从 kivy 下拉列表中删除所有按钮

Question

我是 Python 新手，我试图解决这个问题，但我不可能做到这一点。 下拉菜单是通过 mqtt 动态填充的（这里例如是蚊子），在选择了一个值后，我需要更改 Screen，当我返回带有下拉菜单的屏幕时，它应该是空的。

有人有一些想法吗？ 提前谢谢你。

main.py

#-*-coding:utf8;-*-
#qpy:2
#qpy:kivy
#!/usr/bin/python
#@@@@@@ -*- coding: utf-8 -*-

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.core.window import Window
#from kivy.properties import DictProperty

import xmlrpclib
import calendar
import datetime
from urllib3.util.timeout import current_time
from datetime import date, time, timedelta
import locale
from kivy.uix.togglebutton import ToggleButton

from kivy.properties import ListProperty
from threading import Thread
import paho.mqtt.client as mqtt
import time
from time import sleep
from ConfigParser import SafeConfigParser



class CustomDropDownChip(DropDown):
    def __init__(self, **kwargs):
        super(CustomDropDownChip, self).__init__(**kwargs)
        notes = chip_list
        for note in notes:
            btn = Button(text='%s' % note, size_hint_y=None, height=int(Window.height)/10)
            btn.bind(on_release=lambda btn: self.select('CHIP: ' + btn.text))
            self.add_widget(btn)

class StartScreen(Screen):
    pass

class InsertBox(Screen):
    global chip_list
    chip_list = []
    global chip_list_empty
    chip_list_empty = []
    global connected_flag
    consommables = ListProperty([])

    def buttons_down(self):
        app = App.get_running_app()
        app.chip_value = self.ids.id_chip.text
        app.InsertSelection = 'InsertBoxConfirm'

    def on_connect(self, mqttc, obj, flags, rc):
        if rc==0:
            mqttc.connected_flag=True
            connected_flag = True
            print("connected OK")
        else:
            print("Bad connection Returned code=",rc)
    def on_disconnect(self, mqttc, obj, rc):
        pass

    def on_message(self, mqttc, obj, msg):
        response = str(msg.payload)
        if response not in chip_list:
            sleep(1)
            chip_list.append(response)
        if mqttc.connected_flag == False:
            mqttc.on_disconnect()
    def on_publish(self, mqttc, obj, mid):
        print("mid: "+str(mid))
    def on_subscribe(self, mqttc, obj, mid, granted_qos):
        print("Subscribed: "+str(mid)+" "+str(granted_qos))
    def on_log(self, mqttc, obj, level, string):
        print(string)
    def __init__(self, **kwargs):
        super(InsertBox, self).__init__(**kwargs)
    def stop_mqtt(self):
        mqttc.disconnect()
    def start_mqtt(self):
        self.read_chip()
    def read_chip(self, *args):
        global t
        t = Thread(target=self.read_).start()
    def read_(self):

        mqtt.Client.connected_flag=False#create flag in class
        connected_flag = False

        global mqttc
        mqttc = mqtt.Client(transport="websockets")
        mqttc.on_message = self.on_message
        mqttc.on_connect = self.on_connect
        mqttc.on_publish = self.on_publish
        mqttc.on_subscribe = self.on_subscribe
        mqttc.on_log = self.on_log
        mqttc.connect("test.mosquitto.org", 8080, 60)
        mqttc.subscribe("temp/random", 0)
        mqttc.loop_forever()



    def consume(self, *args):
        while self.consommables and time() < (Clock.get_time() + MAX_TIME):
            item = self.consommables.pop(0)  # i want the first one
            label = Factory.MyLabel(text=item)
            self.root.ids.id_chip.text = label #add_widget(label)

#    @classmethod
    def reset_chip_list(self):
        chip_list = chip_list_empty


class InsertBoxConfirm(Screen):
    def buttons_set(self):
        InsertBox.buttons_set()
    def buttons_reset(self):
        InsertBox.buttons_reset()

class MyScreenManager(ScreenManager):

    def SetChip(self, value):
        pass

class testdropdownApp(App):
    title = "Kivy Drop-Down List Demo"
    chip_list = chip_list_empty
    chip_value = ''

    def build(self):
        return MyScreenManager()

