blind

commit 9fa7221a87817fe41a12a9cbdaa4bac6ee67b07d
parent 1870c353eb4697290cf7f49861e5d1b8699e3cd3
Author: Mattias Andrée <maandree@kth.se>
Date:   Sun,  8 Jan 2017 08:00:53 +0100

Add vu-stack

Signed-off-by: Mattias Andrée <maandree@kth.se>

Diffstat:
M
src/util.h
 | 
25
+++++++++++++++++++++++++
A
src/vu-stack.c
 | 
171
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 196 insertions(+), 0 deletions(-)
diff --git a/src/util.h b/src/util.h
@@ -1,5 +1,6 @@
 /* See LICENSE file for copyright and license details. */
 
+#include <math.h>
 #include <stdio.h>
 
 #define ELEMENTSOF(ARRAY) (sizeof(ARRAY) / sizeof(*(ARRAY)))
@@ -33,3 +34,27 @@ DEF_STR_TO_INT(toi, int, tolli, long long int)
 int fshut(FILE *fp, const char *fname);
 void enfshut(int status, FILE *fp, const char *fname);
 void efshut(FILE *fp, const char *fname);
+
+static inline double
+srgb_encode(double t)
+{
+	double sign = 1;
+	if (t < 0) {
+		t = -t;
+		sign = -1;
+	}
+	t = t <= 0.0031306684425217108 ? 12.92 * t : 1.055 * pow(t, 1 / 2.4) - 0.055;
+	return t * sign;
+}
+
+static inline double
+srgb_decode(double t)
+{
+	double sign = 1;
+	if (t < 0) {
+		t = -t;
+		sign = -1;
+	}
+	t = t <= 0.0031306684425217108 * 12.92 ? t / 12.92 : pow((t + 0.055) / 1.055, 2.4);
+	return t * sign;
+}
diff --git a/src/vu-stack.c b/src/vu-stack.c
@@ -0,0 +1,171 @@
+/* See LICENSE file for copyright and license details. */
+#include "arg.h"
+#include "util.h"
+
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+struct file
+{
+	int fd;
+	unsigned char buf[1024];
+	size_t ptr;
+	const char *file;
+};
+
+static unsigned int
+clip(unsigned int value)
+{
+	return value < 0 ? 0 : value > 255 ? 255 : value;
+}
+
+static void
+blend(struct file *files, size_t n_files, size_t n)
+{
+	double r1, g1, b1, a1;
+	double r2, g2, b2, a2;
+	size_t i, j;
+	for (i = 0; i < n; i += 4) {
+		r1 = srgb_decode(files->buf[i + 0] / 255.);
+		g1 = srgb_decode(files->buf[i + 1] / 255.);
+		b1 = srgb_decode(files->buf[i + 2] / 255.);
+		a1 = files->buf[i + 3] / 255.;
+		for (j = 1; j < n_files;) {
+			r2 = srgb_decode(files[j].buf[i + 0] / 255.);
+			g2 = srgb_decode(files[j].buf[i + 1] / 255.);
+			b2 = srgb_decode(files[j].buf[i + 2] / 255.);
+			a2 = files[j].buf[i + 3] / 255.;
+			a2 /= ++j;
+			r1 = r1 * a1 * (1 - a2) + r2 * a2;
+			g1 = g1 * a1 * (1 - a2) + g2 * a2;
+			b1 = b1 * a1 * (1 - a2) + b2 * a2;
+			a1 = a1 * (1 - a2) + a2;
+		}
+		r1 = srgb_encode(r1) * 255 + 0.5;
+		g1 = srgb_encode(g1) * 255 + 0.5;
+		b1 = srgb_encode(b1) * 255 + 0.5;
+		a1 = a1 * 255 * 0.5;
+		files->buf[i + 0] = clip((unsigned int)r1);
+		files->buf[i + 1] = clip((unsigned int)g1);
+		files->buf[i + 2] = clip((unsigned int)b1);
+		files->buf[i + 3] = clip((unsigned int)a1);
