PNG.cc

Go to the documentation of this file.

#include "PNG.hh"
 
#include "File.hh"
#include "MSXException.hh"
#include "PixelOperations.hh"
#include "Version.hh"
 
#include "endian.hh"
#include "narrow.hh"
#include "one_of.hh"
#include "vla.hh"
#include "cstdiop.hh"
 
#include <png.h>
#include <SDL.h>
 
#include <array>
#include <bit>
#include <cassert>
#include <cstring>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <limits>
#include <tuple>
 
namespace openmsx::PNG {
 
[[noreturn]] static void handleError(png_structp png_ptr, png_const_charp error_msg)
{
        const auto* operation = std::bit_cast<const char*>(
                png_get_error_ptr(png_ptr));
        throw MSXException("Error while ", operation, " PNG: ", error_msg);
}
 
static void handleWarning(png_structp png_ptr, png_const_charp warning_msg)
{
        const auto* operation = std::bit_cast<const char*>(
                png_get_error_ptr(png_ptr));
        std::cerr << "Warning while " << operation << " PNG: "
                << warning_msg << '\n';
}
 
/*
The copyright notice below applies to the original PNG load code, which was
imported from SDL_image 1.2.10, file "IMG_png.c", function "IMG_LoadPNG_RW".
===============================================================================
        File: SDL_png.c
     Purpose: A PNG loader and saver for the SDL library
    Revision:
  Created by: Philippe Lavoie          (2 November 1998)
              lavoie@zeus.genie.uottawa.ca
 Modified by:
 
 Copyright notice:
          Copyright (C) 1998 Philippe Lavoie
 
          This library is free software; you can redistribute it and/or
          modify it under the terms of the GNU Library General Public
          License as published by the Free Software Foundation; either
          version 2 of the License, or (at your option) any later version.
 
          This 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
          Library General Public License for more details.
 
          You should have received a copy of the GNU Library General Public
          License along with this library; if not, write to the Free
          Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 
    Comments: The load and save routine are basically the ones you can find
             in the example.c file from the libpng distribution.
 
  Changes:
    1999-05-17: Modified to use the new SDL data sources - Sam Lantinga
    2009-12-29: Modified for use in openMSX - Maarten ter Huurne
                                              and Wouter Vermaelen
 
===============================================================================
*/
 
struct PNGReadHandle {
        PNGReadHandle() = default;
        PNGReadHandle(const PNGReadHandle&) = delete;
        PNGReadHandle(PNGReadHandle&&) = delete;
        PNGReadHandle& operator=(const PNGReadHandle&) = delete;
        PNGReadHandle& operator=(PNGReadHandle&&) = delete;
        ~PNGReadHandle()
        {
                if (ptr) {
                        png_destroy_read_struct(&ptr, info ? &info : nullptr, nullptr);
                }
        }
 
        png_structp ptr = nullptr;
        png_infop info = nullptr;
};
 
static void readData(png_structp ctx, png_bytep area, png_size_t size)
{
        auto* file = std::bit_cast<File*>(png_get_io_ptr(ctx));
        file->read(std::span{area, size});
}
 
SDLSurfacePtr load(const std::string& filename, bool want32bpp)
{
        File file(filename);
 
        try {
                // Create the PNG loading context structure.
                PNGReadHandle png;
                png.ptr = png_create_read_struct(
                        PNG_LIBPNG_VER_STRING,
                        const_cast<char*>("decoding"), handleError, handleWarning);
                if (!png.ptr) {
                        throw MSXException("Failed to allocate main struct");
                }
 
                // Allocate/initialize the memory for image information.
                png.info = png_create_info_struct(png.ptr);
                if (!png.info) {
                        throw MSXException("Failed to allocate image info struct");
                }
 
                // Set up the input control.
                png_set_read_fn(png.ptr, &file, readData);
 
                // Read PNG header info.
                png_read_info(png.ptr, png.info);
                png_uint_32 width, height;
                int bit_depth, color_type, interlace_type;
                png_get_IHDR(png.ptr, png.info, &width, &height, &bit_depth,
                             &color_type, &interlace_type, nullptr, nullptr);
 
                // Tell libpng to strip 16 bit/color files down to 8 bits/color.
                png_set_strip_16(png.ptr);
 
