在python中检测按键?

问题:在python中检测按键?

我正在用python开发一个秒表类型的程序,我想知道如何检测是否按下了一个键(例如p表示暂停,s表示停止),而我不希望它像raw_input这样等待用户输入,然后继续执行。有人知道如何在while循环中执行此操作吗?

另外,我想做这个跨平台的,但是如果那不可能,那么我的主要开发目标是linux

I am making a stopwatch type program in python and I would like to know how to detect if a key is pressed (such as p for pause and s for stop), and I would not like it to be something like raw_input that waits for the user’s input before continuing execution. Anyone know how to do this in a while loop?

Also, I would like to make this cross-platform, but if that is not possible, then my main development target is linux


回答 0

Python有一个具有许多功能的键盘模块。安装它,也许使用以下命令:

pip3 install keyboard

然后在如下代码中使用它:

import keyboard  # using module keyboard
while True:  # making a loop
    try:  # used try so that if user pressed other than the given key error will not be shown
        if keyboard.is_pressed('q'):  # if key 'q' is pressed 
            print('You Pressed A Key!')
            break  # finishing the loop
    except:
        break  # if user pressed a key other than the given key the loop will break

Python has a keyboard module with many features. Install it, perhaps with this command:

pip3 install keyboard

Then use it in code like:

import keyboard  # using module keyboard
while True:  # making a loop
    try:  # used try so that if user pressed other than the given key error will not be shown
        if keyboard.is_pressed('q'):  # if key 'q' is pressed 
            print('You Pressed A Key!')
            break  # finishing the loop
    except:
        break  # if user pressed a key other than the given key the loop will break

回答 1

对于那些在窗户上努力寻找可行答案的人,我的是:pynput

from pynput.keyboard import Key, Listener

def on_press(key):
    print('{0} pressed'.format(
        key))

def on_release(key):
    print('{0} release'.format(
        key))
    if key == Key.esc:
        # Stop listener
        return False

# Collect events until released
with Listener(
        on_press=on_press,
        on_release=on_release) as listener:
    listener.join()

上面的功能将打印您所按的任何键,并在您释放“ esc”键时启动操作。键盘文档在这里用于更多变化的用法。

马库斯·冯·布罗迪(Markus von Broady)强调了一个潜在的问题,即:这个答案并不需要您在当前窗口中激活此脚本,Windows的解决方案是:

from win32gui import GetWindowText, GetForegroundWindow
current_window = (GetWindowText(GetForegroundWindow()))
desired_window_name = "Stopwatch" #Whatever the name of your window should be

#Infinite loops are dangerous.
while True: #Don't rely on this line of code too much and make sure to adapt this to your project.
    if current_window == desired_window_name:

        with Listener(
            on_press=on_press,
            on_release=on_release) as listener:
            listener.join()

For those who are on windows and were struggling to find an working answer here’s mine: pynput

from pynput.keyboard import Key, Listener

def on_press(key):
    print('{0} pressed'.format(
        key))

def on_release(key):
    print('{0} release'.format(
        key))
    if key == Key.esc:
        # Stop listener
        return False

# Collect events until released
with Listener(
        on_press=on_press,
        on_release=on_release) as listener:
    listener.join()

The function above will print whichever key you are pressing plus start an action as you release the ‘esc’ key. The keyboard documentation is here for a more variated usage.

Markus von Broady highlighted a potential issue that is: This answer doesn’t require you being in the current window to this script be activated, a solution to windows would be:

from win32gui import GetWindowText, GetForegroundWindow
current_window = (GetWindowText(GetForegroundWindow()))
desired_window_name = "Stopwatch" #Whatever the name of your window should be

#Infinite loops are dangerous.
while True: #Don't rely on this line of code too much and make sure to adapt this to your project.
    if current_window == desired_window_name:

        with Listener(
            on_press=on_press,
            on_release=on_release) as listener:
            listener.join()

回答 2

正如OP关于raw_input的提及-这意味着他想要cli解决方案。Linux:curses是您想要的(Windows PDCurses)。Curses是cli软件的图形API,您不仅可以检测关键事件,还可以实现更多目标。

该代码将检测按键,直到按下新行为止。

import curses
import os

def main(win):
    win.nodelay(True)
    key=""
    win.clear()                
    win.addstr("Detected key:")
    while 1:          
        try:                 
           key = win.getkey()         
           win.clear()                
           win.addstr("Detected key:")
           win.addstr(str(key)) 
           if key == os.linesep:
              break           
        except Exception as e:
           # No input   
           pass         

curses.wrapper(main)

As OP mention about raw_input – that means he want cli solution. Linux: curses is what you want (windows PDCurses). Curses, is an graphical API for cli software, you can achieve more than just detect key events.

