from graphics import *
# you need to download graphics.py and place it in the same folder as this code
def HTree(n, size,  x, y, win): 
        ''' (int, float, float, float, GraphWin) -> NoneType
        draw an HTree
        the first int is the order of the H Tree, 
        size is the size of the horizontal and vertical line  of each H tree
        x, y are the cordinate of the middle of the horizontal line of the H
        '''
        
        if (n > 0):
                
                x0 = x - size/2
                x1 = x + size/2
                y0 = y - size/2
                y1 = y + size/2
                      
              
                line = Line(Point(x0, y), Point(x1, y)) 
                line.setWidth(2)
                line.draw(win)    
                line = Line(Point(x0, y0), Point(x0, y1)) 
                line.setWidth(2)
                line.draw(win)    
                line = Line(Point(x1, y0), Point(x1, y1)) 
                line.setWidth(2)
                line.draw(win)    
           
                HTree(n-1, size/2, x0, y0, win)
                HTree(n-1, size/2, x0, y1, win)
                HTree(n-1, size/2, x1, y0, win)
                HTree(n-1, size/2, x1, y1, win)
        
    

if (__name__ == "__main__"):
        # title and dimensions
        win = GraphWin('HTree', 500, 500) 
        # first parameter shows the order
        # if you want to see a clear HTree try the order of 1 -  6
        # if you want to see how slow a recursive function can work, try it with order > 6
        
        HTree(5, 200,  win.getWidth()/2, win.getWidth()/2, win) 
        message = Text(Point(win.getWidth()/2, 20), 'Click anywhere inside the window to quit.')
        message.draw(win)
        win.getMouse()
        win.close()