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/*
* Copyright (c) 2021, Pierre Hoffmeister
* Copyright (c) 2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Aziz Berkay Yesilyurt <abyesilyurt@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Concepts.h>
#include <AK/String.h>
#include <LibCrypto/Checksum/CRC32.h>
#include <LibGfx/Bitmap.h>
#include <LibGfx/PNGWriter.h>
namespace Gfx {
class PNGChunk {
using data_length_type = u32;
public:
explicit PNGChunk(String);
auto const& data() const { return m_data; };
String const& type() const { return m_type; };
void reserve(size_t bytes) { m_data.ensure_capacity(bytes); }
template<typename T>
void add_as_big_endian(T);
template<typename T>
void add_as_little_endian(T);
void add_u8(u8);
template<typename T>
void add(T*, size_t);
void store_type();
void store_data_length();
u32 crc();
private:
template<typename T>
requires(IsUnsigned<T>) void add(T);
ByteBuffer m_data;
String m_type;
};
class NonCompressibleBlock {
public:
void finalize(PNGChunk&);
void add_byte_to_block(u8 data, PNGChunk&);
u32 adler_s1() const { return m_adler_s1; }
u32 adler_s2() const { return m_adler_s2; }
private:
void add_block_to_chunk(PNGChunk&, bool);
void update_adler(u8);
bool full() { return m_non_compressible_data.size() == 65535; }
Vector<u8> m_non_compressible_data;
u16 m_adler_s1 { 1 };
u16 m_adler_s2 { 0 };
};
PNGChunk::PNGChunk(String type)
: m_type(move(type))
{
add<data_length_type>(0);
store_type();
}
void PNGChunk::store_type()
{
m_data.append(type().bytes());
}
void PNGChunk::store_data_length()
{
auto data_length = BigEndian<u32>(m_data.size() - sizeof(data_length_type) - m_type.length());
__builtin_memcpy(m_data.offset_pointer(0), &data_length, sizeof(u32));
}
u32 PNGChunk::crc()
{
u32 crc = Crypto::Checksum::CRC32({ m_data.offset_pointer(sizeof(data_length_type)), m_data.size() - sizeof(data_length_type) }).digest();
return crc;
}
template<typename T>
requires(IsUnsigned<T>) void PNGChunk::add(T data)
{
m_data.append(&data, sizeof(T));
}
template<typename T>
void PNGChunk::add(T* data, size_t size)
{
m_data.append(data, size);
}
template<typename T>
void PNGChunk::add_as_little_endian(T data)
{
auto data_out = AK::convert_between_host_and_little_endian(data);
add(data_out);
}
template<typename T>
void PNGChunk::add_as_big_endian(T data)
{
auto data_out = AK::convert_between_host_and_big_endian(data);
add(data_out);
}
void PNGChunk::add_u8(u8 data)
{
add(data);
}
void NonCompressibleBlock::add_byte_to_block(u8 data, PNGChunk& chunk)
{
m_non_compressible_data.append(data);
update_adler(data);
if (full()) {
add_block_to_chunk(chunk, false);
m_non_compressible_data.clear_with_capacity();
}
}
void NonCompressibleBlock::add_block_to_chunk(PNGChunk& png_chunk, bool last)
{
png_chunk.add_u8(last);
u16 len = m_non_compressible_data.size();
u16 nlen = ~len;
png_chunk.add_as_little_endian(len);
png_chunk.add_as_little_endian(nlen);
png_chunk.add(m_non_compressible_data.data(), m_non_compressible_data.size());
}
void NonCompressibleBlock::finalize(PNGChunk& chunk)
{
add_block_to_chunk(chunk, true);
}
void NonCompressibleBlock::update_adler(u8 data)
{
m_adler_s1 = (m_adler_s1 + data) % 65521;
m_adler_s2 = (m_adler_s2 + m_adler_s1) % 65521;
}
void PNGWriter::add_chunk(PNGChunk& png_chunk)
{
png_chunk.store_data_length();
u32 crc = png_chunk.crc();
png_chunk.add_as_big_endian(crc);
m_data.append(png_chunk.data().data(), png_chunk.data().size());
}
void PNGWriter::add_png_header()
{
const u8 png_header[8] = { 0x89, 'P', 'N', 'G', 13, 10, 26, 10 };
m_data.append(png_header, sizeof(png_header));
}
void PNGWriter::add_IHDR_chunk(u32 width, u32 height, u8 bit_depth, u8 color_type, u8 compression_method, u8 filter_method, u8 interlace_method)
{
PNGChunk png_chunk { "IHDR" };
png_chunk.add_as_big_endian(width);
png_chunk.add_as_big_endian(height);
png_chunk.add_u8(bit_depth);
png_chunk.add_u8(color_type);
png_chunk.add_u8(compression_method);
png_chunk.add_u8(filter_method);
png_chunk.add_u8(interlace_method);
add_chunk(png_chunk);
}
void PNGWriter::add_IEND_chunk()
{
PNGChunk png_chunk { "IEND" };
add_chunk(png_chunk);
}
void PNGWriter::add_IDAT_chunk(Gfx::Bitmap const& bitmap)
{
PNGChunk png_chunk { "IDAT" };
png_chunk.reserve(bitmap.size_in_bytes());
u16 CMF_FLG = 0x81d;
png_chunk.add_as_big_endian(CMF_FLG);
NonCompressibleBlock non_compressible_block;
for (int y = 0; y < bitmap.height(); ++y) {
non_compressible_block.add_byte_to_block(0, png_chunk);
for (int x = 0; x < bitmap.width(); ++x) {
auto pixel = bitmap.get_pixel(x, y);
non_compressible_block.add_byte_to_block(pixel.red(), png_chunk);
non_compressible_block.add_byte_to_block(pixel.green(), png_chunk);
non_compressible_block.add_byte_to_block(pixel.blue(), png_chunk);
non_compressible_block.add_byte_to_block(pixel.alpha(), png_chunk);
}
}
non_compressible_block.finalize(png_chunk);
png_chunk.add_as_big_endian(non_compressible_block.adler_s2());
png_chunk.add_as_big_endian(non_compressible_block.adler_s1());
add_chunk(png_chunk);
}
ByteBuffer PNGWriter::encode(Gfx::Bitmap const& bitmap)
{
PNGWriter writer;
writer.add_png_header();
writer.add_IHDR_chunk(bitmap.width(), bitmap.height(), 8, 6, 0, 0, 0);
writer.add_IDAT_chunk(bitmap);
writer.add_IEND_chunk();
return ByteBuffer::copy(writer.m_data);
}
}
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