                // Extract multiple pixels with bit depths of 1, 2, and 4 from a single
                // byte into separate bytes (useful for paletted and grayscale images).
                png_set_packing(png.ptr);
 
                // The following enables:
                // - transformation of grayscale images of less than 8 to 8 bits
                // - changes paletted images to RGB
                // - adds a full alpha channel if there is transparency information in a tRNS chunk
                png_set_expand(png.ptr);
 
                if (want32bpp) {
                        png_set_filler(png.ptr, 0xff, PNG_FILLER_AFTER);
                }
 
                // always convert grayscale to RGB
                //  together with all the above conversions, the resulting image will
                //  be either RGB or RGBA with 8 bits per component.
                png_set_gray_to_rgb(png.ptr);
 
                png_read_update_info(png.ptr, png.info);
 
                png_get_IHDR(png.ptr, png.info, &width, &height, &bit_depth,
                             &color_type, &interlace_type, nullptr, nullptr);
 
                // Allocate the SDL surface to hold the image.
                constexpr unsigned MAX_SIZE = 2048;
                if (width > MAX_SIZE) {
                        throw MSXException(
                                "Attempted to create a surface with excessive width: ",
                                width, ", max ", MAX_SIZE);
                }
                if (height > MAX_SIZE) {
                        throw MSXException(
                                "Attempted to create a surface with excessive height: ",
                                height, ", max ", MAX_SIZE);
                }
                int bpp = png_get_channels(png.ptr, png.info) * 8;
                assert(bpp == one_of(24, 32));
                PixelOperations pixelOps;
                SDLSurfacePtr surface(width, height, bpp,
                                      pixelOps.getRmask(), pixelOps.getGmask(), pixelOps.getBmask(),
                                      ((bpp == 32) ? pixelOps.getAmask() : 0));
 
                // Create the array of pointers to image data.
                VLA(png_bytep, rowPointers, height);
                for (auto row : xrange(height)) {
                        rowPointers[row] = std::bit_cast<png_bytep>(
                                surface.getLinePtr(row));
                }
 
                // Read the entire image in one go.
                png_read_image(png.ptr, rowPointers.data());
 
                // In some cases it can't read PNGs created by some popular programs
                // (ACDSEE), we do not want to process comments, so we omit png_read_end
                //png_read_end(png.ptr, png.info);
 
                return surface;
        } catch (MSXException& e) {
                throw MSXException(
                        "Error while loading PNG file \"", filename, "\": ",
                        e.getMessage());
        }
}
 
 
/* PNG save code by Darren Grant sdl@lokigames.com */
/* heavily modified for openMSX by Joost Damad joost@lumatec.be */
 
struct PNGWriteHandle {
        PNGWriteHandle() = default;
        PNGWriteHandle(const PNGWriteHandle&) = delete;
        PNGWriteHandle(PNGWriteHandle&&) = delete;
        PNGWriteHandle& operator=(const PNGWriteHandle&) = delete;
        PNGWriteHandle& operator=(PNGWriteHandle&&) = delete;
        ~PNGWriteHandle()
        {
                if (ptr) {
                        png_destroy_write_struct(&ptr, info ? &info : nullptr);
                }
        }
 
        png_structp ptr = nullptr;
        png_infop info = nullptr;
};
 
static void writeData(png_structp ctx, png_bytep area, png_size_t size)
{
        auto* file = std::bit_cast<File*>(png_get_io_ptr(ctx));
        file->write(std::span{area, size});
}
 
static void flushData(png_structp ctx)
{
        auto* file = std::bit_cast<File*>(png_get_io_ptr(ctx));
        file->flush();
}
 
static void IMG_SavePNG_RW(size_t width, std::span<const void*> rowPointers,
                           const std::string& filename, bool color)
{
        auto height = rowPointers.size();
        assert(width  <= std::numeric_limits<png_uint_32>::max());
        assert(height <= std::numeric_limits<png_uint_32>::max());
        try {
                File file(filename, File::OpenMode::TRUNCATE);
 
                PNGWriteHandle png;
                png.ptr = png_create_write_struct(
                        PNG_LIBPNG_VER_STRING,
                        const_cast<char*>("encoding"), handleError, handleWarning);
                if (!png.ptr) {
                        throw MSXException("Failed to allocate main struct");
                }
 
