103 lines
2.9 KiB
C++
103 lines
2.9 KiB
C++
#pragma once
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#include <cstdint> // Para uint8_t, uint16_t, uint32_t
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#include <vector> // Para vector
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namespace GIF
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{
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// Constantes definidas con constexpr, en lugar de macros
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constexpr uint8_t EXTENSION_INTRODUCER = 0x21;
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constexpr uint8_t IMAGE_DESCRIPTOR = 0x2C;
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constexpr uint8_t TRAILER = 0x3B;
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constexpr uint8_t GRAPHIC_CONTROL = 0xF9;
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constexpr uint8_t APPLICATION_EXTENSION = 0xFF;
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constexpr uint8_t COMMENT_EXTENSION = 0xFE;
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constexpr uint8_t PLAINTEXT_EXTENSION = 0x01;
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#pragma pack(push, 1)
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struct ScreenDescriptor
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{
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uint16_t width;
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uint16_t height;
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uint8_t fields;
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uint8_t background_color_index;
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uint8_t pixel_aspect_ratio;
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};
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struct RGB
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{
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uint8_t r, g, b;
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};
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struct ImageDescriptor
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{
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uint16_t image_left_position;
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uint16_t image_top_position;
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uint16_t image_width;
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uint16_t image_height;
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uint8_t fields;
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};
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#pragma pack(pop)
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struct DictionaryEntry
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{
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uint8_t byte;
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int prev;
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int len;
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};
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struct Extension
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{
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uint8_t extension_code;
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uint8_t block_size;
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};
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struct GraphicControlExtension
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{
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uint8_t fields;
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uint16_t delay_time;
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uint8_t transparent_color_index;
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};
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struct ApplicationExtension
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{
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uint8_t application_id[8];
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uint8_t version[3];
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};
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struct PlaintextExtension
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{
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uint16_t left, top, width, height;
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uint8_t cell_width, cell_height;
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uint8_t foreground_color, background_color;
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};
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class Gif
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{
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public:
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// Descompone (uncompress) el bloque comprimido usando LZW.
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// Este método puede lanzar std::runtime_error en caso de error.
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void decompress(int code_length, const uint8_t *input, int input_length, uint8_t *out);
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// Carga la paleta (global color table) a partir de un buffer,
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// retornándola en un vector de uint32_t (cada color se compone de R, G, B).
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std::vector<uint32_t> loadPalette(const uint8_t *buffer);
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// Carga el stream GIF; devuelve un vector con los datos de imagen sin comprimir y
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// asigna el ancho y alto mediante referencias.
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std::vector<uint8_t> loadGif(const uint8_t *buffer, uint16_t &w, uint16_t &h);
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private:
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// Lee los sub-bloques de datos y los acumula en un std::vector<uint8_t>.
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std::vector<uint8_t> readSubBlocks(const uint8_t *&buffer);
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// Procesa el Image Descriptor y retorna el vector de datos sin comprimir.
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std::vector<uint8_t> processImageDescriptor(const uint8_t *&buffer, const std::vector<RGB> &gct, int resolution_bits);
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// Procesa el stream completo del GIF y devuelve los datos sin comprimir.
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std::vector<uint8_t> processGifStream(const uint8_t *buffer, uint16_t &w, uint16_t &h);
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};
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} // namespace GIF
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