Question

我正在尝试使用kivy在raspberryPi上制作嵌入式应用程序，我有一个xinitrc调用我的应用程序，并且开始屏幕加载正常，但是当我按下“ 1”或“ 2”时，我的应用程序将转到第二个屏幕，并立即跳回到开始屏幕，直到我偶然碰到了ctrl为止：

 Exception in thread Thread-4:
 Traceback (most recent call last):
   File "/usr/lib/python2.7/threading.py", line 801, in __bootstrap_inner
     self.run()
       File "/usr/lib/python2.7/threading.py", line 754, in run
         self.__target(*self.__args, **self.__kwargs)
       File "/usr/lib/python2.7/dist-packages/kivy/input/providers/hidinput.py", line 701, in _thread_run
         process_as_mouse_or_keyboard(*infos)
       File "/usr/lib/python2.7/dist-packages/kivy/input/providers/hidinput.py", line 551, in process_as_mouse_or_keyboard
         Keyboard.keycodes[l.lower()],
     KeyError: 'ctrl'

然后一切正常。我感觉这与我所要进入的极简主义环境有关。也许甚至还没有加载东西，但是sleep 15并不能解决问题，我可以在不到15秒的时间内按ctrl，所以似乎不是。也许我只是在错误地启动键盘。这是一个展示这种行为的小程序：

from __future__ import print_function
from kivy.app import App
from kivy.lang import Builder
from kivy.config import Config
from kivy.base import runTouchApp
from kivy.properties import ListProperty
from kivy.uix.boxlayout import BoxLayout
from kivy.core.window import Window
from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition

import time
import random
import os

class StartScreen(Screen):
    pass

class SecondScreen(Screen):
    pass

class RootWidget(BoxLayout):
    pass

class MyScreenManager(ScreenManager):
    pass

root_widget = Builder.load_string('''
#:import hex kivy.utils.get_color_from_hex
MyScreenManager:
    StartScreen:
    SecondScreen:

<StartScreen>:
    name: 'start'
    kbContainer: kbContainer
    BoxLayout:
        id: kbContainer
        canvas.before:
            Color:
                rgba: hex('#0000b1ff')
            Rectangle:
                pos: self.pos
                size: self.size
        orientation: 'vertical'
        Label:
            text: 'Welcome to the Example!'
            color: hex('#f8ee3fff')
            font_size: 30
        BoxLayout:
            Button:
                background_normal: ''
                background_color: hex('#0000b1ff')
                #color: hex('#cc2729ff')
                color: hex('#f8ee3fff')
                text: 'go to second'
                font_size: 30
                on_release: app.root.current = 'second'

<SecondScreen>:
    name: 'second'
    BoxLayout:
        canvas.before:
            Color:
                rgba: hex('#0000b1ff')
            Rectangle:
                pos: self.pos
                size: self.size
        orientation: 'vertical'
        Label:
            text: 'SecondScreen'
            font_size: 30
        BoxLayout:
            canvas.before:
                Color:
                    rgba: hex('#0000b1ff')
                Rectangle:
                    pos: self.pos
                    size: self.size
            orientation: 'vertical'
            padding: 10
            spacing: 10
            Button:
                background_normal: ''
                border: (22,22,22,22)
                background_color: hex('#f8ee3fff')
                color: hex('#cc2729ff')
                text: 'go to start!'
                font_size: 30
                on_release: app.root.current = 'start'
''')


class ExampleApp(App):
    def __init__(self, **kwargs):
        super(ExampleApp, self).__init__(**kwargs)
        self._keyboard = Window.request_keyboard(
            self._keyboard_closed, self, 'text')
        if self._keyboard.widget:
            pass
        self._keyboard.bind(on_key_down=self._on_keyboard_down)

    def _keyboard_closed(self):
        print('My keyboard have been closed!')
        self._keyboard.unbind(on_key_down=self._on_keyboard_down)
        self._keyboard = None

    def _on_keyboard_down(self, keyboard, keycode, text, modifiers):
        print('The key', keycode, 'have been pressed')
        print(' - text is %r' % text)
        print(' - modifiers are %r' % modifiers)
        if self.sm.current == "start":
            if keycode[1] == '1':
                self.sm.current = "second"
            elif keycode[1] == '2':
                self.sm.current = "second"
        elif self.sm.current == "second":
            if keycode[1] == '1':
                self.sm.current = "start"
            elif keycode[1] == '2':
                self.sm.current = "start"

        return True

    def build(self):
        self.sm = root_widget
        self.sm.current = "start"
        return self.sm

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

Answer 1

在您的Kivy App中，定义了两个根窗口小部件。一个来自kv文件MyScreenManager:，另一个来自Python代码return self.sm。删除第二个根窗口小部件，如下所示。

def build(self):
    self.sm = root_widget
    return self.sm

Screen Manager » Default First Screen Displayed

默认情况下，添加到ScreenManager中的第一个屏幕将是显示

Answer 2

崩溃实际上是由于hidinput无法正确处理ctrl键引起的。我已经在hidinput中修复了此问题，一旦我弄清楚了如何也不让键码传递到我开始使用kivy的shell中，我将尝试对其进行PR。

使用屏幕管理器从xinitrc上，kivy捕获键盘在raspberrypi上的行为异常

2 个答案: