = PNG_LIBPNG_VER_STRING;
#endif
} // namespace iscan
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