Use png.h in gfxx.c

3 files changed, 123 insertions, 47 deletions

diff --git a/gfx/Makefile b/gfx/Makefile
index 22198835..20ff5ecd 100644
--- a/gfx/Makefile
+++ b/gfx/Makefile
@@ -5,7 +5,7 @@ BINS = brot gfxx
 MAN1 = $(BINS:%=man/%.1)
 
 CFLAGS += -Wall -Wextra -Wpedantic
-LDLIBS = -lm -lz
+LDLIBS = -lm
 LDLIBS_cocoa = -framework Cocoa
 LDLIBS_x11 = -lX11
 
@@ -18,6 +18,8 @@ brot.o gfxx.o: gfx.h
 
 cocoa.o fb.o x11.o: gfx.h
 
+gfxx.o: png.h
+
 brot: brot.o $(GFX).o
 	$(CC) $(LDFLAGS) brot.o $(GFX).o $(LDLIBS) $(LDLIBS_$(GFX)) -o $@
 
diff --git a/gfx/gfxx.c b/gfx/gfxx.c
index 94f6cf55..019d4fe9 100644
--- a/gfx/gfxx.c
+++ b/gfx/gfxx.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2018, Curtis McEnroe <programble@gmail.com>
+/* 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
@@ -14,7 +14,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <arpa/inet.h>
 #include <err.h>
 #include <fcntl.h>
 #include <math.h>
@@ -27,9 +26,9 @@
 #include <sys/stat.h>
 #include <sysexits.h>
 #include <unistd.h>
-#include <zlib.h>
 
 #include "gfx.h"
+#include "png.h"
 
 #define MAX(a, b) ((a) > (b) ? (a) : (b))
 #define MASK(b) ((1 << (b)) - 1)
@@ -329,22 +328,6 @@ static void outOpen(const char *ext) {
 	}
 }
 
-static uint32_t crc;
-static void pngWrite(const void *ptr, size_t size) {
-	fwrite(ptr, size, 1, out.file);
-	if (ferror(out.file)) err(EX_IOERR, "%s", out.path);
-	crc = crc32(crc, ptr, size);
-}
-static void pngUint(uint32_t host) {
-	uint32_t net = htonl(host);
-	pngWrite(&net, 4);
-}
-static void pngChunk(const char *type, uint32_t size) {
-	pngUint(size);
-	crc = crc32(0, Z_NULL, 0);
-	pngWrite(type, 4);
-}
-
 static void pngDump(uint32_t *src, size_t srcWidth, size_t srcHeight) {
 	int error;
 
@@ -360,43 +343,26 @@ static void pngDump(uint32_t *src, size_t srcWidth, size_t srcHeight) {
 		}
 	}
 
-	uLong deflateSize = compressBound(sizeof(data));
-	uint8_t deflate[deflateSize];
-	error = compress(deflate, &deflateSize, data, sizeof(data));
-	if (error != Z_OK) errx(EX_SOFTWARE, "compress: %d", error);
-
 	outOpen("png");
 	if (!out.file) return;
 
-	const uint8_t Signature[8] = "\x89PNG\r\n\x1A\n";
-	const uint8_t Header[] = { 8, 2, 0, 0, 0 }; // 8-bit truecolor
 	const char Software[] = "Software";
 	formatOptions();
 	uint8_t sbit[3] = { MAX(bits[R], 1), MAX(bits[G], 1), MAX(bits[B], 1) };
 
-	pngWrite(Signature, sizeof(Signature));
-
-	pngChunk("IHDR", 4 + 4 + sizeof(Header));
-	pngUint(srcWidth);
-	pngUint(srcHeight);
-	pngWrite(Header, sizeof(Header));
-	pngUint(crc);
-
-	pngChunk("tEXt", sizeof(Software) + strlen(options));
-	pngWrite(Software, sizeof(Software));
-	pngWrite(options, strlen(options));
-	pngUint(crc);
+	pngHead(out.file, srcWidth, srcHeight, 8, PNGTruecolor);
 
