Kivy将图像放置在动态生成的按钮的特定位置上

Question

我想在创建的每个按钮的左侧放置圆形图像，就像在消息传递应用程序上一样。图片将通过服务器发送。我已经有使用PIL的代码，也可以将图像制作成圆形。我只是不知道如何将它们放置在每个按钮的角上。

应用程序的Python文件：

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.properties import ObjectProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.lang import Builder
from kivy.clock import mainthread
from kivy.uix.button import Button
from kivy.uix.popup import Popup
from kivy.uix.label import Label
from kivy.uix.button import Button
from kivy.properties import BooleanProperty, StringProperty
from kivy.uix.image import AsyncImage


Builder.load_file('main.kv')

login_plz = Popup(title='Please login',
              content=Label(text='You need to login first'),
              size_hint=(None, None), size=(400, 400),
              auto_dismiss=True)


class Menu(BoxLayout):
    access_denied = BooleanProperty(True)


class ScreenLogIn(Screen):

    @mainthread
    def verify_credentials(self):
        popup = Popup(title='Try again',
                  content=Label(text='Wrong Email/Password'),
                  size_hint=(None, None), size=(400, 400),
                  auto_dismiss=True)

        try:
            if len(self.ids.login.text) > 20 or   len(self.ids.passw.text) > 32:
                popup.open()
            elif self.ids.login.text == "a" and self.ids.passw.text == "a":
                App.get_running_app().root.access_denied = False
                self.manager.current = "match"
            else:
                App.get_running_app().root.access_denied = True
                popup.open()
        except Exception as e:
            pass


class ScreenNearUsers(Screen):

    @mainthread
    def on_enter(self):
        if App.get_running_app().root.access_denied is True:
            self.manager.current = 'login'
            login_plz.open()
        else:
            for i in xrange(101):
                button = Button(text="B_" + str(i))
                self.ids.grid.add_widget(button)


class ScreenMatch(Screen):

    def on_enter(self, *args):
        if App.get_running_app().root.access_denied is True:
            self.manager.current = 'login'
            login_plz.open()
        else:
            for i in range(10):
                src = "http://placehold.it/480x270.png&text=slide-%d&.png" % i
                image = AsyncImage(source=src, allow_stretch=True, keep_ratio=False,opacity=1,size_hint=(1, 1.3),
                               pos_hint={'center_x': 0.5, 'center_y': 0.75}, border=True)
                self.ids.carousel.add_widget(image)


class ScreenChats(Screen):

    def on_enter(self, *args):
        if App.get_running_app().root.access_denied is True:
            self.manager.current = 'login'
            login_plz.open()
        else:
            for i in range(50):
                button = Button(text='Some_name')
                self.ids.chat_layout.add_widget(button)


class ScreenUserProfile(Screen):

    def on_enter(self, *args):
        if App.get_running_app().root.access_denied is True:
            self.manager.current = 'login'
            login_plz.open()
        else:
            pass


class Manager(ScreenManager):
    screen_log_in = ObjectProperty(None)
    screen_near_user = ObjectProperty(None)
    screen_match = ObjectProperty(None)
    screen_chats = ObjectProperty(None)
    screen_user_profile = ObjectProperty(None)


class MenuApp(App):

    def build(self):
        return Menu()

    def on_start(self):
        self.current_screen = 'login'


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

这是主要Kv：

<Menu>:
    manager: screen_manager
    orientation: "vertical"
    id: action

    ActionBar:
        size_hint_y: 0.1
        background_color: 0, 0, 1000, 10
        background_normal: ""
        ActionView:
            ActionPrevious:
                app_icon:""
                with_previous: False

                text:"    [b]Dhobiwala.com[/b]"

                markup:True
                font_size:"16dp"
            ActionButton:
                id: near_users
                size_hint: 1, 1
                height: self.texture_size[ 1 ]
                width: self.texture_size[ 0 ] + 40
                minimum_width: self.texture_size[ 0 ] + 60

               halign: "center"
               icon: 'icons/internet.png'
               disabled: True if root.access_denied else False
               on_press: root.manager.current = 'near_users'
           ActionButton:
               id: matching_bar
               size_hint: 1, 1

               height: self.texture_size[ 1 ]
               width: self.texture_size[ 0 ] + 40
               minimum_width: -self.texture_size[ 0 ] + 60
               halign: "center"
               text: "Matching"
               disabled: True if root.access_denied else False
               on_press: root.manager.current= 'match'
           ActionButton:
               id: chat
               size_hint: 1, 1

               height: self.texture_size[ 1 ]
               width: self.texture_size[ 0 ] + 40
               minimum_width: self.texture_size[ 0 ] + 60

               halign: "center"
               text: "chat"
               disabled: True if root.access_denied else False
               on_press: root.manager.current = 'chats'
           ActionButton:
               id: profile
               size_hint: 1, 1

               height: self.texture_size[ 1 ]
               width: self.texture_size[ 0 ] + 40
               minimum_width: self.texture_size[ 0 ] + 60

               halign: "center"
               text: "Profile"
               disabled: True if root.access_denied else False
               on_press: root.manager.current = 'profile'
    Manager:
        id: screen_manager

<ScreenLogIn>:
    id: login_screen
    BoxLayout:
        orientation: "vertical"
        padding: 20, 20
        spacing: 50
        TextInput:
            id: login
            size_hint_y: None

            multiline: False
        TextInput:
            id: passw
            size_hint_y: None
            multiline: False
            password: True # hide password
        Button:
            text: "Log In"
            on_release: root.verify_credentials()

<ScreenNearUsers>:
    ScrollView:
        GridLayout:
            id: grid
            size_hint_y: None
            height: self.minimum_height
            cols: 2
            row_default_height: '20dp'
            row_force_default: True
            spacing: 0, 0
            padding: 0, 0


<ScreenMatch>:
    name: 'Carousel'
    fullscreen: True

    BoxLayout:
       size_hint_y: None
       height: '48dp'

       Button:
           text: 'last user'
           id: last_user

       Button:
            text: 'like'

       Button:
           text: 'super like'
           on_release: carousel.load_previous()

       Button:
           text: 'Dislike'
           on_release: carousel.load_next()

    AnchorLayout:
        anchor_x: 'center'
        anchor_y: 'center'

    Carousel:
        id: carousel
        loop: last_user.state == 'down'


<ScreenChats>:

    ScrollView:        
        GridLayout:
            id: chat_layout
            size_hint_y: None
            height: self.minimum_height
            cols: 1
            row_default_height: '125dp'
            row_force_default: True
            spacing: 0, 0
            padding: 0, 0


<ScreenUserProfile>:

    Button:
        text: "stuff4"

<Manager>:
    id: screen_manager
    screen_log_in: screen_log_in
    screen_near_users: screen_near_users
    screen_match: screen_match
    screen_chats: screen_chats
    screen_user_profile: screen_user_profile

    ScreenLogIn:
        id: screen_log_in
        name: 'login'
        manager: screen_manager

    ScreenNearUsers:
        id: screen_near_users
        name: 'near_users'
        manager: screen_manager

    ScreenMatch:
        id: screen_match
        name: 'match'
        manager: screen_manager

    ScreenChats:
        id: screen_chats
        name: 'chats'
        manager: screen_manager

    ScreenUserProfile:
        id: screen_user_profile
        name: 'profile'
        manger: screen_manager

我将使按钮透明，因此我不必担心在圆形图像外部显示的按钮的角。

带有所需位置示例的图片