Property

Difference between Properties and Binding.

In brief:

  • Properties make it easy to pass updates from the python side to the user interface

  • Binding passes the changes that happened on the user interface to the python side.

    from kivy.app import App from kivy.uix.boxlayout import BoxLayout from kivy.lang import Builder from kivy.properties import StringProperty from kivy.properties import ObjectProperty from kivy.uix.textinput import TextInput from kivy.event import EventDispatcher Builder.load_string(""" [email protected] size_hint:0.3,1 [email protected] text: “Result” size_hint: 0.5,1 [email protected] text: “+1” size_hint: 0.1,1
    [email protected]: multiline: False size_hint:0.1,1

    <Tuto_Property>: orientation: “vertical” padding:10,10 spacing: 10 Label: text: “Press the 3 button (+1) several times and then modify the number in the TextInput.The first counter (with StringProperty but no binding) doesn’t take into account the change that happened in the app, but the second one does.String Property makes it easy to pass the update from the python side to the user interface, binding pass the changes that happened on the user interface to the python side. " text_size: self.size padding: 20,20

     Property_no_Binding:
     Property_with_Binding:
     Simple:
    

    <Property_no_Binding>: spacing: 10 label_ObjectProperty: result CustLab1: text: “With Property but no Binding” CustButton: on_press: root.counter_textInput_StringProperty() CustTextInput: id:textinput_id text: root.textInput_StringProperty CustLab2: id: result

    <Property_with_Binding>: spacing: 10 label_ObjectProperty: result CustLab1: text: “With Property and Binding” CustButton: on_press: root.counter_textInput_StringProperty() CustTextInput: id:textinput_id text: root.textInput_StringProperty on_text: root.textInput_StringProperty = self.text ## this is the binding CustLab2: id: result

    spacing: 10 CustLab1: text: "Without Property" CustButton: on_press: root.simple(textinput_id, result) CustTextInput: id:textinput_id text: "0" CustLab2: id: result

    “””)

    class Property_no_Binding(BoxLayout): textInput_StringProperty= StringProperty(“0”) label_ObjectProperty = ObjectProperty(None) def counter_textInput_StringProperty(self): self.label_ObjectProperty.text= (“Before the counter was updated:\n\n textinput_id.text:” + self.ids.textinput_id.text + “\n\n textInput_StringProperty:” + self.textInput_StringProperty) self.textInput_StringProperty =str(int(self.textInput_StringProperty)+1)

    class Property_with_Binding(BoxLayout): textInput_StringProperty= StringProperty(“0”) label_ObjectProperty = ObjectProperty(None) def counter_textInput_StringProperty(self): self.label_ObjectProperty.text= (“Before the counter was updated:\n\n textinput_id.text:” + self.ids.textinput_id.text + “\n\n textInput_StringProperty:” + self.textInput_StringProperty) self.textInput_StringProperty =str(int(self.textInput_StringProperty)+1)
    pass

    class Simple(BoxLayout): def simple(self,textinput_id, result): result.text = (“Before the counter was updated:\n\nIn the TextInput:” + textinput_id.text) textinput_id.text = str(int(textinput_id.text) + 1) pass class Tuto_Property(BoxLayout):

     # def __init__(self, **kwargs):
         # super(All, self).__init__(**kwargs)
         # app=App.get_running_app()
         # self.objproper_number.bind(text=lambda *a: self.change(app))
         # print(self.parent)
    
     # def counter(self,app): 
         # print("Stringproperty:",app.numbertext) 
         # print("ObjectProperty:",self.objproper_number.text)
         # print("text:",self.ids.number.text,"\n")
         # app.numbertext=str(int(app.numbertext)+1)
    
     # def change(self, app):
         # app.numbertext=self.objproper_number.text
     pass
    

    class MyApp(App): numbertext = StringProperty(“0”) def build(self):
    return Tuto_Property()

    MyApp().run()