#----------------------------------------------------------------------
# Bounce ball - Copyright (C) October 19, 2018 -- Dr. William T. Verts
#----------------------------------------------------------------------

import time

def addEllipse (Canvas,X,Y,Xradius,Yradius,NewColor=black):
    addOval(Canvas,X-Xradius,Y-Yradius,2*Xradius,2*Yradius,NewColor)
    return

def addEllipseFilled (Canvas,X,Y,Xradius,Yradius,NewColor=black):
    addOvalFilled(Canvas,X-Xradius,Y-Yradius,2*Xradius,2*Yradius,NewColor)
    return

def addCircle (Canvas,X,Y,Radius,NewColor=black):
    addEllipse(Canvas,X,Y,Radius,Radius,NewColor)
    return

def addCircleFilled (Canvas,X,Y,Radius,NewColor=black):
    addEllipseFilled(Canvas,X,Y,Radius,Radius,NewColor)
    return

def Main():
    W = 800
    H = 500
    C = makeColor(30,190,255)
    Canvas = makeEmptyPicture(W,H,C)
    show(Canvas)
    X = W / 2
    Y = H / 2
    Xdirection = 1
    Ydirection = 1
    Radius = 75
    
    while True:
        #addRectFilled(Canvas,0,0,W,H,C) 
        setAllPixelsToAColor(Canvas,C)       # Does the same thing as previous line, but faster      
        addCircleFilled(Canvas,X,Y,Radius,red)        
        repaint(Canvas)
        time.sleep(0.01)
        
        X = X + Xdirection
        Y = Y + Ydirection
        if (X > W-Radius): Xdirection = -1
        if (X <   Radius): Xdirection = +1
        if (Y > H-Radius): Ydirection = -1
        if (Y <   Radius): Ydirection = +1
    
    return