Python/Kivy：手动设置页面 - 在 .kv 文件中实现文本大小

Question

我正在尝试在我的 Kivy 应用中实现手动创建的设置页面。在这种情况下，我在使用应用程序内部的实际设置时遇到了问题。为了演示这个问题，请使用这个最小的例子：

Python 文件“main.py”，我在其中尝试在两个全局变量 first_size 和 second_size 中写入当前字体大小，然后我想在 Kivy 文件中访问它们：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from settingsjson import settings_json
from kivy.properties import NumericProperty

import settings

class MainMenu(Screen):
    pass

class ScreenManagement(ScreenManager):
    pass

presentation = Builder.load_file("style.kv")

class MyApp(App):
    def build(self):
        global first_size, second_size
        first_size = NumericProperty(settings.sizes[settings.options[0]]["first_label"])
        second_size = NumericProperty(settings.sizes[settings.options[0]]["second_label"])
        return presentation

    def build_config(self, config):
        config.setdefaults('settings', {
            'test_size': settings.options[0]
            })

    def build_settings(self, settings):
        settings.add_json_panel('Own Settings',
                                self.config,
                                data=settings_json)

    def reset_labels(self, first_labelsize, second_labelsize):
        global first_size, second_size
        first_size = NumericProperty(first_labelsize)
        second_size = NumericProperty(second_labelsize)

    def on_config_change(self, config, section, key, value):
        first_labelsize = settings.sizes[value]['first_label']
        second_labelsize = settings.sizes[value]['second_label']
        self.reset_labels(first_labelsize, second_labelsize)

myApp = MyApp()
myApp.run()

Python 文件“settingsjson.py”，包含新的设置页面：

import json
import settings

settings_json = json.dumps([
    {'type': 'title',
     'title': 'Settings'},
    {'type': 'options',
     'title': 'Size',
     'desc': 'Test size',
     'options': settings.options,
     'section': 'settings',
     'key': 'test_size'}])

将设置菜单中的两个选项与字体大小相关联的字典的 Python 文件“settings.py”：

options = ['small', 'large']

small = {'first_label': 20, 'second_label': 15}
large = {'first_label': 30, 'second_label': 25}

sizes = {options[0]: small, options[1]: large}

最后是 Kivy 文件“style.kv”：

ScreenManagement:
    MainMenu:

## accessing first global variable (not working)
<Button>:
    font_size: root.first_size

## accessing second global variable (not working either)
<TwoLineButton@Button>:
    font_size: root.second_size


<MainMenu>:
    name: "main"
    FloatLayout:
        Button:
            size_hint: 0.5, 0.2
            pos_hint: {"top": 0.5, "right": 1}
            text: "One-line dummy"
        TwoLineButton:
            size_hint: 0.5, 0.2
            pos_hint: {"top": 0.5, "left": 1}
            text: "This is a two-line\n dummy"
            halign: "center"

        Button:
            on_release:
                app.open_settings()
            text: "Settings"
            font_size: self.height/4
            pos_hint: {"top": 0.1, "right": 0.5}
            size_hint: 0.2, 0.1

如您所见，当前形式的代码不起作用，因为我无法访问 Kivy 文件中的两个字体大小变量。如果我将 Kivy 文件中的 font_size 属性设置为常量值，应用程序运行没有问题，但当然不允许设置菜单中的更改生效。

有没有办法在Kivy文件中访问main.py-file中的全局变量来重置两种按钮的字体大小？

由于我必须在不止一个屏幕中更改设置，因此我需要一个全局独立于类的解决方案。

我很感激每一种提示......

Answer 1

这里有一个稍微不同的方法，使用 on_ 回调在数值属性改变时自动改变字体大小。注意first_size和second_size必须在加载style.kv之前定义

Main.py：

from kivy.app import App
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from settingsjson import settings_json
from kivy.properties import NumericProperty

import settings

class MainMenu(Screen):
    pass

class ScreenManagement(ScreenManager):
    pass


class MyApp(App):
    first_size = NumericProperty(settings.sizes[settings.options[0]]["first_label"])
    second_size = NumericProperty(settings.sizes[settings.options[0]]["second_label"])

    def on_first_size(self, instance, value):
        self.main_menu.ids['button1'].font_size = value

    def on_second_size(self, instance, value):
        self.main_menu.ids['button2'].font_size = value

    def build(self):
        presentation = Builder.load_file("style.kv")
        self.main_menu = presentation.current_screen
        return presentation

    def build_config(self, config):
        config.setdefaults('settings', {
        'test_size': settings.options[0]
        })

    def build_settings(self, settings):
        settings.add_json_panel('Own Settings',
                            self.config,
                            data=settings_json)

    def on_config_change(self, config, section, key, value):
        self.first_size = settings.sizes[value]['first_label']
        self.second_size = settings.sizes[value]['second_label']

myApp = MyApp()
myApp.run()

和style.kv：

ScreenManagement:
MainMenu:

<MainMenu>:
    name: "main"
    FloatLayout:
        Button:
            id: button1
            font_size: app.first_size
            size_hint: 0.5, 0.2
            pos_hint: {"top": 0.5, "right": 1}
            text: "One-line dummy"
        Button:
            id: button2
            font_size: app.second_size
            size_hint: 0.5, 0.2
            pos_hint: {"top": 0.5, "left": 1}
            text: "This is a two-line\n dummy"
            halign: "center"

        Button:
            on_release:
                app.open_settings()
            text: "Settings"
            font_size: self.height/4
            pos_hint: {"top": 0.1, "right": 0.5}
            size_hint: 0.2, 0.1

Answer 2

不确定这是否适合您，但在 .kv 文件中删除您的 Button 和 TwoLineButton 定义，并从布局中的实际 Button 定义中访问 root.first_size 和 root.second_size：

FloatLayout:
    Button:
        font_size: root.first_size
        size_hint: 0.5, 0.2
        pos_hint: {"top": 0.5, "right": 1}
        text: "One-line dummy"
    Button:
        font_size: root.second_size
        size_hint: 0.5, 0.2
        pos_hint: {"top": 0.5, "left": 1}
        text: "This is a two-line\n dummy"
        halign: "center"

它引用的“根”是“MainMenu”，因此在您的 MainMenu 类中添加类级别变量“first_size”和“second_size”：

class MainMenu(Screen):
    first_size = NumericProperty(settings.sizes[settings.options[0]]["first_label"])
    second_size = NumericProperty(settings.sizes[settings.options[0]]["second_label"])

由于这些不是实例变量，您可以在导入 MainMenu 的任何位置将它们作为“MainMenu.first_size”和“MainMenu.second_size”引用。