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/*************************************************************************
* Copyright (C) 2009 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library is distributed in the hope that it will be *
* useful, but WITHOUT ANY WARRANTY; without even the implied warranty *
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "dimensionxx.hpp"
#include <cstdio>
namespace Dimension
{
PNG_Writer::PNG_Writer(Canvas& canvas, std::ostream& ostr)
: m_canvas(&canvas), m_ostr(&ostr), m_written(false)
{
// Optimize the canvas for PNG export
dmnsn_png_optimize_canvas(m_canvas->dmnsn());
}
// PNG_Writer destructor. Call write() to write the PNG file if not already
// written, but catch any exceptions and instead report the error with
// dmnsn_error() to avoid throwing from a destructor.
PNG_Writer::~PNG_Writer()
{
if (!m_written) {
try {
write();
} catch (...) {
dmnsn_error(SEVERITY_MEDIUM,
"Writing canvas to PNG failed in PNG_Writer destructor.");
}
}
}
// Write the PNG file. Uses the FILE_Cookie() interface to make a FILE*
// corresponding to an std::ostream (including std::ostringstream, etc).
void PNG_Writer::write()
{
if (m_written) {
// Does writing a PNG file twice make sense?
throw Dimension_Error("Attempt to write canvas to PNG twice.");
}
// Make the C++/C I/O interface
FILE_Cookie cookie(*m_ostr);
// Write the PNG file
if (dmnsn_png_write_canvas(m_canvas->dmnsn(), cookie.file()) != 0) {
// The actual write operation failed, for some reason
throw Dimension_Error("Writing canvas to PNG failed.");
}
m_written = true; // We've written the file now, don't do it again
}
// Write a PNG file in the background
Progress
PNG_Writer::write_async()
{
if (m_written) {
// Does writing a PNG file twice make sense?
throw Dimension_Error("Attempt to write canvas to PNG twice.");
}
m_written = true; // We've written the file now, don't do it again
// Object to persist local variables past function return
Persister persister;
// Make the C++/C I/O interface
FILE_Cookie* cookie = new FILE_Cookie(*m_ostr);
persister.persist(cookie);
// Start the asynchronous task
dmnsn_progress *progress
= dmnsn_png_write_canvas_async(m_canvas->dmnsn(), cookie->file());
if (!progress) {
throw Dimension_Error("Starting background PNG write failed.");
}
// Return the Progress object
return Progress(progress, persister);
}
// Construct a PNG reader
PNG_Reader::PNG_Reader(std::istream& istr)
: m_istr(&istr), m_read(false) { }
// Read a canvas from a PNG file. Uses the FILE_Cookie() interface to make a
// FILE* corresponding to an std::istream
Canvas
PNG_Reader::read()
{
if (m_read) {
// Does reading a PNG file twice make sense?
throw Dimension_Error("Attempt to read canvas from PNG twice.");
}
// Make the C++/C I/O interface
FILE_Cookie cookie(*m_istr);
// Read the canvas from a PNG file
dmnsn_canvas* canvas = dmnsn_png_read_canvas(cookie.file());
if (!canvas) {
// The read operation failed
throw Dimension_Error("Reading canvas from PNG failed.");
}
// Only set m_read if nothing threw an exception
Canvas ret(canvas);
m_read = true;
return ret;
}
// Read a PNG file in the background
Progress
PNG_Reader::read_async()
{
if (m_read) {
// Does reading a PNG file twice make sense?
throw Dimension_Error("Attempt to read canvas from PNG twice.");
}
// Don't read again
m_read = true;
// Object to persist local variables past function return
Persister persister;
// Store a pointer to a dmnsn_canvas* in the persister to later construct
// the PNG_Writer
dmnsn_canvas** canvas = new dmnsn_canvas*;
persister.persist(canvas);
// Make the C++/C I/O interface
FILE_Cookie* cookie = new FILE_Cookie(*m_istr);
persister.persist(cookie);
// Start the asynchronous task
dmnsn_progress *progress
= dmnsn_png_read_canvas_async(canvas, cookie->file());
if (!progress) {
throw Dimension_Error("Starting background PNG read failed.");
}
// Return the Progress object
return Progress(progress, persister);
}
// Construct an input PNG_Writer from a background task
Canvas
PNG_Reader::finish(Progress& progress)
{
// Will throw if progress is not from a PNG_Writer::read_async call
dmnsn_canvas** canvas
= progress.persister().first<dmnsn_canvas*>().persisted();
try {
progress.finish();
} catch (...) {
dmnsn_delete_canvas(*canvas);
throw;
}
return Canvas(*canvas);
}
}
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