使用屏幕1中的按钮在Kivy中更改屏幕2中的标签文本

Question

我一直试图改变布局2中的label2文本，layout1中的button1，但它似乎不起作用，当我按下按钮时，什么也没有发生

代码如下:

class layout1(GridLayout):
def __init__(self,**kwargs):
super().__init__(**kwargs)
self.cols = 2
self.button1 = Button(text = "Button 1 changes screen 2", on_press = self.change_label)
self.add_widget(self.button1)
self.change_button = Button(text = "move to screen 2", on_press = self.change_screen)
self.add_widget(self.change_button)
def change_screen(self, instance):
practice_app.sm.current = "screen2"
def change_label(self,instance):
func_layout = layout2()
func_layout.label2.text = "changed"
class layout2(GridLayout):
def __init__(self, **kwargs):
super().__init__(**kwargs)
self.cols = 2
self.label2 = Label(text = "this should change")
self.add_widget(self.label2)

class TestApp(App):
def build(self):
self.sm = ScreenManager()
screen1 = Screen(name = "screen1")
screen1.add_widget(layout1())
self.sm.add_widget(screen1)
screen2 = Screen(name = "screen2")
screen2.add_widget(layout2())
self.sm.add_widget(screen2)
return self.sm
if __name__ == "__main__":
practice_app = TestApp()
practice_app.run()

Answer 1

有很多方法可以做你想做的事。由于您没有使用kv，也许最简单的方法是保存对layout2的引用。这是你的build()方法的修改版本，这样做:

class TestApp(App):
def build(self):
self.sm = ScreenManager()
screen1 = Screen(name = "screen1")
screen1.add_widget(layout1())
self.sm.add_widget(screen1)
screen2 = Screen(name = "screen2")
self.layout2 = layout2()  # save reference to layout2
screen2.add_widget(self.layout2)
self.sm.add_widget(screen2)
return self.sm

然后，在change_label()方法中使用该引用:

def change_label(self,instance):
# func_layout = layout2()  #  creates a new instance of layout2 (not the one in the GUI)
func_layout = App.get_running_app().layout2
func_layout.label2.text = "changed"