Wait data for full screen refresh.

There is no partial refresh and the full refresh is slow => wait few
seconds for other data to arrive before refreshing instead of
refreshing every many times.

raspberry/python/mqtt2epaper.py

@@ -45,6 +45,8 @@ white = inkyphat.WHITE
 black = inkyphat.BLACK
 grey = inkyphat.RED
 
+new_data_flag = False
+
 #############
 # CALLBACKS #
 #############
@@ -63,6 +65,8 @@ def on_connect(client, userdata, flags, rc):
 def on_message(client, userdata, msg):
     """Callback for managing data sent by MQTT broker"""
 
+    global new_data_flag
+
     top=msg.topic[len(mqtt_topic)-1:].strip()
     #List of the subtopics
     subtopics = top.split("/")
@@ -99,7 +103,8 @@ def on_message(client, userdata, msg):
                           "{:6.1f}{}  ".format(val['value'], val['unit']),
                           font=data_font,
                           fill=black)
-            inkyphat.show()
+            new_data_flag = True
+            update_display()
 
     # Print feather's date and time on epaper display
     elif subtopics[0] == "SYS":
@@ -114,31 +119,34 @@ def on_message(client, userdata, msg):
                 dt_texte = payload
             print(dt_texte)
             # First erase old text
-            inkyphat.rectangle((0, 31, inkyphat.WIDTH, 45), fill=white)
+            inkyphat.rectangle((0, date_line, inkyphat.WIDTH, data1_line - 2), fill=white)
             # and draw the new date
             inkyphat.text((0, 31), dt_texte, font=font12, fill=black)
-
-            inkyphat.show()
+            new_data_flag = True
+            update_display()
 
 def on_message_camera(client, userdata, msg):
     """Update display with info from camera (camera shooting new picture or name
     of the last photo)"""
 
+    global new_data_flag
+
     pl = msg.payload.decode()
     print("{} : {} ({})".format(msg.topic, pl, type(pl)))
 
     # If a picture is been taken
     if pl == "1" and msg.topic == camera_mqtt_topic + "/shooting" :
-        inkyphat.rectangle((0, inkyphat.HEIGHT - 13, inkyphat.WIDTH, inkyphat.HEIGHT), fill=white)
-        inkyphat.text((0, inkyphat.HEIGHT - 13), "Shooting photo...              ", font=font12, fill=black)
-        inkyphat.show()
+        text = "Shooting photo...              "
+        inkyphat.rectangle((0, inkyphat.HEIGHT - 12, inkyphat.WIDTH, inkyphat.HEIGHT), fill=white)
+        inkyphat.text((0, inkyphat.HEIGHT - 12), text, font=font12, fill=black)
+        new_data_flag = True
 
     #Last picture name (with date/time)
     if msg.topic == camera_mqtt_topic + "/last_photo":
+        text = "Last: {}".format(pl)
+        new_data_flag = True
         inkyphat.rectangle((0, inkyphat.HEIGHT - 12, inkyphat.WIDTH, inkyphat.HEIGHT), fill=white)
-        inkyphat.text((0, inkyphat.HEIGHT - 12), "Last: " + pl, font=font12, fill=black)
-        inkyphat.show()
-
+        inkyphat.text((0, inkyphat.HEIGHT - 12), text, font=font12, fill=black)
 
 def on_disconnect(client, userdata, msg):
     """Disconnection callback"""
@@ -146,6 +154,29 @@ def on_disconnect(client, userdata, msg):
         print("Unexpected disconnection : {}".format(msg))
     exit()
 
+############
+# Function #
+############
+
+def update_display():
+    global new_data_flag
+    global refresh_timer
+    global refresh_rate
+
+    if new_data_flag == True:
+        if refresh_timer < 0:
+            # New data just arrived : wait for other data for a short period
+            print("new data...")
+            refresh_timer = time.time() + refresh_rate
+        elif time.time() >= refresh_timer :
+            # No new data to display : update the screen and reset the flags!
+            print("Refresh eink screen with new data ! ({} / {})".format(refresh_timer, time.time()))
+            inkyphat.show()
+            new_data_flag = False
+            refresh_timer = -1
+            print("OK")
+    return
+
 ########
 # Main #
 ########
@@ -196,8 +227,6 @@ inkyphat.line((0, data2_line - 1, inkyphat.WIDTH, data2_line - 1), fill=black)
 inkyphat.line((0, data_table_bottom_line, inkyphat.WIDTH, data_table_bottom_line), fill=black)
 inkyphat.line((inkyphat.WIDTH / 2, data1_line - 1, inkyphat.WIDTH / 2, data_table_bottom_line), fill=black)
 
-inkyphat.show()
-
 #Connect to MQTT broker and loop...
 mqtt_client = mqtt.Client(mqtt_client_id, clean_session=True)
 mqtt_client.username_pw_set(mqtt_user, mqtt_pass)
@@ -210,4 +239,9 @@ mqtt_client.message_callback_add(camera_mqtt_topic + "/#", on_message_camera)
 print(mqtt_host + ":" + str(mqtt_port))
 mqtt_client.connect(mqtt_host, int(mqtt_port), 60)
 
-mqtt_client.loop_forever()
+refresh_rate = 5
+refresh_timer = -1
+
+while True:
+    mqtt_client.loop()
+    update_display()