仅在新程序启动后显示任务。基维

Question

晚上好。我正在学习 kivy 并尝试制作类似“微软要做”的东西。但我有一个问题。现在我正在做一个添加任务的功能。主要思想：

当我单击“添加任务”（带加号图标的按钮）按钮时，我的屏幕会更改为“AddingNewTaskScreen”。
在 AddingNewTaskScreen class 中，我创建了一个函数“”addTask，它从 TextInput 获取文本并将其添加到文本文件中。然后它在“MainMenuScreen”
在 MainMenuScreen class（这是第一个屏幕）中，在构造函数中我调用了一个“taskRead”函数，它从文本文件中获取文本并将其写入数组。然后它在 MDList 中添加数组元素，然后将此 MDList 添加到 ScrollView。

它可以工作，但它需要在新程序启动后向我显示任务。例如：我添加了任务，但“MainMenuScreen”没有显示任何内容。但是当我重新启动我的程序时，一切都在 ScrollView 中。如果您有任何解决方法，请告诉我，我将不胜感激。感谢您的提前。

main.py

from kivy.uix.button import Button
from kivy.uix.screenmanager import Screen, ScreenManager
from kivy.core.window import Window
from kivy.uix.widget import Widget
from kivymd.app import MDApp
from kivymd.uix.list import OneLineListItem, MDList
from kivy.properties import ObjectProperty
from kivy.uix.scrollview import ScrollView
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition

class MainMenuScreen(Screen):
    listBox = ObjectProperty()
    theme_changer = ObjectProperty()
    search_task = ObjectProperty()
    all_tasks = ObjectProperty()
    important_tasks = ObjectProperty()
    create_list = ObjectProperty()
    completed_tasks = ObjectProperty()
    list_name = ObjectProperty()
    sort = ObjectProperty()
    rename = ObjectProperty()
    add_button = ObjectProperty()
    scroll = ScrollView()
    list_view = MDList()

    def __init__(self, **kw):
        super().__init__(**kw)
        self.taskRead()

    def taskRead(self):

        sv = open('tasks.txt', 'r', encoding='utf-8')
        arr = sv.read().split('\n')
        sv.close()
        for i in range(len(arr)):
            self.list_view.add_widget(OneLineListItem(text=arr[i], on_press=self.scr))
            self.add_widget(MDList())
        self.scroll.add_widget(self.list_view)
        self.listBox.add_widget(self.scroll)

    def scr(self, value):
        self.manager.transition = FadeTransition()
        self.manager.current = 'goodbye_screen'


class ToDoListApp(MDApp):

    def __init__(self, **kw):
        super().__init__(**kw)

    def build(self):
        self.theme_cls.theme_style = "Dark"
        Window.size = (1300, 700)
        sm = ScreenManager()
        sm.add_widget(MainMenuScreen(name='main_menu_screen'))
        sm.add_widget(ImportantOrCompletedTaskCheckScreen(name='goodbye_screen'))
        sm.add_widget(AddingNewTaskScreen(name='adding_newTask_screen'))
        return sm


class AddingNewTaskScreen(Screen):
    taskToTxt = ObjectProperty()
    addTaskButton = ObjectProperty()

    def __init__(self, **kw):
        super().__init__(**kw)

    def addTask(self):
        task_text = str(self.taskToTxt.text)
        sv = open('tasks.txt', 'a', encoding='utf-8')
        sv.writelines(str(task_text) + '\n')
        sv.close()
        ToDoListApp.get_running_app().root.current = "main_menu_screen"


# Class for another problem
class ImportantOrCompletedTaskCheckScreen(Screen):
    pass


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

todolist.kv

<MainMenuScreen@Screen>:
    listBox:listBox
    rename:rename
    search_task:search_task
    theme_changer:theme_changer
    all_tasks:all_tasks
    important_tasks:important_tasks
    create_list:create_list
    completed_tasks:completed_tasks
    list_name:list_name
    sort:sort
    #add_button:add_button
    orientation: 'vertical'

    # right lateral panel
    BoxLayout:
        BoxLayout:
            size_hint: '0.3', '0.8'
            pos_hint: {'y': 0.17}
            orientation: 'vertical'
            GridLayout:
                cols: 1
                rows: 9
                MDRoundFlatButton:
                    id: theme_changer
                    size_hint: 0.5, 0.3
                    text: 'Light theme'
                    line_color: 1,1,1,1
                    elevation_normal: 0
                    on_press: root.change_theme()
                BoxLayout:
                    size_hint: 1, 0.5
                MDRoundFlatButton:
                    size_hint: 1, 0.7
                    text: 'All tasks'
                    line_color: 1,1,1,1
                    id: all_tasks
                BoxLayout:
                    size_hint: 1, 0.08
                MDRoundFlatButton:
                    size_hint: 1, 0.7
                    text: 'Important'
                    line_color: 1,1,1,1
                    id: important_tasks
                BoxLayout:
                    size_hint: 1, 0.08
                MDRoundFlatButton:
                    size_hint: 1, 0.7
                    text: '+ Create \nlist'
                    line_color: 1,1,1,1
                    id: create_list
                BoxLayout:
                    size_hint: 1, 0.08
                MDRoundFlatButton:
                    size_hint: 1, 0.7
                    text: 'Completed \ntasks'
                    line_color: 1,1,1,1
                    id: completed_tasks


