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RetroArch/gfx/rpng/rpng.c

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/* RetroArch - A frontend for libretro.
* Copyright (C) 2010-2013 - Hans-Kristian Arntzen
*
* RetroArch is free software: you can redistribute it and/or modify it under the terms
* of the GNU General Public License as published by the Free Software Found-
* ation, either version 3 of the License, or (at your option) any later version.
*
* RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with RetroArch.
* If not, see <http://www.gnu.org/licenses/>.
*/
#include "rpng.h"
#ifdef WANT_MINIZ
#include "../../deps/miniz/zlib.h"
#else
#include <zlib.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "../../hash.h"
// Decodes a subset of PNG standard.
// Does not handle much outside 24/32-bit RGB(A) images.
//
// Missing: Adam7 interlace, 16 bpp, various color formats.
#undef GOTO_END_ERROR
#define GOTO_END_ERROR() do { \
fprintf(stderr, "[RPNG]: Error in line %d.\n", __LINE__); \
ret = false; \
goto end; \
} while(0)
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
#endif
static const uint8_t png_magic[8] = {
0x89, 'P', 'N', 'G', 0x0d, 0x0a, 0x1a, 0x0a,
};
struct png_chunk
{
uint32_t size;
char type[4];
uint8_t *data;
};
struct png_ihdr
{
uint32_t width;
uint32_t height;
uint8_t depth;
uint8_t color_type;
uint8_t compression;
uint8_t filter;
uint8_t interlace;
};
enum png_chunk_type
{
PNG_CHUNK_NOOP = 0,
PNG_CHUNK_ERROR,
PNG_CHUNK_IHDR,
PNG_CHUNK_IDAT,
PNG_CHUNK_PLTE,
PNG_CHUNK_IEND
};
static uint32_t dword_be(const uint8_t *buf)
{
return (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3] << 0);
}
static bool read_chunk_header(FILE *file, struct png_chunk *chunk)
{
uint8_t dword[4] = {0};
if (fread(dword, 1, 4, file) != 4)
return false;
chunk->size = dword_be(dword);
if (fread(chunk->type, 1, 4, file) != 4)
return false;
return true;
}
struct
{
const char *id;
enum png_chunk_type type;
} static const chunk_map[] = {
{ "IHDR", PNG_CHUNK_IHDR },
{ "IDAT", PNG_CHUNK_IDAT },
{ "IEND", PNG_CHUNK_IEND },
{ "PLTE", PNG_CHUNK_PLTE },
};
struct idat_buffer
{
uint8_t *data;
size_t size;
};
static enum png_chunk_type png_chunk_type(const struct png_chunk *chunk)
{
for (unsigned i = 0; i < ARRAY_SIZE(chunk_map); i++)
{
if (memcmp(chunk->type, chunk_map[i].id, 4) == 0)
return chunk_map[i].type;
}
return PNG_CHUNK_NOOP;
}
static bool png_read_chunk(FILE *file, struct png_chunk *chunk)
{
free(chunk->data);
chunk->data = (uint8_t*)calloc(1, chunk->size + sizeof(uint32_t)); // CRC32
if (!chunk->data)
return false;
if (fread(chunk->data, 1, chunk->size + sizeof(uint32_t), file) != (chunk->size + sizeof(uint32_t)))
{
free(chunk->data);
return false;
}
// Ignore CRC.
