使用python和kivy的小部件类（例如下拉列表）的值

我想在代码的其他地方使用下拉菜单中选择的值，特别是填充MyData类

一些背景：我最初的问题是如何让按钮工作得到了回答，谢谢。答案显示选择值时如何打印该值。但是，除了on_release=lambda btn:printbtn.text语句之外，我似乎无法访问或打印所选内容

下面的代码有一些简单的print语句来显示我试图跟踪的值。上面的注释解释了输出

我的主要问题是：

1为什么每次调用MyPopup时都会打印默认pos值？注意：调用MyPopup时传递的值会立即打印出来

2我如何从MyColor获得颜色选择

3“self.drop.bindon_select=lambda实例，x:setattrself，'text'，x”具体做什么？如果它将“self.text”设置为所选内容，我如何访问该值注意：“self.text”不会给我颜色

4如何将pos和颜色输入MyData

.py：

from kivy.app import App
from kivy.uix.widget import Widget
from kivy.lang import Builder
from kivy.uix.dropdown import DropDown
from kivy.uix.popup import Popup
from kivy.uix.button import Button
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.graphics import Color, Rectangle
from kivy.factory import Factory

class AddTouch(Widget):
    def __init__(self, **kwargs):
        super(AddTouch, self).__init__(**kwargs)
        with self.canvas:
            Color(1, 0, 0, 0.5, mode="rgba")
            self.rect = Rectangle(pos=(0, 0), size=(10, 10))
    def on_touch_down(self, touch):
        self.rect.pos = touch.pos
    def on_touch_move(self, touch):
        self.rect.pos = touch.pos
    def on_touch_up(self, touch):
        # final position
        self.rect.pos = touch.pos
        MyPopup(pos=touch.pos)


class MyPopup(Popup):
    def __init__(self, pos=[0,0]):
        super(MyPopup, self).__init__(pos=[0,0])
        self.pos = pos
        self.title = 'Select Color'
        self.color = MyColor.text
        # when MyPopup is called this first prints:
        #   from MyPopup [0, 0], <StringProperty name=text>
        # then immediately prints (for example)
        #   from MyPopup [758.0, 500.0], <StringProperty name=text>
        print('from MyPopup {}, {}'.format(self.pos, self.color))

    def save(self):
        # when save button is clicked this prints:
        #    from MyPopup.save [0, 0], <StringProperty name=text>
        print('from MyPopup.save {}, {}'.format(self.pos,self.color))
        MyData(self.pos, self.color)


class MyColor(Button):
    def __init__(self, **kwargs):
        super(MyColor, self).__init__(**kwargs)
        self.drop = DropDown()
        colorlist = ['black', 'red', 'orange', 'yellow', 'green', 'blue', 'purple', 'pink', 'white']
        for index in colorlist:
            btn = Button(text='%s' % index, size_hint_y=None, height=44)
            btn.bind(on_release=lambda btn: self.drop.select(btn.text))
            self.drop.add_widget(btn)
        self.bind(on_release=self.drop.open)
        # I thought this would 'setattr' of self.text to the selected value
        self.drop.bind(on_select=lambda instance, x: setattr(self, 'text', x))

class MyData:
    def __init__(self, pos,color):
        # this prints :
        #    from MyData [0, 0], <StringProperty name=text>
        print('from MyData {}, {}'.format(pos,color))

# using kivy screen for consistency
class MainWindow(Screen):
    pass
class WindowManager(ScreenManager):
    pass
kv = Builder.load_file("dropdown.kv")
class MyMainApp(App):
    def build(self):
        return kv

if __name__ == "__main__":
    MyMainApp().run()

.kv：

#:import Factory kivy.factory.Factory

WindowManager:
    MainWindow:

<MainWindow>:
    name: "main"
    AddTouch:
        on_touch_up:
            Factory.MyPopup().open()

<MyPopup>:
    text:'Enter Data'
    auto_dismiss: False
    FloatLayout:
        MyColor:
            text: 'Value'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":1}
        Button:
            text: 'Save'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":0.5}
            on_press: root.save()
            on_release: root.dismiss()

---

您可以使用id输入子部件：

<MyPopup>:
    text:'Enter Data'
    auto_dismiss: False
    FloatLayout:
        MyColor:
            id: MyColor
            text: 'Value'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":1}
        Button:
            id: Button1
            text: 'Save'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":0.5}
            on_press: root.save()
            on_release: root.dismiss()

替代语法：

print(self.ids["Button1"].text)

---

您可以使用id输入子部件：

<MyPopup>:
    text:'Enter Data'
    auto_dismiss: False
    FloatLayout:
        MyColor:
            id: MyColor
            text: 'Value'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":1}
        Button:
            id: Button1
            text: 'Save'
            size_hint: 1,0.5
            pos_hint: {"x": 0,"top":0.5}
            on_press: root.save()
            on_release: root.dismiss()

替代语法：

print(self.ids["Button1"].text)