Kivy中点击按钮关闭Popup报错的技术求助

问题描述 #

使用Kivy开发登录界面，当用户输入密码不一致时弹出Popup提示，但点击弹窗内的"understood"按钮尝试关闭时，出现以下错误：

TypeError: PopupWindow.understood() missing 1 required positional argument: 'popup'

错误原因 #

1. PopupWindow错误继承了Screen类：它作为弹窗的内容控件，不需要是Screen，应该继承布局类（如FloatLayout）。
2. understood方法定义冗余参数：创建弹窗时已经将popupwindow对象赋值给了show.popup，不需要再传popup参数。
3. 弹窗关闭逻辑错误：原代码中popup.manager.current.dismiss()写法完全错误，关闭弹窗直接调用popup.dismiss()即可。
4. 不必要的Screen注册：将PopupWindow添加到WindowManager中是多余的，因为它不是一个独立页面。

修复步骤 #

1. 修改Python代码 #

import kivy
from kivy.app import App
from kivy.lang import Builder
from kivy.properties import ObjectProperty
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.popup import Popup
from kivy.uix.floatlayout import FloatLayout

kivy.require('2.2.1')


class FirstWindow(Screen):
    username = ObjectProperty(None)
    password = ObjectProperty(None)
    re_password = ObjectProperty(None)

    def PopupWindow(self):
        show = PopupWindow()
        popupwindow = Popup(
            title="Warning!", content=show, size_hint=(None, None), size=(400, 400)
        )
        popupwindow.open()
        show.popup = popupwindow

    def log_in(self):
        if self.username.text.strip() and self.password.text.strip() == self.re_password.text.strip():
            print("Greetings! ", self.username.text)
            print("your password is: ", self.password.text)
            self.manager.current = "second"
        elif self.password.text.strip() != self.re_password.text.strip():
            print("please check your inputs: ")
            print("your input for password: ", self.password.text)
            print("your input for re_password: ", self.re_password.text)
            self.PopupWindow()
        else:
            if not self.username.text.strip():
                print("Username is required!")
            if not self.password.text.strip():
                print("Password is required!")
            if not self.re_password.text.strip():
                print("Re-password is required!")

    def clear_input(self):
        self.username.text = ""
        self.password.text = ""
        self.re_password.text = ""
        print("cleared!")


class SecondWindow(Screen):
    def back_button(self):
        self.manager.current = "create"


class ThirdWindow(Screen):
    pass


# 修改：继承FloatLayout而非Screen
class PopupWindow(FloatLayout):
    # 修改：移除冗余的popup参数，直接使用已赋值的self.popup
    def understood(self):
        self.popup.dismiss()


class WindowManager(ScreenManager):
    pass


class MainApp(App):
    def build(self):
        kv = Builder.load_file("my.kv")
        return kv

if __name__ == '__main__':
    MainApp().run()

2. 修改kv文件 #

WindowManager:
    FirstWindow:
    SecondWindow:
    ThirdWindow:
    # 移除：不再需要将PopupWindow注册为Screen

<FirstWindow>:
    name: "create"
    username: username
    password: password
    re_password: re_password

    BoxLayout:
        orientation: "vertical"
        spacing: 5
        padding: 50
        cols: 1
        Image:
            source: "447.png"
            size_hint_y: 0.1
        Label:
            text: "User_Login"
            size_hint_y: 0.1
        BoxLayout:
            orientation: "horizontal"
            size_hint_y: 0.1
            padding: 15

            Label:
                text: "User_Name: "
            TextInput:
                id: username
                multiline: False
        BoxLayout:
            orientation: "horizontal"
            size_hint_y: 0.1
            padding: 15

            Label:
                text: "Enter_Password: "
            TextInput:
                id: password
                multiline: False
        BoxLayout:
            orientation: "horizontal"
            size_hint_y: 0.1
            padding: 15

            Label:
                text: "Re_Enter_Password: "
            TextInput:
                id: re_password
                multiline: False
        BoxLayout:
            orientation: "horizontal"
            size_hint_y: 0.1
            pos_hint: {'center_x': 0.5}
            spacing: 10

            Button:
                text: "Clear"
                on_press: root.clear_input()

            Button:
                text: "Submit"
                on_press: root.log_in()

<SecondWindow>:
    name: "second"

    BoxLayout:
        orientation: "vertical"
        spacing: 5
        padding: 50
        Label:
            text: "You just Logged in!"
        Button:
            text: "Back"
            on_press: root.back_button()

<PopupWindow>:
    # 移除：不需要name属性，因为不是Screen
    BoxLayout:
        orientation: "vertical"
        Label:
            text: "please check your password"
        Button:
            text: "understood"
            on_release: root.understood()

额外优化点 #

• 原代码中size_hint_y: "0.1dp"写法错误，size_hint是比例值，不需要加单位，改成size_hint_y: 0.1即可。
• 将multiline: "False"改为multiline: False，因为该属性接受布尔值而非字符串。
• log_in方法中的条件判断优化，用elif替代第二个if，避免逻辑分支冲突。

内容的提问来源于stack exchange，提问作者Jubibani