From a5b1e209417b7d3f5b0099642dd317c312f79377 Mon Sep 17 00:00:00 2001
From: Nicholas Marriott <nicholas.marriott@gmail.com>
Date: Thu, 28 Nov 2019 14:20:22 +0000
Subject: [PATCH] Add a flag to disable blocking while sending a SIXEL image
 (turned off when the buffer hits 0 size).

---
 tmux.h | 1 +
 tty.c  | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/tmux.h b/tmux.h
index 7c901b9d..b1e7f44e 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1203,6 +1203,7 @@ struct tty {
 #define TTY_OPENED 0x20
 #define TTY_FOCUS 0x40
 #define TTY_BLOCK 0x80
+#define TTY_NOBLOCK 0x100
 	int		 flags;
 
 	struct tty_term	*term;
diff --git a/tty.c b/tty.c
index cae2fd24..da21645f 100644
--- a/tty.c
+++ b/tty.c
@@ -211,6 +211,11 @@ tty_block_maybe(struct tty *tty)
 	size_t		 size = EVBUFFER_LENGTH(tty->out);
 	struct timeval	 tv = { .tv_usec = TTY_BLOCK_INTERVAL };
 
+	if (size == 0)
+		tty->flags &= ~TTY_NOBLOCK;
+	else if (tty->flags & TTY_NOBLOCK)
+		return (0);
+
 	if (size < TTY_BLOCK_START(tty))
 		return (0);
 
@@ -1872,6 +1877,7 @@ tty_cmd_rawsixel(struct tty *tty, const struct tty_ctx *ctx)
 	int	flags = (tty->term->flags|tty->term_flags);
 
 	if ((flags & TERM_SIXEL) || tty_term_has(tty->term, TTYC_SXL)) {
+		tty->flags |= TTY_NOBLOCK;
 		tty_add(tty, ctx->ptr, ctx->num);
 		if (!ctx->more)
 			tty_invalidate(tty);