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/*
* Copyright (C) 2018 Curtis McEnroe <june@causal.agency>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <arpa/inet.h>
#include <err.h>
#include <math.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include <zlib.h>
struct Hsv {
double h, s, v;
};
struct Rgb {
uint8_t r, g, b;
};
static struct Rgb toRgb(struct Hsv hsv) {
double c = hsv.v * hsv.s;
double h = hsv.h / 60.0;
double x = c * (1.0 - fabs(fmod(h, 2.0) - 1.0));
double m = hsv.v - c;
double r = m, g = m, b = m;
if (h <= 1.0) { r += c; g += x; }
else if (h <= 2.0) { r += x; g += c; }
else if (h <= 3.0) { g += c; b += x; }
else if (h <= 4.0) { g += x; b += c; }
else if (h <= 5.0) { r += x; b += c; }
else if (h <= 6.0) { r += c; b += x; }
return (struct Rgb) { r * 255.0, g * 255.0, b * 255.0 };
}
static uint32_t crc;
static void pngWrite(const void *ptr, size_t size) {
fwrite(ptr, size, 1, stdout);
if (ferror(stdout)) err(EX_IOERR, "(stdout)");
crc = crc32(crc, ptr, size);
}
static void pngInt(uint32_t host) {
uint32_t net = htonl(host);
pngWrite(&net, 4);
}
static void pngChunk(const char *type, uint32_t size) {
pngInt(size);
crc = crc32(0, Z_NULL, 0);
pngWrite(type, 4);
}
enum { NONE, SUB, UP, AVERAGE, PAETH };
static void png(const struct Hsv *hsv, uint8_t len) {
uint32_t swatchWidth = 64;
uint32_t swatchHeight = 64;
uint32_t columns = 8;
uint32_t rows = (len + columns - 1) / columns;
uint32_t width = swatchWidth * columns;
uint32_t height = swatchHeight * rows;
pngWrite("\x89PNG\r\n\x1A\n", 8);
pngChunk("IHDR", 13);
pngInt(width);
pngInt(height);
pngWrite("\x08\x03\0\0\0", 5);
pngInt(crc);
pngChunk("PLTE", 3 * len);
for (uint8_t i = 0; i < len; ++i) {
struct Rgb rgb = toRgb(hsv[i]);
pngWrite(&rgb, 3);
}
pngInt(crc);
uint8_t data[height][1 + width];
memset(data, 0, sizeof(data));
for (uint32_t y = 0; y < height; ++y) {
data[y][0] = (y % swatchHeight) ? UP : SUB;
}
for (uint8_t i = 0; i < len; ++i) {
uint32_t y = swatchHeight * (i / columns);
uint32_t x = swatchWidth * (i % columns);
data[y][1 + x] = x ? 1 : i;
}
uLong size = compressBound(sizeof(data));
uint8_t deflate[size];
int error = compress(deflate, &size, (Byte *)data, sizeof(data));
if (error != Z_OK) errx(EX_SOFTWARE, "compress: %d", error);
pngChunk("IDAT", size);
pngWrite(deflate, size);
pngInt(crc);
pngChunk("IEND", 0);
pngInt(crc);
}
int main() {
struct Hsv scheme[16] = {
{ 0.0, 1.0, 1.0 },
{ 45.0, 1.0, 1.0 },
{ 90.0, 1.0, 1.0 },
{ 135.0, 1.0, 1.0 },
{ 180.0, 1.0, 1.0 },
{ 225.0, 1.0, 1.0 },
{ 270.0, 1.0, 1.0 },
{ 315.0, 1.0, 1.0 },
{ 0.0, 0.5, 1.0 },
{ 45.0, 0.5, 1.0 },
{ 90.0, 0.5, 1.0 },
{ 135.0, 0.5, 1.0 },
{ 180.0, 0.5, 1.0 },
{ 225.0, 0.5, 1.0 },
{ 270.0, 0.5, 1.0 },
{ 315.0, 0.5, 1.0 },
};
png(scheme, 16);
return EX_OK;
}
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