return true;
}
static void png_free_chunk(struct png_chunk *chunk)
{
free(chunk->data);
chunk->data = NULL;
}
static bool png_parse_ihdr(FILE *file, struct png_chunk *chunk, struct png_ihdr *ihdr)
{
bool ret = true;
if (!png_read_chunk(file, chunk))
return false;
if (chunk->size != 13)
GOTO_END_ERROR();
ihdr->width = dword_be(chunk->data + 0);
ihdr->height = dword_be(chunk->data + 4);
ihdr->depth = chunk->data[8];
ihdr->color_type = chunk->data[9];
ihdr->compression = chunk->data[10];
ihdr->filter = chunk->data[11];
ihdr->interlace = chunk->data[12];
if (ihdr->width == 0 || ihdr->height == 0)
GOTO_END_ERROR();
if (ihdr->color_type == 2 || ihdr->color_type == 4 || ihdr->color_type == 6)
{
if (ihdr->depth != 8 && ihdr->depth != 16)
GOTO_END_ERROR();
}
else if (ihdr->color_type == 0)
{
static const unsigned valid_bpp[] = { 1, 2, 4, 8, 16 };
bool correct_bpp = false;
for (unsigned i = 0; i < ARRAY_SIZE(valid_bpp); i++)
{
if (valid_bpp[i] == ihdr->depth)
{
correct_bpp = true;
break;
}
}
if (!correct_bpp)
GOTO_END_ERROR();
}
else if (ihdr->color_type == 3)
{
static const unsigned valid_bpp[] = { 1, 2, 4, 8 };
bool correct_bpp = false;
for (unsigned i = 0; i < ARRAY_SIZE(valid_bpp); i++)
{
if (valid_bpp[i] == ihdr->depth)
{
correct_bpp = true;
break;
}
}
if (!correct_bpp)
GOTO_END_ERROR();
}
else
GOTO_END_ERROR();
#ifdef RPNG_TEST
fprintf(stderr, "IHDR: (%u x %u), bpc = %u, palette = %s, color = %s, alpha = %s, adam7 = %s.\n",
ihdr->width, ihdr->height,
ihdr->depth, ihdr->color_type == 3 ? "yes" : "no",
ihdr->color_type & 2 ? "yes" : "no",
ihdr->color_type & 4 ? "yes" : "no",
ihdr->interlace == 1 ? "yes" : "no");
#endif
if (ihdr->compression != 0)
GOTO_END_ERROR();
//if (ihdr->interlace != 0) // No Adam7 supported.
// GOTO_END_ERROR();
end:
png_free_chunk(chunk);
return ret;
}
// Paeth prediction filter.
static inline int paeth(int a, int b, int c)
{
int p = a + b - c;
int pa = abs(p - a);
int pb = abs(p - b);
int pc = abs(p - c);
if (pa <= pb && pa <= pc)
return a;
else if (pb <= pc)
return b;
else
return c;
}
static inline void copy_line_rgb(uint32_t *data, const uint8_t *decoded, unsigned width, unsigned bpp)
{
bpp /= 8;
for (unsigned i = 0; i < width; i++)
{
uint32_t r = *decoded;
decoded += bpp;
uint32_t g = *decoded;
decoded += bpp;
uint32_t b = *decoded;
decoded += bpp;
data[i] = (0xffu << 24) | (r << 16) | (g << 8) | (b << 0);
}
}
static inline void copy_line_rgba(uint32_t *data, const uint8_t *decoded, unsigned width, unsigned bpp)
{
bpp /= 8;
for (unsigned i = 0; i < width; i++)
{
uint32_t r = *decoded;
decoded += bpp;
uint32_t g = *decoded;
decoded += bpp;
uint32_t b = *decoded;
decoded += bpp;
uint32_t a = *decoded;
decoded += bpp;
data[i] = (a << 24) | (r << 16) | (g << 8) | (b << 0);
}
}
static inline void copy_line_bw(uint32_t *data, const uint8_t *decoded, unsigned width, unsigned depth)
{
if (depth == 16)
{
for (unsigned i = 0; i < width; i++)
{
uint32_t val = decoded[i << 1];
data[i] = (val * 0x010101) | (0xffu << 24);
