#!/usr/bin/env python2
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import Button
Builder.load_string('''
#:kivy 1.6
[SideBar@BoxLayout]:
content: content
orientation: 'vertical'
size_hint: ctx.size_hint if hasattr(ctx, 'size_hint') else (1, 1)
Image:
source: ctx.image
size_hint: (1, None)
height: root.width
GridLayout:
cols: 2
# just add a id that can be accessed later on
id: content
<Root>:
Button:
center_x: root.center_x
text: 'press to add_widgets'
size_hint: .2, .2
on_press:
# what comes after `:` is basically normal python code
sb.content.clear_widgets()
# however using a callback that you can control in python
# gives you more control
root.load_content(sb.content)
SideBar:
id: sb
size_hint: .2, 1
image: 'data/images/image-loading.gif'
''')
class Root(FloatLayout):
def load_content(self, content):
for but in range(20):
content.add_widget(Button(
text=str(but)))
class MyApp(App):
def build(self):
return Root()
if __name__ == '__main__':
MyApp().run()
我希望内联注释使示例足够清晰。在这种情况下，我们只是将内容的 ref 传递给将小部件添加到内容的函数。
在某些情况下，您可能希望访问 Widget 作为您自己类的属性。在这种情况下，您可以使用以下方法。
上面的方法基本上是添加了一个与id同名的ObjectProperty ，将id所引用的widget的引用传递给它。因此，您现在拥有一个与 python 类中的 id 同名的属性，以便于访问。使用上述方法，您的代码将如下所示。
#!/usr/bin/env python2
from kivy.app import App
from kivy.lang import Builder
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import Button
from kivy.properties import ObjectProperty
Builder.load_string('''
#:kivy 1.6
[SideBar@BoxLayout]:
content: content
orientation: 'vertical'
size_hint: ctx.size_hint if hasattr(ctx, 'size_hint') else (1, 1)
Image:
source: ctx.image
size_hint: (1, None)
height: root.width
GridLayout:
cols: 2
# just add a id that can be accessed later on
id: content
<Root>:
content: sb.content
Button:
center_x: root.center_x
text: 'press to add_widgets'
size_hint: .2, .2
on_press:
sb.content.clear_widgets()
root.load_content()
SideBar:
id: sb
size_hint: .2, 1
image: 'data/images/image-loading.gif'
''')
class Root(FloatLayout):
content = ObjectProperty(None)
'''This is initialised to None and in kv code at line 28
above (the one with `content: sb.content`) a ref to the
actual content is passed'''
def load_content(self):
content = self.content
for but in range(20):
content.add_widget(Button(
text=str(but)))
class MyApp(App):
def build(self):
return Root()
if __name__ == '__main__':
MyApp().run()