BFR 2 (Big Fucking Restructureixon) (dos)
Este es el primer commit de la reestructuració. En caso de pánico, tornar al commit anterior. - [FIX] Llevada basura varia (pos no en queda...) - [NEW] mogut el codi font a ./source/ - [NEW] lagueirtofile nou per a compilar en windows y linux, release i debug. mac res, que no se ni si funciona lagueirto. - [NEW] WARNING!!! make ja no funciona. Mantinc encara el Makefile per a referència.
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174
source/gifenc.h
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174
source/gifenc.h
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <string.h>
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#define MAX_DICT_SIZE 4096
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namespace gif
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{
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typedef struct {
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int prefix;
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uint8_t character;
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} DictEntry;
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typedef struct {
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uint8_t *data;
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size_t size;
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size_t capacity;
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int bit_pos;
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uint32_t bit_buffer;
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} BitStream;
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void bitstream_init(BitStream *bs) {
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bs->capacity = 256;
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bs->size = 0;
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bs->data = (uint8_t*)malloc(bs->capacity);
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bs->bit_pos = 0;
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bs->bit_buffer = 0;
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}
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void bitstream_write(BitStream *bs, uint16_t code, int code_size) {
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bs->bit_buffer |= ((uint32_t)code) << bs->bit_pos;
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bs->bit_pos += code_size;
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while (bs->bit_pos >= 8) {
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if (bs->size >= bs->capacity) {
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bs->capacity *= 2;
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bs->data = (uint8_t*)realloc(bs->data, bs->capacity);
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}
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bs->data[bs->size++] = bs->bit_buffer & 0xFF;
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bs->bit_buffer >>= 8;
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bs->bit_pos -= 8;
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}
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}
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void bitstream_flush(BitStream *bs) {
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if (bs->bit_pos > 0) {
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if (bs->size >= bs->capacity) {
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bs->capacity *= 2;
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bs->data = (uint8_t*)realloc(bs->data, bs->capacity);
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}
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bs->data[bs->size++] = bs->bit_buffer & 0xFF;
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}
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}
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uint8_t *lzw_compress(uint8_t *input, int width, int height, int min_code_size, size_t *out_size) {
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int clear_code = 1 << min_code_size;
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int end_code = clear_code + 1;
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int next_code = end_code + 1;
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int code_size = min_code_size + 1;
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DictEntry dict[MAX_DICT_SIZE];
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int dict_len = next_code;
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BitStream bs;
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bitstream_init(&bs);
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bitstream_write(&bs, clear_code, code_size);
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int prefix = input[0];
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for (int i = 1; i < width * height; i++) {
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uint8_t c = input[i];
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// Search for prefix + c in dictionary
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int found = -1;
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for (int j = end_code + 1; j < dict_len; j++) {
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if (dict[j].prefix == prefix && dict[j].character == c) {
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found = j;
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break;
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}
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}
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if (found != -1) {
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prefix = found; // Extend prefix
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} else {
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bitstream_write(&bs, prefix, code_size); // Emit current prefix
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if (dict_len < MAX_DICT_SIZE) {
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if (dict_len == (1 << code_size) && code_size < 12) code_size++;
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dict[dict_len].prefix = prefix;
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dict[dict_len].character = c;
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dict_len++;
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} else {
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bitstream_write(&bs, clear_code, code_size);
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dict_len = end_code + 1;
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code_size = min_code_size + 1;
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}
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prefix = c; // Start new prefix
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}
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}
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// Emit final prefix and end code
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bitstream_write(&bs, prefix, code_size);
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bitstream_write(&bs, end_code, code_size);
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bitstream_flush(&bs);
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*out_size = bs.size;
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return bs.data;
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}
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void write_gif(const char *filename, uint8_t *pixels, int width, int height, uint8_t *palette, int palette_size) {
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FILE *f = fopen(filename, "wb");
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if (!f) {
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perror("Failed to open file");
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return;
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}
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// Header
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fwrite("GIF89a", 1, 6, f);
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// Determine min_code_size from palette_size
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int palette_depth = 0;
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while ((1 << palette_depth) < palette_size) palette_depth++;
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const int min_code_size = palette_depth < 2 ? 2 : palette_depth; // GIF spec requires at least 2
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printf("min_code_size: %i\n", palette_depth);
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// Logical Screen Descriptor
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uint8_t packed_field = palette ? (0x80 | ((palette_depth - 1) << 4) | (palette_depth - 1)) : 0x00;
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uint8_t screen_desc[] = {
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uint8_t(width & 0xFF), uint8_t((width >> 8) & 0xFF),
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uint8_t(height & 0xFF), uint8_t((height >> 8) & 0xFF),
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packed_field, // GCT flag + color resolution + size
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0x00, // Background color index
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0x00 // Pixel aspect ratio
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};
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fwrite(screen_desc, 1, sizeof(screen_desc), f);
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// Global Color Table (if provided)
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if (palette) {
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int gct_size = 1 << palette_depth;
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fwrite(palette, 1, gct_size * 3, f);
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}
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// Image Descriptor
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uint8_t image_desc[] = {
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0x2C, 0, 0, 0, 0,
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uint8_t(width & 0xFF), uint8_t((width >> 8) & 0xFF),
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uint8_t(height & 0xFF), uint8_t((height >> 8) & 0xFF),
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0x00 // No local color table
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};
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fwrite(image_desc, 1, sizeof(image_desc), f);
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// LZW-compressed image data
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fwrite(&min_code_size, 1, 1, f);
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size_t compressed_size;
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uint8_t *compressed = lzw_compress(pixels, width, height, min_code_size, &compressed_size);
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// Write as sub-blocks
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size_t offset = 0;
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while (offset < compressed_size) {
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uint8_t block_size = (compressed_size - offset > 255) ? 255 : (uint8_t)(compressed_size - offset);
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fwrite(&block_size, 1, 1, f);
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fwrite(compressed + offset, 1, block_size, f);
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offset += block_size;
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}
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fputc(0x00, f); // Block terminator
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// Trailer
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fputc(0x3B, f);
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free(compressed);
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fclose(f);
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}
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}
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