Question

我一直在尝试实现一个动画循环，以解决在按箭头键后移动画布项目时遇到的轻微延迟，但现在卡住了。我的代码如下所示，我认为这样可以在按下某个键时启用循环，并在按键被解除时循环停止，但运行该程序不会导致画布项移动。首先，是动画循环的想法是正确的吗？其次，我/我应该在哪里调用“移动”功能来使项目移动？请帮忙 - 谢谢！

from tkinter import *

x = 10
y = 10
a = 100
b = 100
direction = None

def move():
    global x_vel
    global y_vel
    global direction
    if direction is not None:
        canvas1.move(rect, x_vel,y_vel)
        after(33,move)

def on_keypress(event):
    global direction
    global x_vel
    global y_vel
    if event.keysym == "Left":
        direction == "left"
        x_vel = -5
        y_vel = 0
    if event.keysym == "Right":
        direction == "right"
        x_vel = 5
        y_vel = 0
    if event.keysym == "Down":
        direction == "down"
        x_vel = 0
        y_vel = 5
    if event.keysym == "Up":
        direction == "up"
        x_vel = 0
        y_vel = -5

def on_keyrelease(event):
    global direction
    direction = None


window = Tk()
window.geometry("400x200")

#canvas and drawing
canvas1=Canvas(window, height = 200, width = 400)
canvas1.grid(row=0, column=0, sticky=W)
coord = [x, y, a, b]
rect = canvas1.create_rectangle(*coord, outline="#fb0", fill="#fb0")

#capturing keyboard inputs and assigning to function
window.bind_all('<KeyPress>', on_keypress)
window.bind_all('<KeyRelease>', on_keyrelease)
window.mainloop()

Answer 1

move永远不会被召唤。

after

widget。

def move():
    global x_vel
    global y_vel
    global direction
    if direction is not None:
        canvas1.move(rect, x_vel,y_vel)
    window.after(33,move)  # Indetation.

分配到direction：==的错字应为=。
```
direction = "left"
```

Answer 2

像

这样的重复代码

if event.keysym == "Left":
    direction == "left"
    x_vel = -5
    y_vel = 0
if event.keysym == "Right":
    direction == "right"
    x_vel = 5
    y_vel = 0
if event.keysym == "Down":
    direction == "down"
    x_vel = 0
    y_vel = 5
if event.keysym == "Up":
    direction == "up"
    x_vel = 0
    y_vel = -5

通常可以更紧凑地编写。在模块范围，定义一个字典。

dir_vel = {
    'Left': ('left', -5 0),
    'Right': ('right', 5, 0),
    'Down': ('down', 0, 5),
    'Up': ('up', 0, -5),
}

然后在on_keypress中，用

替换上面的替换

    direction, x_vel, y_vel = dir_vel[event.keysym]

如何让我的动画循环工作？

2 个答案: