guizero Raspberry Pi: 按钮 -> 命令序列问题

Question

要求：在guizero App上按下一个按钮应该首先设置一个文本值，然后执行一个功能（这里是一个简单的time.sleep()；本来是一个子进程）；执行该功能后，应显示结果文本；

#!/usr/bin/python3
# -*- coding: utf-8 -*-

from guizero import App, PushButton, Text
import subprocess
import time

# Action you would like to perform
def counter0():
    global s0
    text0.value = int(text0.value) + 1  # works
    text1.value = s0                    # works

def counter1():
    global s0
    text1.value = s0       # display a status value - but does not (!)
    time.sleep(1)          # originally a subprocess is called here; works
    text1.value = "ready"  # only diplays this after a delay

s0="start something after pressing butt1"

app = App("Hello world", layout="grid")

text0 = Text(app, text="1", align="left", grid=[0,1])
text1 = Text(app, text=s0, align="left",grid=[0,8] )
butt1 = PushButton(app, text="Button", command=counter1, align="left", grid=[0,2])
text0.repeat(10000, counter0)  # Schedule call to counter() every 1000ms

app.display()

很可能我不理解 guizero 背后的想法。对如何管理此类要求有任何想法吗？

Answer 1

如果我没有正确理解你的问题，你的具体问题在这里：

    text1.value = s0       # display a status value - but does not (!)

这不起作用，因为 guizero 框架正在同步执行函数：在函数返回之前，不会执行其他代码——包括更新显示的代码。

如果你想：

在运行使用 subprocess
运行一些命令
命令完成后显示一条消息

然后您将需要重写您的逻辑，这样您的应用程序就不会等待 `counter1 完成。异步运行宁代码的一种选择是运行它在一个单独的线程中。例如：

from guizero import App, PushButton, Text
import threading
import time


# Action you would like to perform
def counter0():
    global s0
    text0.value = int(text0.value) + 1  # works
    text1.value = s0                    # works


def run_command():
    time.sleep(1)          # originally a subprocess is called here; works
    text1.value = "ready"  # only diplays this after a delay


def counter1():
    global s0
    text1.value = "Running command..."
    threading.Thread(target=run_command).start()


s0 = "start something after pressing butt1"

app = App("Hello world", layout="grid")

text0 = Text(app, text="1", align="left", grid=[0, 1])
text1 = Text(app, text=s0, align="left", grid=[0, 8])
butt1 = PushButton(app, text="Button", command=counter1,
                   align="left", grid=[0, 2])
text0.repeat(10000, counter0)

app.display()

运行使用上面的代码会给你以下行为：

guizero Raspberry Pi: 按钮 -> 命令序列问题

guizero Raspberry Pi: button -> command sequence problems

python

tkinter

python-3.x

raspberry-pi3

guizero