}
}
else
{
static const unsigned mul_table[] = { 0, 0xff, 0x55, 0, 0x11, 0, 0, 0, 0x01 };
unsigned mul = mul_table[depth];
unsigned mask = (1 << depth) - 1;
for (unsigned i = 0, bit = 0; i < width; i++, bit += depth)
{
unsigned byte = bit >> 3;
unsigned val = decoded[byte] >> (8 - depth - (bit & 7));
val &= mask;
val *= mul;
data[i] = (val * 0x010101) | (0xffu << 24);
}
}
}
static inline void copy_line_gray_alpha(uint32_t *data, const uint8_t *decoded, unsigned width,
unsigned bpp)
{
bpp /= 8;
for (unsigned i = 0; i < width; i++)
{
uint32_t gray = *decoded;
decoded += bpp;
uint32_t alpha = *decoded;
decoded += bpp;
data[i] = (gray * 0x010101) | (alpha << 24);
}
}
static inline void copy_line_plt(uint32_t *data, const uint8_t *decoded, unsigned width, unsigned depth, const uint32_t *palette)
{
unsigned mask = (1 << depth) - 1;
for (unsigned i = 0, bit = 0; i < width; i++, bit += depth)
{
unsigned byte = bit >> 3;
unsigned val = decoded[byte] >> (8 - depth - (bit & 7));
val &= mask;
data[i] = palette[val];
}
}
static void png_pass_geom(const struct png_ihdr *ihdr,
unsigned width, unsigned height,
unsigned *bpp_out, unsigned *pitch_out, size_t *pass_size)
{
unsigned bpp;
unsigned pitch;
switch (ihdr->color_type)
{
case 0:
bpp = (ihdr->depth + 7) / 8;
pitch = (ihdr->width * ihdr->depth + 7) / 8;
break;
case 2:
bpp = (ihdr->depth * 3 + 7) / 8;
pitch = (ihdr->width * ihdr->depth * 3 + 7) / 8;
break;
case 3:
bpp = (ihdr->depth + 7) / 8;
pitch = (ihdr->width * ihdr->depth + 7) / 8;
break;
case 4:
bpp = (ihdr->depth * 2 + 7) / 8;
pitch = (ihdr->width * ihdr->depth * 2 + 7) / 8;
break;
case 6:
bpp = (ihdr->depth * 4 + 7) / 8;
pitch = (ihdr->width * ihdr->depth * 4 + 7) / 8;
break;
default:
bpp = 0;
pitch = 0;
break;
}
if (pass_size)
*pass_size = (pitch + 1) * ihdr->height;
if (bpp_out)
*bpp_out = bpp;
if (pitch_out)
*pitch_out = pitch;
}
static bool png_reverse_filter(uint32_t *data, const struct png_ihdr *ihdr,
const uint8_t *inflate_buf, size_t inflate_buf_size, const uint32_t *palette)
{
bool ret = true;
unsigned bpp;
unsigned pitch;
size_t pass_size;
png_pass_geom(ihdr, ihdr->width, ihdr->height, &bpp, &pitch, &pass_size);
if (inflate_buf_size < pass_size)
return false;
uint8_t *prev_scanline = (uint8_t*)calloc(1, pitch);
uint8_t *decoded_scanline = (uint8_t*)calloc(1, pitch);
if (!decoded_scanline || !decoded_scanline)
GOTO_END_ERROR();
for (unsigned h = 0; h < ihdr->height;
h++, inflate_buf += pitch, data += ihdr->width)
{
unsigned filter = *inflate_buf++;
switch (filter)
{
case 0: // None
memcpy(decoded_scanline, inflate_buf, pitch);
break;
case 1: // Sub
for (unsigned i = 0; i < bpp; i++)
decoded_scanline[i] = inflate_buf[i];
for (unsigned i = bpp; i < pitch; i++)
decoded_scanline[i] = decoded_scanline[i - bpp] + inflate_buf[i];
break;
case 2: // Up
for (unsigned i = 0; i < pitch; i++)
decoded_scanline[i] = prev_scanline[i] + inflate_buf[i];
break;
case 3: // Average
for (unsigned i = 0; i < bpp; i++)
{
uint8_t avg = prev_scanline[i] >> 1;