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

testdropdown.kv

#:kivy 1.10.0
#:import Factory kivy.factory.Factory

<CustomDropDownChip>:
    on_select:
        app.root.ids.InsertBox.ids.id_chip.text = '{}'.format(args[1])
        app.root.SetChip(args[1])


<StartScreen>:
    name: 'StartScreen'
    Button:
        text: 'Start'
        on_release:
            root.manager.transition.direction = 'left'
            root.manager.transition.duration = 0
            root.manager.current = 'InsertBox'


<InsertBox>:
    name: 'InsertBox'
    id: test00 
    on_enter:
        root.reset_chip_list()
        root.start_mqtt()
    on_leave:
        root.stop_mqtt()

    GridLayout:
        rows: 2
        id: test01
        GridLayout:
            rows: 1
            size_hint_y: .27
            padding: 5
            Button:
                id: id_chip
                text: 'Select chip'
#                    size_hint_y: .5
                spacing: 5
                on_release: Factory.CustomDropDownChip().open(self)

        GridLayout:
            size_hint_y: .2
            height: .15
            cols: 2
            BoxLayout:
                padding: 5
                orientation: 'horizontal'
                size: root.size
                pos: root.pos
                spacing: 5
#                height: .15
                Button:
                    text: "Back"
                    on_press:
                        root.reset_chip_list()
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'StartScreen'
                Button:
                    text: 'OK'
                    on_press:
                        root.buttons_down()
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'InsertBoxConfirm'

<InsertBoxConfirm>:
    name: 'InsertBoxConfirm'
    on_pre_enter:
        id_chip_label.text = app.chip_value
    GridLayout:
        rows: 2
        id: id_InsertBoxConfirm
        GridLayout:
            rows: 1
            size_hint_y: .27
            padding: 5
            Label:
                id: id_chip_label
                text: 'valore CHIP'

        GridLayout:
            size_hint_y: .2
            height: .15
            cols: 1
            BoxLayout:
                padding: 5
                orientation: 'horizontal'
                size: root.size
                pos: root.pos
                spacing: 5
                Button:
                    text: 'OK'
                    id: button_ok
                    on_press:
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'InsertBox'


<MyScreenManager>:
    StartScreen:
        id: 'StartScreen'
        name: 'StartScreen'
    InsertBox:
        id: InsertBox
        name: 'InsertBox'
    InsertBoxConfirm:
        id: InsertBoxConfirm
        name: 'InsertBoxConfirm'

Answer 1

有关详细信息，请参阅概述、sn-ps 和示例。

概述

kv 文件

1. 删除导入语句，#:import Factory kivy.factory.Factory
2. 将root.reset_chip_list() 从on_enter: 移动到on_leave:
3. 将Factory.CustomDropDownChip().open(self) 替换为新的回调方法root.create_open_customdropdown(self)
4. 从on_press:返回按钮中删除root.reset_chip_list()，因为当我们离开屏幕时，它会自动触发on_leave:事件。
5. 将 app.chip_value 替换为 root.manager.chip_value，因为我们会将变量 chip_value 从 App 类移动到根类。

片段 - kv 文件

            Button:
                id: id_chip
                text: 'Select chip'
                spacing: 5
                on_release:
                    root.create_open_customdropdown(self)

Python 代码

1. 添加导入语句，from kivy.properties import BooleanProperty, ObjectProperty
2. 从class InsertBox(Screen): 中删除变量（全局chip_list；全局chip_list_empty；全局connected_flag）
3. 将chip_list = [] 替换为chip_list = ListProperty([])； chip_list_empty = [] 与 chip_list_empty = ListProperty([]);并添加connected_flag = BooleanProperty(False)
4. 在 class InsertBox(Screen): 的类级别添加 ObjectProperty dropdown = ObjectProperty(None)，以便我们可以使用它来连接到 CustomDropDownChip 对象并将其删除。
5. 实现一个新方法，create_open_customdropdown(self, instance): inside class InsertBox(Screen):
6. 在方法中，将chip_list替换为self.chip_list； chip_list_empty 与 self.chip_list_empty; connected_flag 与 self.connected_flag
7. 从class testdropdownApp(): 中删除chip_list = chip_list_empty
8. 将chip_value = '' 从class testdropdownApp() 移动到class MyScreenManager():
9. 在SetChip() 方法中，将pass 替换为self.chip_value = value
10. 在CustomDropDownChip的构造函数中，添加chip_list作为参数；删除notes = chip_list；并将notes 替换为chip_list

