301 lines
11 KiB
C++
301 lines
11 KiB
C++
#include "gif.h"
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#include <SDL3/SDL_log.h> // Para SDL_LogError, SDL_LogCategory, SDL_LogInfo
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#include <cstring> // Para memcpy, size_t
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#include <stdexcept> // Para runtime_error
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#include <string> // Para char_traits, operator==, basic_string, string
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namespace GIF
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{
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inline void readBytes(const uint8_t *&buffer, void *dst, size_t size)
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{
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std::memcpy(dst, buffer, size);
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buffer += size;
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}
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void Gif::decompress(int code_length, const uint8_t *input, int input_length, uint8_t *out)
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{
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if (code_length < 2 || code_length > 12)
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Invalid LZW code length: %d", code_length);
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throw std::runtime_error("Invalid LZW code length");
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}
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int i, bit;
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int prev = -1;
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std::vector<DictionaryEntry> dictionary;
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int dictionary_ind;
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unsigned int mask = 0x01;
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int reset_code_length = code_length;
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int clear_code = 1 << code_length;
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int stop_code = clear_code + 1;
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int match_len = 0;
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dictionary.resize(1 << (code_length + 1));
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for (dictionary_ind = 0; dictionary_ind < (1 << code_length); dictionary_ind++)
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{
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dictionary[dictionary_ind].byte = static_cast<uint8_t>(dictionary_ind);
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dictionary[dictionary_ind].prev = -1;
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dictionary[dictionary_ind].len = 1;
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}
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dictionary_ind += 2;
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while (input_length > 0)
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{
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int code = 0;
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for (i = 0; i < (code_length + 1); i++)
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{
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if (input_length <= 0)
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Unexpected end of input in decompress");
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throw std::runtime_error("Unexpected end of input in decompress");
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}
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bit = ((*input & mask) != 0) ? 1 : 0;
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mask <<= 1;
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if (mask == 0x100)
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{
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mask = 0x01;
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input++;
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input_length--;
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}
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code |= (bit << i);
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}
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if (code == clear_code)
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{
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code_length = reset_code_length;
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dictionary.resize(1 << (code_length + 1));
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for (dictionary_ind = 0; dictionary_ind < (1 << code_length); dictionary_ind++)
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{
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dictionary[dictionary_ind].byte = static_cast<uint8_t>(dictionary_ind);
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dictionary[dictionary_ind].prev = -1;
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dictionary[dictionary_ind].len = 1;
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}
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dictionary_ind += 2;
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prev = -1;
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continue;
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}
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else if (code == stop_code)
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{
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break;
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}
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if (prev > -1 && code_length < 12)
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{
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if (code > dictionary_ind)
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "LZW error: code (%d) exceeds dictionary_ind (%d)", code, dictionary_ind);
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throw std::runtime_error("LZW error: code exceeds dictionary_ind.");
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}
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int ptr;
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if (code == dictionary_ind)
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{
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ptr = prev;
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while (dictionary[ptr].prev != -1)
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ptr = dictionary[ptr].prev;
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dictionary[dictionary_ind].byte = dictionary[ptr].byte;
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}
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else
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{
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ptr = code;
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while (dictionary[ptr].prev != -1)
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ptr = dictionary[ptr].prev;
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dictionary[dictionary_ind].byte = dictionary[ptr].byte;
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}
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dictionary[dictionary_ind].prev = prev;
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dictionary[dictionary_ind].len = dictionary[prev].len + 1;
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dictionary_ind++;
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if ((dictionary_ind == (1 << (code_length + 1))) && (code_length < 11))
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{
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code_length++;
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dictionary.resize(1 << (code_length + 1));
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}
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}
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prev = code;
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if (code < 0 || static_cast<size_t>(code) >= dictionary.size())
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Invalid LZW code %d, dictionary size %lu", code, static_cast<unsigned long>(dictionary.size()));
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throw std::runtime_error("LZW error: invalid code encountered");
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}
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int curCode = code;
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match_len = dictionary[curCode].len;
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while (curCode != -1)
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{
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out[dictionary[curCode].len - 1] = dictionary[curCode].byte;
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if (dictionary[curCode].prev == curCode)
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Internal error; self-reference detected.");
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throw std::runtime_error("Internal error in decompress: self-reference");
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}
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curCode = dictionary[curCode].prev;
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}
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out += match_len;
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}
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}
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std::vector<uint8_t> Gif::readSubBlocks(const uint8_t *&buffer)
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{
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std::vector<uint8_t> data;
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uint8_t block_size = *buffer;
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buffer++;
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while (block_size != 0)
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{
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data.insert(data.end(), buffer, buffer + block_size);
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buffer += block_size;
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block_size = *buffer;
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buffer++;
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}
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return data;
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}