decoded_scanline[i] = avg + inflate_buf[i];
}
for (unsigned i = bpp; i < pitch; i++)
{
uint8_t avg = (decoded_scanline[i - bpp] + prev_scanline[i]) >> 1;
decoded_scanline[i] = avg + inflate_buf[i];
}
break;
case 4: // Paeth
for (unsigned i = 0; i < bpp; i++)
decoded_scanline[i] = paeth(0, prev_scanline[i], 0) + inflate_buf[i];
for (unsigned i = bpp; i < pitch; i++)
decoded_scanline[i] = paeth(decoded_scanline[i - bpp], prev_scanline[i], prev_scanline[i - bpp]) + inflate_buf[i];
break;
default:
GOTO_END_ERROR();
}
if (ihdr->color_type == 0)
copy_line_bw(data, decoded_scanline, ihdr->width, ihdr->depth);
else if (ihdr->color_type == 2)
copy_line_rgb(data, decoded_scanline, ihdr->width, ihdr->depth);
else if (ihdr->color_type == 3)
copy_line_plt(data, decoded_scanline, ihdr->width, ihdr->depth, palette);
else if (ihdr->color_type == 4)
copy_line_gray_alpha(data, decoded_scanline, ihdr->width, ihdr->depth);
else if (ihdr->color_type == 6)
copy_line_rgba(data, decoded_scanline, ihdr->width, ihdr->depth);
memcpy(prev_scanline, decoded_scanline, pitch);
}
end:
free(decoded_scanline);
free(prev_scanline);
return ret;
}
struct adam7_pass
{
unsigned x;
unsigned y;
unsigned stride_x;
unsigned stride_y;
};
static void deinterlace_pass(uint32_t *data, const struct png_ihdr *ihdr,
const uint32_t *input, unsigned pass_width, unsigned pass_height, const struct adam7_pass *pass)
{
data += pass->y * ihdr->width + pass->x;
for (unsigned y = 0; y < pass_height; y++, data += ihdr->width * pass->stride_y, input += pass_width)
{
uint32_t *out = data;
for (unsigned x = 0; x < pass_width; x++, out += pass->stride_x)
*out = input[x];
}
}
static bool png_reverse_filter_adam7(uint32_t *data, const struct png_ihdr *ihdr,
const uint8_t *inflate_buf, size_t inflate_buf_size, const uint32_t *palette)
{
static const struct adam7_pass passes[] = {
{ 0, 0, 8, 8 },
{ 4, 0, 8, 8 },
{ 0, 4, 4, 8 },
{ 2, 0, 4, 4 },
{ 0, 2, 2, 4 },
{ 1, 0, 2, 2 },
{ 0, 1, 1, 2 },
};
for (unsigned pass = 0; pass < ARRAY_SIZE(passes); pass++)
{
if (ihdr->width <= passes[pass].x || ihdr->height <= passes[pass].y) // Empty pass
continue;
unsigned pass_width = (ihdr->width - passes[pass].x + passes[pass].stride_x - 1) / passes[pass].stride_x;
unsigned pass_height = (ihdr->height - passes[pass].y + passes[pass].stride_y - 1) / passes[pass].stride_y;
uint32_t *tmp_data = (uint32_t*)malloc(pass_width * pass_height * sizeof(uint32_t));
if (!tmp_data)
return false;
struct png_ihdr tmp_ihdr = *ihdr;
tmp_ihdr.width = pass_width;
tmp_ihdr.height = pass_height;
size_t pass_size;
png_pass_geom(&tmp_ihdr, pass_width, pass_height, NULL, NULL, &pass_size);
if (pass_size > inflate_buf_size)
{
free(tmp_data);
return false;
}
if (!png_reverse_filter(tmp_data, &tmp_ihdr, inflate_buf, pass_size, palette))
{
free(tmp_data);
return false;
}
inflate_buf += pass_size;
inflate_buf_size -= pass_size;
deinterlace_pass(data, ihdr, tmp_data, pass_width, pass_height, &passes[pass]);
free(tmp_data);
}
