单击按钮更改图像

Question

这是我的第一个 python 编程代码。我正在尝试通过单击按钮更改图像。我有 2 个按钮，Start Conversation 和 Stop Conversation。

当表单加载时没有图像。当开始按钮被点击时，将显示ABC图像。单击停止按钮时，应显示 xyz 图像。

我面临的问题是，当我单击开始时，会出现相应的图像，但是当我单击停止时，会出现新图像但之前的图像并没有消失。两个图像一个接一个地显示

我的代码在下面

root = Tk()
prompt = StringVar()
root.title("AVATAR")
label = Label(root, fg="dark green")
label.pack()

frame = Frame(root,background='red')
frame.pack()

函数定义

def Image1():
  image = Image.open("C:\Python27\Agent.gif")
  photo = ImageTk.PhotoImage(image)
  canvas = Canvas(height=200,width=200)
  canvas.image = photo  # <--- keep reference of your image
  canvas.create_image(0,0,anchor='nw',image=photo)
  canvas.pack()

def Image2():
  image = Image.open("C:\Python27\Hydrangeas.gif")
  photo = ImageTk.PhotoImage(image)
  canvas = Canvas(height=200,width=200)
  canvas.image = photo  # <--- keep reference of your image
  canvas.create_image(0,0,anchor='nw',image=photo)
  canvas.pack()

#Invoking through button
TextWindow = Label(frame,anchor = tk.NW, justify = tk.LEFT, bg= 'white', fg   = 'blue', textvariable = prompt, width = 75, height=20)
TextWindow.pack(side = TOP)

conversationbutton = Button(frame, text='Start    Conversation',width=25,fg="green",command = Image1)
conversationbutton.pack(side = RIGHT)

stopbutton = Button(frame, text='Stop',width=25,fg="red",command = Image2)
stopbutton.pack(side = RIGHT)

root.mainloop()

Answer 1

最重要的问题是在创建新图像之前没有清除画布。使用以下命令启动您的（按钮）功能：

canvas.delete("all")

但是，您的画布也是如此；你继续创造它。更好地拆分画布的创建和设置图像：

from Tkinter import *

root = Tk()
prompt = StringVar()
root.title("AVATAR")
label = Label(root, fg="dark green")
label.pack()

frame = Frame(root,background='red')
frame.pack()

# Function definition

# first create the canvas
canvas = Canvas(height=200,width=200)
canvas.pack()

def Image1():
    canvas.delete("all")
    image1 = PhotoImage(file = "C:\Python27\Agent.gif")
    canvas.create_image(0,0,anchor='nw',image=image1)
    canvas.image = image1

def Image2():
    canvas.delete("all")
    image1 = PhotoImage(file = "C:\Python27\Hydrangeas.gif")
    canvas.create_image(0,0,anchor='nw',image=image1)
    canvas.image = image1

#Invoking through button
TextWindow = Label(frame,anchor = NW, justify = LEFT, bg= 'white', fg   = 'blue', textvariable = prompt, width = 75, height=20)
TextWindow.pack(side = TOP)

conversationbutton = Button(frame, text='Start    Conversation',width=25,fg="green",command = Image1)
conversationbutton.pack(side = RIGHT)

stopbutton = Button(frame, text='Stop',width=25,fg="red",command = Image2)
stopbutton.pack(side = RIGHT)

root.mainloop()

这也防止了按钮按下时窗口有些奇怪的扩展。 要使代码适合python3，请将from Tkinter import* 替换为from tkinter import*