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std::vector<uint8_t> Gif::processImageDescriptor(const uint8_t *&buffer, const std::vector<RGB> &gct, int resolution_bits)
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{
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ImageDescriptor image_descriptor;
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readBytes(buffer, &image_descriptor, sizeof(ImageDescriptor));
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uint8_t lzw_code_size;
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readBytes(buffer, &lzw_code_size, sizeof(uint8_t));
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std::vector<uint8_t> compressed_data = readSubBlocks(buffer);
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int uncompressed_data_length = image_descriptor.image_width * image_descriptor.image_height;
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std::vector<uint8_t> uncompressed_data(uncompressed_data_length);
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decompress(lzw_code_size, compressed_data.data(), static_cast<int>(compressed_data.size()), uncompressed_data.data());
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return uncompressed_data;
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}
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std::vector<uint32_t> Gif::loadPalette(const uint8_t *buffer)
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{
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uint8_t header[6];
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std::memcpy(header, buffer, 6);
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buffer += 6;
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ScreenDescriptor screen_descriptor;
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std::memcpy(&screen_descriptor, buffer, sizeof(ScreenDescriptor));
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buffer += sizeof(ScreenDescriptor);
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std::vector<uint32_t> global_color_table;
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if (screen_descriptor.fields & 0x80)
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{
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int global_color_table_size = 1 << (((screen_descriptor.fields & 0x07) + 1));
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global_color_table.resize(global_color_table_size);
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for (int i = 0; i < global_color_table_size; ++i)
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{
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uint8_t r = buffer[0];
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uint8_t g = buffer[1];
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uint8_t b = buffer[2];
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global_color_table[i] = (r << 16) | (g << 8) | b;
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buffer += 3;
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}
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}
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return global_color_table;
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}
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std::vector<uint8_t> Gif::processGifStream(const uint8_t *buffer, uint16_t &w, uint16_t &h)
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{
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uint8_t header[6];
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std::memcpy(header, buffer, 6);
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buffer += 6;
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std::string headerStr(reinterpret_cast<char *>(header), 6);
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if (headerStr != "GIF87a" && headerStr != "GIF89a")
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{
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SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Formato de archivo GIF inválido: %s", headerStr.c_str());
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throw std::runtime_error("Formato de archivo GIF inválido.");
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}
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SDL_LogInfo(SDL_LOG_CATEGORY_TEST, "Procesando GIF con cabecera: %s", headerStr.c_str());
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ScreenDescriptor screen_descriptor;
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readBytes(buffer, &screen_descriptor, sizeof(ScreenDescriptor));
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w = screen_descriptor.width;
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h = screen_descriptor.height;
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SDL_LogInfo(SDL_LOG_CATEGORY_TEST, "Resolución del GIF: %dx%d", w, h);
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int color_resolution_bits = ((screen_descriptor.fields & 0x70) >> 4) + 1;
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std::vector<RGB> global_color_table;
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if (screen_descriptor.fields & 0x80)
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{
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int global_color_table_size = 1 << (((screen_descriptor.fields & 0x07) + 1));
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global_color_table.resize(global_color_table_size);
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std::memcpy(global_color_table.data(), buffer, 3 * global_color_table_size);
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buffer += 3 * global_color_table_size;
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}
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uint8_t block_type = *buffer++;
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while (block_type != TRAILER)
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{
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if (block_type == EXTENSION_INTRODUCER)
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{
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uint8_t extension_label = *buffer++;
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switch (extension_label)
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{
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case GRAPHIC_CONTROL:
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{
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uint8_t blockSize = *buffer++;
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buffer += blockSize;
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uint8_t subBlockSize = *buffer++;
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while (subBlockSize != 0)
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{
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buffer += subBlockSize;
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subBlockSize = *buffer++;
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}
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break;
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}
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case APPLICATION_EXTENSION:
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case COMMENT_EXTENSION:
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case PLAINTEXT_EXTENSION:
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{
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uint8_t blockSize = *buffer++;
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buffer += blockSize;
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uint8_t subBlockSize = *buffer++;
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while (subBlockSize != 0)
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{
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buffer += subBlockSize;
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subBlockSize = *buffer++;
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}
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break;
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}
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default:
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{
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uint8_t blockSize = *buffer++;
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buffer += blockSize;
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uint8_t subBlockSize = *buffer++;
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while (subBlockSize != 0)
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{
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buffer += subBlockSize;
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subBlockSize = *buffer++;
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}
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break;
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}
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}
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}
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else if (block_type == IMAGE_DESCRIPTOR)
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{
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return processImageDescriptor(buffer, global_color_table, color_resolution_bits);
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}
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else
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{
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SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "Unrecognized block type: 0x%X", block_type);
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return std::vector<uint8_t>{};
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}
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block_type = *buffer++;
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}
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SDL_LogInfo(SDL_LOG_CATEGORY_TEST, "GIF procesado correctamente.");
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return std::vector<uint8_t>{};
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}
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std::vector<uint8_t> Gif::loadGif(const uint8_t *buffer, uint16_t &w, uint16_t &h)
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{
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return processGifStream(buffer, w, h);
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}
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} // namespace GIF
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