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#ifndef PNG_H
#define PNG_H
#include <stdint.h>
#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include "tinyff/result.h"
#include "tinyff/common.h"
#include "tinyff/stream.h"
// External
#include "ext/tinf.h"
static const unsigned char PNG_SIGNATURE[8] = {
0x89, 'P', 'N', 'G', 0x0D, 0x0A, 0x1A, 0x0A
};
typedef enum {
FF_PNG_MODE_NONE = 0,
FF_PNG_MODE_DIRECT_COLOR, // pixels
FF_PNG_MODE_PALETTE // palette
} ff_png_mode;
typedef struct {
// Raw stream handle
ff_stream *raw;
// Image dimensions
uint32_t width;
uint32_t height;
// Color information
uint8_t bit_depth;
uint8_t color_type;
// Interlace method
uint8_t interlace_method;
// Image data
ff_png_mode image_mode;
union {
uint8_t* pixels;
uint8_t* imap; // Map of all the indices defines in PLTE
} data;
// Palette (if needed; can be left NULL if it's direct color)
uint8_t* palette;
uint32_t palette_size;
bool valid;
ff_result last_error;
} ff_png_ctx;
// Small BpP helper function
static inline uint16_t ff_png_bpp(ff_png_ctx *ctx)
{
int16_t byte_depth = ctx->bit_depth / 8;
switch (ctx->color_type) {
case 0: // Grayscale
return byte_depth * 1; // Gray
case 2: // Truecolor
return byte_depth * 3; // R, G, B
case 3: // Indexed-color
return byte_depth * 1; // Index
case 4: // Grayscale with alpha
return byte_depth * 2; // Gray w/ alpha
case 6: // Truecolor with alpha
return byte_depth * 4; // R, G, B w/ alpha
default:
return 0; // damn, you corrupt
}
}
// Chunk handling
typedef (*ff_png_chunk_handler_ptr)(uint8_t *buf, size_t len, ff_png_ctx* ctx);
typedef struct {
const char *type;
ff_png_chunk_handler_ptr handler;
} ff_png_chunk_handler;
// Handler declarations
// Massive W.I.P
// Required by definition
ff_result ff_png_header_handler(uint8_t *buf, size_t len, ff_png_ctx* ctx); // IHDR
ff_result ff_png_palette_handler(uint8_t *buf, size_t len, ff_png_ctx* ctx); // PLTE
ff_result ff_png_data_handler(uint8_t *buf, size_t len, ff_png_ctx* ctx); // IDAT
ff_result ff_png_end_handler(uint8_t *buf, size_t len, ff_png_ctx* ctx); // IEND
const ff_png_chunk_handler ff_png_chunk_handlers[] = {
{"IHDR", ff_png_header_handler},
{"IDAT", ff_png_data_handler},
{"IEND", ff_png_end_handler},
{"PLTE", ff_png_palette_handler},
// From now on, the handlers will be for ancillary chunks
{NULL, NULL} // Terminator
};
ff_result ff_png_isvalid(ff_stream *stream);
ff_result ff_open_png(ff_stream *stream, ff_png_ctx **out_ctx);
#endif
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