Python 通行证；关于“U启动数据”；要创建MyScreen和MyImage，需要ScreenManager中的屏幕名称_Python_Python 3.x_Kivy

Python 通行证；关于“U启动数据”；要创建MyScreen和MyImage，需要ScreenManager中的屏幕名称

python python-3.x

Python 通行证；关于“U启动数据”；要创建MyScreen和MyImage，需要ScreenManager中的屏幕名称,python,python-3.x,kivy,Python,Python 3.x,Kivy,我正在使用Kivy库创建一个主要使用Python代码的应用程序。我是Python和Kivy的新手。这里是我的一些代码片段我试图将定义为“启动”的图像传递给导航按钮@ikolim帮我找出了问题所在。你可以在下面看到我的评论小部件 class NavButton(GridLayout): def __init__(self, **kwargs): super(NavButton, self).__init__(**kwargs) self.rows =

我正在使用Kivy库创建一个主要使用Python代码的应用程序。我是Python和Kivy的新手。这里是我的一些代码片段

我试图将定义为“启动”的图像传递给导航按钮@ikolim帮我找出了问题所在。你可以在下面看到我的评论

小部件

class NavButton(GridLayout):

    def __init__(self, **kwargs):
        super(NavButton, self).__init__(**kwargs)
        self.rows = 1
        frame = FloatLayout(id = "frame")
        grid1 = MyGrid(
            rows = 1,
            cols = 5,
            pos_hint = {"top":1, "left": 1},
            size_hint = [1, .2]                         )
        grid1.set_background(0.95,0.95,0.95,1)

        grid1.add_widget(MyButton(
            source = "img/settings.png",
            size_hint = [0.2,0.2]                       ))
        grid1.add_widget(MyButton(
            source = "img/arrow-left.png"               ))
        city_icon = Image(
            source="img/image1.png",
            id="city_icon",
            size_hint=[0.8, 0.8])

        self.ids.cityicon = city_icon
        grid1.add_widget(city_icon)
        grid1.add_widget(MyButton(
            source = "img/arrow-right.png"              ))
        grid1.add_widget(MyButton(
            source = "img/globe.png",
            size_hint = [0.2,0.2]                       ))
        frame.add_widget(grid1)
        self.add_widget(frame)

屏风屏幕管理器这就是我搞砸的地方！显然，您必须定义主屏幕的名称（即

homescreen=homescreen（name=“home\u screen”）

），否则启动应用程序时，它不会更新导航按钮的图像。我不知道为什么，但我只是想为未来的程序员强调一下这一点

 class MyScreenManager(ScreenManager):

        def __init__(self, **kwargs):
        super(MyScreenManager, self).__init__(**kwargs)
        homescreen = Homescreen()
        self.add_widget(homescreen)
        self.ids.screenmanager =  self

    def change_screen(self, name):
         self.current = name

建设者 @ikolim再次感谢您的支持。

解决方案2 要解决此问题，需要以下增强功能

类NavButton（）

替换self.ids.cityicon=“cityicon” 带有

self.ids.cityicon=city\u图标


删除self.bind（on_start=self.update_image）
和方法update_image（）
启动（）时的方法
更换主屏幕=
Main.get\u running\u app（）.root.get\u screen（“主屏幕”）with
homescreen=self.root.get\u screen（“主屏幕”）
替换
frame.children[3]。children[0]。children[0]。children[2]。源代码with
homescreen.ids.navbutton.ids.cityicon.source
删除行（frame=homescreen.children[0]
，navbutton=
frame.children[3]
，和打印（…）
）
代码片段-py文件
示例-main.py
输出

解决方案1

使用函数获取应用程序的实例
将self
添加到my_city

代码片段-py文件
通过setter方法更改变量就足够了，还是要在构造函数中“更改”此图片？因为如果你想在构造器中使用变量，只需将变量my_city设为全局变量。。。也许有更好的方法，但我认为这是最简单的。不工作。。。也许我做错了什么。仍在寻找解决方法。。。也许有一个绑定函数。。。不知道如何使用它，但是…你有没有收到任何错误？请在Google Drive或GitHubIs中共享您更新的应用程序。图片是数据库中的“it Rome”，数据类型是什么，BLOB？请参阅更新的帖子了解解决方案2的详细信息。您好@ikolim，我更新了代码，但没有更改。我很高兴看到它在你们的终端上工作。有没有可能是别的地方出了问题？这里是链接
 class MyScreenManager(ScreenManager):

        def __init__(self, **kwargs):
        super(MyScreenManager, self).__init__(**kwargs)
        homescreen = Homescreen()
        self.add_widget(homescreen)
        self.ids.screenmanager =  self

    def change_screen(self, name):
         self.current = name

GUI = Builder.load_file("main.kv")

class Main(App):

    def build(self):
        return GUI

    def on_start(self):

        self.mynewimage = "image2"
        homescreen = self.root.get_screen("home_screen")
        homescreen.ids.navbutton.ids.cityicon.source = f"img/{self.mynewimage}.png"


