131 lines
5.2 KiB
C++
131 lines
5.2 KiB
C++
#include "Decoder/Png.hpp"
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#include <algorithm>
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#include <array>
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#include <climits>
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#include <cstddef>
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#include <mutex>
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#include <stdexcept>
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#define STB_IMAGE_WRITE_STATIC
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#define STB_IMAGE_WRITE_IMPLEMENTATION
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#define STBI_WRITE_NO_STDIO
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#include "stb_image_write.h"
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#define STB_IMAGE_STATIC
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#define STB_IMAGE_IMPLEMENTATION
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#define STBI_ONLY_PNG
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#define STBI_NO_STDIO
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#include "stb_image.h"
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namespace Decoder::Png {
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namespace {
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constexpr std::array<std::uint8_t, 8> SIGNATURE = {0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A};
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constexpr std::size_t CHUNK_OVERHEAD = 12;
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constexpr std::size_t IHDR_SIZE = 13;
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constexpr std::uint32_t MAX_DIMENSION = 0x7FFFFFFF;
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std::uint32_t readBigEndian32(const std::uint8_t* bytes) {
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return static_cast<std::uint32_t>(bytes[0]) << 24 | static_cast<std::uint32_t>(bytes[1]) << 16
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| static_cast<std::uint32_t>(bytes[2]) << 8 | static_cast<std::uint32_t>(bytes[3]);
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}
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bool isChunkType(const std::uint8_t* bytes, const char* type) {
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return std::equal(bytes, bytes + 4, type);
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}
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bool isValidFormat(std::uint8_t bitDepth, std::uint8_t colorType) {
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switch (colorType) {
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case 0:
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return bitDepth == 1 || bitDepth == 2 || bitDepth == 4 || bitDepth == 8 || bitDepth == 16;
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case 3:
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return bitDepth == 1 || bitDepth == 2 || bitDepth == 4 || bitDepth == 8;
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case 2:
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case 4:
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case 6:
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return bitDepth == 8 || bitDepth == 16;
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default:
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return false;
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}
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}
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void appendBytes(void* context, void* data, int size) {
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auto* output = static_cast<std::vector<std::uint8_t>*>(context);
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const auto* bytes = static_cast<const std::uint8_t*>(data);
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output->insert(output->end(), bytes, bytes + size);
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}
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} // namespace
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std::optional<Header> ParseHeader(std::span<const std::uint8_t> png) {
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const std::size_t firstChunk = SIGNATURE.size();
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if (png.size() < firstChunk + CHUNK_OVERHEAD + IHDR_SIZE) return std::nullopt;
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if (!std::equal(SIGNATURE.begin(), SIGNATURE.end(), png.begin())) return std::nullopt;
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if (readBigEndian32(&png[firstChunk]) != IHDR_SIZE || !isChunkType(&png[firstChunk + 4], "IHDR")) return std::nullopt;
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const std::uint8_t* ihdr = &png[firstChunk + 8];
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Header header{};
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header.width = readBigEndian32(ihdr);
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header.height = readBigEndian32(ihdr + 4);
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header.bitDepth = ihdr[8];
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header.colorType = static_cast<ColorType>(ihdr[9]);
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header.interlaced = ihdr[12] == 1;
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if (header.width == 0 || header.height == 0 || header.width > MAX_DIMENSION || header.height > MAX_DIMENSION) return std::nullopt;
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if (!isValidFormat(ihdr[8], ihdr[9]) || ihdr[10] != 0 || ihdr[11] != 0 || ihdr[12] > 1) return std::nullopt;
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std::size_t offset = firstChunk + CHUNK_OVERHEAD + IHDR_SIZE;
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while (png.size() - offset >= CHUNK_OVERHEAD) {
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const std::uint32_t length = readBigEndian32(&png[offset]);
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const std::uint8_t* type = &png[offset + 4];
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if (isChunkType(type, "tRNS")) header.hasTransparency = true;
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if (isChunkType(type, "tRNS") || isChunkType(type, "IDAT") || isChunkType(type, "IEND")) break;
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if (length > png.size() - offset - CHUNK_OVERHEAD) break;
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offset += CHUNK_OVERHEAD + length;
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}
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return header;
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}
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std::optional<Image> Decode(std::span<const std::uint8_t> png) {
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if (png.empty() || png.size() > INT_MAX) return std::nullopt;
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int width = 0;
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int height = 0;
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int channels = 0;
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stbi_uc* decoded = stbi_load_from_memory(png.data(), static_cast<int>(png.size()), &width, &height, &channels, 4);
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if (!decoded) return std::nullopt;
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Image image{static_cast<std::uint32_t>(width), static_cast<std::uint32_t>(height), {}};
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image.pixels.assign(decoded, decoded + static_cast<std::size_t>(image.width) * image.height * 4);
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stbi_image_free(decoded);
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return image;
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}
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std::vector<std::uint8_t> Encode(std::span<const std::uint8_t> pixels, std::uint32_t width, std::uint32_t height,
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std::uint32_t channels, EncodeOptions options) {
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if (channels < 1 || channels > 4) throw std::invalid_argument("Png::Encode: channels must be 1-4");
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if (options.compressionLevel < 0 || options.compressionLevel > 9 || options.filter < -1 || options.filter > 4) {
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throw std::invalid_argument("Png::Encode: unsupported options");
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}
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if (width == 0 || height == 0 || static_cast<std::uint64_t>(width) * channels > INT_MAX || height > INT_MAX) {
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throw std::invalid_argument("Png::Encode: unsupported image size");
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}
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if (pixels.size() < static_cast<std::size_t>(width) * height * channels) {
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throw std::invalid_argument("Png::Encode: pixel buffer is too small");
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}
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std::vector<std::uint8_t> output;
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const int stride = static_cast<int>(width * channels);
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static std::mutex optionsMutex;
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std::lock_guard lock(optionsMutex);
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stbi_write_png_compression_level = options.compressionLevel;
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stbi_write_force_png_filter = options.filter;
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const int written = stbi_write_png_to_func(appendBytes, &output, static_cast<int>(width), static_cast<int>(height),
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static_cast<int>(channels), pixels.data(), stride);
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if (written == 0) throw std::runtime_error("Png::Encode: encoding failed");
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return output;
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}
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} // namespace Decoder::Png
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