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#include "tinyff/image/png.h"
#include "tinyff/dbg.h"
#include "png.h"
ff_result ff_png_isvalid(ff_stream *stream)
{
ff_dprintf("png: validating signature\n");
char raw_sig[8];
if (stream->read(raw_sig, 8, stream->user) != 8) {
ff_dprintf("png: failed to read signature bytes\n");
return FF_RESULT_ERROR_INVALID_FILE;
}
ff_dprintf(
"png: signature read: %02X %02X %02X %02X %02X %02X %02X %02X\n",
raw_sig[0], raw_sig[1], raw_sig[2], raw_sig[3],
raw_sig[4], raw_sig[5], raw_sig[6], raw_sig[7]
);
if (memcmp(raw_sig, PNG_SIGNATURE, 8) != 0) {
ff_dprintf("png: signature mismatch\n");
return FF_RESULT_ERROR_INVALID_PNG_SIGNITURE;
}
ff_dprintf("png: signature valid\n");
return FF_RESULT_OK;
}
ff_result ff_open_png(ff_stream *stream, ff_png_ctx **out_ctx)
{
ff_png_ctx *ctx = malloc(sizeof(ff_png_ctx));
if (!ctx) return FF_RESULT_ERROR_MEMORY_ALLOCATION;
// Init
memset(ctx, 0, sizeof(*ctx));
ctx->image_mode = FF_PNG_MODE_NONE;
ctx->raw = stream;
ctx->last_error = FF_RESULT_OK;
if (ctx->raw->read == NULL) {
ff_dprintf("png: stream failed to read\n");
free(ctx);
ctx->last_error = FF_RESULT_ERROR_READ_FILE_FAILURE;
return FF_RESULT_ERROR_READ_FILE_FAILURE;
}
ff_dprintf("png: stream read successfully\n");
ff_result res = ff_png_isvalid(ctx->raw);
if (res != FF_RESULT_OK) {
ff_dprintf("png: validation failed (%d)\n", res);
free(ctx);
ctx->last_error = res;
return res;
}
ff_dprintf("png: validation passed\n");
ctx->valid = true;
*out_ctx = ctx;
ff_dprintf("png: open_png reached WIP end\n");
return FF_RESULT_OK;
}
// Handlers
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
}
}
ff_result ff_png_header_handler(uint8_t *buf, size_t len, ff_png_ctx *ctx)
{
ff_dprintf("png: IHDR chunk received (len=%zu)\n", len);
if (len != 13) {
ff_dprintf("png: invalid IHDR length\n");
return FF_RESULT_ERROR_INVALID_FILE;
}
uint32_t w = get_big_endian(buf);
uint32_t h = get_big_endian(buf + 4);
ff_dprintf("Width: %u\n", w);
ff_dprintf("Height: %u\n", h);
ff_dprintf("Bit depth: %u\n", buf[8]);
ff_dprintf("Color type: %u\n", buf[9]);
ff_dprintf("Compression method: %u\n", buf[10]);
ff_dprintf("Filter method: %u\n", buf[11]);
ff_dprintf("Interlace method: %u\n", buf[12]);
ctx->width = w;
ctx->height = h;
ctx->bit_depth = buf[8];
ctx->color_type = buf[9];
ctx->interlace_method = buf[12];
ff_dprintf("png: IHDR stored in context\n");
return FF_RESULT_OK;
}
ff_result ff_png_palette_handler(uint8_t *buf, size_t len, ff_png_ctx *ctx)
{
ff_dprintf("png: PLTE chunk received (len=%zu)\n", len);
if (len % 3 != 0) {
ff_dprintf("png: invalid PLTE length\n");
return FF_RESULT_ERROR_INVALID_FILE;
}
uint16_t num_entries = len / 3;
ff_dprintf("png: PLTE contains %u palette entries\n", num_entries);
ctx->palette_size = num_entries;
ctx->palette = malloc(len);
if (!ctx->palette) return FF_RESULT_ERROR_MEMORY_ALLOCATION;
for (uint16_t i = 0; i < num_entries; i++) {
// There's 4 bytes per entry just because if there's
// a tRNS chunk later, we can just fill in the alpha values
ctx->palette[i * 4 + 0] = buf[i * 3 + 0]; // R
ctx->palette[i * 4 + 1] = buf[i * 3 + 1]; // G
ctx->palette[i * 4 + 2] = buf[i * 3 + 2]; // B
}
return FF_RESULT_OK;
}
ff_result ff_png_data_handler(uint8_t *buf, size_t len, ff_png_ctx *ctx)
{
ff_dprintf("png: IDAT chunk received (len=%zu)\n", len);
uint8_t *uncompressed_data = NULL;
// Getting the size is weird cause it could the sample count
// could be different based on color type and bit depth
size_t uncompressed_size = ctx->width * ctx->height * ff_png_bpp(ctx);
uncompressed_data = malloc(uncompressed_size);
if (!uncompressed_data) {
ff_dprintf("png: failed to allocate memory for uncompressed data\n");
return FF_RESULT_ERROR_MEMORY_ALLOCATION;
}
if (tinf_uncompress(uncompressed_data, uncompressed_size, buf, len) != TINF_OK) {
ff_dprintf("png: failed to uncompress IDAT data\n");
free(uncompressed_data);
return FF_RESULT_ERROR_DECOMPRESSION_FAILURE;
}
ff_dprintf("png: IDAT data uncompressed successfully\n");
// Now we parse the uncompressed data into our pixel buffer
// However I don't understand Adam7 so interlaced images are not supported yet
if (ctx->interlace_method != 0) {
ff_dprintf("png: interlaced images are not supported yet\n");
free(uncompressed_data);
return FF_RESULT_WARN_NO_IMPL;
}
// Now I am very inexperienced so I'm doing what I think is right
// TODO: Review this code later
// Iterate over every scanline
for (int iline = 0; iline < ctx->height; iline++) {
// Make some variables so it's not hella unreadable
size_t bpp = ff_png_bpp(ctx);
size_t scanline_start = iline * (1 + (ctx->width * bpp));
uint8_t filter_type = uncompressed_data[scanline_start];
//
}
// Ahh yes, the memory demons
// We must not fall before them
// We must study the patterns of their ways
// The buddha has truely been testing us
free(uncompressed_data);
return FF_RESULT_WARN_NO_IMPL;
}
ff_result ff_png_end_handler(uint8_t *buf, size_t len, ff_png_ctx *ctx)
{
ff_dprintf("png: IEND chunk received (len=%zu)\n", len);
ff_dprintf("png: all chunks received\n");
return FF_RESULT_OK;
}
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