Python - Similate RETURN键盘按下

Question

How can I simulate the RETURN keyboard press?

I have created a program which opens the print window in Firefox (through using the shortcut crtl+p). I now need to press RETURN to send this webpage to the printer.

Failed attempts:

1.

from selenium.webdriver.common.keys import Keys
element=browser.find_element_by_xpath("//body")
element.send_keys(Keys.RETURN)

2.

from selenium.webdriver import ActionChains
act = ActionChains(browser)
act.key_down(Keys.RETURN)
act.key_up(Keys.RETURN)

Both likely fail because their scope lies within the web browser whereas the print window pop up box lies in a scope outside the web browser.

Code:

import time
from selenium import webdriver

# Initialise the webdriver
browser = webdriver.Firefox()
time.sleep(3)

# Login to webpage
browser.get('www.google.com')
element=browser.find_element_by_xpath("//body")
element.send_keys(Keys.CONTROL, 'p')

Answer 1

import ctypes

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):
    print('a')
    extra = ctypes.c_ulong(0)
    ii_ = Input_I()
    ii_.ki = KeyBdInput( hexKeyCode, 0x48, 0, 0, ctypes.pointer(extra) )
    x = Input( ctypes.c_ulong(1), ii_ )
    SendInput(1, ctypes.pointer(x), ctypes.sizeof(x))

def ReleaseKey(hexKeyCode):
    print('b')
    extra = ctypes.c_ulong(0)
    ii_ = Input_I()
    ii_.ki = KeyBdInput( hexKeyCode, 0x48, 0x0002, 0, ctypes.pointer(extra) )
    x = Input( ctypes.c_ulong(1), ii_ )
    SendInput(1, ctypes.pointer(x), ctypes.sizeof(x))

def PressEnter():
    time.sleep(2)
    print('Running: Press Enter')
    PressKey(0x0D)      # 0x0D = Enter
    time.sleep(0.2)
    ReleaseKey(0x0D)