python - 更新 Kivy 中子对象小部件的位置(Python 不是 .kv)

Question

我有一个添加和定位自定义小部件对象的父小部件，但是当调整窗口大小时，它们不会更新它们的位置...

import kivy
from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.graphics import Color, Line, Ellipse, Rectangle
from kivy.metrics import dp
from kivy.uix.widget import Widget


class circleChild(Widget):
    def __init__(self, *args, **kwargs):
        self.pos = kwargs.get('_pos')
        self.size = kwargs.get('_size')
        super(circleChild, self).__init__()
        with self.canvas:
            Color(0.4, 0.6, 0.9, 1)  # ConrflowerBlue
            Ellipse(pos=self.pos, size=self.size, width=dp(2))


class RootWidget(BoxLayout):
    def __init__(self, *args, **kwargs):
        BoxLayout.__init__(self, *args, **kwargs)
        self.bind(pos=self.draw)
        self.bind(size=self.draw)
        self.layout1 = BoxLayout()
        self.layout2 = BoxLayout(opacity=0.8)
        self.add_widget(self.layout1)
        self.add_widget(self.layout2)
        self.childrenAdded = False

    def draw(self, *args):
        with self.canvas.before:
            Color(.8, .8, .8, 1)  # LightGrey
            self.bg = Rectangle(pos=self.pos, size=self.size)
        self.layout1.canvas.clear()
        with self.layout1.canvas:
            Color(0, 0, 0, 1)  # Black
            Line(
                points=[
                    self.center_x, self.center_y - 200, self.center_x,
                    self.center_y + 200
                ],
                width=dp(2))
            Line(
                points=[
                    self.center_x - 200, self.center_y, self.center_x + 200,
                    self.center_y
                ],
                width=dp(2))
        if not self.childrenAdded:
            self.addChildren()

    def addChildren(self, *args):
        circle1 = circleChild(
            _pos=[self.center_x + 100, self.center_y + 100], _size=[100, 100])
        circle2 = circleChild(
            _pos=[self.center_x + 100, self.center_y - 200], _size=[100, 100])
        circle3 = circleChild(
            _pos=[self.center_x - 200, self.center_y + 100], _size=[100, 100])
        circle4 = circleChild(
            _pos=[self.center_x - 200, self.center_y - 200], _size=[100, 100])
        self.layout2.add_widget(circle1)
        self.layout2.add_widget(circle2)
        self.layout2.add_widget(circle3)
        self.layout2.add_widget(circle4)
        self.childrenAdded = True


class PositionChildren(App):
    title = "PositionChildren"

    def build(self):
        return RootWidget()


if __name__ == "__main__":
    PositionChildren().run()

结果:

问题是在调整窗口大小时，会发生这种情况:

如何在 python 中重新定位 childWidgets？

Answer 1

我发现您在创建 _pos 或 _size 等新属性时变得复杂，相反，您应该只使用现有属性 pos 和 size，另一方面，您每时每刻都在使用 Canvas ，而不是重复使用元素。

考虑到上述情况，简单的解决方案是:

from kivy.app import App
from kivy.graphics import Color, Line, Ellipse, Rectangle
from kivy.metrics import dp
from kivy.uix.widget import Widget

class circleChild(Widget):
    def __init__(self, **kwargs):
        super(circleChild, self).__init__(**kwargs)
        self.draw()
        self.bind(pos=self.redraw, size=self.redraw)

    def draw(self):
        with self.canvas:
            Color(0.4, 0.6, 0.9, 1)  # ConrflowerBlue
            self.ellipse = Ellipse(width=dp(2))

    def redraw(self, *args):
        # reuse
        self.ellipse.pos = self.pos
        self.ellipse.size = self.size

class RootWidget(Widget):
    def __init__(self, **kwargs):
        super(RootWidget, self).__init__(**kwargs)
        self.draw()
        self.bind(pos=self.redraw, size=self.redraw)

        self.circle1 = circleChild(size=[100, 100])
        self.circle2 = circleChild(size=[100, 100])
        self.circle3 = circleChild(size=[100, 100])
        self.circle4 = circleChild(size=[100, 100])
        for c in (self.circle1, self.circle2, self.circle3, self.circle4):
            self.add_widget(c)

    def draw(self):
        with self.canvas.before:
            Color(.8, .8, .8, 1)  # LightGrey
            self.bg = Rectangle(pos=self.pos, size=self.size)
            Color(0, 0, 0, 1)  # Black
            self.vline = Line(width=dp(2))
            self.hline = Line(width=dp(2))

    def redraw(self, *args):
        # reuse
        self.bg.pos = self.pos
        self.bg.size = self.size
        self.vline.points = [
            self.center_x, 
            self.center_y - 200, 
            self.center_x,
            self.center_y + 200
        ]
        self.hline.points=[
            self.center_x - 200, 
            self.center_y, 
            self.center_x + 200,
            self.center_y
        ]
        self.circle1.pos = [self.center_x + 100, self.center_y + 100]
        self.circle2.pos = [self.center_x + 100, self.center_y - 200]
        self.circle3.pos = [self.center_x - 200, self.center_y + 100]
        self.circle4.pos = [self.center_x - 200, self.center_y - 200]

class PositionChildren(App):
    title = "PositionChildren"

    def build(self):
        return RootWidget(size=(100, 100))

if __name__ == "__main__":
    PositionChildren().run()