在 Kivy 中将对象居中

2022-01-15 00:00:00 python kivy user-interface layout

问题描述

我正在尝试在布局内居中放置一个圆圈.我目前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.这是我的代码正在生成的内容...

I am trying to center a circle inside a layout. I'm currently doing some padding calculations, but I'm also looking for a better way. I imagine one of the predefined layouts may be a better choice. Here's what my code is producing...

对于方形布局:

对于宽布局:

这是正确的行为，很好，但有更好的方法吗?例如，我可以想象这对于非圆形形状会变得混乱.

This is the right behavior, which is great, but is there a better way? I can imagine this getting messy with non-circle shapes, for example.

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()

还有 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

解决方案

Snippet using FloatLayout, size_hint and pos_hint:

Snippet using FloatLayout, size_hint and pos_hint:

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()

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