This code will detect keys until new line is pressed.

import curses
import os

def main(win):
    win.nodelay(True)
    key=""
    win.clear()                
    win.addstr("Detected key:")
    while 1:          
        try:                 
           key = win.getkey()         
           win.clear()                
           win.addstr("Detected key:")
           win.addstr(str(key)) 
           if key == os.linesep:
              break           
        except Exception as e:
           # No input   
           pass         

curses.wrapper(main)

回答 3

使用keyboard模块可以做更多的事情。

以下是一些方法:


方法1:

使用功能read_key()

import keyboard

while True:
    if keyboard.read_key() == "p":
        print("You pressed p")
        break

p按下该键将打破循环。


方法2:

使用功能wait

import keyboard

keyboard.wait("p")
print("You pressed p")

它将等待您按下p并继续按下代码。


方法3:

使用功能on_press_key

import keyboard

keyboard.on_press_key("p", lambda _:print("You pressed p"))

它需要一个回调函数。我_之所以使用,是因为键盘功能将键盘事件返回到该功能。

一旦执行,当按下键时它将运行该功能。您可以通过运行以下行来停止所有挂钩:

keyboard.unhook_all()

方法4:

user8167727已经回答了这种方法,但是我不同意他们编写的代码。它将使用该函数,is_pressed但以另一种方式:

import keyboard

while True:
    if keyboard.is_pressed("p"):
        print("You pressed p")
        break

p按下将打破循环。


笔记:

  • keyboard 将从整个操作系统读取按键。
  • keyboard 在Linux上需要root

There are more things which can be done with keyboard module.

Here are some of the methods:


Method #1:

Using the function read_key():

import keyboard

while True:
    if keyboard.read_key() == "p":
        print("You pressed p")
        break

This is gonna break the loop as the key p is pressed.


Method #2:

Using function wait:

import keyboard

keyboard.wait("p")
print("You pressed p")

It will wait for you to press p and continue the code as it is pressed.


Method #3:

Using the function on_press_key:

import keyboard

keyboard.on_press_key("p", lambda _:print("You pressed p"))

It needs a callback function. I used _ because the keyboard function returns the keyboard event to that function.

Once executed, it will run the function when the key is pressed. You can stop all hooks by running this line:

keyboard.unhook_all()

Method #4:

This method is sort of already answered by user8167727 but I disagree with the code they made. It will be using the function is_pressed but in an other way:

import keyboard

while True:
    if keyboard.is_pressed("p"):
        print("You pressed p")
        break

It will break the loop as p is pressed.


Notes:

  • keyboard will read keypresses from the whole OS.
  • keyboard requires root on linux

回答 4

对于Windows,您可以这样使用msvcrt

   import msvcrt
   while True:
       if msvcrt.kbhit():
           key = msvcrt.getch()
           print(key)   # just to show the result

For Windows you could use msvcrt like this:

   import msvcrt
   while True:
       if msvcrt.kbhit():
           key = msvcrt.getch()
           print(key)   # just to show the result

回答 5

使用此代码查找按下了哪个键

from pynput import keyboard

def on_press(key):
    try:
        print('alphanumeric key {0} pressed'.format(
            key.char))
    except AttributeError:
        print('special key {0} pressed'.format(
            key))

def on_release(key):
    print('{0} released'.format(
        key))
    if key == keyboard.Key.esc:
        # Stop listener
        return False

# Collect events until released
with keyboard.Listener(
        on_press=on_press,
        on_release=on_release) as listener:
    listener.join()

Use this code for find the which key pressed

from pynput import keyboard

def on_press(key):
    try:
        print('alphanumeric key {0} pressed'.format(
            key.char))
    except AttributeError:
        print('special key {0} pressed'.format(
            key))

def on_release(key):
    print('{0} released'.format(
        key))
    if key == keyboard.Key.esc:
        # Stop listener
        return False

# Collect events until released
with keyboard.Listener(
        on_press=on_press,
        on_release=on_release) as listener:
    listener.join()

回答 6

使用PyGame拥有一个窗口,然后您可以获取关键事件。

对于这封信p

import pygame, sys
import pygame.locals

pygame.init()
BLACK = (0,0,0)
WIDTH = 1280
HEIGHT = 1024
windowSurface = pygame.display.set_mode((WIDTH, HEIGHT), 0, 32)

windowSurface.fill(BLACK)

while True:
    for event in pygame.event.get():
        if event.key == pygame.K_p: # replace the 'p' to whatever key you wanted to be pressed
             pass #Do what you want to here
        if event.type == pygame.locals.QUIT:
             pygame.quit()
             sys.exit()

Use PyGame to have a window and then you can get the key events.

