import tkinter

x = 0
ani = 0

def animation():
    global x, ani
    x = x + 4
    if x == 480:
        x = 0
    canvas.delete('BG')
    canvas.create_image(x - 240, 150, image = img_bg, tag = 'BG')
    canvas.create_image(x + 240, 150, image = img_bg, tag = 'BG')
    ani = (ani + 1) % 4
    canvas.create_image(240, 200, image = img_dog[ani], tag = 'BG')
    root.after(200, animation)

root = tkinter.Tk()
root.title('動畫')
canvas = tkinter.Canvas(width = 480, height = 300)
canvas.pack()
img_bg = tkinter.PhotoImage(file = 'images/park.png')

img_dog = [
    tkinter.PhotoImage(file = 'images/dog0.png'),
    tkinter.PhotoImage(file = 'images/dog1.png'),
    tkinter.PhotoImage(file = 'images/dog2.png'),
    tkinter.PhotoImage(file = 'images/dog3.png')
]

animation()
root.mainloop()