twgrops--- via Python-list wrote:
> Hi I am new here and to python,
>
> I am currently studying towards my degree in computer science and have to
> build a program but I have hit a brick wall. I am trying to make an image
> move around the canvas. I can make a rectangle move using the following:
>
> #test rectangle
> id1=canvas.create_rectangle(3,7,3+10,7+10)
>
> # Generate x and y coordinates for 500 timesteps
> for t in range(1, 500):
>
> x1,y1,x2,y2=canvas.coords(id1)
>
> # If a boundary has been crossed, reverse the direction
> if x1 >= x_max:
> vx = -10.0
> if y1 <= y_min:
> vy = 5.0
> if y2 >= y_max:
> vy = -5.0
> if x1 <= x_min:
> vx = 10.0
>
> # Reposition the robot
> canvas.coords(id1,x1+vx,y1+vy,x2+vx,y2+vy)
> canvas.update()
>
> # Pause for 0.1 seconds, then delete the image
> time.sleep(0.1)
You should never use sleep() in conjunction with tkinter. Instead make a
little function that schedules itself for invocation after a few
milliseconds:
def move():
... # move sprits
root.after(100, move) # have tkinter call move()
# again after 100 milliseconds
That way the event loop is undisturbed and the application can respond to
user input.
> However i would like my image/sprite to move around:
>
> objecttank=canvas.create_image(950,650,image=gif6, anchor= NW)
>
> from what i gather it is because an image only has two axis, x and y but
> the rectangle seems to have 4 values, my error code keeps saying expecting
> 4 but got 2.
Always provide the exact code causing the error, and the traceback it
generated. Use copy and paste instead of paraphrasing.
> Can anyone help me in the right direction, many thanks tom.
I think I have done this before, but cannot find it atm, so instead of a
link here's a new demo:
try:
import tkinter as tk
except ImportError:
import Tkinter as tk
import random
WIDTH = 1024
HEIGHT = 768
def random_speed():
return random.choice([-1, 1]) * random.randrange(5, 15)
def random_image(canvas, image):
"""Place `image` on `canvas` with random pos and speed.
"""
return Image(
canvas,
image,
random.randrange(WIDTH-image.width()),
random.randrange(HEIGHT-image.height()),
random_speed(),
random_speed(),
)
class Image(object):
def __init__(self, canvas, image, x, y, vx, vy):
self.canvas = canvas
self.image = image
self.x = x
self.y = y
self.vx = vx
self.vy = vy
self.w = image.width()
self.h = image.height()
self.id = canvas.create_image(x, y, image=image, anchor=tk.NW)
@property
def right(self):
return self.x + self.w
@property
def bottom(self):
return self.y + self.h
def move(self):
self.x += self.vx
self.y += self.vy
self.canvas.move(self.id, self.vx, self.vy)
if self.bottom > HEIGHT or self.y < 0:
self.vy = - self.vy
if self.right > WIDTH or self.x < 0:
self.vx = - self.vx
def move():
for image in images:
image.move()
root.after(50, move)
if __name__ == "__main__":
root = tk.Tk()
ball = tk.PhotoImage(file="ball.gif")
canvas = tk.Canvas(root, width=WIDTH, height=HEIGHT)
canvas.pack()
images = [random_image(canvas, ball) for _ in range(10)]
move()
root.mainloop()
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