Home > Backend Development > Python Tutorial > How do I detect keyboard input in a Python script running from the terminal?

How do I detect keyboard input in a Python script running from the terminal?

DDD
Release: 2024-10-29 12:37:02
Original
1028 people have browsed it

How do I detect keyboard input in a Python script running from the terminal?

How to detect keyboard input in a script from the terminal?

Synchronous/Blocking key capture:

A simple input or raw_input, a blocking function which returns text typed by a user once they press a newline.

<code class="python">typedString = raw_input()</code>
Copy after login

A simple blocking function that waits for the user to press a single key, then returns that key

<code class="python">class _Getch:
 &quot;&quot;&quot;Gets a single character from standard input.  Does not echo to the
screen. From http://code.activestate.com/recipes/134892/&quot;&quot;&quot;
def __init__(self):
  try:
    self.impl = _GetchWindows()
  except ImportError:
    try:
      self.impl = _GetchMacCarbon()
    except(AttributeError, ImportError):
      self.impl = _GetchUnix()

def __call__(self): return self.impl()


class _GetchUnix:
def __init__(self):
  import tty, sys, termios # import termios now or else you'll get the Unix version on the Mac

def __call__(self):
  import sys, tty, termios
  fd = sys.stdin.fileno()
  old_settings = termios.tcgetattr(fd)
  try:
    tty.setraw(sys.stdin.fileno())
    ch = sys.stdin.read(1)
  finally:
    termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
  return ch

class _GetchWindows:
def __init__(self):
  import msvcrt

def __call__(self):
  import msvcrt
  return msvcrt.getch()

class _GetchMacCarbon:
&quot;&quot;&quot;
A function which returns the current ASCII key that is down;
if no ASCII key is down, the null string is returned.  The
page http://www.mactech.com/macintosh-c/chap02-1.html was
very helpful in figuring out how to do this.
&quot;&quot;&quot;
def __init__(self):
  import Carbon
  Carbon.Evt #see if it has this (in Unix, it doesn't)

def __call__(self):
  import Carbon
  if Carbon.Evt.EventAvail(0x0008)[0]==0: # 0x0008 is the keyDownMask
    return ''
  else:
    #
    # The event contains the following info:
    # (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
    #
    # The message (msg) contains the ASCII char which is
    # extracted with the 0x000000FF charCodeMask; this
    # number is converted to an ASCII character with chr() and
    # returned
    #
    (what,msg,when,where,mod)=Carbon.Evt.GetNextEvent(0x0008)[1]
    return chr(msg &amp; 0x000000FF)


def getKey():
  inkey = _Getch()
  import sys
  for i in xrange(sys.maxint):
    k=inkey()
    if k<>'':break

  return k</code>
Copy after login

Asynchronous key capture:

A callback that is called with the pressed key whenever the user types a key into the command prompt, even when typing things into an interpreter (a keylogger)

Callbacks have not yet been implemented.

A callback that is called with the typed text after the user presses enter (a less realtime keylogger)

Callbacks have not yet been implemented.

A callback that is called with the keys pressed when a program is running (say, in a for loop or while loop)

Windows:

<code class="python">import threading
from win32api import STD_INPUT_HANDLE
from win32console import GetStdHandle, KEY_EVENT, ENABLE_ECHO_INPUT, ENABLE_LINE_INPUT, ENABLE_PROCESSED_INPUT


class KeyAsyncReader():
  def __init__(self):
    self.stopLock = threading.Lock()
    self.stopped = True
    self.capturedChars = &quot;&quot;

    self.readHandle = GetStdHandle(STD_INPUT_HANDLE)
    self.readHandle.SetConsoleMode(ENABLE_LINE_INPUT|ENABLE_ECHO_INPUT|ENABLE_PROCESSED_INPUT)



  def startReading(self, readCallback):
    self.stopLock.acquire()

    try:
      if not self.stopped:
        raise Exception(&quot;Capture is already going&quot;)

      self.stopped = False
      self.readCallback = readCallback

      backgroundCaptureThread = threading.Thread(target=self.backgroundThreadReading)
      backgroundCaptureThread.daemon = True
      backgroundCaptureThread.start()
    except:
      self.stopLock.release()
      raise

    self.stopLock.release()


  def backgroundThreadReading(self):
    curEventLength = 0
    curKeysLength = 0
    while True:
      eventsPeek = self.readHandle.PeekConsoleInput(10000)

      self.stopLock.acquire()
      if self.stopped:
        self.stopLock.release()
        return
      self.stopLock.release()


      if len(eventsPeek) == 0:
        continue

      if not len(eventsPeek) == curEventLength:
        if self.getCharsFromEvents(eventsPeek[curEventLength:]):
          self.stopLock.acquire()
          self.stopped = True
          self.stopLock.release()
          break

        curEventLength = len(eventsPeek)



  def getCharsFromEvents(self, eventsPeek):
    callbackReturnedTrue = False
    for curEvent in eventsPeek:
      if curEvent.EventType == KEY_EVENT:
              if ord(curEvent.Char) == 0 or not curEvent.KeyDown:
                pass
              else:
                curChar = str(curEvent.Char)
                if self.readCallback(curChar) == True:
                  callbackReturnedTrue = True


    return callbackReturnedTrue

  def stopReading(self):
    self.stopLock.acquire()
    self.stopped = True
    self.stopLock.release()</code>
Copy after login

Polling:

The user simply wants to be able to do something when a key is pressed, without having to wait for that key (so this should be non-blocking). Thus they call a poll() function and that either returns a key, or returns None. This can either be lossy (if they take too long to between poll they can miss a key) or non-lossy (the poller will store the history of all keys pressed, so when the poll() function requests them they will always be returned in the order pressed).

Windows and OS X (and maybe Linux):

<code class="python">global isWindows

isWindows = False
try:
  from win32api import STD_INPUT_HANDLE
  from win32console import GetStdHandle, KEY_EVENT, ENABLE_ECHO_INPUT, ENABLE_LINE_INPUT, ENABLE_PROCESSED_INPUT
  isWindows = True
except ImportError as e:
  import sys
  import select
  import termios


class KeyPoller():
  def __enter__(self):
    global isWindows
    if isWindows:
      self.readHandle = GetStdHandle(STD_INPUT_HANDLE)
      self.readHandle.SetConsoleMode(ENABLE_LINE_INPUT|ENABLE_ECHO_INPUT|ENABLE_PROCESSED_INPUT)
      
      self.curEventLength = 0
      self.curKeysLength = 0
      
      self.capturedChars = []
    else:
      # Save the terminal settings
      self.fd = sys.stdin.fileno()
      self.new_term = termios.tcgetattr(self.fd)
      self.old_term = termios.tcgetattr(self.fd)
      
      # New terminal setting unbuffered
      self.new_term[3] = (self.new_term[3] &amp; ~termios.ICANON &amp; ~termios.ECHO)
      termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.new_term)
      
    return self
  
  def __exit__(self, type, value, traceback):
    if isWindows:
      pass
    else:
      termios.tcsetattr(self.fd, termios.TCSAFLUSH, self.old_term)
  
  def poll(self):
    if isWindows:
      if not len(self.capturedChars) == 0:
        return self.capturedChars.pop(0)

      eventsPeek = self.readHandle.PeekConsoleInput(10000)
</code>
Copy after login

The above is the detailed content of How do I detect keyboard input in a Python script running from the terminal?. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template