return true;
}
static bool png_append_idat(FILE *file, const struct png_chunk *chunk, struct idat_buffer *buf)
{
uint8_t *new_buffer = (uint8_t*)realloc(buf->data, buf->size + chunk->size);
if (!new_buffer)
return false;
buf->data = new_buffer;
if (fread(buf->data + buf->size, 1, chunk->size, file) != chunk->size)
return false;
if (fseek(file, sizeof(uint32_t), SEEK_CUR) < 0)
return false;
buf->size += chunk->size;
return true;
}
static bool png_read_plte(FILE *file, uint32_t *buffer, unsigned entries)
{
if (entries > 256)
return false;
uint8_t buf[256 * 3];
if (fread(buf, 3, entries, file) != entries)
return false;
for (unsigned i = 0; i < entries; i++)
{
uint32_t r = buf[3 * i + 0];
uint32_t g = buf[3 * i + 1];
uint32_t b = buf[3 * i + 2];
buffer[i] = (r << 16) | (g << 8) | (b << 0) | (0xffu << 24);
}
if (fseek(file, sizeof(uint32_t), SEEK_CUR) < 0)
return false;
return true;
}
bool rpng_load_image_argb(const char *path, uint32_t **data, unsigned *width, unsigned *height)
{
*data = NULL;
*width = 0;
*height = 0;
bool ret = true;
FILE *file = fopen(path, "rb");
if (!file)
return false;
fseek(file, 0, SEEK_END);
long file_len = ftell(file);
rewind(file);
bool has_ihdr = false;
bool has_idat = false;
bool has_iend = false;
bool has_plte = false;
uint8_t *inflate_buf = NULL;
size_t inflate_buf_size = 0;
z_stream stream = {0};
struct idat_buffer idat_buf = {0};
struct png_ihdr ihdr = {0};
uint32_t palette[256] = {0};
char header[8];
if (fread(header, 1, sizeof(header), file) != sizeof(header))
GOTO_END_ERROR();
if (memcmp(header, png_magic, sizeof(png_magic)) != 0)
GOTO_END_ERROR();
// feof() apparently isn't triggered after a seek (IEND).
for (long pos = ftell(file); pos < file_len && pos >= 0; pos = ftell(file))
{
struct png_chunk chunk = {0};
if (!read_chunk_header(file, &chunk))
GOTO_END_ERROR();
switch (png_chunk_type(&chunk))
{
case PNG_CHUNK_NOOP:
default:
if (fseek(file, chunk.size + sizeof(uint32_t), SEEK_CUR) < 0)
GOTO_END_ERROR();
break;
case PNG_CHUNK_ERROR:
GOTO_END_ERROR();
case PNG_CHUNK_IHDR:
if (has_ihdr || has_idat || has_iend)
GOTO_END_ERROR();
if (!png_parse_ihdr(file, &chunk, &ihdr))
GOTO_END_ERROR();
has_ihdr = true;
break;
case PNG_CHUNK_PLTE:
if (!has_ihdr || has_plte || has_iend || has_idat)
GOTO_END_ERROR();
if (chunk.size % 3)
GOTO_END_ERROR();
if (!png_read_plte(file, palette, chunk.size / 3))
GOTO_END_ERROR();
has_plte = true;
break;
case PNG_CHUNK_IDAT:
if (!has_ihdr || has_iend || (ihdr.color_type == 3 && !has_plte))
GOTO_END_ERROR();
if (!png_append_idat(file, &chunk, &idat_buf))
GOTO_END_ERROR();
has_idat = true;
break;
case PNG_CHUNK_IEND:
if (!has_ihdr || !has_idat)
GOTO_END_ERROR();
if (fseek(file, sizeof(uint32_t), SEEK_CUR) < 0)
GOTO_END_ERROR();
has_iend = true;
break;
}
}
if (!has_ihdr || !has_idat || !has_iend)
GOTO_END_ERROR();
if (inflateInit(&stream) != Z_OK)
GOTO_END_ERROR();
png_pass_geom(&ihdr, ihdr.width, ihdr.height, NULL, NULL, &inflate_buf_size);
if (ihdr.interlace == 1) // To be sure.
