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LinVAM/keyboard/_generic.py

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2019-04-09 00:20:07 +10:00
# -*- coding: utf-8 -*-
from threading import Thread, Lock
import traceback
import functools
try:
from queue import Queue
except ImportError:
from Queue import Queue
class GenericListener(object):
lock = Lock()
def __init__(self):
self.handlers = []
self.listening = False
self.queue = Queue()
def invoke_handlers(self, event):
for handler in self.handlers:
try:
if handler(event):
# Stop processing this hotkey.
return 1
except Exception as e:
traceback.print_exc()
def start_if_necessary(self):
"""
Starts the listening thread if it wans't already.
"""
self.lock.acquire()
try:
if not self.listening:
self.init()
self.listening = True
self.listening_thread = Thread(target=self.listen)
self.listening_thread.daemon = True
self.listening_thread.start()
self.processing_thread = Thread(target=self.process)
self.processing_thread.daemon = True
self.processing_thread.start()
finally:
self.lock.release()
def pre_process_event(self, event):
raise NotImplementedError('This method should be implemented in the child class.')
def process(self):
"""
Loops over the underlying queue of events and processes them in order.
"""
assert self.queue is not None
while True:
event = self.queue.get()
if self.pre_process_event(event):
self.invoke_handlers(event)
self.queue.task_done()
def add_handler(self, handler):
"""
Adds a function to receive each event captured, starting the capturing
process if necessary.
"""
self.start_if_necessary()
self.handlers.append(handler)
def remove_handler(self, handler):
""" Removes a previously added event handler. """
while handler in self.handlers:
self.handlers.remove(handler)