b1display: screensaver in readme and control.py

Signed-off-by: Daniel Schaefer <dhs@frame.work>

Author: JohnAZoidberg

b1display/README.md

@@ -5,6 +5,12 @@ It's 4.2 inches in size and mounted in portrait orientation.
 Because it's optimized for power, the recommended framerate is 1 FPS.
 But it can go up to 32 FPS.
 
+The current panel is susceptible to image retention, so the display will start
+up with the screen saver. If you send a command to draw anything on the display,
+the screensaver will exit.
+Currently it does not re-appear after a timeout, it will only re-appear on the
+next power-on or after waking from sleep.
+
 ## Controlling
 
 ### Display System Status
@@ -56,6 +62,8 @@ Options:
           Display a simple pattern [possible values: white, black]
       --invert-screen [<INVERT_SCREEN>]
           Invert screen on/off [possible values: true, false]
+      --screen-saver [<SCREEN_SAVER>]
+          Screensaver on/off [possible values: true, false]
       --image-bw <IMAGE_BW>
           Display black&white image (300x400px)
       --clear-ram

control.py

@@ -39,6 +39,8 @@ class CommandVals(IntEnum):
     InvertScreen = 0x15
     SetPixelColumn = 0x16
     FlushFramebuffer = 0x17
+    ClearRam = 0x18
+    ScreenSaver = 0x19
     Version = 0x20
 
 
@@ -192,6 +194,8 @@ def main():
                         action=argparse.BooleanOptionalAction)
     parser.add_argument("--invert-screen", help="Invert display",
                         action=argparse.BooleanOptionalAction)
+    parser.add_argument("--screen-saver", help="Turn on/off screensaver",
+                        action=argparse.BooleanOptionalAction)
     parser.add_argument("--b1image", help="On the B1 display, show a PNG or GIF image in black and white only)",
                         type=argparse.FileType('rb'))
 
@@ -256,7 +260,7 @@ def main():
         snake_embedded()
     elif args.game_of_life_embedded is not None:
         game_of_life_embedded(args.game_of_life_embedded)
-    elif args.quit_embedded_game is not None:
+    elif args.quit_embedded_game:
         send_command(CommandVals.GameControl, [GameControlVal.Quit])
     elif args.pong_embedded:
         pong_embedded()
@@ -276,6 +280,8 @@ def main():
         display_on_cmd(args.display_on)
     elif args.invert_screen is not None:
         invert_screen_cmd(args.invert_screen)
+    elif args.screen_saver is not None:
+        screen_saver_cmd(args.screen_saver)
     elif args.b1image is not None:
         b1image_bl(args.b1image)
     elif args.version:
@@ -1063,6 +1069,10 @@ def invert_screen_cmd(invert):
     send_command(CommandVals.InvertScreen, [invert])
 
 
+def screen_saver_cmd(on):
+    send_command(CommandVals.ScreenSaver, [on])
+
+
 # 5x6 symbol font. Leaves 2 pixels on each side empty
 # We can leave one row empty below and then the display fits 5 of these digits.