Question

我是kivy的新手，并尝试为我的覆盆子制作小型OSD。

我的.kv文件如下所示：

BoxLayout:
    orientation: 'vertical'
    Label:
        text_size: self.size
        text: 'OSD'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    GridLayout:
        cols: 2
        Label:
            text_size: self.size
            text: 'Total entries in DB: '
            font_size: 30
            bold: False
            halign:  'left'
            size_hint: 1, .1
        Label:
            id: total_db
            text_size: self.size
            text: '366 000 '
            font_size: 30
            bold: True
            color: 0, 1, 0, 1
            halign:  'center'
            size_hint: 1, .1
        Label:
            text_size: self.size
            text: 'Info 1: '
            font_size: 30
            bold: False
            halign: 'left'
            size_hint: 1, .1
        Label:
            id: marked_update
            text_size: self.size
            text: '1328 '
            color: 1, 0, 0, 1
            font_size: 30
            bold: True
            halign:  'center'
            size_hint: 1, .1
    Label:
        text_size: self.size
        text: 'Activity'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    Label:
        text: ''
        font_size: 10
        halign: 'center'
        valign: 'top'
        size_hint: 1, .08

    GridLayout:
        cols: 4
        Button:
            text: 'DS 01'
            font_size: 25
            background_color: 1, 0, 0, 1
        Button:
            text: 'DS 02'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 03'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 04'
            font_size: 25
            background_color: 0, 1, 0, 1

这产生了我想要的外观。我想定期更新带有ID的两个标签文本，我将在稍后提取的值...但我甚至无法从python中更新它们，如下所示：

import kivy
kivy.require('1.10.1')

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.clock import Clock

class BoxLayout(BoxLayout):
    def __init__(self, **kwargs):
        super(BoxLayout, self).__init__(**kwargs)
        Clock.schedule_once(self.update_txt, 0)

    def update_txt(self, *args):
        self.label.ids.marked_update.txt='updated from python'

class osdApp(App):
    def build(self):
        self.title = 'OSD'
        return BoxLayout()


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

我正在考虑启动调用update_txt函数的时钟，这可能会改变值，但我不断得到错误，即id不存在......等等，我是面向对象编程的新手，我可以算出这个简单的事情

Answer 1

对于在 kivy 中寻找 on_load 事件而找到解决此问题的方法的任何人，我都找到了解决方案。 kivy 中的 App 类提供了一个成员函数 on_start(self)，一旦应用程序完成构建和加载，就会调用该函数。我们只需要在应用程序加载完毕后添加我们想要调用的函数。例如：

class MyApp(App):
  def build(self):
    ...
  def on_start(self):
    super().on_start(self)
    my_f()
    update_texts()

Answer 2

一些观察结果：

作为评论@eyllanesc，您不应将子类命名为它继承的类。
self.label.ids.marked_update.txt不正确。它应该是self.ids.marked_update.text。
将您的根小部件声明为kv规则。

您的代码可能是：

main.py

import kivy
kivy.require('1.10.0')

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock


class RootWidget(BoxLayout):

    def __init__(self, **kwargs):
        super(BoxLayout, self).__init__(**kwargs)
        Clock.schedule_once(self.update_txt, 0.1)

    def update_txt(self, *args):
        self.ids.marked_update.text = 'updated from python'


class OsdApp(App):
    def build(self):
        self.title = 'OSD'
        return RootWidget()


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

<强> osd.kv：

<RootWidget>:
    orientation: 'vertical'
    Label:
        text_size: self.size
        text: 'OSD'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    GridLayout:
        cols: 2
        Label:
            text_size: self.size
            text: 'Total entries in DB: '
            font_size: 30
            bold: False
            halign:  'left'
            size_hint: 1, .1
        Label:
            id: total_db
            text_size: self.size
            text: '366 000 '
            font_size: 30
            bold: True
            color: 0, 1, 0, 1
            halign:  'center'
            size_hint: 1, .1
        Label:
            text_size: self.size
            text: 'Info 1: '
            font_size: 30
            bold: False
            halign: 'left'
            size_hint: 1, .1
        Label:
            id: marked_update
            text_size: self.size
            text: '1328 '
            color: 1, 0, 0, 1
            font_size: 30
            bold: True
            halign:  'center'
            size_hint: 1, .1
    Label:
        text_size: self.size
        text: 'Activity'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    Label:
        text: ''
        font_size: 10
        halign: 'center'
        valign: 'top'
        size_hint: 1, .08

    GridLayout:
        cols: 4
        Button:
            text: 'DS 01'
            font_size: 25
            background_color: 1, 0, 0, 1
        Button:
            text: 'DS 02'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 03'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 04'
            font_size: 25
            background_color: 0, 1, 0, 1

但是，我建议使用kivy属性而不是id：

<强> main.py ：

import kivy
kivy.require('1.10.0')

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.properties import StringProperty


class RootWidget(BoxLayout):
    marked_text = StringProperty()

    def __init__(self, **kwargs):
        super(BoxLayout, self).__init__(**kwargs)
        self.update_txt()

    def update_txt(self, *args):
        self.marked_text ='updated from python'


class OsdApp(App):
    def build(self):
        self.title = 'OSD'
        return RootWidget()


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

<强> osd.kv：

<RootWidget>:
    id: root_layout
    orientation: 'vertical'
    marked_text: '1328 '

    Label:
        text_size: self.size
        text: 'OSD'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    GridLayout:
        cols: 2
        Label:
            text_size: self.size
            text: 'Total entries in DB: '
            font_size: 30
            bold: False
            halign:  'left'
            size_hint: 1, .1
        Label:
            id: total_db
            text_size: self.size
            text: '366 000 '
            font_size: 30
            bold: True
            color: 0, 1, 0, 1
            halign:  'center'
            size_hint: 1, .1
        Label:
            text_size: self.size
            text: 'Info 1: '
            font_size: 30
            bold: False
            halign: 'left'
            size_hint: 1, .1
        Label:
            id: marked_update
            text_size: self.size
            text: root_layout.marked_text
            color: 1, 0, 0, 1
            font_size: 30
            bold: True
            halign:  'center'
            size_hint: 1, .1
    Label:
        text_size: self.size
        text: 'Activity'
        font_size: 50
        bold: True
        halign: 'center'
        valign: 'top'
        size_hint: 1, .3
    Label:
        text: ''
        font_size: 10
        halign: 'center'
        valign: 'top'
        size_hint: 1, .08

    GridLayout:
        cols: 4
        Button:
            text: 'DS 01'
            font_size: 25
            background_color: 1, 0, 0, 1
        Button:
            text: 'DS 02'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 03'
            font_size: 25
            background_color: 0, 1, 0, 1
        Button:
            text: 'DS 04'
            font_size: 25
            background_color: 0, 1, 0, 1

在加载时更新kivy中的标签文本

2 个答案: