From 6dd4954eaf74783497e1b8abfd52a67e7295035d Mon Sep 17 00:00:00 2001
From: swsamleo <wei.shao@rmit.edu.au>
Date: Wed, 22 Feb 2023 18:08:01 -0800
Subject: [PATCH 1/2] add listener and change single_2lanefree_carla

---
 .../single_2lanefree_carla.py                 | 14 +++-
 .../utils/keyboard_listener.py                | 76 +++++++++++++++++++
 2 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 opencda/scenario_testing/utils/keyboard_listener.py

diff --git a/opencda/scenario_testing/single_2lanefree_carla.py b/opencda/scenario_testing/single_2lanefree_carla.py
index 3aebe5d37..4e22ba3ec 100644
--- a/opencda/scenario_testing/single_2lanefree_carla.py
+++ b/opencda/scenario_testing/single_2lanefree_carla.py
@@ -16,7 +16,7 @@
 from opencda.scenario_testing.evaluations.evaluate_manager import \
     EvaluationManager
 from opencda.scenario_testing.utils.yaml_utils import load_yaml
-
+from opencda.scenario_testing.utils.keyboard_listener import KeyListener
 
 def run_scenario(opt, config_yaml):
     try:
@@ -55,8 +55,20 @@ def run_scenario(opt, config_yaml):
                               current_time=scenario_params['current_time'])
 
         spectator = scenario_manager.world.get_spectator()
+
+        # initialize a key listener and start monitoring the keyboard
+        kl = KeyListener()
+        kl.start()
+
         # run steps
         while True:
+            # press esc to end the program
+            # press p to pause demonstration
+            if kl.keys['esc']:
+                exit(0)
+            if kl.keys['p']:
+                continue
+
             scenario_manager.tick()
             transform = single_cav_list[0].vehicle.get_transform()
             spectator.set_transform(carla.Transform(
diff --git a/opencda/scenario_testing/utils/keyboard_listener.py b/opencda/scenario_testing/utils/keyboard_listener.py
new file mode 100644
index 000000000..f029edd3c
--- /dev/null
+++ b/opencda/scenario_testing/utils/keyboard_listener.py
@@ -0,0 +1,76 @@
+from pynput import keyboard
+
+
+class KeyListener(object):
+    """
+    A keyboard listener class to record the states of keys.
+
+    Parameters
+    ----------
+    None
+
+    Attributes
+    ----------
+    keys : dict
+        Keyboard keys and states
+    """
+    def __init__(self):
+        """
+        Initialize a listener instance
+        """
+        self.keys = {'p': False, 'esc': False}
+
+    def start(self):
+        """
+        Start keyboard listening
+
+        Parameters
+        ----------
+        None
+
+        Returns
+        -------
+        None
+        """
+        listener = keyboard.Listener(
+            on_press=self.on_press,
+            on_release=self.on_release)
+        listener.start()
+
+    def on_press(self, key):
+        """
+        Update the dict when a key is pressed
+
+        Parameters
+        ----------
+        key: A KeyCode represents the description of a key code used by the operating system.
+
+        Returns
+        -------
+        Update the dict keys
+        """
+        try:
+            print(f'alphanumeric key {key.char} pressed')
+            if key.char in self.keys:
+                self.keys[key.char] = not self.keys[key.char]
+            else:
+                self.keys[key] = False
+        except AttributeError:
+            print(f'special key {key} pressed')
+
+    def on_release(self, key):
+        """
+        Update the dict keys when a key is released
+
+        Parameters
+        ----------
+        key: A KeyCode represents the description of a key code used by the operating system.
+
+        Returns
+        -------
+        Update the dict keys
+        """
+        if key == keyboard.Key.esc:
+            self.keys['esc'] = True
+
+

From 49210e60be59c4735549d6baff4f3ef9c9cddeb6 Mon Sep 17 00:00:00 2001
From: swsamleo <wei.shao@rmit.edu.au>
Date: Thu, 23 Feb 2023 10:23:15 -0800
Subject: [PATCH 2/2] update keyboard_listener.py with comments

---
 opencda/scenario_testing/utils/keyboard_listener.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/opencda/scenario_testing/utils/keyboard_listener.py b/opencda/scenario_testing/utils/keyboard_listener.py
index f029edd3c..2eadc027d 100644
--- a/opencda/scenario_testing/utils/keyboard_listener.py
+++ b/opencda/scenario_testing/utils/keyboard_listener.py
@@ -1,3 +1,10 @@
+# -*- coding: utf-8 -*-
+"""
+keyboard listener: a keyboard listenr to record typeing and can be used for pasue, resume and stop the program using multi-threading.
+"""
+# Author: Wei Shao <weishao@ucdavis.edu>
+# License: TDG-Attribution-NonCommercial-NoDistrib
+
 from pynput import keyboard
 
 
@@ -74,3 +81,4 @@ def on_release(self, key):
             self.keys['esc'] = True
 
 
+