+	}
+}
+
+static void
+stack(struct file *files, size_t n_files, size_t n)
+{
+	double r1, g1, b1, a1;
+	double r2, g2, b2, a2;
+	size_t i, j;
+	for (i = 0; i < n; i += 4) {
+		r1 = srgb_decode(files->buf[i + 0] / 255.);
+		g1 = srgb_decode(files->buf[i + 1] / 255.);
+		b1 = srgb_decode(files->buf[i + 2] / 255.);
+		a1 = files->buf[i + 3] / 255.;
+		for (j = 1; j < n_files; j++) {
+			r2 = srgb_decode(files[j].buf[i + 0] / 255.);
+			g2 = srgb_decode(files[j].buf[i + 1] / 255.);
+			b2 = srgb_decode(files[j].buf[i + 2] / 255.);
+			a2 = files[j].buf[i + 3] / 255.;
+			r1 = r1 * a1 * (1 - a2) + r2 * a2;
+			g1 = g1 * a1 * (1 - a2) + g2 * a2;
+			b1 = b1 * a1 * (1 - a2) + b2 * a2;
+			a1 = a1 * (1 - a2) + a2;
+		}
+		r1 = srgb_encode(r1) * 255 + 0.5;
+		g1 = srgb_encode(g1) * 255 + 0.5;
+		b1 = srgb_encode(b1) * 255 + 0.5;
+		a1 = a1 * 255 * 0.5;
+		files->buf[i + 0] = clip((unsigned int)r1);
+		files->buf[i + 1] = clip((unsigned int)g1);
+		files->buf[i + 2] = clip((unsigned int)b1);
+		files->buf[i + 3] = clip((unsigned int)a1);
+	}
+}
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-b] bottom-image ... top-image\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct file *files;
+	size_t n_files;
+	int blend_flag = 0;
+	size_t i, j, n;
+	ssize_t r;
+	size_t closed;
+
+	ARGBEGIN {
+	case 'b':
+		blend_flag = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc < 2)
+		usage();
+
+	n_files = (size_t)argc;
+	files = calloc(n_files, sizeof(*files));
+	if (!files)
+		eprintf("calloc:");
+
+	for (i = 0; i < n_files; i++) {
+		files[i].fd = open(argv[i], O_RDONLY);
+		if (files[i].fd < 0)
+			eprintf("open %s:", argv[i]);
+		files[i].file = argv[i];
+	}
+
+	while (n_files) {
+		n = SIZE_MAX;
+		for (i = 0; i < n_files; i++) {
+			r = read(files[i].fd, files[i].buf + files[i].ptr, sizeof(files[i].buf) - files[i].ptr);
+			if (r < 0) {
+				eprintf("read %s:", files[i].file);
+			} else if (r == 0) {
+				close(files[i].fd);
+				files[i].fd = -1;
+			} else {
+				files[i].ptr += (size_t)r;
+			}
+			if (files[i].ptr && files[i].ptr < n)
+				n = files[i].ptr;
+		}
+		n -= n & 3;
+
+		(blend_flag ? blend : stack)(files, n_files, n);
+		for (j = 0; j < n;) {
+			r = write(STDOUT_FILENO, files->buf + j, n - j);
+			if (r < 0)
+				eprintf("write <stdout>:");
+			j += (size_t)r;
+		}
+
+		closed = SIZE_MAX;
+		for (i = 0; i < n_files; i++) {
+			memmove(files[i].buf, files[i].buf + n, files[i].ptr -= n);
+			if (files[i].ptr < 4 && files[i].fd < 0 && closed == SIZE_MAX)
+				closed = i;
+		}
+		if (closed != SIZE_MAX) {
+			for (i = (j = closed) + 1; i < n_files; i++)
+				if (files[i].ptr < 4 && files[i].fd < 0)
+					files[j++] = files[i];
+			n_files = j;
+		}
+	}
+
+	return 0;
+}