TypeError：back缺少1个必需的位置参数：“ image_number”

如何解决TypeError：back缺少1个必需的位置参数：“ image_number”

我试图用tkinter制作一个可以工作的图像查看器。但是由于某种原因，后退按钮将无法使用。每次尝试使用后退按钮时，我都会不断收到TypeError：back（）缺少1个必需的位置参数：“ image_number”。我是python的新手，所以这可能是一个明显的错误。另外，您还必须使用自己的照片进行测试。

视频链接：https://www.youtube.com/watchv=zg4c92pNFeo&list=PLCC34OHNcOtoC6GglhF3ncJ5rLwQrLGnV&index=9

from tkinter import *
from PIL import ImageTk,Image



root = Tk()
root.title("Image viewer")

my_img1 = ImageTk.PhotoImage(Image.open("images/iu.gif"))
my_img2 = ImageTk.PhotoImage(Image.open("images/player2.ico"))
my_img3 = ImageTk.PhotoImage(Image.open("images/Codm.PNG"))
my_img4 = ImageTk.PhotoImage(Image.open("images/Heroes online.png"))
my_img5 = ImageTk.PhotoImage(Image.open("images/Google search.png"))

image_list = [my_img1,my_img2,my_img3,my_img4,my_img5]

my_label = Label(image=my_img1)
my_label.grid(row=0,column=0,columnspan=3)

def forward(image_number):
    global my_label
    global button_forward
    global button_back

    my_label.grid_forget()
    my_label= Label(image=image_list[image_number-1])
    button_forward= Button(root,text= ">>",command= lambda : forward(image_number+1))
    button_back= Button(root,text= "<<",command= lambda : back(image_number-1))

    if image_number == 5:
        button_forward = Button(root,text=">>",state= DISABLED)

    my_label.grid(row=0,columnspan=3)
    button_quit.grid(row=1,column=1)
    button_forward.grid(row=1,column=2)

def back(image_number):
    global my_label
    global button_forward
    global button_back

    my_label.grid_forget()
    my_label = Label(image=image_list[image_number-1])
    button_forward = Button(root,command=lambda: forward(image_number+1))
    button_back = Button(root,text="<<",command=lambda: back(image_number-1))

    my_label.grid(row=0,column=2)



button_back = Button(root,command= back)
button_quit = Button(root,text= "Exit program",command=root.quit)
button_forward = Button(root,text = ">>",command= lambda : forward(2))

button_back.grid(row=1,column=0)
button_quit.grid(row=1,column=1)
button_forward.grid(row=1,column=2)


root.mainloop()

这是我不断收到的错误

Exception in Tkinter callback
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/tkinter/__init__.py",line 1883,in __call__
    return self.func(*args)
TypeError: back() missing 1 required positional argument: 'image_number'

解决方法

您可以采取以下措施来清理此代码：

• 创建不含单个变量的图像列表
• 不要为每张照片重新创建标签和按钮
• 使用全局图像索引来指示当前图像
• 使用按钮更改索引，并调用相同的功能来更新标签和按钮状态。

尝试以下代码：

from tkinter import *
from PIL import ImageTk,Image

root = Tk()
root.title("Image viewer")

image_list = [  # all images
ImageTk.PhotoImage(Image.open("images/iu.gif")),ImageTk.PhotoImage(Image.open("images/player2.ico")),ImageTk.PhotoImage(Image.open("images/Codm.PNG")),ImageTk.PhotoImage(Image.open("images/Heroes online.png")),ImageTk.PhotoImage(Image.open("images/Google search.png"))
]

image_number = 0  # current image

my_label = Label(image=image_list[image_number])  # holds photo
my_label.grid(row=0,column=0,columnspan=3)

def forward():  # forward button
    global image_number
    image_number+=1 # next photo
    updatelabel()
    
def back():  # back button
    global image_number
    image_number-=1  # previous photo
    updatelabel()
    
def updatelabel():  # show current photo
    my_label.configure(image=image_list[image_number]) # show image
    my_label.image = image_list[image_number]  # prevent garbage collection
    button_forward["state"] = "normal"    
    button_back["state"] = "normal"    
    if image_number == len(image_list)-1: # if last image
       button_forward["state"] = "disabled"
    if image_number == 0:    # if first image
       button_back["state"] = "disabled"


button_back = Button(root,text= "<<",command= back)
button_back["state"] = "disabled"  # start at first photo
button_quit = Button(root,text= "Exit program",command=root.quit)
button_forward = Button(root,text = ">>",command= lambda : forward())

button_back.grid(row=1,column=0)
button_quit.grid(row=1,column=1)
button_forward.grid(row=1,column=2)

root.mainloop()