133 lines
4.0 KiB
C++
133 lines
4.0 KiB
C++
/*
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* Copyright (C) 2016 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "png_writer.hpp"
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static constexpr std::array<uint8_t, 8> png_file_header { {
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0x89, 0x50, 0x4e, 0x47,
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0x0d, 0x0a, 0x1a, 0x0a,
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} };
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static constexpr std::array<uint8_t, 25> png_ihdr_screen_capture { {
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0x00, 0x00, 0x00, 0x0d, // IHDR length
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0x49, 0x48, 0x44, 0x52, // IHDR type
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0x00, 0x00, 0x00, 0xf0, // width = 240
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0x00, 0x00, 0x01, 0x40, // height = 320
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0x08, // bit_depth = 8
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0x02, // color_type = 2
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0x00, // compression_method = 0
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0x00, // filter_method = 0
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0x00, // interlace_method = 0
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0x0d, 0x8a, 0x66, 0x04, // CRC
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} };
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static constexpr std::array<uint8_t, 4> png_idat_chunk_type { {
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0x49, 0x44, 0x41, 0x54, // IDAT type
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} };
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static constexpr std::array<uint8_t, 12> png_iend { {
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0x00, 0x00, 0x00, 0x00, // IEND length
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0x49, 0x45, 0x4e, 0x44, // IEND type
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0xae, 0x42, 0x60, 0x82, // CRC
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} };
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Optional<File::Error> PNGWriter::create(
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const std::filesystem::path& filename
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) {
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const auto create_error = file.create(filename);
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if( create_error.is_valid() ) {
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return create_error;
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}
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file.write(png_file_header);
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file.write(png_ihdr_screen_capture);
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write_chunk_header(
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2 + height * (5 + 1 + width * 3) + 4,
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png_idat_chunk_type
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);
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constexpr std::array<uint8_t, 2> zlib_header { 0x78, 0x01 }; // Zlib CM, CINFO, FLG.
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write_chunk_content(zlib_header);
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return { };
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}
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PNGWriter::~PNGWriter() {
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write_chunk_content(adler_32.bytes());
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write_chunk_crc();
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file.write(png_iend);
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}
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void PNGWriter::write_scanline(const std::array<ui::ColorRGB888, 240>& scanline) {
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constexpr uint8_t scanline_filter_type = 0;
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constexpr uint32_t deflate_block_length = 1 + sizeof(scanline);
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const std::array<uint8_t, 6> deflate_and_scanline_header {
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static_cast<uint8_t>((scanline_count == (height - 1)) ? 0x01 : 0x00), // DEFLATE header bits, bfinal=0, btype=00
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static_cast<uint8_t>((deflate_block_length >> 0) & 0xff), // Length LSB
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static_cast<uint8_t>((deflate_block_length >> 8) & 0xff), // Length MSB
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static_cast<uint8_t>((deflate_block_length >> 0) & 0xff) ^ 0xff, // ~Length LSB
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static_cast<uint8_t>((deflate_block_length >> 8) & 0xff) ^ 0xff, // ~Length MSB
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scanline_filter_type,
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};
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write_chunk_content(deflate_and_scanline_header);
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adler_32.feed(scanline_filter_type);
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adler_32.feed(scanline);
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// Small writes to avoid some sort of large-transfer plus block
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// boundary FatFs or SDC driver bug?
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write_chunk_content(&scanline[ 0], 80 * sizeof(ui::ColorRGB888));
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write_chunk_content(&scanline[ 80], 80 * sizeof(ui::ColorRGB888));
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write_chunk_content(&scanline[160], 80 * sizeof(ui::ColorRGB888));
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scanline_count++;
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}
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void PNGWriter::write_chunk_header(
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const size_t length,
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const std::array<uint8_t, 4>& type
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) {
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write_uint32_be(length);
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crc.reset();
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write_chunk_content(type);
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}
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void PNGWriter::write_chunk_content(const void* const p, const size_t count) {
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file.write(p, count);
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crc.process_bytes(p, count);
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}
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void PNGWriter::write_chunk_crc() {
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write_uint32_be(crc.checksum());
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}
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void PNGWriter::write_uint32_be(const uint32_t v) {
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file.write(std::array<uint8_t, 4> { {
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static_cast<uint8_t>((v >> 24) & 0xff),
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static_cast<uint8_t>((v >> 16) & 0xff),
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static_cast<uint8_t>((v >> 8) & 0xff),
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static_cast<uint8_t>((v >> 0) & 0xff),
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} });
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}
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