From 2287381a307c8ea4609b4d8bb673ce78160a71a7 Mon Sep 17 00:00:00 2001
From: June McEnroe <june@causal.agency>
Date: Wed, 14 Nov 2018 01:29:53 -0500
Subject: Factor out png.h

---
 bin/png.h | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 bin/png.h

(limited to 'bin/png.h')

diff --git a/bin/png.h b/bin/png.h
new file mode 100644
index 00000000..63c80342
--- /dev/null
+++ b/bin/png.h
@@ -0,0 +1,92 @@
+/* Copyright (C) 2018  June 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 <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+#include <zlib.h>
+
+enum {
+	PNGGrayscale,
+	PNGTruecolor = 2,
+	PNGIndexed,
+	PNGAlpha,
+};
+
+enum {
+	PNGNone,
+	PNGSub,
+	PNGUp,
+	PNGAverage,
+	PNGPaeth,
+};
+
+static uint32_t pngCRC;
+static inline void pngWrite(FILE *file, const void *ptr, size_t len) {
+	if (!fwrite(ptr, len, 1, file)) err(EX_IOERR, "pngWrite");
+	pngCRC = crc32(pngCRC, ptr, len);
+}
+static inline void pngInt32(FILE *file, uint32_t n) {
+	n = htonl(n);
+	pngWrite(file, &n, 4);
+}
+static inline void pngChunk(FILE *file, char type[static 4], uint32_t len) {
+	pngInt32(file, len);
+	pngCRC = crc32(0, Z_NULL, 0);
+	pngWrite(file, type, 4);
+}
+
+static inline void pngHead(
+	FILE *file, uint32_t width, uint32_t height, uint8_t depth, uint8_t color
+) {
+	pngWrite(file, "\x89PNG\r\n\x1A\n", 8);
+	pngChunk(file, "IHDR", 13);
+	pngInt32(file, width);
+	pngInt32(file, height);
+	pngWrite(file, &depth, 1);
+	pngWrite(file, &color, 1);
+	pngWrite(file, "\0\0\0", 3);
+	pngInt32(file, pngCRC);
+}
+
+static inline void pngPalette(FILE *file, const uint8_t *pal, uint32_t len) {
+	pngChunk(file, "PLTE", len);
+	pngWrite(file, pal, len);
+	pngInt32(file, pngCRC);
+}
+
+static inline void pngData(FILE *file, const uint8_t *data, uint32_t len) {
+	uLong zlen = compressBound(len);
+	uint8_t *zdata = malloc(zlen);
+	if (!zlen) err(EX_OSERR, "malloc");
+
+	int error = compress(zdata, &zlen, data, len);
+	if (error != Z_OK) errx(EX_SOFTWARE, "compress: %d", error);
+
+	pngChunk(file, "IDAT", zlen);
+	pngWrite(file, zdata, zlen);
+	pngInt32(file, pngCRC);
+
+	free(zdata);
+}
+
+static inline void pngTail(FILE *file) {
+	pngChunk(file, "IEND", 0);
+	pngInt32(file, pngCRC);
+}
-- 
cgit 1.4.1