this is amidar movement

main.py

@@ -39,8 +39,13 @@ class Random:
 # screen coords range ±120 each side
 
 class Box(Responder):
-    STEP_DELAY = 250
+    STEP_DELAY      = 250
     TURN_DELAY_BASE = 1400
+    MOVE_DELAY      = 100
+    TOP             = -90
+    BOTTOM          = 70 # so its always a bit visible
+    LEFT            = -90
+    RIGHT           = 70
 
     def __init__(self):
         self.random = Random()
@@ -48,6 +53,9 @@ class Box(Responder):
         self.choose_turn_delay()
         self.step = 0
         self.step_delay = Box.STEP_DELAY
+        self.move_delay = Box.MOVE_DELAY
+        self.x = -10
+        self.y = -10
 
     def draw(self, ctx):
         self.clear(ctx)
@@ -61,7 +69,7 @@ class Box(Responder):
 
     def image(self, ctx):
         path = image_path(self.direction, self.step)
-        ctx.image(path, -10, -10, -1, -1)
+        ctx.image(path, self.x, self.y, -1, -1)
 
     @staticmethod
     def coord(d):
@@ -82,7 +90,7 @@ class Box(Responder):
         ctx.rectangle(0, 0, *Box.coord(self.direction)).fill()
 
     def text(self, ctx):
-        msg = f"{self.turn_delay}; {self.step_delay}; {self.direction}; {self.step}"
+        msg = f"{self.x}, {self.y}"
         ctx.font_size = 16.0
         ctx.text_align = ctx.CENTER
         ctx.rgb(1, 1, 1).move_to(0, -100).text(msg)
@@ -93,6 +101,7 @@ class Box(Responder):
     def update_delay(self, Δ):
         self.turn_delay -= Δ
         self.step_delay -= Δ
+        self.move_delay -= Δ
         if self.turn_delay <= 0:
             old_delay = self.turn_delay
             self.choose_direction()
@@ -100,11 +109,43 @@ class Box(Responder):
         if self.step_delay <= 0:
             self.step_delay = Box.STEP_DELAY
             self.step = (self.step + 1) & 3
+        if self.move_delay <= 0:
+            self.move_delay += Box.MOVE_DELAY
+            self.move()
 
     def choose_direction(self):
         self.direction = self.random.direction()
 
     def choose_turn_delay(self, subtract=0):
-        self.turn_delay = self.random.delay() - subtract
+        self.turn_delay = self.random.delay() + subtract
+
+    def at_edge(self):
+        return ((self.direction == UP    and self.y <= Box.TOP) or
+                (self.direction == DOWN  and self.y >= Box.BOTTOM) or
+                (self.direction == LEFT  and self.x <= Box.LEFT) or
+                (self.direction == RIGHT and self.x >= Box.RIGHT))
+
+    def flip_direction(self):
+        if self.direction == UP:
+            self.direction = DOWN
+        elif self.direction == LEFT:
+            self.direction = RIGHT
+        elif self.direction == DOWN:
+            self.direction = UP
+        elif self.direction == RIGHT:
+            self.direction = LEFT
+
+    def move(self):
+        if self.at_edge():
+            self.flip_direction()
+
+        if self.direction == UP:
+            self.y -= 5
+        elif self.direction == LEFT:
+            self.x -= 5
+        elif self.direction == DOWN:
+            self.y += 5
+        elif self.direction == RIGHT:
+            self.x += 5
 
 run_responder(Box())