Python箭头键不响应Paddle

Question

Here is my problem that i just can't seem to figure out.

Here is part of my code:

from tkinter import*
import random
import time

class Paddle:
    def turn_left(self, evt):
            self.y = -3
    def turn_right(self, evt):
            self.y = 3

def __init__(self, canvas, color):
    self.canvas = canvas
    self.id = canvas.create_rectangle(0, 150, 30, 250, fill = color)
    self.y = 0
    self.canvas_height = self.canvas.winfo_height()
    self.canvas_width = self.canvas.winfo_width()
    self.canvas.bind_all('<KeyPress-a>', self.turn_left)
    self.canvas.bind_all('<KeyPress-d>', self.turn_right)


def draw(self):
    self.canvas.move(self.id, 0, self.y)
    pos = self.canvas.coords(self.id)
    if pos[1] <= 0:
        self.y = 0
    if pos[3] >= f00:
        self.y = 0        

ball = Ball(canvas, 'orange')
paddle = Paddle(canvas, "blue")

while 1:
    ball.draw()
    tk.update_idletasks()
    tk.update()
    time.sleep(0.01)

and the Paddle doesn't respond to 'a' and 'd' at all.

Now if i take out the 'evt', run the code, and press 'a' or 'd' it gives me an

error, so Python knows I am pressing the keys...

Now what exactly did i do wrong?

Answer 1

In while you simply forgot

paddle.draw()

so keys change self.y but it doesn't execute draw() which moves paddle.

(and name self.y is missleading - it doesn't change paddle position directly)

---

Full working version with other changes (but without ball)

import tkinter as tk
import time

# --- classes ---

class Paddle:

    def __init__(self, canvas, color, x, y, key_up, key_down):
        self.canvas = canvas
        self.canvas_height = self.canvas.winfo_height()
        self.canvas_width = self.canvas.winfo_width()

        # if window (and canvas) doesn't exist (yet) then it has size (1,1)
        print('canvas size:', self.canvas_height, self.canvas_width)

        self.id = canvas.create_rectangle(x-15, y-50, x+15, y+50, fill=color)

        self.move_y = 0

        self.canvas.bind_all(key_up, self.turn_left)
        self.canvas.bind_all(key_down, self.turn_right)

    def turn_left(self, evt):
        self.move_y = -3

    def turn_right(self, evt):
        self.move_y = 3

    def draw(self):
        if self.move_y != 0:
            pos = self.canvas.coords(self.id)
            if pos[1] <= 0 and self.move_y < 0:
                self.move_y = 0
            if pos[3] >= self.canvas_height and self.move_y > 0:
                self.move_y = 0
            self.canvas.move(self.id, 0, self.move_y)

# --- main ---

root = tk.Tk()

canvas = tk.Canvas(root, width=300, height=300)
canvas.pack()

# to create window and canvas 
root.update()

paddle1 = Paddle(canvas, "blue", 15, 150, '<a>', '<d>')
paddle2 = Paddle(canvas, "red", 300-15, 150, '<Up>', '<Down>')

while True:
    paddle1.draw()
    paddle2.draw()
    root.update_idletasks()
    root.update()
    time.sleep(0.01)