`class MyWidget(Widget):`
您的根小部件是MyWidget
它继承自一个Widget
而不是来自其中一种布局,因此无法控制其子级的大小如上所述here http://kivy.org/docs/api-kivy.uix.layout.html#understanding-size-hint-property-in-widget,“size_hint 是一个值的元组,由layouts管理孩子的体型”。
您的根小部件确实占据了窗口的整个空间。您可以通过向画布添加一个矩形来测试这一点MyWidget
像这样::
with self.canvas.before:
Color(1,0,0,1)
Rectangle(pos=self.pos, size=self.size)
你应该熟悉画布,canvas.before 和 canvas.after http://kivy.org/docs/api-kivy.graphics.instructions.html#kivy.graphics.instructions.Canvas。它们基本上是指令组,前组在小部件的画布指令之前绘制,后组在之后绘制。
Kivy 中一个关键的不同之处是小部件的大小调整/布局会延迟到下一帧,因此如果您只是将上面的代码片段添加到代码中,如下所示:
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.label import Label
from kivy.uix.widget import Widget
from kivy.uix.gridlayout import GridLayout
from kivy.graphics import *
class MyWidget(Widget):
def __init__(self, **kwargs):
# I'd make sure to pass of kwargs through to the super
# as there are widgets's that process their initial
# arguments through.
super(MyWidget, self).__init__(**kwargs)
grid_layout = GridLayout(cols=3)
grid_layout.add_widget(Button(text='A'))
grid_layout.add_widget(Button(text='B'))
grid_layout.add_widget(Label(text='text'))
grid_layout.add_widget(Label(text='other'))
grid_layout.add_widget(Button(text='text'))
self.add_widget(grid_layout)
with self.canvas.before:
Color(1,0,0,1)
Rectangle(pos=self.pos, size=self.size)
class MyApp(App):
def build(self):
return MyWidget()
if __name__ == '__main__':
MyApp().run()
这只会在小部件的初始位置和大小处显示一个红色矩形,当时它的默认位置和大小分别为 (0, 0) 和 (100, 100)。
为了使红色矩形符合小部件的大小,我们应该bind http://kivy.org/docs/api-kivy.event.html#kivy.event.EventDispatcher.bind它的大小与小部件的大小相同,如下所示::
...
grid_layout.add_widget(Button(text='text'))
self.add_widget(grid_layout)
with self.canvas.before:
Color(1,0,0,1)
self.rect = Rectangle(pos=self.pos, size=self.size)
self.bind(size=self.update_rect)
def update_rect(self, instance, value):
self.rect.pos = self.pos
self.rect.size = self.size
class MyApp(App):
def build(self):
...
正如上面代码的输出所示,您的小部件占据了整个窗口的大小。但是,这并不能解决您的问题,子布局仍然保持其原始位置和原始大小。这是因为小部件无法控制其子级的大小,如上所述。
您在这里有两种选择,要么更新小部件的子部件的大小和位置,就像更新矩形一样(多个子部件很快就会变得复杂),要么使用其中一个布局作为您的根小部件。
这也可以在 kv 中完成,如下所示::
from kivy.app import App
from kivy.uix.widget import Widget
from kivy.lang import Builder
Builder.load_string('''
# this is the rule for MyWidget that defines
# what MyWidget looks like i.e.drawing
# instructions and widgets etc
<MyWidget>:
canvas.before:
Color:
rgba: 1, 0, 0, 1
Rectangle:
# this implicitly binds the size of the
# rect to the size of the widget
size: self.size
# self here still refers to the widget as Rectangle is only a
# graphics instruction and not a widget
pos: self.pos
GridLayout:
cols: 3
# root here refers to the `MyWidget`, bind the size of the
# GridLayout to the size of your root widget
size: root.size
Button:
text: 'A'
Button:
text: 'B'
Label:
text: 'text'
Label:
text: 'other'
Button:
text: 'text'
''')
class MyWidget(Widget):
pass
class MyApp(App):
def build(self):
return MyWidget()
if __name__ == '__main__':
MyApp().run()
上面的示例将子窗口小部件的大小绑定到其父窗口小部件的大小。我仍然建议使用布局作为根小部件,并且不要对嵌套布局犹豫不决。