如何将画布添加到布局（python kivy）

Question

I want to add some canvas to Layout, but when I launch this small code it writes "black" screen...

I use kivy 1.10 and python 3.6.4

Can anyone help me ?

following code :

from kivy.app import App
from kivy.graphics import Color,Bezier
from kivy.uix.anchorlayout import AnchorLayout

class AncLayout(AnchorLayout):  
    with AnchorLayout().canvas:
        Color(.1,.88,.71,.57)
        Bezier(points = (100,100,70,70,40,70,100,100),    
               segments = 120,
               dash_length = 9,
               dash_offset = 3)

class MasterApp(App):
    def build(self):
        return AncLayout()  


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

Great thanks for any help )

Answer 1

The problem is that you are adding the curves to an AnchorLayout that you have created and you have not added to your application, the next line with AnchorLayout().canvas creates a new Anchorlayout . You must do this task in the constructor:

from kivy.app import App
from kivy.graphics import Color,Bezier
from kivy.uix.anchorlayout import AnchorLayout

class AncLayout(AnchorLayout):
    def __init__(self, *args, **kwargs):
        AnchorLayout.__init__(self, *args, **kwargs)
        with self.canvas:
            Color(.1,.88,.71,.57)
            Bezier(points = (100,100,70,70,40,70,100,100),    
                   segments = 120,
                   dash_length = 9,
                   dash_offset = 3)

class MasterApp(App):
    def build(self):
        return AncLayout()  


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