inflate_buf_size *= 2;
inflate_buf = (uint8_t*)malloc(inflate_buf_size);
if (!inflate_buf)
GOTO_END_ERROR();
stream.next_in = idat_buf.data;
stream.avail_in = idat_buf.size;
stream.avail_out = inflate_buf_size;
stream.next_out = inflate_buf;
if (inflate(&stream, Z_FINISH) != Z_STREAM_END)
{
inflateEnd(&stream);
GOTO_END_ERROR();
}
inflateEnd(&stream);
*width = ihdr.width;
*height = ihdr.height;
*data = (uint32_t*)malloc(ihdr.width * ihdr.height * sizeof(uint32_t));
if (!*data)
GOTO_END_ERROR();
if (ihdr.interlace == 1)
{
if (!png_reverse_filter_adam7(*data, &ihdr, inflate_buf, stream.total_out, palette))
GOTO_END_ERROR();
}
else if (!png_reverse_filter(*data, &ihdr, inflate_buf, stream.total_out, palette))
GOTO_END_ERROR();
end:
if (file)
fclose(file);
if (!ret)
free(*data);
free(idat_buf.data);
free(inflate_buf);
return ret;
}
#ifdef HAVE_ZLIB_DEFLATE
static void dword_write_be(uint8_t *buf, uint32_t val)
{
*buf++ = (uint8_t)(val >> 24);
*buf++ = (uint8_t)(val >> 16);
*buf++ = (uint8_t)(val >> 8);
*buf++ = (uint8_t)(val >> 0);
}
static bool png_write_crc(FILE *file, const uint8_t *data, size_t size)
{
uint32_t crc = crc32_calculate(data, size);
uint8_t crc_raw[4] = {0};
dword_write_be(crc_raw, crc);
return fwrite(crc_raw, 1, sizeof(crc_raw), file) == sizeof(crc_raw);
}
static bool png_write_ihdr(FILE *file, const struct png_ihdr *ihdr)
{
uint8_t ihdr_raw[] = {
'0', '0', '0', '0', // Size
'I', 'H', 'D', 'R',
0, 0, 0, 0, // Width
0, 0, 0, 0, // Height
ihdr->depth,
ihdr->color_type,
ihdr->compression,
ihdr->filter,
ihdr->interlace,
};
dword_write_be(ihdr_raw + 0, sizeof(ihdr_raw) - 8);
dword_write_be(ihdr_raw + 8, ihdr->width);
dword_write_be(ihdr_raw + 12, ihdr->height);
if (fwrite(ihdr_raw, 1, sizeof(ihdr_raw), file) != sizeof(ihdr_raw))
return false;
if (!png_write_crc(file, ihdr_raw + sizeof(uint32_t), sizeof(ihdr_raw) - sizeof(uint32_t)))
return false;
return true;
}
static bool png_write_idat(FILE *file, const uint8_t *data, size_t size)
{
if (fwrite(data, 1, size, file) != size)
return false;
if (!png_write_crc(file, data + sizeof(uint32_t), size - sizeof(uint32_t)))
return false;
return true;
}
static bool png_write_iend(FILE *file)
{
const uint8_t data[] = {
0, 0, 0, 0,
'I', 'E', 'N', 'D',
};
if (fwrite(data, 1, sizeof(data), file) != sizeof(data))
return false;
if (!png_write_crc(file, data + sizeof(uint32_t), sizeof(data) - sizeof(uint32_t)))
return false;
return true;
}
static void copy_argb_line(uint8_t *dst, const uint32_t *src, unsigned width)
{
for (unsigned i = 0; i < width; i++)
{
uint32_t col = src[i];
*dst++ = (uint8_t)(col >> 16);
*dst++ = (uint8_t)(col >> 8);
*dst++ = (uint8_t)(col >> 0);
*dst++ = (uint8_t)(col >> 24);
}
}
static void copy_bgr24_line(uint8_t *dst, const uint8_t *src, unsigned width)
{
for (unsigned i = 0; i < width; i++, dst += 3, src += 3)
{
dst[2] = src[0];
dst[1] = src[1];
dst[0] = src[2];
}
}
static unsigned count_sad(const uint8_t *data, size_t size)
{
unsigned cnt = 0;