片段 - Python 代码

class CustomDropDownChip(DropDown):
    def __init__(self, chip_list, **kwargs):
        super(CustomDropDownChip, self).__init__(**kwargs)
        for note in chip_list:
            btn = Button(text='%s' % note, size_hint_y=None, height=int(Window.height)/10)
            btn.bind(on_release=lambda btn: self.select('CHIP: ' + btn.text))
            self.add_widget(btn)
...
class InsertBox(Screen):
    consommables = ListProperty([])
    chip_list = ListProperty([])
    chip_list_empty = ListProperty([])
    connected_flag = BooleanProperty(False)
    dropdown = ObjectProperty(None)

    def create_open_customdropdown(self, instance):
        self.dropdown = CustomDropDownChip(self.chip_list)
        self.dropdown.open(instance)
...
    def reset_chip_list(self):
        print("\tlen(chip_list)=", len(self.chip_list))
        self.chip_list = self.chip_list_empty
        print("\tlen(chip_list)=", len(self.chip_list))

        if self.dropdown is not None:
            self.remove_widget(self.dropdown)

示例

main.py

​​>

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.dropdown import DropDown
from kivy.uix.button import Button
from kivy.core.window import Window
from datetime import time
from threading import Thread
import paho.mqtt.client as mqtt
import time
from time import sleep
from kivy.factory import Factory
from kivy.clock import Clock
from kivy.properties import BooleanProperty, ListProperty, ObjectProperty

MAX_TIME = 1/60.


class CustomDropDownChip(DropDown):
    def __init__(self, chip_list, **kwargs):
        super(CustomDropDownChip, self).__init__(**kwargs)
        for note in chip_list:
            btn = Button(text='%s' % note, size_hint_y=None, height=int(Window.height)/10)
            btn.bind(on_release=lambda btn: self.select('CHIP: ' + btn.text))
            self.add_widget(btn)


class StartScreen(Screen):
    pass


class InsertBox(Screen):
    consommables = ListProperty([])
    chip_list = ListProperty([])
    chip_list_empty = ListProperty([])
    connected_flag = BooleanProperty(False)
    dropdown = ObjectProperty(None)

    def create_open_customdropdown(self, instance):
        self.dropdown = CustomDropDownChip(self.chip_list)
        self.dropdown.open(instance)

    def buttons_down(self):
        app = App.get_running_app()
        app.InsertSelection = 'InsertBoxConfirm'

    def on_connect(self, mqttc, obj, flags, rc):
        if rc==0:
            mqttc.connected_flag = True
            self.connected_flag = True
            print("connected OK")
        else:
            print("Bad connection Returned code=",rc)

    def on_disconnect(self, mqttc, obj, rc):
        pass

    def on_message(self, mqttc, obj, msg):

        response = str(msg.payload)
        if response not in self.chip_list:
            sleep(1)
            self.chip_list.append(response)

        if mqttc.connected_flag == False:
            mqttc.on_disconnect()

    def on_publish(self, mqttc, obj, mid):
        print("mid: "+str(mid))

    def on_subscribe(self, mqttc, obj, mid, granted_qos):
        print("Subscribed: "+str(mid)+" "+str(granted_qos))

    def on_log(self, mqttc, obj, level, string):
        print(string)

    def __init__(self, **kwargs):
        super(InsertBox, self).__init__(**kwargs)

    def stop_mqtt(self):
        mqttc.disconnect()

    def start_mqtt(self):
        self.read_chip()

    def read_chip(self, *args):
        global t
        t = Thread(target=self.read_).start()

    def read_(self):

        mqtt.Client.connected_flag = False  # create flag in class
        self.connected_flag = False

