self.pos 的 Kivy 布局背景问题

Question

我有一个 kv 语言的标签背景图像，但在 python 中重新创建它以为我的标签添加 HoverBehavior 属性。

曾经：

<RockLayout>
canvas:
    Rectangle:
        pos: self.pos
        size: self.size
        source: 'data/images/gui_elements/rock_label.png'

成为：

class RockLayout(FloatLayout, HoverBehavior):  # BoxLayout
def __init__(self, widget, **kwargs):
    super().__init__(**kwargs)
    widget.size_hint = (.8, .8)
    widget.pos_hint = ({'center_x': .5, 'center_y': .52})
    self.add_widget(widget)
    with self.canvas.before:
        Rectangle(source='data/images/gui_elements/rock_label.png', pos=self.pos, size=self.size)

def on_enter(self, *args):
    self.canvas.before.clear()
    with self.canvas.before:
        Rectangle(source='data/images/gui_elements/rock_label_hover.png', pos=self.pos, size=self.size)

def on_leave(self, *args):
    self.canvas.before.clear()
    with self.canvas.before:
        Rectangle(source='data/images/gui_elements/rock_label.png', pos=self.pos, size=self.size)

这导致 canvas.before 中的 self.pos 在初始化时没有更新，self.pos 等于 0 . 当我调整窗口大小时，图像的位置不会改变。 如何在python中声明背景图片，而不是.kv语言？

It's happens now

self.pos isn't updated when I resize the window

What I need to get

如何在python中正确使用kivylayuot背景图片？

Answer 1

    def on_size(self, *args):
        self.bg.size = self.size
        self.bg.pos = self.pos