From 1631fca75013a28db8ee5666fb1f2ad79bfeffe4 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sun, 8 Jan 2017 10:32:53 +0100
Subject: Add vu-dissolve
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 src/vu-dissolve.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 src/vu-dissolve.c

(limited to 'src')

diff --git a/src/vu-dissolve.c b/src/vu-dissolve.c
new file mode 100644
index 0000000..1ec8b87
--- /dev/null
+++ b/src/vu-dissolve.c
@@ -0,0 +1,97 @@
+/* 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>
+
+static unsigned int
+clip(unsigned int value)
+{
+	return value > 255 ? 255 : value;
+}
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-r] -f frames -w width -h height\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int reverse = 0;
+	size_t frames = 0, width = 0, height = 0;
+	unsigned char buf[8096];
+	size_t frame, h, w, max;
+	size_t ptr = 0, n, i, fm;
+	ssize_t r;
+	double a;
+
+	ARGBEGIN {
+	case 'f':
+		if (tozu(EARGF(usage()), 2, SIZE_MAX, &frames))
+			eprintf("argument of -f must be an integer in [2, %zu]\n", SIZE_MAX);
+		break;
+	case 'w':
+		if (tozu(EARGF(usage()), 1, SIZE_MAX, &width))
+			eprintf("argument of -w must be an integer in [1, %zu]\n", SIZE_MAX);
+		break;
+	case 'h':
+		if (tozu(EARGF(usage()), 1, SIZE_MAX, &height))
+			eprintf("argument of -h must be an integer in [1, %zu]\n", SIZE_MAX);
+		break;
+	case 'r':
+		reverse = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc || !frames || !width || !height)
+		usage();
+
+	fm = frames - 1;
+	for (frame = 0; frame < frames; frame++) {
+		for (h = height; h--;) {
+			for (w = width << 2; w; w -= n) {
+				max = sizeof(buf) - ptr < w ? sizeof(buf) - ptr : w;
+				r = read(STDIN_FILENO, buf + ptr, max);
+				if (r < 0)
+					eprintf("read <stdin>:");
+				if (r == 0)
+					eprintf("content is shorter than specified\n");
+				n = ptr += (size_t)r;
+				n -= n & 3;
+				if (reverse) {
+					for (i = 0; i < n; i += 4) {
+						a = buf[i + 3];
+						a = a * (double)frame / fm;
+						a += 0.5;
+						buf[i + 3] = clip((unsigned int)a);
+					}
+				} else {
+					for (i = 0; i < n; i += 4) {
+						a = buf[i + 3];
+						a = a * (double)(fm - frame) / fm;
+						a += 0.5;
+						buf[i + 3] = clip((unsigned int)a);
+					}
+				}
+				for (i = 0; i < n; i += (size_t)r) {
+					r = write(STDOUT_FILENO, buf + i, n - i);
+					if (r < 0)
+						eprintf("write <stdout>:");
+				}
+				memmove(buf, buf + n, ptr -= n);
+			}
+		}
+	}
+
+	return 0;
+}
-- 
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