        global mqttc
        mqttc = mqtt.Client(transport="websockets")
        mqttc.on_message = self.on_message
        mqttc.on_connect = self.on_connect
        mqttc.on_publish = self.on_publish
        mqttc.on_subscribe = self.on_subscribe
        mqttc.on_log = self.on_log
        mqttc.connect("test.mosquitto.org", 8080, 60)
        mqttc.subscribe("temp/random", 0)
        mqttc.loop_forever()

    def consume(self, *args):
        while self.consommables and time() < (Clock.get_time() + MAX_TIME):
            item = self.consommables.pop(0)  # i want the first one
            label = Factory.MyLabel(text=item)
            self.root.ids.id_chip.text = label #add_widget(label)

#    @classmethod
    def reset_chip_list(self):
        print("\tlen(chip_list)=", len(self.chip_list))
        self.chip_list = self.chip_list_empty
        print("\tlen(chip_list)=", len(self.chip_list))

        if self.dropdown is not None:
            self.remove_widget(self.dropdown)


class InsertBoxConfirm(Screen):
    def buttons_set(self):
        InsertBox.buttons_set()

    def buttons_reset(self):
        InsertBox.buttons_reset()


class MyScreenManager(ScreenManager):
    chip_value = ''

    def SetChip(self, value):
        self.chip_value = value


class testdropdownApp(App):
    title = "Kivy Drop-Down List Demo"

    def build(self):
        return MyScreenManager()

    def on_stop(self):
        self.root.ids.InsertBox.stop_mqtt()


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

testdropdown.kv

#:kivy 1.11.0

<CustomDropDownChip>:
    on_select:
        app.root.ids.InsertBox.ids.id_chip.text = '{}'.format(args[1])
        app.root.SetChip(args[1])


<StartScreen>:
    name: 'StartScreen'
    Button:
        text: 'Start'
        on_release:
            root.manager.transition.direction = 'left'
            root.manager.transition.duration = 0
            root.manager.current = 'InsertBox'


<InsertBox>:
    name: 'InsertBox'
    id: test00
    on_enter:
        root.start_mqtt()
    on_leave:
        root.stop_mqtt()
        root.reset_chip_list()

    GridLayout:
        rows: 2
        id: test01
        GridLayout:
            rows: 1
            size_hint_y: .27
            padding: 5
            Button:
                id: id_chip
                text: 'Select chip'
#                    size_hint_y: .5
                spacing: 5
                on_release:
                    root.create_open_customdropdown(self)

        GridLayout:
            size_hint_y: .2
            height: .15
            cols: 2
            BoxLayout:
                padding: 5
                orientation: 'horizontal'
                size: root.size
                pos: root.pos
                spacing: 5
#                height: .15
                Button:
                    text: "Back"
                    on_press:
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'StartScreen'
                Button:
                    text: 'OK'
                    on_press:
                        root.buttons_down()
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'InsertBoxConfirm'

<InsertBoxConfirm>:
    name: 'InsertBoxConfirm'
    on_pre_enter:
        id_chip_label.text = root.manager.chip_value

    GridLayout:
        rows: 2
        id: id_InsertBoxConfirm
        GridLayout:
            rows: 1
            size_hint_y: .27
            padding: 5
            Label:
                id: id_chip_label
                text: 'valore CHIP'

        GridLayout:
            size_hint_y: .2
            height: .15
            cols: 1
            BoxLayout:
                padding: 5
                orientation: 'horizontal'
                size: root.size
                pos: root.pos
                spacing: 5
                Button:
                    text: 'OK'
                    id: button_ok
                    on_press:
                        root.manager.transition.direction = 'left'
                        root.manager.transition.duration = 0
                        root.manager.current = 'InsertBox'


<MyScreenManager>:
    StartScreen:
        id: 'StartScreen'
        name: 'StartScreen'
    InsertBox:
        id: InsertBox
        name: 'InsertBox'
    InsertBoxConfirm:
        id: InsertBoxConfirm
        name: 'InsertBoxConfirm'

输出

Answer 2

给你：

for child in self.mydropdownsomething.children[:]:
    self.mydropdownsomething.remove_widget(child)

其中 mydropdownsomething 是您动态添加下拉按钮的对象。