For the letter p:

import pygame, sys
import pygame.locals

pygame.init()
BLACK = (0,0,0)
WIDTH = 1280
HEIGHT = 1024
windowSurface = pygame.display.set_mode((WIDTH, HEIGHT), 0, 32)

windowSurface.fill(BLACK)

while True:
    for event in pygame.event.get():
        if event.key == pygame.K_p: # replace the 'p' to whatever key you wanted to be pressed
             pass #Do what you want to here
        if event.type == pygame.locals.QUIT:
             pygame.quit()
             sys.exit()

回答 7

所以我根据这篇文章(使用msvcr库和Python 3.7)制作了这款游戏。

以下是游戏的“主要功能”,即检测所按下的按键:

# Requiered libraries - - - -
import msvcrt
# - - - - - - - - - - - - - -


def _secret_key(self):
    # Get the key pressed by the user and check if he/she wins.

    bk = chr(10) + "-"*25 + chr(10)

    while True:

        print(bk + "Press any key(s)" + bk)
        #asks the user to type any key(s)

        kp = str(msvcrt.getch()).replace("b'", "").replace("'", "")
        # Store key's value.

        if r'\xe0' in kp:
            kp += str(msvcrt.getch()).replace("b'", "").replace("'", "")
            # Refactor the variable in case of multi press.

        if kp == r'\xe0\x8a':
            # If user pressed the secret key, the game ends.
            # \x8a is CTRL+F12, that's the secret key.

            print(bk + "CONGRATULATIONS YOU PRESSED THE SECRET KEYS!\a" + bk)
            print("Press any key to exit the game")
            msvcrt.getch()
            break
        else:
            print("    You pressed:'", kp + "', that's not the secret key(s)\n")
            if self.select_continue() == "n":
                if self.secondary_options():
                    self._main_menu()
                break

如果您想要该porgram的完整源代码,则可以在这里查看或下载它:

秘钥游戏(GitHub)

(注意:秘密按键为:Ctrl+ F12

我希望您可以作为一个例子,并为那些来此信息的人提供帮助。

So I made this ..kind of game.. based on this post (using msvcr library and Python 3.7).

The following is the “main function” of the game, that is detecting the keys pressed:

# Requiered libraries - - - -
import msvcrt
# - - - - - - - - - - - - - -


def _secret_key(self):
    # Get the key pressed by the user and check if he/she wins.

    bk = chr(10) + "-"*25 + chr(10)

    while True:

        print(bk + "Press any key(s)" + bk)
        #asks the user to type any key(s)

        kp = str(msvcrt.getch()).replace("b'", "").replace("'", "")
        # Store key's value.

        if r'\xe0' in kp:
            kp += str(msvcrt.getch()).replace("b'", "").replace("'", "")
            # Refactor the variable in case of multi press.

        if kp == r'\xe0\x8a':
            # If user pressed the secret key, the game ends.
            # \x8a is CTRL+F12, that's the secret key.

            print(bk + "CONGRATULATIONS YOU PRESSED THE SECRET KEYS!\a" + bk)
            print("Press any key to exit the game")
            msvcrt.getch()
            break
        else:
            print("    You pressed:'", kp + "', that's not the secret key(s)\n")
            if self.select_continue() == "n":
                if self.secondary_options():
                    self._main_menu()
                break

If you want the full source code of the porgram you can see it or download it from here:

The Secret Key Game (GitHub)

(note: the secret keypress is: Ctrl+F12)

I hope you can serve as an example and help for those who come to consult this information.


回答 8

我建议您使用PyGame并添加一个事件句柄。

http://www.pygame.org/docs/ref/event.html

I would suggest you use PyGame and add an event handle.

http://www.pygame.org/docs/ref/event.html


回答 9

key = cv2.waitKey(1)

这是来自openCV软件包。它无需等待即可检测到按键。

key = cv2.waitKey(1)

This is from the openCV package. It detects a keypress without waiting.