尝试使用 tkinter 提高动画速度时出现 TypeError

Question

我正在尝试完成从入门到使用 Python 编程的家庭作业。 它希望我能够使用向上和向下键分别增加和减少速度。我有汽车的启动（我仍然需要完成形状），我有一个按钮来启动和停止汽车，它工作正常。但是，当我尝试使用书中的示例（increaseSpeed 和 reductionSpeed 函数）运行它时，它给了我“TypeError：increaseSpeed() 需要 1 个位置参数，但给出了 2 个”。我不知道如何在我的代码中纠正这个问题，它开始让我感到沮丧。这本书甚至没有告诉你为什么它使用 sleepTime 来提高它最初用于示例的消息的速度。

from tkinter import *


class controlAnimation:
  def __init__(self):
    window = Tk()
    window.title("Racing Car")


    self.width = 250
    self.height = 100
    self.canvas = Canvas(window, bg="white", width=self.width, height=self.height)
    self.canvas.pack()
    frame = Frame(window)
    frame.pack()
    btStop = Button(frame, text = "Stop", command = self.stop)
    btStop.pack(side=LEFT)
    btStart = Button(frame, text = "Start", command = self.start)
    btStart.pack(side=RIGHT)
    self.x=0

    self.sleepTime = 100
    self.canvas.create_rectangle(self.x,90,self.x+60,80,fill="black", tags = "car")
    self.canvas.create_oval(self.x+10, 90, self.x+20, 100, fill = "black",tags = "car")

    self.dx=3
    self.isStopped = False
    self.animate()



    window.bind("<Up>", self.increaseSpeed)
    window.bind("<Down>", self.decreaseSpeed)
    window.mainloop()
  def stop(self):
    self.isStopped = True
  def start(self):
    self.isStopped = False
    self.animate()
  def increaseSpeed(self):
    if self.sleepTime>5:
    self.sleepTime-=20
  def decreaseSpeed(self):
    self.sleepTime+=20

  def animate(self): # Move the message 
     while not self.isStopped:
      self.canvas.move("car", self.dx,0) 
      self.canvas.after(self.sleepTime) 
      self.canvas.update() 
      if self.x < self.width:
          self.x += self.dx 
      else:
        self.x = 0 

        self.canvas.create_rectangle(self.x-60,90,self.x,80,fill="black", tags = "car")
        self.canvas.create_oval(self.x-50, 90, self.x-40, 100, fill = "black",tags = "car")
controlAnimation()    

Answer 1

.bind() 方法返回一个事件并将其传递给给定的函数。

看看这里：

def increaseSpeed(self):
    if self.sleepTime>5:self.sleepTime-=20
def decreaseSpeed(self):
    self.sleepTime+=20

这两个函数都没有任何参数，所以你会看到一个错误

所以你需要做这样的事情：

def increaseSpeed(self,event = None): #or def increaseSpeed(self,*args):
    #[...]
def decreaseSpeed(self,event = None): #or def decreaseSpeed(self,*args):
    #[...]

这是最终的工作代码 -

from tkinter import *


class controlAnimation:
  def __init__(self):
    window = Tk()
    window.title("Racing Car")


    self.width = 250
    self.height = 100
    self.canvas = Canvas(window, bg="white", width=self.width, height=self.height)
    self.canvas.pack()
    frame = Frame(window)
    frame.pack()
    btStop = Button(frame, text = "Stop", command = self.stop)
    btStop.pack(side=LEFT)
    btStart = Button(frame, text = "Start", command = self.start)
    btStart.pack(side=RIGHT)
    self.x=0

    self.sleepTime = 100
    self.canvas.create_rectangle(self.x,90,self.x+60,80,fill="black", tags = "car")
    self.canvas.create_oval(self.x+10, 90, self.x+20, 100, fill = "black",tags = "car")

    self.dx=3
    self.isStopped = False
    self.animate()



    window.bind("<Up>", self.increaseSpeed)
    window.bind("<Down>", self.decreaseSpeed)
    window.mainloop()
  def stop(self):
    self.isStopped = True
  def start(self):
    self.isStopped = False
    self.animate()
  def increaseSpeed(self,event = None): #or def increaseSpeed(self,*args):
    if self.sleepTime>5:self.sleepTime-=20
  def decreaseSpeed(self,event = None): #or def increaseSpeed(self,*args):
    self.sleepTime+=20

  def animate(self): # Move the message 
     while not self.isStopped:
      self.canvas.move("car", self.dx,0) 
      self.canvas.after(self.sleepTime) 
      self.canvas.update() 
      if self.x < self.width:
          self.x += self.dx 
      else:
        self.x = 0 

        self.canvas.create_rectangle(self.x-60,90,self.x,80,fill="black", tags = "car")
        self.canvas.create_oval(self.x-50, 90, self.x-40, 100, fill = "black",tags = "car")
controlAnimation() 