for (size_t i = 0; i < size; i++)
cnt += abs((int8_t)data[i]);
return cnt;
}
static unsigned filter_up(uint8_t *target, const uint8_t *line, const uint8_t *prev,
unsigned width, unsigned bpp)
{
width *= bpp;
for (unsigned i = 0; i < width; i++)
target[i] = line[i] - prev[i];
return count_sad(target, width);
}
static unsigned filter_sub(uint8_t *target, const uint8_t *line,
unsigned width, unsigned bpp)
{
width *= bpp;
for (unsigned i = 0; i < bpp; i++)
target[i] = line[i];
for (unsigned i = bpp; i < width; i++)
target[i] = line[i] - line[i - bpp];
return count_sad(target, width);
}
static unsigned filter_avg(uint8_t *target, const uint8_t *line, const uint8_t *prev,
unsigned width, unsigned bpp)
{
width *= bpp;
for (unsigned i = 0; i < bpp; i++)
target[i] = line[i] - (prev[i] >> 1);
for (unsigned i = bpp; i < width; i++)
target[i] = line[i] - ((line[i - bpp] + prev[i]) >> 1);
return count_sad(target, width);
}
static unsigned filter_paeth(uint8_t *target, const uint8_t *line, const uint8_t *prev,
unsigned width, unsigned bpp)
{
width *= bpp;
for (unsigned i = 0; i < bpp; i++)
target[i] = line[i] - paeth(0, prev[i], 0);
for (unsigned i = bpp; i < width; i++)
target[i] = line[i] - paeth(line[i - bpp], prev[i], prev[i - bpp]);
return count_sad(target, width);
}
static bool rpng_save_image(const char *path, const uint8_t *data,
unsigned width, unsigned height, unsigned pitch, unsigned bpp)
{
bool ret = true;
struct png_ihdr ihdr = {0};
size_t encode_buf_size = 0;
uint8_t *encode_buf = NULL;
uint8_t *deflate_buf = NULL;
uint8_t *rgba_line = NULL;
uint8_t *up_filtered = NULL;
uint8_t *sub_filtered = NULL;
uint8_t *avg_filtered = NULL;
uint8_t *paeth_filtered = NULL;
uint8_t *prev_encoded = NULL;
uint8_t *encode_target = NULL;
z_stream stream = {0};
FILE *file = fopen(path, "wb");
if (!file)
GOTO_END_ERROR();
if (fwrite(png_magic, 1, sizeof(png_magic), file) != sizeof(png_magic))
GOTO_END_ERROR();
ihdr.width = width;
ihdr.height = height;
ihdr.depth = 8;
ihdr.color_type = bpp == sizeof(uint32_t) ? 6 : 2; // RGBA or RGB
if (!png_write_ihdr(file, &ihdr))
GOTO_END_ERROR();
encode_buf_size = (width * bpp + 1) * height;
encode_buf = (uint8_t*)malloc(encode_buf_size);
if (!encode_buf)
GOTO_END_ERROR();
prev_encoded = (uint8_t*)calloc(1, width * bpp);
if (!prev_encoded)
GOTO_END_ERROR();
rgba_line = (uint8_t*)malloc(width * bpp);
up_filtered = (uint8_t*)malloc(width * bpp);
sub_filtered = (uint8_t*)malloc(width * bpp);
avg_filtered = (uint8_t*)malloc(width * bpp);
paeth_filtered = (uint8_t*)malloc(width * bpp);
if (!rgba_line || !up_filtered || !sub_filtered || !avg_filtered || !paeth_filtered)
GOTO_END_ERROR();
encode_target = encode_buf;
for (unsigned h = 0; h < height;
h++, encode_target += width * bpp, data += pitch)
{
if (bpp == sizeof(uint32_t))
copy_argb_line(rgba_line, (const uint32_t*)data, width);
else
copy_bgr24_line(rgba_line, data, width);
// Try every filtering method, and choose the method
// which has most entries as zero.
