Kivy+Python+Raspberry如何实现倒计时

Question

我对python编程很陌生，目前正在使用Kivy和python构建一个摄影棚。在

一般来说，它是工作的（我可以按下按钮，它启动功能，拍摄3张照片，并在屏幕上更新tumbnail），但我无法更改标签文本（actionLabel）以在takePhotos功能启动之前显示倒计时。在

import os, time, Image, sys, datetime, subprocess,glob


import kivy
kivy.require('1.10.0') # replace with your current kivy version !

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.gridlayout import GridLayout
from kivy.uix.label import Label
from kivy.uix.image import Image as kivyImage
from kivy.clock import Clock
from kivy.graphics import Color, Rectangle

import RPi.GPIO as GPIO 

#GPIO varialbes
#buttonPin = 23
GPIO.setmode(GPIO.BCM)
GPIO.setup(23,GPIO.IN)
GPIO_status = False

# Some variables
photoTitle = "My first Photobox!"
total_photos = 3 #Number of photos to be takes

#Function for photo taking
def takePhotos():

    #Take first picture - Folder for inbound pictures /home/pi/PB_Inbox/photobooth%H%M%S.jpg
    time.sleep(3)
    subprocess.call("gphoto2 --capture-image-and-download --filename /home/pi/PB_Inbox/photobooth%H%M%S.jpg", shell=True)
        #Take all other picture
        for x in range (0,total_photos-1):
            subprocess.call("gphoto2 --capture-image-and-download --filename /home/pi/PB_Inbox/photobooth%H%M%S.jpg", shell=True)
    #Process pictures
    subprocess.call("sudo sh /home/pi/Documents/Photo_Booth/Image_prep_3", shell=True)
    print('done')


class MyApp(App):
    # Display the latest thumbnail
    photo = kivyImage(source="/home/pi/PB_Thumb/Thumb.png")
    actionLabel = Label(text="Push the button", size_hint=(1, 0.2),color=[1,0,0,1],font_size='40sp')

    def build(self):
            # Set up the layout
            photobox = GridLayout(rows=3, spacing=10, padding=10)

            # Create the UI objects (and bind them to callbacks, if necessary)
            headerLabel = Label(text="The Greatest Photobox", size_hint=(1, 0.1),font_size='40sp') # Button: 20% width, 100% height

            # Add the UI elements to the layout
            photobox.add_widget(headerLabel)
            photobox.add_widget(self.photo)
            photobox.add_widget(self.actionLabel)

            # Periodically refresh the displayed photo using the callback function
            Clock.schedule_interval(self.callback, 0.3)

            return photobox      

    # Callback for thumbnail refresh and listening to GPIO for input
    def callback(self, instance):
        self.photo.reload()
        if self.readSensor() == False:
            pass
            #print('waiting')
        else:
            #provided as an argument
            takePhotos()

    #Read status of the sensor and return True if Buzzer has been pushed
    def readSensor(self):
        sensor = GPIO.input(23)
        if sensor == 1:
            return True
        else:
            return False

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

有人能教我怎么做吗？在

泰铢

Answer 1

1. 使用Clock.create_trigger触发倒计时。在
2. 移除睡觉时间（3） 在函数中，takePhotos（）。在
3. 使用打卡一次时间表调用函数takePhotos（）即Clock.schedule_once(takePhotos, 3)
4. 将Kivy应用程序分成Python脚本和kv文件。在

Programming Guide » Events and Properties

In Kivy applications, you have to avoid long/infinite loops or sleeping.

示例

在主.py在

import os, time, sys, datetime, subprocess, glob

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.clock import Clock
from kivy.properties import ObjectProperty, NumericProperty

import RPi.GPIO as GPIO

# GPIO variables
# buttonPin = 23
GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN)
GPIO_status = False

# Some variables
total_photos = 3    # Number of photos to be takes


# Function for photo taking
def takePhotos(dt):

    # Take 3 picture
    for x in range(total_photos):
        subprocess.call("gphoto2  capture-image-and-download  filename /home/pi/PB_Inbox/photobooth%H%M%S.jpg", shell=True)

    # Process pictures
    subprocess.call("sudo sh /home/pi/Documents/Photo_Booth/Image_prep_3", shell=True)
    print('done')


class PhotoBox(BoxLayout):
    photo = ObjectProperty(None)
    action_button = ObjectProperty(None)
    count_down_trigger = ObjectProperty(None)
    count = NumericProperty(3)

    def __init__(self, **kwargs):
        super(PhotoBox, self).__init__(**kwargs)
        # Display the latest thumbnail
        self.photo.source = "/home/pi/PB_Thumb/Thumb.png"
        self.count_down_trigger = Clock.create_trigger(self.count_down, 1)

    def on_press_camera_button(self):
        self.count = 3
        self.count_down_trigger()

    def count_down(self, dt):
        self.action_button.text = str(self.count)
        self.count -= 1
        if self.count >= 0:
            self.count_down_trigger()
        else:
            self.action_button.text = "Say Cheese!"
            # Periodically refresh the displayed photo using the callback function
            # Clock.schedule_interval(self.callback, 0.3)    # infinite loop
            Clock.schedule_once(self.callback, 0.3)
            self.action_button.text = "Push the button"    # reset text

    # Callback for thumbnail refresh and listening to GPIO for input
    def callback(self, dt):
        self.photo.reload()
        if self.readSensor():
            # provided as an argument
            Clock.schedule_once(takePhotos, 3)  # call takePhotos method once after 3 seconds
        else:
            pass
            #print('waiting')

    # Read status of the sensor and return True if Buzzer has been pushed
    def readSensor(self):
        sensor = True   # GPIO.input(23)
        if sensor == 1:
            return True
        else:
            return False


class MyApp(App):
    title = "My first Photobox!"

    def build(self):
        return PhotoBox()


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

在千伏在

^{pr2}$

输出