From 091974e6c54795d343e4aef12d38c06f568aaf25 Mon Sep 17 00:00:00 2001
From: Julian Oes <julian@oes.ch>
Date: Wed, 11 Dec 2024 10:00:36 +1300
Subject: [PATCH] listener: only clear screen with multiple messages (#24019)

* listener: only clear screen with multiple messages

* listener: fully clear before printing again

Otherwise, we end up seeing artifacts from the previous print.
---
 src/systemcmds/topic_listener/listener_main.cpp | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/systemcmds/topic_listener/listener_main.cpp b/src/systemcmds/topic_listener/listener_main.cpp
index 83ca22ddd710..28244869f90f 100644
--- a/src/systemcmds/topic_listener/listener_main.cpp
+++ b/src/systemcmds/topic_listener/listener_main.cpp
@@ -113,9 +113,6 @@ void listener(const orb_id_t &id, unsigned num_msgs, int topic_instance,
 		fds[1].fd = sub;
 		fds[1].events = POLLIN;
 
-		// Clear screen
-		dprintf(1, "\033[2J\n");
-
 		while (msgs_received < num_msgs) {
 
 			if (poll(&fds[0], 2, int(MESSAGE_TIMEOUT_S * 1000)) > 0) {
@@ -142,8 +139,13 @@ void listener(const orb_id_t &id, unsigned num_msgs, int topic_instance,
 				if (fds[1].revents & POLLIN) {
 					msgs_received++;
 
-					// Move cursor to home position
-					dprintf(1, "\033[H");
+					if (num_msgs > 1) {
+						// Clear screen
+						dprintf(1, "\033[2J\n");
+						// Move cursor to home position
+						dprintf(1, "\033[H");
+					}
+
 					PX4_INFO_RAW("\nTOPIC: %s instance %d #%d\n", id->o_name, topic_instance, msgs_received);
 
 					int ret = listener_print_topic(id, sub);