From e2c40b8d6cabc68eda634e103d0824fb58d5908b Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Mon, 6 Jul 2009 16:36:47 +0000 Subject: Change C++ canvas import/export semantics. --- libdimensionxx/png.cpp | 143 ++++++++++++++++++++----------------------------- 1 file changed, 58 insertions(+), 85 deletions(-) (limited to 'libdimensionxx/png.cpp') diff --git a/libdimensionxx/png.cpp b/libdimensionxx/png.cpp index b626269..1f61e72 100644 --- a/libdimensionxx/png.cpp +++ b/libdimensionxx/png.cpp @@ -23,57 +23,42 @@ namespace Dimension { - PNG_Canvas::PNG_Canvas(std::istream& istr) - : Canvas(), m_istr(&istr), m_ostr(0), m_written(false) + PNG_Writer::PNG_Writer(Canvas& canvas, std::ostream& ostr) + : m_canvas(&canvas), m_ostr(&ostr), m_written(false) { - read(); + // Optimize the canvas for PNG export + dmnsn_png_optimize_canvas(m_canvas->dmnsn()); } - PNG_Canvas::PNG_Canvas(unsigned int x, unsigned int y, std::ostream& ostr) - : Canvas(x, y), m_istr(0), m_ostr(&ostr), m_written(false) - { } - - PNG_Canvas::PNG_Canvas(std::istream& istr, std::ostream& ostr) - : Canvas(), m_istr(&istr), m_ostr(&ostr), m_written(false) - { - read(); - } - - // PNG_Canvas destructor. Call write() to write the PNG file if not already + // 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_Canvas::~PNG_Canvas() + PNG_Writer::~PNG_Writer() { - if (m_ostr && !m_written) { + if (!m_written) { try { write(); } catch (...) { dmnsn_error(SEVERITY_MEDIUM, - "Writing canvas to PNG failed in PNG_Canvas destructor."); + "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_Canvas::write() + 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."); } - if (!m_ostr) { - // Don't call write() if we're not an output PNG_Canvas... - throw Dimension_Error("Attempt to write canvas to PNG without an output" - " stream."); - } - // Make the C++/C I/O interface FILE_Cookie cookie(*m_ostr); // Write the PNG file - if (dmnsn_png_write_canvas(m_canvas, cookie.file())) { + if (dmnsn_png_write_canvas(m_canvas->dmnsn(), cookie.file())) { // The actual write operation failed, for some reason throw Dimension_Error("Writing canvas to PNG failed."); } @@ -83,19 +68,13 @@ namespace Dimension // Write a PNG file in the background Progress - PNG_Canvas::write_async() + 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."); } - if (!m_ostr) { - // Don't call write_async() if we're not an output PNG_Canvas... - throw Dimension_Error("Attempt to write canvas to PNG without an output" - " stream."); - } - m_written = true; // We've written the file now, don't do it again // Object to persist local variables past function return @@ -107,7 +86,7 @@ namespace Dimension // Start the asynchronous task dmnsn_progress *progress - = dmnsn_png_write_canvas_async(m_canvas, cookie->file()); + = dmnsn_png_write_canvas_async(m_canvas->dmnsn(), cookie->file()); if (!progress) { throw Dimension_Error("Starting background PNG write failed."); } @@ -116,20 +95,58 @@ namespace Dimension 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_Canvas::read_async(std::istream& istr) + 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_Canvas + // 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(istr); + FILE_Cookie* cookie = new FILE_Cookie(*m_istr); persister.persist(cookie); // Start the asynchronous task @@ -143,11 +160,11 @@ namespace Dimension return Progress(progress, persister); } - // Construct an input PNG_Canvas from a background task - PNG_Canvas::PNG_Canvas(Progress& progress) - : Canvas(), m_istr(0), m_ostr(0), m_written(false) + // Construct an input PNG_Writer from a background task + Canvas + PNG_Reader::finish(Progress& progress) { - // Will throw if progress is not from a PNG_Canvas::read_async call + // Will throw if progress is not from a PNG_Writer::read_async call dmnsn_canvas** canvas = progress.persister().first().persisted(); @@ -158,50 +175,6 @@ namespace Dimension throw; } - m_canvas = *canvas; - } - - // Construct an I/O PNG_Canvas from a background task - PNG_Canvas::PNG_Canvas(Progress& progress, std::ostream& ostr) - : Canvas(), m_istr(0), m_ostr(&ostr), m_written(false) - { - // Will throw if progress is not from a PNG_Canvas::read_async call - dmnsn_canvas** canvas - = progress.persister().first().persisted(); - - try { - progress.finish(); - } catch (...) { - dmnsn_delete_canvas(*canvas); - throw; - } - - m_canvas = *canvas; - } - - // Protected constructor which sets the canvas to NULL for now - PNG_Canvas::PNG_Canvas(std::ostream& ostr) - : Canvas(), m_istr(0), m_ostr(&ostr), m_written(false) - { } - - // Read a canvas from a PNG file. Uses the FILE_Cookie() interface to make a - // FILE* corresponding to an std::istream (including std::istringstream, etc). - void PNG_Canvas::read() - { - if (!m_istr) { - // read() is private, and only called from the appropriate constructors, - // so this REALLY shouldn't happen. - throw Dimension_Error("Attempt to read canvas from PNG without an input" - " stream."); - } - - // Make the C++/C I/O interface - FILE_Cookie cookie(*m_istr); - - // Read the canvas from a PNG file - if (!(m_canvas = dmnsn_png_read_canvas(cookie.file()))) { - // The read operation failed - throw Dimension_Error("Reading canvas from PNG failed."); - } + return Canvas(*canvas); } } -- cgit v1.2.3