Simulating a keypress in python

Question

Alright, I know this question looks like a duplicate, but I don't think it is. I've read other posts about fake key presses which involve ctypes and SendKey. However, I've tried these and they don't work quite as I want. I don't want something that is similar to an actual keystroke, I want something that does EXACTLY the same thing as a keystroke. I've run some tests with ctypes, and I noticed the key presses don't behave the same as a real keystroke.

For example, if I open up notepad and hold down the A key, I get one A character, and about a second later it starts filling up with As. When I run PressKey() for A, it types a single A and that's it. I still have to run ReleaseKey() for A after it so other programs don't get messed up.

I need some way to do something like realKeyPress('A') and have it behave exactly like I pressed the A key. Also, thanks guys, you're always so fast to respond with nice answers!

I don't think this is what I'm looking for. I don't want to be able to catch input from a user, I want to make it seem like the user pressed a key on the keyboard. — catsock
– catsock, Commented Feb 12, 2015 at 22:56
Should this question have a "Windows" tag? It seems to be specific to Windows... — psmears
– psmears, Commented Feb 13, 2015 at 13:53

catsock · Accepted Answer · 2015-02-12 23:28:33Z

So I used ctypes after all. I modified the ctypes code after reading up on another answer similar to this topic. Here's the finished code:

import ctypes
import time

SendInput = ctypes.windll.user32.SendInput

# C struct redefinitions 
PUL = ctypes.POINTER(ctypes.c_ulong)
class KeyBdInput(ctypes.Structure):
    _fields_ = [("wVk", ctypes.c_ushort),
                ("wScan", ctypes.c_ushort),
                ("dwFlags", ctypes.c_ulong),
                ("time", ctypes.c_ulong),
                ("dwExtraInfo", PUL)]

class HardwareInput(ctypes.Structure):
    _fields_ = [("uMsg", ctypes.c_ulong),
                ("wParamL", ctypes.c_short),
                ("wParamH", ctypes.c_ushort)]

class MouseInput(ctypes.Structure):
    _fields_ = [("dx", ctypes.c_long),
                ("dy", ctypes.c_long),
                ("mouseData", ctypes.c_ulong),
                ("dwFlags", ctypes.c_ulong),
                ("time",ctypes.c_ulong),
                ("dwExtraInfo", PUL)]

class Input_I(ctypes.Union):
    _fields_ = [("ki", KeyBdInput),
                 ("mi", MouseInput),
                 ("hi", HardwareInput)]

class Input(ctypes.Structure):
    _fields_ = [("type", ctypes.c_ulong),
                ("ii", Input_I)]

# Actuals Functions

def PressKey(hexKeyCode):
    extra = ctypes.c_ulong(0)
    ii_ = Input_I()
    ii_.ki = KeyBdInput( 0, hexKeyCode, 0x0008, 0, ctypes.pointer(extra) )
    x = Input( ctypes.c_ulong(1), ii_ )
    ctypes.windll.user32.SendInput(1, ctypes.pointer(x), ctypes.sizeof(x))

def ReleaseKey(hexKeyCode):
    extra = ctypes.c_ulong(0)
    ii_ = Input_I()
    ii_.ki = KeyBdInput( 0, hexKeyCode, 0x0008 | 0x0002, 0, ctypes.pointer(extra) )
    x = Input( ctypes.c_ulong(1), ii_ )
    ctypes.windll.user32.SendInput(1, ctypes.pointer(x), ctypes.sizeof(x))

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