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/*
* Copyright (C) 2017 Vabishchevich Nikolay <vabnick@gmail.com>
*
* This file is part of libass.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "image.h"
#include <png.h>
bool read_png(const char *path, Image16 *img)
{
FILE *fp = fopen(path, "rb");
if (!fp)
return false;
png_structp png =
png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png) {
fclose(fp);
return false;
}
png_infop info = png_create_info_struct(png);
if (!info) {
png_destroy_read_struct(&png, NULL, NULL);
fclose(fp);
return false;
}
png_byte *volatile buf = NULL;
png_byte **volatile rows = NULL;
if (setjmp(png_jmpbuf(png))) {
free(buf);
free(rows);
png_destroy_read_struct(&png, &info, NULL);
fclose(fp);
return false;
}
png_init_io(png, fp);
png_read_info(png, info);
uint32_t w = png_get_image_width(png, info);
uint32_t h = png_get_image_height(png, info);
int type = png_get_color_type(png, info);
int depth = png_get_bit_depth(png, info);
if (w > 0xFFFF || h > 0xFFFF || type != PNG_COLOR_TYPE_RGBA) {
png_destroy_read_struct(&png, &info, NULL);
fclose(fp);
return false;
}
ptrdiff_t stride = 8 * w;
buf = malloc(stride * h);
rows = malloc(h * sizeof(png_byte *));
if (!buf || !rows) {
free(buf);
free(rows);
png_destroy_read_struct(&png, &info, NULL);
fclose(fp);
return false;
}
png_byte *ptr = buf;
ptrdiff_t half = 4 * w;
if (depth == 8)
ptr += half;
else
png_set_swap(png);
for (uint32_t i = 0; i < h; i++) {
rows[i] = ptr;
ptr += stride;
}
png_read_image(png, rows);
png_read_end(png, NULL);
free(rows);
png_destroy_read_struct(&png, &info, NULL);
fclose(fp);
// convert to premultiplied with inverted alpha
if (depth == 8) {
uint8_t *ptr = (uint8_t *) buf;
for (uint32_t y = 0; y < h; y++) {
for (uint32_t x = 0; x < w; x++) {
uint8_t r = ptr[half + 4 * x + 0];
uint8_t g = ptr[half + 4 * x + 1];
uint8_t b = ptr[half + 4 * x + 2];
uint8_t a = ptr[half + 4 * x + 3];
uint16_t ra = (uint16_t) r * a;
uint16_t ga = (uint16_t) g * a;
uint16_t ba = (uint16_t) b * a;
ptr[8 * x + 0] = ptr[8 * x + 1] = (ra + (ra >> 8) + 128) >> 8;
ptr[8 * x + 2] = ptr[8 * x + 3] = (ga + (ga >> 8) + 128) >> 8;
ptr[8 * x + 4] = ptr[8 * x + 5] = (ba + (ba >> 8) + 128) >> 8;
ptr[8 * x + 6] = ptr[8 * x + 7] = ~a;
}
ptr += stride;
}
} else {
uint16_t *ptr = (uint16_t *) buf;
for (uint32_t y = 0; y < h; y++) {
for (uint32_t x = 0; x < w; x++) {
uint16_t r = ptr[4 * x + 0];
uint16_t g = ptr[4 * x + 1];
uint16_t b = ptr[4 * x + 2];
uint16_t a = ptr[4 * x + 3];
uint32_t ra = (uint32_t) r * a;
uint32_t ga = (uint32_t) g * a;
uint32_t ba = (uint32_t) b * a;
ptr[4 * x + 0] = (ra + (ra >> 16) + (1 << 15)) >> 16;
ptr[4 * x + 1] = (ga + (ga >> 16) + (1 << 15)) >> 16;
ptr[4 * x + 2] = (ba + (ba >> 16) + (1 << 15)) >> 16;
ptr[4 * x + 3] = ~a;
}
ptr += half;
}
}
img->width = w;
img->height = h;
img->buffer = (uint16_t *) buf;
return true;
}
static bool write_png(const char *path, uint32_t width, uint32_t height,
ptrdiff_t stride, const void *buffer, int depth)
{
FILE *fp = fopen(path, "wb");
if (!fp)
return false;
png_structp png =
png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png) {
fclose(fp);
return false;
}
png_infop info = png_create_info_struct(png);
if (!info) {
png_destroy_write_struct(&png, NULL);
fclose(fp);
return false;
}
png_byte **rows = malloc(height * sizeof(png_byte *));
if (!rows) {
png_destroy_write_struct(&png, &info);
fclose(fp);
return false;
}
png_byte *ptr = (png_byte *) buffer;
for (uint32_t i = 0; i < height; i++) {
rows[i] = (png_byte *) ptr;
ptr += stride;
}
if (setjmp(png_jmpbuf(png))) {
free(rows);
png_destroy_write_struct(&png, &info);
fclose(fp);
return false;
}
png_init_io(png, fp);
png_set_IHDR(png, info, width, height, depth,
PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
png_write_info(png, info);
if (depth > 8)
png_set_swap(png);
png_write_image(png, rows);
png_write_end(png, NULL);
free(rows);
png_destroy_write_struct(&png, &info);
fclose(fp);
return true;
}
bool write_png8(const char *path, Image8 *img)
{
uint8_t *ptr = img->buffer;
size_t size = (size_t) img->width * img->height;
for (size_t i = 0; i < size; i++) {
uint8_t alpha = ~ptr[3];
if (alpha) {
const uint32_t offs = (uint32_t) 1 << 15;
uint32_t inv = ((uint32_t) 255 << 16) / alpha + 1;
// equivalent to (255 * ptr[k] + alpha / 2) / alpha
ptr[0] = (ptr[0] * inv + offs) >> 16;
ptr[1] = (ptr[1] * inv + offs) >> 16;
ptr[2] = (ptr[2] * inv + offs) >> 16;
}
ptr[3] = alpha;
ptr += 4;
}
return write_png(path, img->width, img->height,
4 * img->width, img->buffer, 8);
}
bool write_png16(const char *path, Image16 *img)
{
uint16_t *ptr = img->buffer;
size_t size = (size_t) img->width * img->height;
for (size_t i = 0; i < size; i++) {
uint16_t alpha = ~ptr[3];
if (alpha) {
const uint64_t offs = (uint64_t) 1 << 32;
uint64_t inv = ((uint64_t) 65535 << 33) / alpha + 1;
// equivalent to (65535 * ptr[k] + alpha / 2) / alpha
ptr[0] = (ptr[0] * inv + offs) >> 33;
ptr[1] = (ptr[1] * inv + offs) >> 33;
ptr[2] = (ptr[2] * inv + offs) >> 33;
}
ptr[3] = alpha;
ptr += 4;
}
return write_png(path, img->width, img->height,
8 * img->width, img->buffer, 16);
}
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