在Kivy中居物体

Question

我想在布局中居中一个圆圈。我正在做一些填充计算，但我也在寻找更好的方法。我想其中一个预定义的布局可能是更好的选择。这是我的代码产生的......

对于方形布局：

对于宽版面：

这是正确的行为，这很好，但有更好的方法吗？例如，我可以想象这会使非圆形变得混乱。

这是我的代码：

#!/usr/bin/kivy
import kivy
kivy.require('1.7.2')

from random import random
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.uix.gridlayout import GridLayout
from kivy.uix.anchorlayout import AnchorLayout
from kivy.uix.relativelayout import RelativeLayout
from kivy.graphics import Color, Ellipse, Rectangle

class MinimalApp(App):
    title = 'My App'
    def build(self):
        root = RootLayout()
        return(root)

class RootLayout(AnchorLayout):
    pass

class Circley(RelativeLayout):
    pass

if __name__ == '__main__':
    MinimalApp().run()

和KV：

#:kivy 1.7.2
#:import kivy kivy

<RootLayout>:
    anchor_x: 'center'                              # I think this /is/ centered
    anchor_y: 'center' 
    canvas.before:
        Color:
            rgba: 0.4, 0.4, 0.4, 1
        Rectangle:
            pos: self.pos
            size: self.size
    Circley:
        anchor_x: 'center'                          # this is /not/ centered.
        anchor_y: 'center' 
        canvas.before:
            Color:
                rgba: 0.94, 0.94, 0.94, 1
            Ellipse:
                size: min(self.size), min(self.size)
                pos: 0.5*self.size[0] - 0.5*min(self.size), 0.5*self.size[1] - 0.5*min(self.size)
                Label:
                    text: unicode(self.size)    # this is /not/ appearing
                    color: 1,0,0,1

Answer 1

使用FloatLayout，size_hint和pos_hint：

的代码段

from kivy.app import App
from kivy.lang import Builder

kv = '''
FloatLayout:
    Widget:
        size: min(root.size), min(root.size)
        size_hint: None, None
        pos_hint: {'center_x': .5, 'center_y': .5}
        canvas:
            Color:
                rgb: 1, 0, 0
            Ellipse:    
                size: self.size
                pos: self.pos
'''
Builder.load_string(kv)

class MyApp(App):
    def build(self):
        return Builder.load_string(kv)

MyApp().run()

日本国旗：

from kivy.app import App
from kivy.lang import Builder

kv = '''
FloatLayout:
    canvas:
        Color:
            rgb: 1, 1, 1
        Rectangle:    
            size: self.size
            pos: self.pos   
    Widget:
        size: min(root.size)/2, min(root.size)/2
        size_hint: None, None
        pos_hint: {'center_x': .5, 'center_y': .5}
        canvas:
            Color:
                rgb: 1, 0, 0
            Ellipse:    
                size: self.size
                pos: self.pos
'''
Builder.load_string(kv)

class MyApp(App):
    def build(self):
        return Builder.load_string(kv)

MyApp().run()