                // Allocate/initialize the image information data.  REQUIRED
                png.info = png_create_info_struct(png.ptr);
                if (!png.info) {
                        // Couldn't create image information for PNG file
                        throw MSXException("Failed to allocate image info struct");
                }
 
                // Set up the output control.
                png_set_write_fn(png.ptr, &file, writeData, flushData);
 
                // Mark this image as being generated by openMSX and add creation time.
                std::string version = Version::full();
                std::array<png_text, 2> text;
                text[0].compression = PNG_TEXT_COMPRESSION_NONE;
                text[0].key  = const_cast<char*>("Software");
                text[0].text = const_cast<char*>(version.c_str());
                text[1].compression = PNG_TEXT_COMPRESSION_NONE;
                text[1].key  = const_cast<char*>("Creation Time");
 
                // A buffer size of 20 characters is large enough till the year
                // 9999. But the compiler doesn't understand calendars and
                // warns that the snprintf output could be truncated (e.g.
                // because the year is -2147483647). To silence this warning
                // (and also to work around the windows _snprintf stuff) we add
                // some extra buffer space.
                static constexpr size_t size = (10 + 1 + 8 + 1) + 44;
                time_t now = time(nullptr);
                struct tm* tm = localtime(&now);
                std::array<char, size> timeStr;
                snprintf(timeStr.data(), sizeof(timeStr), "%04d-%02d-%02d %02d:%02d:%02d",
                         1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday,
                         tm->tm_hour, tm->tm_min, tm->tm_sec);
                text[1].text = timeStr.data();
 
                png_set_text(png.ptr, png.info, text.data(), narrow<int>(text.size()));
 
                png_set_IHDR(png.ptr, png.info,
                             narrow<png_uint_32>(width), narrow<png_uint_32>(height),
                             8,
                             color ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_GRAY,
                             PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
                             PNG_FILTER_TYPE_BASE);
 
                // Write the file header information.  REQUIRED
                png_write_info(png.ptr, png.info);
 
                // Write out the entire image data in one call.
                png_write_image(
                        png.ptr,
                        std::bit_cast<png_bytep*>(const_cast<void**>(rowPointers.data())));
                png_write_end(png.ptr, png.info);
        } catch (MSXException& e) {
                throw MSXException(
                        "Error while writing PNG file \"", filename, "\": ",
                        e.getMessage());
        }
}
 
static void save(SDL_Surface* image, const std::string& filename)
{
        SDLAllocFormatPtr frmt24(SDL_AllocFormat(
                Endian::BIG ? SDL_PIXELFORMAT_BGR24 : SDL_PIXELFORMAT_RGB24));
        SDLSurfacePtr surf24(SDL_ConvertSurface(image, frmt24.get(), 0));
 
        // Create the array of pointers to image data
        VLA(const void*, row_pointers, image->h);
        for (auto i : xrange(image->h)) {
                row_pointers[i] = surf24.getLinePtr(i);
        }
 
        IMG_SavePNG_RW(image->w, row_pointers, filename, true);
}
 
void saveRGBA(size_t width, std::span<const uint32_t*> rowPointers,
              const std::string& filename)
{
        // this implementation creates 1 extra copy, can be optimized if required
        auto height = narrow<unsigned>(rowPointers.size());
        static constexpr int bpp = 32;
        PixelOperations pixelOps;
        SDLSurfacePtr surface(
                narrow<unsigned>(width), height, bpp,
                pixelOps.getRmask(), pixelOps.getGmask(),
                pixelOps.getBmask(), pixelOps.getAmask());
        for (auto y : xrange(height)) {
                memcpy(surface.getLinePtr(y),
                       rowPointers[y], width * sizeof(uint32_t));
        }
        save(surface.get(), filename);
}
 
void saveGrayscale(size_t width, std::span<const uint8_t*> rowPointers_,
                   const std::string& filename)
{
        std::span rowPointers{std::bit_cast<const void**>(rowPointers_.data()),
                              rowPointers_.size()};
        IMG_SavePNG_RW(width, rowPointers, filename, false);
}
 
} // namespace openmsx::PNG