From 4a3ac9442a7e6fb810f3c56b4a00ffa120cae475 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sun, 9 Apr 2017 11:19:31 +0200
Subject: Add blind-skip-pattern
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 Makefile                 |  1 +
 TODO                     |  1 -
 man/blind-next-frame.1   |  3 +-
 man/blind-skip-pattern.1 | 26 +++++++++++++++
 src/blind-skip-pattern.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 113 insertions(+), 2 deletions(-)
 create mode 100644 man/blind-skip-pattern.1
 create mode 100644 src/blind-skip-pattern.c

diff --git a/Makefile b/Makefile
index b791e17..377adb9 100644
--- a/Makefile
+++ b/Makefile
@@ -28,6 +28,7 @@ BIN =\
 	blind-set-luma\
 	blind-set-saturation\
 	blind-single-colour\
+	blind-skip-pattern\
 	blind-split\
 	blind-stack\
 	blind-time-blur\
diff --git a/TODO b/TODO
index e5bfc30..163fd36 100644
--- a/TODO
+++ b/TODO
@@ -14,7 +14,6 @@ blind-affine-colour	apply an affine transformation to the colour of each pixel,
 				-l for linear transformation,
 				-p for transforming each pixel with their own transformation.
 blind-invert-chroma	invert the chroma
-blind-skip-pattern	discard frames according to pattern, e.g. every other frame
 blind-from-sent		convert a sent presentation to a one-frame-per-slide blind video
 
 blind-from-video: add options to:
diff --git a/man/blind-next-frame.1 b/man/blind-next-frame.1
index 55fe74f..fe888cb 100644
--- a/man/blind-next-frame.1
+++ b/man/blind-next-frame.1
@@ -50,7 +50,8 @@ An error occurred.
 .BR blind-read-head (1),
 .BR blind-write-head (1),
 .BR blind-to-image (1),
-.BR blind-from-image (1)
+.BR blind-from-image (1),
+.BR blind-skip-pattern (1)
 .SH AUTHORS
 Mattias Andrée
 .RI < maandree@kth.se >
diff --git a/man/blind-skip-pattern.1 b/man/blind-skip-pattern.1
new file mode 100644
index 0000000..4565820
--- /dev/null
+++ b/man/blind-skip-pattern.1
@@ -0,0 +1,26 @@
+.TH BLIND-SKIP-PATTERN 1 blind
+.SH NAME
+blind-skip-pattern - Skips frames in a video according to pattern
+.SH SYNOPSIS
+.B blind-skip-pattern
+.RI ( skipped-frames
+|
+.RI + included-frames )\ ...
+.SH DESCRIPTION
+For every argument,
+.B blind-skip-pattern
+skips
+.I skipped-frames
+frames from stdin or prints
+.I included-frames
+frames from stdin to stdout,
+until the end of stdin is reached.
+After the last argument,
+.B blind-skip-pattern
+jumps back to the first argument.
+.SH SEE ALSO
+.BR blind (7),
+.BR blind-next-frame (1),
+.SH AUTHORS
+Mattias Andrée
+.RI < maandree@kth.se >
diff --git a/src/blind-skip-pattern.c b/src/blind-skip-pattern.c
new file mode 100644
index 0000000..1debeca
--- /dev/null
+++ b/src/blind-skip-pattern.c
@@ -0,0 +1,84 @@
+/* See LICENSE file for copyright and license details. */
+#include "stream.h"
+#include "util.h"
+
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+
+USAGE("(skipped-frames | +included-frames) ...")
+
+static int
+process_frame(struct stream *stream, int include, size_t rown)
+{
+	size_t h, n;
+	int anything = 0;
+
+	for (h = stream->height; h;) {
+		h--;
+		for (n = rown; n; n -= stream->ptr) {
+			stream->ptr = 0;
+			if (!eread_stream(stream, n))
+				goto done;
+			anything = 1;
+			if (include)
+				ewriteall(STDOUT_FILENO, stream->buf, stream->ptr, "<stdout>");
+		}
+	}
+done:
+
+	if (anything && (h || n || stream->frames))
+		eprintf("%s: is shorted than expected\n", stream->file);
+
+	return !anything;
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct stream stream;
+	int i, include;
+	size_t f, n, rown, total = 0;
+	char *includes;
+	size_t *ns;
+
+	UNOFLAGS(!argc);
+
+	stream.fd = STDIN_FILENO;
+	stream.file = "<stdin>";
+	einit_stream(&stream);
+
+	includes = emalloc((size_t)argc);
+	ns = ecalloc((size_t)argc, sizeof(*ns));
+
+	for (i = 0; i < argc; i++) {
+		include = argv[i][0] == '+';
+		n = etozu_arg(include ? "included frame count" : "skipped frame count",
+			      argv[i] + include, 0, SIZE_MAX);
+		ns[i] = n;
+		includes[i] = (char)include;
+	}
+	if (!total)
+		eprintf("null pattern is not allowed");
+
+	for (i = 0, total = 0, f = stream.frames;; i = (i + 1) % argc) {
+		include = (int)includes[i];
+		for (n = ns[i]; n-- && f--;)
+			total += (size_t)include;
+	}
+
+	stream.frames = total;
+	fprint_stream_head(stdout, &stream);
+	efflush(stdout, "<stdout>");
+
+	rown = stream.width * stream.pixel_size;
+	for (i = 0;; i = (i + 1) % argc) {
+		include = (int)includes[i];
+		n = ns[i];
+		while (n-- && process_frame(&stream, include, rown));
+	}
+
+	free(includes);
+	free(ns);
+	return 0;
+}
-- 
cgit v1.2.3-70-g09d2