// This is probably not very optimal, but it's very simple to implement.
unsigned none_score = count_sad(rgba_line, width * bpp);
unsigned up_score = filter_up(up_filtered, rgba_line, prev_encoded, width, bpp);
unsigned sub_score = filter_sub(sub_filtered, rgba_line, width, bpp);
unsigned avg_score = filter_avg(avg_filtered, rgba_line, prev_encoded, width, bpp);
unsigned paeth_score = filter_paeth(paeth_filtered, rgba_line, prev_encoded, width, bpp);
uint8_t filter = 0;
unsigned min_sad = none_score;
const uint8_t *chosen_filtered = rgba_line;
if (sub_score < min_sad)
{
filter = 1;
chosen_filtered = sub_filtered;
min_sad = sub_score;
}
if (up_score < min_sad)
{
filter = 2;
chosen_filtered = up_filtered;
min_sad = up_score;
}
if (avg_score < min_sad)
{
filter = 3;
chosen_filtered = avg_filtered;
min_sad = avg_score;
}
if (paeth_score < min_sad)
{
filter = 4;
chosen_filtered = paeth_filtered;
min_sad = paeth_score;
}
*encode_target++ = filter;
memcpy(encode_target, chosen_filtered, width * bpp);
memcpy(prev_encoded, rgba_line, width * bpp);
}
deflate_buf = (uint8_t*)malloc(encode_buf_size * 2); // Just to be sure.
if (!deflate_buf)
GOTO_END_ERROR();
stream.next_in = encode_buf;
stream.avail_in = encode_buf_size;
stream.next_out = deflate_buf + 8;
stream.avail_out = encode_buf_size * 2;
deflateInit(&stream, 9);
if (deflate(&stream, Z_FINISH) != Z_STREAM_END)
{
deflateEnd(&stream);
GOTO_END_ERROR();
}
deflateEnd(&stream);
memcpy(deflate_buf + 4, "IDAT", 4);
dword_write_be(deflate_buf + 0, stream.total_out);
if (!png_write_idat(file, deflate_buf, stream.total_out + 8))
GOTO_END_ERROR();
if (!png_write_iend(file))
GOTO_END_ERROR();
end:
if (file)
fclose(file);
free(encode_buf);
free(deflate_buf);
free(rgba_line);
free(prev_encoded);
free(up_filtered);
free(sub_filtered);
free(avg_filtered);
free(paeth_filtered);
return ret;
}
bool rpng_save_image_argb(const char *path, const uint32_t *data,
unsigned width, unsigned height, unsigned pitch)
{
return rpng_save_image(path, (const uint8_t*)data, width, height, pitch, sizeof(uint32_t));
}
bool rpng_save_image_bgr24(const char *path, const uint8_t *data,
unsigned width, unsigned height, unsigned pitch)
{
return rpng_save_image(path, (const uint8_t*)data, width, height, pitch, 3);
}
#endif
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