make liveplotter not steal focus and terminate as expected

tools/liveplotter.py

@@ -19,20 +19,32 @@ plt.ion()
 global vals
 vals = []
 
+# Make sure the script terminates when the user closes the plotter
+cancellation_token = threading.Event()
+def handle_close(evt):
+    cancellation_token.set()
+fig = plt.figure()
+fig.canvas.mpl_connect('close_event', handle_close)
+
 def fetch_data():
     global vals
-    while True:
-        vals.append(my_odrive.motor0.encoder.pll_pos)
+    global cancellation_token
+    while not cancellation_token.is_set():
+        vals.append(my_odrive.motor0.timing_log.TIMING_LOG_FOC_CURRENT)
         if len(vals) > num_samples:
             vals = vals[-num_samples:]
         time.sleep(1/data_rate)
 
+# TODO: use animation for better UI performance, see:
+# https://matplotlib.org/examples/animation/simple_anim.html
 def plot_data():
     global vals
-    while True:
+    global cancellation_token
+    while not cancellation_token.is_set():
         plt.clf()
         plt.plot(vals)
-        plt.pause(1/plot_rate)
+        #time.sleep(1/plot_rate)
+        fig.canvas.flush_events()
 
 fetch_thread = threading.Thread(target=fetch_data, daemon=True)
 fetch_thread.start()