如何在 kivy 中使用弹出滑块更改字体大小？

Question

嗨，这里是我的一个简单 RSTDocument 编辑器的代码。 我正在尝试使用弹出窗口中的滑块更改 RSTdocument 的基本字体大小。我怎样才能做到这一点 ？？我尝试使用slider_id.value，但没有成功。

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.popup import Popup

Builder.load_string('''
<RST_GUI>:

    padding: 5
    spacing: 2
    orientation: 'vertical'

    BoxLayout:
        size_hint: (.5, .1)
        pos_hint: {'center_x': .5, 'center_y': 0.5}
        Button:
            text: 'Font Size'
            on_press: root.font_size()
    BoxLayout:
        TextInput:
            id: textinput
            tab_width: 5
        Splitter:
            sizeable_from: 'right'
            min_size: '5'
            RstDocument:
                show_errors: True
                base_font_size: #slider_id.value or something possible?
                text: textinput.text

<font_size>:

    size_hint: (.5, .3)
    pos_hint: {'center_x': .5, 'center_y': 0.5}
    title: "  Font size: " + str(slider_id.value)
    Slider:
        min: 20
        max: 50
        value:31
        step: 1
        id: slider_id


''')


class RST_GUI(BoxLayout):

    def font_size(self):
        font_size().open()    

class font_size(Popup):
    pass

class RST(App):
    def build(self):
        return RST_GUI()

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

Answer 1

id 的范围仅限于声明它的规则，因此，您不能执行base_font_size: slider_id.value。有几种方法可以做你想做的事，一种可能性是在你的 RST_GUI 类中创建一个属性，它是弹出窗口的一个实例，并使用 NumericProperty 来设置字体大小：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.popup import Popup
from kivy.properties import NumericProperty


Builder.load_string('''
<RST_GUI>:
    font_size: 31
    padding: 5
    spacing: 2
    orientation: 'vertical'

    BoxLayout:
        size_hint: (.5, .1)
        pos_hint: {'center_x': .5, 'center_y': 0.5}
        Button:
            text: 'Font Size'
            on_press: root.open_font_popup()

    BoxLayout:
        TextInput:
            id: textinput
            tab_width: 5

        Splitter:
            sizeable_from: 'right'
            min_size: '5'
            RstDocument:
                show_errors: True
                base_font_size: root.font_size
                text: textinput.text

<FontSizePopup>:
    font_size: slider_id.value
    size_hint: (.5, .3)
    pos_hint: {'center_x': .5, 'center_y': 0.5}
    title: "  Font size: " + str(slider_id.value)
    Slider:
        min: 20
        max: 50
        value:31
        step: 1
        id: slider_id
''')


class RST_GUI(BoxLayout):
    font_size = NumericProperty()

    def __init__(self, **kwargs):
        super(RST_GUI, self).__init__(**kwargs)
        self.font_popup = FontSizePopup()
        self.font_popup.bind(font_size=self.change_font_size)

    def open_font_popup(self):
        self.font_popup.open()

    def change_font_size(self, instance, value):
        self.font_size = value


class FontSizePopup(Popup):
    pass


class RST(App):
    def build(self):
        return RST_GUI()

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