Answer 2

当使用widget.bind("<Event>", func) 时，函数会向函数传递一个额外的事件，您可以根据需要使用它，但显然您不需要它，因此您可以将 init 中的绑定替换为：

    # You can either get the event using lambda if you don't want anything to do with it like this:
    window.bind("<Up>", lambda event: self.increaseSpeed)
    window.bind("<Down>", lambda event2: self.decreaseSpeed)

或者在你的函数中这样做：

# Or you can pass it as an argument in your function
def increaseSpeed(self, event):
    if self.sleepTime > 5:
        self.sleepTime -= 20

def decreaseSpeed(self, event):
    self.sleepTime += 20

我相信这就是你想要达到的目标：

from tkinter import *


class CarAnimation:
    def __init__(self):
        self.canvas_width = 550
        self.canvas_height = 280
        self.car_body_width = 100
        self.car_body_height = 50
        self.car_wheel_width = 20
        self.car_wheel_height = 20
        self.car_top_left = 0
        self.move_by = 1
        self.delay = 20
        self.default_delay = 10
        self.car_is_moving = False
        self.root = Tk()
        self.root.resizable(False, False)
        self.root.title("Car Animation!")
        self.car_canvas = Canvas(self.root, width=self.canvas_width, height=self.canvas_height, background="white",
                                 highlightthickness=0)
        # If you have more shapes in the canvas that you do not want to get affected by the movement store them as
        # below and call the move function for each of them, I just stored them in a variable for demonstration purposes
        self.car_body = self.car_canvas.create_rectangle(0, 0, self.car_body_width, self.car_body_height)
        self.car_wheel1 = self.car_canvas.create_oval(0, self.car_body_height, self.car_wheel_width,
                                                      self.car_body_height+self.car_wheel_height)
        self.car_wheel2 = self.car_canvas.create_oval(self.car_body_width-self.car_wheel_width, self.car_body_height,
                                                      self.car_body_width, self.car_body_height+self.car_wheel_height)
        self.start_btn = Button(self.root, text="Start Car", command=self.start_car)
        self.stop_btn = Button(self.root, text="Stop Car", command=self.stop_car)
        self.car_canvas.pack(side=TOP)
        self.start_btn.pack(side=BOTTOM, pady=5)
        self.stop_btn.pack(side=BOTTOM)
        self.root.bind("<Up>", self.decrease_delay)
        self.root.bind("<Down>", self.increase_delay)
        self.root.mainloop()

    def start_car(self):
        if not self.car_is_moving:
            self.car_is_moving = True
            self.move_car()

    def stop_car(self):
        if self.car_is_moving:
            self.car_is_moving = False

    def move_car(self):
        # Instead of storing the car's top left position and appending to it, you can also
        # 'self.car_canvas.coords(self.car_body)[0]' so that it would return the shape's coords
        if self.car_is_moving and self.car_top_left < self.canvas_width:
            self.car_top_left += self.move_by
            # You can store their layer numbers and move them one by one but since there were no more shapes
            # I decided to move all of them at once using 'ALL'
            self.car_canvas.move(ALL, self.move_by, 0)
            self.root.after(self.delay, self.move_car)
        elif self.car_is_moving and self.car_top_left >= self.canvas_width:
            self.car_top_left += -self.canvas_width - self.car_body_width
            self.car_canvas.move(ALL, -self.canvas_width - self.car_body_width, 0)
            self.root.after(self.delay, self.move_car)

    def increase_delay(self, event):
        # Added the if statement below so that the user cannot change the delay when the car is not moving
        if self.car_is_moving:
            self.delay += 10

    def decrease_delay(self, event):
        if self.delay > self.default_delay and self.car_is_moving:
            self.delay -= 10
        # You can just delete this elif statement, I just wanted to print out something to the terminal
        elif self.delay <= self.default_delay and self.car_is_moving:
            print("Delay cannot be lower than default!")


if __name__ == '__main__':
    CarAnimation()

请注意，如代码中所述，您可以使用“self.car_canvas.coords()”而不是存储左上角。如果您对代码有任何疑问，请在 cmets 中提问