物体不能移动

Question

代码没有错误，但我的车无法移动。我是否错误地定义了 for 循环？我还尝试将 for 循环移动到 def moveit(self,vx,vy) 但没有区别。这是我的代码：

from tkinter import *
import tkinter as tk
import time
class Example(tk.Frame):

    def __init__(self, parent):
        tk.Frame.__init__(self)

        #create a canvas
        self.canvas = tk.Canvas(width=600, height=250)
        self.canvas.pack()
        self.road()
        self.crossing()

    def road(self):
        self.canvas.create_line(50, 50, 450, 50)
        self.canvas.create_line(50, 100, 450, 100)

    def crossing(self):
        self.canvas.create_line(350, 50, 350, 100)
        self.canvas.create_line(375, 50, 375, 100)


class Car:
    def __init__(self, x1, y1, x2, y2, vx, vy, color, example):
        self.x1 = x1
        self.y1 = y1
        self.x2 = x2
        self.y2 = y2
        self.vx = vx
        self.vy = vy
        self.color = color
        self.example = example

    def drawit(self, x1, y1, x2, y2, color):
        self.example.canvas.create_rectangle(x1, y1, x2, y2, fill=color)

    def moveit(self, vx, vy):
        self.example.canvas.move(self, vx, vy)

if __name__ == "__main__":
    root = tk.Tk()
    my_canvas = Example(root)
    my_canvas.pack(fill="both", expand=True)
    mycar = Car(60, 60, 125, 90, 20, 0, "red", my_canvas)
    mycar.drawit(60, 60, 125, 90, "red")
    mycar.moveit(20, 0)
    print(mycar.x1)
    root.update()
    root.mainloop()

如有任何帮助，我们将不胜感激

Answer 1

你没有看到你的车在移动，因为你没有给 move 函数提供正确的参数：

self.example.canvas.move(self, vx, vy) ：这里 self 是 Car 对象，它不是 canvas 上代表汽车的矩形的 index/tag。所以什么都没有发生是很正常的。在canvas:

上画车的时候要注册车的索引

def drawit(self, x1, y1, x2, y2, color):
    self.index = self.example.canvas.create_rectangle(x1, y1, x2, y2, fill=color)

然后用self.example.canvas.move(self.index, vx, vy)移动它。

此外，再次将x1、y1、...作为drawit的参数没有意义，因为它们是汽车的属性。您还忘记了在 moveit 中移动时增加汽车的位置，我建议您使用 after 方法而不是 for 循环来创建动画。所以我根据我的建议重写了你的代码：

import tkinter as tk

class Example(tk.Frame):

    def __init__(self, parent):
        tk.Frame.__init__(self)

        #create a canvas
        self.canvas = tk.Canvas(width=600, height=250)
        self.canvas.pack()
        self.road()
        self.crossing()

    def road(self):
        self.canvas.create_line(50, 50, 450, 50)
        self.canvas.create_line(50, 100, 450, 100)

    def crossing(self):
        self.canvas.create_line(350, 50, 350, 100)
        self.canvas.create_line(375, 50, 375, 100)

class Car:
    def __init__(self, x1, y1, x2, y2, vx, vy, color, example):
        self.x1 = x1
        self.y1 = y1
        self.x2 = x2
        self.y2 = y2
        self.vx = vx
        self.vy = vy
        self.color = color
        self.example = example

    def drawit(self):
        self.index = self.example.canvas.create_rectangle(self.x1, self.y1, self.x2, self.y2, fill=self.color)

    def moveit(self):
        self.example.canvas.move(self.index, self.vx, self.vy)
        self.x1 += self.vx
        self.x2 += self.vx
        self.y1 += self.vy
        self.y2 += self.vy
        self.example.after(100, self.moveit)
        
if __name__ == "__main__":
    root = tk.Tk()
    my_canvas = Example(root)
    my_canvas.pack(fill="both", expand=True)
    mycar = Car(60, 60, 125, 90, 20, 0, "red", my_canvas)
    mycar.drawit()
    mycar.moveit()
    root.mainloop()

物体不能移动

The object cannot move

python

tkinter

tkinter-canvas