问题描述

想要设置背景色，但是BoxLayout直接生成的背景色只在左下角占据了一小块，尺寸是[100,100]

代码

class RootWidget(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.orientation = 'horizontal'
        print('BoxLayout.size: %s' % self.size)
        with self.canvas.before:
            Color(1,0,0,1)
            self.rect = Rectangle(size=self.size,
                                  pos=self.pos)
                                  
class TestApp(App):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.title = 'QuickBOM'  # 更改标题文本
    def build(self):
        root = RootWidget()
        root.add_widget(Label(text='中文'))
        root.add_widget(Button(text='试试看'))
        root.add_widget(TextInput())
        return root
        
TestApp().run()

解决方案一

参考说明文档，绑定事件刷新事件

代码

class RootWidget(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.orientation = 'horizontal'
        print('BoxLayout.size: %s' % self.size)
        self.bind(size=self._update_rect, pos=self._update_rect)
        with self.canvas.before:
            Color(1,0,0,1)
            self.rect = Rectangle(size=self.size,
                                  pos=self.pos)
    def _update_rect(self, instance, value):
        self.rect.pos = instance.pos
        self.rect.size = instance.size

解决方案二

利用Window.size

代码

class RootWidget(BoxLayout):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.orientation = 'horizontal'
        print('Window.size: %s' % str(Window.size))
        with self.canvas.before:
            Color(1,0,0,1)
            self.rect = Rectangle(size=Window.size,
                                  pos=self.pos)