加载时更新kivy中的标签文本

Question

我对kivy是全新的，我正试着为我的覆盆子做一个小的OSD。在

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

这就是我想要的样子。我想定期更新的两个标签文本与ID的价值，我提取稍后。。。但我甚至不能从python更新它们，如下所示：

^{pr2}$

我正在考虑启动时钟，它调用update_txt函数，并且可以更改值，但是我一直得到错误的消息：ids不存在。。。等等，我是面向对象编程的新手，我搞不懂这个简单的事情

Answer 1

一些观察结果：

• 作为注释@eyllanesc，您不应该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。

• 将根小部件声明为kv规则。

你的代码可以是：

• 主.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()
  

• 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：

• 主.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()
  

• 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