CSC111 Resizing Graphic Objects

--D. Thiebaut (talk) 11:15, 20 April 2014 (EDT)

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This example uses the graphics library available on this page.

The resize method of the Car class performs the resizing in two steps:

• First all the components of the car are removed. This effectively removes them from the canvas, and forces the canvas to "forgets" them.
• It then calls the __init__() constructor to create a brand new collection of components (body, top, wheels).

# Demo program for resizing a graphic object.
# Highlighted code illustrates the resize method of the Car class.
# D. Thiebaut
#

from graphics111 import *
from random import seed
from random import randrange
from time   import sleep

MAXWIDTH = 800
MAXHEIGHT = 600

         
class Car:
    def __init__( self, x, y, width, height, color ):
        self._x       = x 
        self._y       = y 
        self._width   = width
        self._height  = height
        self._color   = color   # list of 3 ints between 0 and 255

        # build the body
        self._top  = Rectangle( x+width//4, y-height//2,
                                width//2, height//2,
                                color )
        self._body = Rectangle( x, y, width, height, color )
        
        # build the wheels
        self._w1 = Wheel( x + width//4, y + height, width//5 )
        self._w2 = Wheel( x + 3*width//4, y + height, width//5 )
        self._valid = False
        
    def setRandomColor( self ):
        self._top.setRandomColor()
        self._body.setRandomColor()
        
    def getTotalHeight( self ):
        return self._height*2 +  self._width//10

    def getTotalWidth( self ):
        return self._width
        
    def draw( self, canvas ):
        self._canvas = canvas
        self._body.draw( canvas )
        self._top.draw( canvas )
        self._w1.draw( canvas )
        self._w2.draw( canvas )
        
    def move( self, canvas, dx, dy ):
        self._body.move( canvas, dx, dy )
        self._top.move( canvas, dx, dy )
        self._w1.move( canvas, dx, dy )
        self._w2.move( canvas, dx, dy )
        self._x = int( self._x + dx )
        self._y = int( self._y + dy )
        
    def resize( self, canvas, scaleFactor ):
        self._body.remove( canvas )
        self._top.remove( canvas )
        self._w1.remove( canvas )
        self._w2.remove( canvas )
        self.__init__( self._x, self._y,
                    int( self._width * scaleFactor ),
                    int( self._height * scaleFactor ),
                    self._color )
        self.draw( canvas )

# ========================================================
#                        Main Program
# ========================================================
def main():

    # open the window and get access to its canvas
    win = GraphicsWindow(MAXWIDTH, MAXHEIGHT)
    canvas = win.canvas()
        
    # draw something
    p1 = Polygon( (100, 100, 150, 50, 350, 50, 400, 100), (255, 0, 0 ) )
    p1.draw( canvas )

    car1 = Car( 150, 75, 100, 20, (250, 250, 0 ) )
    car1.draw( canvas )

    scaleFactor = 1.05
    for i in range( 0, 40 ):
        car1.resize( canvas, scaleFactor )
        
    # wait and respond to events
    win.wait()
    win.close()
    
main()