python - 应用 pos_hint 后获取小部件 XY 位置

Question

使用 pos_hint 定位小部件(例如 Scatter)后，如何获取当前的 x、y 位置 (pos)？

例如

wid.pos = (250, 350)
print wid.pos  <----- # it print (200, 350). Correct.
wid.pos_hint = {'top':0.9, 'right':0.5}  # moved the widget to other position using pos_hint.
print wid.pos  <----- # it sill print (200, 350) eventhough the widget position has changed.

---

---

编辑:示例代码

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.scatter import Scatter

Builder.load_string(""" 
<Icon@Scatter>: 
    size_hint: .06, .08

    Image:
        size: root.size
        allow_stretch: True
        keep_ratio: True
""")

class Icon(Scatter):
    def __init__(self, **kwargs):
        self.pos = (200, 200)
        self.move()
        super(Icon, self).__init__(**kwargs)

    def move(self):
        print "BEFORE: "
        print self.pos      # print 200, 200
        self.pos_hint = {'top':0.9, 'right':0.5} # assume now Scatter has moved to x800 y500.
        print "AFTER: "
        print self.pos      # it still print 200, 200 :(


class GameApp(App):
    def build(self):
        return Icon()

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

Answer 1

问题是窗口(和布局本身)在分配布局支持的值(如 size_hint 或 pos_hint)后不会立即刷新。它们在窗口刷新后立即更新(直到方法结束)

你基本上可以调用方法do_layout明确地。文档说“当需要布局时，触发器会调用此方法”。我不得不说我不确定显式调用它是否会导致一些问题，因为没有记录这种用法。它对我有用，但要小心:

wid.pos = (250, 350)
print wid.pos  # it prints (200, 350). Correct.
wid.pos_hint = {'top':0.9, 'right':0.5} 
print wid.pos  # it sill print (200, 350) 
wid.do_layout()
print wid.pos  # it should work now

当您让窗口刷新时，即在您实际看到 Scatter(或任何其他 Widget)已经移动之后，这不是必需的。

---

编辑:问题中代码的更正版本

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

Builder.load_string(""" 
<Icon>: 
    size_hint: .06, .08

    Image:
        size: root.size
        allow_stretch: True
        keep_ratio: True

<BaseLayout>:
    icon: _icon
    Icon:
        id: _icon
    Button: 
        text: "Press me"
        size_hint: .1,.05
        on_press: _icon.move()
""")

class Icon(Scatter):
    def __init__(self, **kwargs):
        self.pos = (200, 200)
        super(Icon, self).__init__(**kwargs)

    def move(self):
        print "BEFORE: "
        print self.pos      # print 200, 200
        self.pos_hint = {'top':0.9, 'right':0.5} # assume now Scatter has moved to x800 y500.
        self.parent.do_layout()
        print "AFTER: "
        print self.pos      # it still print 200, 200 :(


class BaseLayout(FloatLayout):
    pass


class GameApp(App):
    def build(self):
        return BaseLayout()

if __name__ == '__m
ain__':
    GameApp().run()