        # top panel
        BoxLayout:
            orientation: 'vertical'
            AnchorLayout:
                anchor_y: 'top'
                size_hint: 1, 0.05
                GridLayout:
                    size_hint: 1, 0.05
                    cols: 4
                    rows: 1
                    Label:
                        text: 'Name'
                        size_hint: 0.5, 0.05
                        id: list_name
                    MDTextField:
                        id:search_task
                        halign: 'center'
                        valign: 'center'
                        hint_text: 'Search'
                        size_hint: 1, None
                        line_color_normal: 0.15,0.15,0.15
                    MDRectangleFlatButton:
                        id: rename
                        text: 'Rename'
                        line_color: 1,1,1,1
                    MDRectangleFlatButton:
                        text: 'Sort'
                        line_color: 1,1,1,1
                        id: sort

            # Center

            BoxLayout:
                orientation: 'vertical'
                size_hint: 0.1, 0.1
                MDFloatingActionButton:
                    icon: "plus"
                    md_bg_color: 'black'
                    on_press: root.manager.current = 'adding_newTask_screen'

            BoxLayout:
                orientation: 'vertical'
                size_hint: 1,1

                BoxLayout:
                    ScrollView:
                        line_color_normal: 1,1,0,1
                        id: listBox

# Screen for another problem
<ImportantOrCompletedTaskCheckScreen@Screen>:
    name: 'goodbye_screen'
    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'center'
        BoxLayout:
            orientation: 'vertical'
            size_hint: 0.5, 0.25
            GridLayout:
                cols: 2
                rows: 1
                size_hint: 0.3, 0.25
                pos_hint: {'x': 0.35}
                MDSwitch:
                    size_hint: 0.3, 0.3
                    theme_text_color: "Custom"
                    text_color: 1, 1, 1, 1
                    line_color: 1, 1, 1, 1
                Label:
                    text: 'Important'
            BoxLayout:
                size_hint: 0, 0.5
            GridLayout:
                cols: 2
                rows: 1
                size_hint: 0.3, 0.25
                pos_hint: {'x': 0.35}
                MDSwitch:
                    text: 'Important'
                    size_hint: 0.3, 0.3
                    theme_text_color: "Custom"
                    text_color: 1, 1, 1, 1
                    line_color: 1, 1, 1, 1
                Label:
                    text: 'Completed'
            AnchorLayout:
                anchor_x: 'center'
                anchor_y: 'center'
                MDRoundFlatButton:
                    text: 'Continue'
                    size_hint: 1, 0.5
                    theme_text_color: "Custom"
                    text_color: 1, 1, 1, 1
                    line_color: 1, 1, 1, 1
                    on_press: root.manager.current='main_menu_screen'


<AddingNewTaskScreen@Screen>:
    taskToTxt:taskToTxt

    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'center'
        BoxLayout:
            orientation: 'vertical'
            size_hint: 0.5, 0.25
            MDTextField:
                id: taskToTxt
                hint_text: 'Name of new task'
                color: 'white'
                halign: 'center'
                valign: 'center'
                size_hint: 1, None
                multiline: False
            AnchorLayout:
                anchor_x: 'center'
                anchor_y: 'center'
                MDRoundFlatButton:
                    text: 'Add task'
                    id: addTaskButton
                    on_press: root.addTask()
                    size_hint: 1, 0.5
                    theme_text_color: "Custom"
                    text_color: 1, 1, 1, 1
                    line_color: 1, 1, 1, 1

Answer 1

在 addTask 中，您应该可以访问主屏幕

main_screen = ToDoListApp.get_running_app().root.get_screen('main_menu_screen')

然后您可以将任务添加到列表

main_screen.list_view.add_widget(OneLineListItem(text=task_text, on_press=main_screen.scr))

    def addTask(self):
        task_text = str(self.taskToTxt.text)
        sv = open('tasks.txt', 'a', encoding='utf-8')
        sv.writelines(str(task_text) + '\n')
        sv.close()
        
        main_screen = ToDoListApp.get_running_app().root.get_screen('main_menu_screen')
        main_screen.list_view.add_widget(OneLineListItem(text=task_text, on_press=main_screen.scr))
        
        ToDoListApp.get_running_app().root.current = "main_menu_screen"

顺便说一句：

ScreenManager 是每个 Screen 的父级，因此您可以用 self.parent.

写得更短

或者您可以使用 self.manager

main_screen = self.parent.get_screen('main_menu_screen')
#main_screen = self.manager.get_screen('main_menu_screen')

# ... code ...

self.parent.current = "main_menu_screen"
#self.manager.current = "main_menu_screen"

在MainMenuScreen中您还可以创建添加单个任务的函数

class MainMenuScreen(Screen):

    def add_task(self, text):
        self.list_view.add_widget(OneLineListItem(text=text, on_press=self.scr))

然后你可以在addTask

中写得更简单

main_screen = self.parent.get_screen('main_menu_screen')
main_screen.add_task(task_text)

并且在 taskRead 中你可以减少 for-loop

for text in arr:
    self.add_task(text)

仅在新程序启动后显示任务。基维

Showing tasks only after new program launch. kivy

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