python/position_control.py at master · larlyssa/python · GitHub

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# position control example

import simplegui

# Initialize globals
WIDTH = 600
HEIGHT = 400
BALL_RADIUS = 20

ball_pos = [WIDTH/2, HEIGHT/2]

# defien event handlers
def draw(canvas):
    canvas.draw_circle(ball_pos, BALL_RADIUS, 2, "Red", "White")

def keydown(key):
    vel = 4
    if key == simplegui.KEY_MAP["left"]:
        ball_pos[0] -= vel
    elif key == simplegui.KEY_MAP["right"]:
        ball_pos[0] += vel
    elif key == simplegui.KEY_MAP["down"]:
        ball_pos[1] += vel
    elif key == simplegui.KEY_MAP["up"]:
        ball_pos[1] -= vel

# create frame
frame = simplegui.create_frame("Positional ball control", WIDTH, HEIGHT)

# register event handlers
frame.set_draw_handler(draw)
frame.set_keydown_handler(keydown)

# start frame
frame.start()