将 ScreeManager 与 Kivy- 按钮布局一起使用时的问题不再有效

Question

所以我在尝试使用屏幕管理器时遇到了问题。因为我必须创建我的屏幕 classes 现在是 (Screen) 而不是 (GridLayout) 才能完全使用屏幕管理器，例如，button/layout 管理无法在 [=23= 中控制】了？它曾经在屏幕上布置 5 列和 3 行，总共 15 个按钮。现在它只显示一个大的（屏幕）而不是网格布局。

class LandingScreen(Screen):
def build(self):
    return presentation
def __init__(self, **kwargs):
    super(LandingScreen, self).__init__(**kwargs)
    self.cols = 5
    self.buttons = []  # add references to all buttons here

    # Loop to make 20 different buttons on screen
    for x in range(15):
        self.buttons.append(Button(text='button ' + str(x)))  # make a reference to the button before adding it in
        self.add_widget(self.buttons[x])
        self.buttons[x].background_normal = 'YOUTUBE.png'

此处的按钮和列设置用于使用此循环创建 3 行 5 个按钮，但由于我将 (Screen) 添加到 class 而不是 (GridLayout)，所以不会。我宁愿不在 .kv 文件中创建所有按钮，因为我认为在 .py 中更容易管理并且对我来说更有意义。

这是我的 .kv 文件：

<GridLayout>:
    cols: 5
    height: 480
    width: 800
    spacing: 25, 20
    padding: 25,25

<MyScreenManager>:
    LandingScreen:
    InputScreen:

<InputScreen>:
    AnchorLayout:

<LandingScreen>:
    GridLayout:
        cols: 5
        height: 480
        width: 800
        spacing: 25, 20
        padding: 25,25

这显然是多余的，因为我试图弄清楚如何让所有 15 个按钮再次显示，而不仅仅是一个。

谢谢！

Answer 1

您想将按钮添加到 Screen 内的 GridLayout，而不是直接添加到 Screen。为此，请使用 id 来引用 GridLayout.

但是，您不能在 __init__ 方法中使用 id，因为在完全初始化相应的小部件之前，不会应用 kv 文件中定义的规则。 Ryan Pi在这个问题中正确提供了解决方案：

Why can't I access the Screen.ids?

另一方面，要稍后更改屏幕，您必须在您的屏幕中定义 name 属性。

您的代码应该是：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.button import Button
from kivy.clock import Clock


kv_text='''\

<MyScreenManager>:
    LandingScreen:
    InputScreen:

<InputScreen@Screen>:
    name: 'input_sc'
    AnchorLayout:
        id: anchor_1

<LandingScreen@Screen>:
    name: 'landing_sc'
    GridLayout:
        id: grid_1
        cols: 5
        height: 480
        width: 800
        spacing: 25, 20
        padding: 25,25
'''

class MyScreenManager(ScreenManager):
    pass


class LandingScreen(Screen):
    def __init__(self, **kwargs):
        super(LandingScreen, self).__init__(**kwargs)
        self.buttons = [] # add references to all buttons here
        Clock.schedule_once(self._finish_init)

    def _finish_init(self, dt):
        self.ids.grid_1.cols = 5

        # Loop to make 20 different buttons on screen
        for x in range(15):
            self.buttons.append(Button(text='button {}'.format(x)))
            self.ids.grid_1.add_widget(self.buttons[x])
            self.buttons[x].background_normal = 'YOUTUBE.png'

class MyKivyApp(App):
    def build(self):
        return MyScreenManager()

def main():
    Builder.load_string(kv_text)
    app = MyKivyApp()
    app.run()

if __name__ == '__main__':
    main()

如果你想使用 Properties 而不是 ids 方法（参见 documentation），你应该这样做：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.uix.button import Button
from kivy.clock import Clock
from kivy.properties import ObjectProperty


kv_text='''\

<MyScreenManager>:
    LandingScreen:
    InputScreen:

<InputScreen@Screen>:
    name: 'input_sc'
    AnchorLayout:
        id: anchor_1

<LandingScreen@Screen>:
    name: 'landing_sc'
    grid_1: grid_1
    GridLayout:
        id: grid_1
        cols: 5
        height: 480
        width: 800
        spacing: 25, 20
        padding: 25,25
'''

class MyScreenManager(ScreenManager):
    pass


class LandingScreen(Screen):

    grid_1 = ObjectProperty(None)    #<<<< Propertie

    def __init__(self, **kwargs):
        super(LandingScreen, self).__init__(**kwargs)
        self.buttons = [] # add references to all buttons here
        Clock.schedule_once(self._finish_init)

    def _finish_init(self, dt):
        self.grid_1.cols = 5
        # Loop to make 20 different buttons on screen
        for x in range(15):
            self.buttons.append(Button(text='button{}'.format(x)))
            self.grid_1.add_widget(self.buttons[x])
            self.buttons[x].background_normal = 'star.png'

class MyKivyApp(App):
    def build(self):
        return MyScreenManager()

def main():
    Builder.load_string(kv_text)
    app = MyKivyApp()
    app.run()

if __name__ == '__main__':
    main()

将 ScreeManager 与 Kivy- 按钮布局一起使用时的问题不再有效

Issue when using ScreeManager with Kivy- buttons layout no longer works

python

user-interface

python-3.x

kivy

kivy-language