基本Kivy Q，定位画布儿童{kivy语言}

Question

Good Evening All

Just wondering if someone can share the info, started playing around with kivy, all I am trying to so is have a basic canvas widget and position a rectangle on the top of the screen, using co-ord 0,0 draws it as the bottom.

it also raised the question that I can set near the top by using, say 0, 400, but how to you make it on the top all the time and resolution independent. I am trying to make a small app as part of learning it and re-enforcing what I've learnt in python so far.

Thanks for any insight

canvas:
        Rectangle:
            pos: self.pos
            size: self.width , self.height / 10

    Label:
        font_size: 25
        top: root.top
        text:"Score"


    Label:
        font_size: 25
        top: root.top
        text:"4000 points"

Answer 1

In kivy canvas point (0, 0) is actually bottom left one. You can calculate top position yourself easily:

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.lang import Builder
from kivy.properties import ListProperty

kv_string = '''
<MyWidget>:
    r_size: [root.size[0]/2, root.size[1]/2]
    canvas:
        Color:
            rgb: 0.1, 0.6, 0.3
        Rectangle:
            size: root.r_size
            pos: 0, root.size[1]-root.r_size[1]
'''

Builder.load_string(kv_string)

class MyWidget(Widget):
    r_size = ListProperty([0, 0])

class TestApp(App):
    def build(self):
        return MyWidget()

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

You can also use FloatLayout , set resolution independent subwidget sizes and positions using pos_hint and size_hint attributes, then draw something within borders of each such widget:

from kivy.app import App
from kivy.uix.floatlayout import FloatLayout
from kivy.lang import Builder

kv_string = '''
<MyWidget>:
    Widget:
        pos_hint: {'center_y': 0.5, 'center_x': 0.5}
        size_hint: 0.2, 0.2
        canvas:
            Color:
                rgb: 0.1, 0.6, 0.3
            Rectangle:
                size: self.size
                pos: self.pos
    Widget:
        pos_hint: {'center_y': 0.5, 'center_x': 0.2}
        size_hint: 0.2, 0.2
        canvas:
            Color:
                rgb: 0.1, 0.6, 0.3
            Rectangle:
                size: self.size
                pos: self.pos
    Widget:
        pos_hint: {'center_y': 0.5, 'center_x': 0.8}
        size_hint: 0.2, 0.2
        canvas:
            Color:
                rgb: 0.1, 0.6, 0.3
            Rectangle:
                size: self.size
                pos: self.pos
    Widget:
        pos_hint: {'center_y': 0.2, 'center_x': 0.5}
        size_hint: 0.2, 0.2
        canvas:
            Color:
                rgb: 0.1, 0.6, 0.3
            Rectangle:
                size: self.size
                pos: self.pos
    Widget:
        pos_hint: {'center_y': 0.8, 'center_x': 0.5}
        size_hint: 0.2, 0.2
        canvas:
            Color:
                rgb: 0.1, 0.6, 0.3
            Rectangle:
                size: self.size
                pos: self.pos
'''

Builder.load_string(kv_string)

class MyWidget(FloatLayout):
    pass

class TestApp(App):
    def build(self):
        return MyWidget()

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