-	pngChunk("sBIT", sizeof(sbit));
-	pngWrite(sbit, sizeof(sbit));
-	pngUint(crc);
+	pngChunk(out.file, "tEXt", sizeof(Software) + strlen(options));
+	pngWrite(out.file, (uint8_t *)Software, sizeof(Software));
+	pngWrite(out.file, (uint8_t *)options, strlen(options));
+	pngInt32(out.file, ~pngCRC);
 
-	pngChunk("IDAT", deflateSize);
-	pngWrite(deflate, deflateSize);
-	pngUint(crc);
+	pngChunk(out.file, "sBIT", sizeof(sbit));
+	pngWrite(out.file, sbit, sizeof(sbit));
+	pngInt32(out.file, ~pngCRC);
 
-	pngChunk("IEND", 0);
-	pngUint(crc);
+	pngData(out.file, data, sizeof(data));
+	pngTail(out.file);
 
 	error = fclose(out.file);
 	if (error) err(EX_IOERR, "%s", out.path);
diff --git a/gfx/png.h b/gfx/png.h
new file mode 100644
index 00000000..4eb4da1f
--- /dev/null
+++ b/gfx/png.h
@@ -0,0 +1,108 @@
+/* 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 <err.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sysexits.h>
+
+static inline uint32_t pngCRCTable(uint8_t n) {
+	static uint32_t table[256];
+	if (table[1]) return table[n];
+	for (int i = 0; i < 256; ++i) {
+		table[i] = i;
+		for (int j = 0; j < 8; ++j) {
+			table[i] = (table[i] >> 1) ^ (table[i] & 1 ? 0xEDB88320 : 0);
+		}
+	}
+	return table[n];
+}
+
+static uint32_t pngCRC;
+
+static inline void pngWrite(FILE *file, const uint8_t *ptr, uint32_t len) {
+	if (!fwrite(ptr, len, 1, file)) err(EX_IOERR, "pngWrite");
+	for (uint32_t i = 0; i < len; ++i) {
+		pngCRC = pngCRCTable(pngCRC ^ ptr[i]) ^ (pngCRC >> 8);
+	}
+}
+static inline void pngInt32(FILE *file, uint32_t n) {
+	pngWrite(file, (uint8_t []) { n >> 24, n >> 16, n >> 8, n }, 4);
+}
+static inline void pngChunk(FILE *file, char type[static 4], uint32_t len) {
+	pngInt32(file, len);
+	pngCRC = ~0;
+	pngWrite(file, (uint8_t *)type, 4);
+}
+
+enum {
+	PNGGrayscale,
+	PNGTruecolor = 2,
+	PNGIndexed,
+	PNGAlpha,
+};
+
+static inline void pngHead(
+	FILE *file, uint32_t width, uint32_t height, uint8_t depth, uint8_t color
+) {
+	pngWrite(file, (uint8_t *)"\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, (uint8_t []) { 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);
+}
+
+enum {
+	PNGNone,
+	PNGSub,
+	PNGUp,
+	PNGAverage,
+	PNGPaeth,
+};
+
+static inline void pngData(FILE *file, const uint8_t *data, uint32_t len) {
+	uint32_t adler1 = 1, adler2 = 0;
+	for (uint32_t i = 0; i < len; ++i) {
+		adler1 = (adler1 + data[i]) % 65521;
+		adler2 = (adler1 + adler2) % 65521;
+	}
+	uint32_t zlen = 2 + 5 * ((len + 0xFFFE) / 0xFFFF) + len + 4;
+	pngChunk(file, "IDAT", zlen);
+	pngWrite(file, (uint8_t []) { 0x08, 0x1D }, 2);
+	for (; len > 0xFFFF; data += 0xFFFF, len -= 0xFFFF) {
+		pngWrite(file, (uint8_t []) { 0x00, 0xFF, 0xFF, 0x00, 0x00 }, 5);
+		pngWrite(file, data, 0xFFFF);
+	}
+	pngWrite(file, (uint8_t []) { 0x01, len, len >> 8, ~len, ~len >> 8 }, 5);
+	pngWrite(file, data, len);
+	pngInt32(file, adler2 << 16 | adler1);
+	pngInt32(file, ~pngCRC);
+}
+
+static inline void pngTail(FILE *file) {
+	pngChunk(file, "IEND", 0);
+	pngInt32(file, ~pngCRC);
+}