From 70b03ed486e3fddcc9416a4a3e38576455ebfe98 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sun, 8 Jan 2017 04:40:23 +0100
Subject: Add vu-set-alpha
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 src/vu-set-alpha.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 src/vu-set-alpha.c

(limited to 'src/vu-set-alpha.c')

diff --git a/src/vu-set-alpha.c b/src/vu-set-alpha.c
new file mode 100644
index 0000000..87a14ae
--- /dev/null
+++ b/src/vu-set-alpha.c
@@ -0,0 +1,138 @@
+/* See LICENSE file for copyright and license details. */
+#include "arg.h"
+#include "util.h"
+
+#include <inttypes.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static void
+usage(void)
+{
+	eprintf("usage: %s [-i] colour-stream alpha-stream\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	int invert = 0;
+	int fd_colour = -1;
+	int fd_alpha = -1;
+	unsigned char buf_colour[1024];
+	unsigned char buf_alpha[1024];
+	size_t ptr_colour = 0;
+	size_t ptr_alpha = 0;
+	ssize_t r;
+	size_t i, n;
+	unsigned long int re, gr, bl, a1, a2;
+
+	ARGBEGIN {
+	case 'i':
+		invert = 1;
+		break;
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 2)
+		usage();
+
+	fd_colour = open(argv[0], O_RDONLY);
+	if (fd_colour < 0)
+		eprintf("open %s:", argv[0]);
+
+	fd_alpha = open(argv[1], O_RDONLY);
+	if (fd_alpha < 0)
+		eprintf("open %s:", argv[1]);
+
+	for (;;) {
+		r = read(fd_colour, buf_colour + ptr_colour, sizeof(buf_colour) - ptr_colour);
+		if (r < 0) {
+			eprintf("read %s:", argv[0]);
+		} else if (r == 0) {
+			close(fd_colour);
+			fd_colour = -1;
+			break;
+		} else {
+			ptr_colour += (size_t)r;
+		}
+
+		r = read(fd_alpha, buf_alpha + ptr_alpha, sizeof(buf_alpha) - ptr_alpha);
+		if (r < 0) {
+			eprintf("read %s:", argv[0]);
+		} else if (r == 0) {
+			close(fd_alpha);
+			fd_alpha = -1;
+			break;
+		} else {
+			ptr_alpha += (size_t)r;
+		}
+
+		n = ptr_colour < ptr_alpha ? ptr_colour : ptr_alpha;
+		n -= n & 3;
+		ptr_colour -= n;
+		ptr_alpha -= n;
+
+		for (i = 0; i < n; i += 4) {
+			re = buf_alpha[i + 0];
+			gr = buf_alpha[i + 1];
+			bl = buf_alpha[i + 2];
+			a1 = buf_alpha[i + 3];
+			a2 = buf_colour[i + 3];
+			re += gr + bl;
+			if (invert)
+				re = 765 - re;
+			a1 *= a2 * re;
+			a1 = (a1 * 2 + 3 * 255 * 255) / (3 * 255 * 255 * 2);
+			buf_colour[i + 3] = a1;
+		}
+
+		for (i = 0; i < n; i++) {
+			r = write(STDOUT_FILENO, buf_colour + i, n - i);
+			if (r < 0)
+				eprintf("write <stdout>:");
+			i += (size_t)r;
+		}
+
+		if ((n & 3) || ptr_colour != ptr_alpha) {
+			memmove(buf_colour, buf_colour + n, ptr_colour);
+			memmove(buf_alpha,  buf_alpha  + n, ptr_alpha);
+		}
+	}
+
+	if (fd_alpha >= 0)
+		close(fd_alpha);
+
+	while (ptr_colour) {
+		r = write(STDOUT_FILENO, buf_colour, ptr_colour);
+		if (r < 0)
+			eprintf("write <stdout>:");
+		ptr_colour -= (size_t)r;
+	}
+
+	if (fd_colour >= 0) {
+		for (;;) {
+			r = read(fd_colour, buf_colour, sizeof(buf_colour));
+			if (r < 0) {
+				eprintf("read %s:", argv[0]);
+			} else if (r == 0) {
+				close(fd_colour);
+				fd_colour = -1;
+				break;
+			} else {
+				n = (size_t)r;
+			}
+
+			r = write(STDOUT_FILENO, buf_colour, n);
+			if (r < 0)
+				eprintf("write <stdout>:");
+			n -= (size_t)r;
+		}
+	}
+
+	return 0;
+}
-- 
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