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

class NavButton(GridLayout):

    def __init__(self, **kwargs):
        super(NavButton, self).__init__(**kwargs)
        ...
        city_icon = Image(
            source="img/settings.png",
            id="city_icon",
            size_hint=[0.8, 0.8])

        self.ids.cityicon = city_icon
        ...


class Main(App):

    ...

    def on_start(self):
        self.my_city = "it-Rome"
        homescreen = self.root.get_screen("home_screen")
        homescreen.ids.navbutton.ids.cityicon.source = f"img/{self.my_city}.png"
    ...

from kivy.app import App
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.gridlayout import GridLayout
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.button import ButtonBehavior
from kivy.uix.label import Label
from kivy.uix.image import Image
from kivy.graphics import Color, Rectangle


class MyButton(ButtonBehavior, Image):
    pass


class ImageButton(ButtonBehavior, Image):
    pass


### Components

class NavButton(GridLayout):

    def __init__(self, **kwargs):
        super(NavButton, self).__init__(**kwargs)
        self.rows = 1
        frame = FloatLayout(id="frame")
        grid1 = MyGrid(
            rows=1,
            cols=5,
            pos_hint={"top": 1, "left": 1},
            size_hint=[1, .2])
        grid1.set_background(0.95, 0.95, 0.95, 1)

        grid1.add_widget(MyButton(
            source="img/settings.png",
            size_hint=[0.2, 0.2]))
        grid1.add_widget(MyButton(
            source="img/arrow-left.png"))
        city_icon = Image(
            source="img/settings.png",
            id="city_icon",
            size_hint=[0.8, 0.8])

        self.ids.cityicon = city_icon

        grid1.add_widget(city_icon)
        grid1.add_widget(MyButton(
            source="img/arrow-right.png"))
        grid1.add_widget(MyButton(
            source="img/globe.png",
            size_hint=[0.2, 0.2]))
        frame.add_widget(grid1)
        self.add_widget(frame)


### Grids

class MyGrid(GridLayout):

    def set_background(self, r, b, g, o):
        self.canvas.before.clear()
        with self.canvas.before:
            Color(r, g, b, o)
            self.rect = Rectangle(pos=self.pos, size=self.size)

        self.bind(pos=self.update_rect,
                  size=self.update_rect)

    def update_rect(self, *args):
        self.rect.pos = self.pos
        self.rect.size = self.size


### Screens

class Homescreen(Screen):

    def __init__(self, **kwargs):
        super(Homescreen, self).__init__(**kwargs)
        frame = FloatLayout(id="frame")
        grid1 = NavButton()
        frame.add_widget(grid1)

        # This grid contains the number of zpots collected

        grid2 = MyGrid(
            cols=1,
            pos_hint={"top": 0.8, "left": 1},
            size_hint=[1, .2], )
        grid2.add_widget(Image(
            source="img/spot.png"))
        grid2.add_widget(Label(
            text="[color=3333ff]20/30[/color]",
            markup=True))
        grid2.set_background(0.95, 0.95, 0.95, 1)
        frame.add_widget(grid2)

        # This grid contains a scrollable list of nearby zpots

        grid3 = MyGrid(
            cols=1,
            pos_hint={"top": 0.6, "left": 1},
            size_hint=[1, .5])
        grid3.set_background(0.95, 0.95, 0.95, 1)
        frame.add_widget(grid3)

        # This grid contains a the map of nearby zpots

        grid4 = MyGrid(
            cols=1,
            pos_hint={"top": 0.1, "left": 1},
            size_hint=[1, .1])
        grid4.set_background(0.95, 0.95, 0.95, 1)
        frame.add_widget(grid4)
        self.ids.navbutton = grid1
        self.add_widget(frame)


class Newscreen(Screen):
    pass


class Settingscreen(Screen):
    pass


### ScreenManager

class MyScreenManager(ScreenManager):

    def __init__(self, **kwargs):
        super(MyScreenManager, self).__init__(**kwargs)
        homescreen = Homescreen(name='home_screen')
        self.add_widget(homescreen)
        self.ids.screenmanager = self

    def change_screen(self, name):
        self.current = name


class TestApp(App):

    def build(self):
        return MyScreenManager()

    def on_start(self):
        self.my_city = "it-Rome"
        homescreen = self.root.get_screen("home_screen")

        print(f"\non_start-Before change: img={homescreen.ids.navbutton.ids.cityicon.source}")
        homescreen.ids.navbutton.ids.cityicon.source = f"img/{self.my_city}.png"
        print(f"\non_start-After change: img={homescreen.ids.navbutton.ids.cityicon.source}")


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

class NavButton(GridLayout):

    def get(self):
        ...
        city_icon = Image(
                source = "img/" + App.get_running_app().my_city,
                size_hint = [0.8,0.8]                       )

...
class Main(App):

    def build(self):
        return GUI

    def on_start(self):
        # get data from DB
        self.my_city = "it-Rome"