# File: Xiang/move2.py
# 
# Red Ball moves on the screen. Changes directions for hitting the border

from graphics import *
MAXX,MAXY = 500,500

def initGraphics():
    win = GraphWin( "Moving Red Ball R=25" , MAXX, MAXY  )
    return win

def main():
    win = initGraphics()
    deltaX, deltaY = 3,3
    message = Text( Point(300,15), "Moving Red Ball r=15" )
    message.draw( win )

    r=15        # radius
    ball = Circle( Point(100,100), r ) # start from P(100,100)
    ball.setFill( "red" )       # ball is red
    ball.draw( win )
 
    for i in range( 500):
        ball.undraw()
        if  not ( 0 <= ball.getCenter().getX() <= MAXX ): # check x,y in frame 
            deltaX = -deltaX     #change direction
        if  not ( 0 <= ball.getCenter().getY() <= MAXY ):
            deltaY = -deltaY
            
        ball.move( deltaX, deltaY )                    
        ball.draw( win )

    win.getMouse()
    win.close()

main()