Cura/cura/Utils/Threading.py
Lipu Fei f521fae152 Fix call_on_qt_thread decorator
CURA-6225

Do thread check in the wrapper function, not outside.
2019-02-15 15:11:11 +01:00

42 lines
1.8 KiB
Python

import functools
import threading
from cura.CuraApplication import CuraApplication
#
# HACK:
#
# In project loading, when override the existing machine is selected, the stacks and containers that are currently
# active in the system will be overridden at runtime. Because the project loading is done in a different thread than
# the Qt thread, something else can kick in the middle of the process. One of them is the rendering. It will access
# the current stacks and container, which have not completely been updated yet, so Cura will crash in this case.
#
# This "@call_on_qt_thread" decorator makes sure that a function will always be called on the Qt thread (blocking).
# It is applied to the read() function of project loading so it can be guaranteed that only after the project loading
# process is completely done, everything else that needs to occupy the QT thread will be executed.
#
class InterCallObject:
def __init__(self):
self.finish_event = threading.Event()
self.result = None
def call_on_qt_thread(func):
@functools.wraps(func)
def _call_on_qt_thread_wrapper(*args, **kwargs):
# If the current thread is the main thread, which is the Qt thread, directly call the function.
current_thread = threading.current_thread()
if isinstance(current_thread, threading._MainThread):
return func(*args, **kwargs)
def _handle_call(ico, *args, **kwargs):
ico.result = func(*args, **kwargs)
ico.finish_event.set()
inter_call_object = InterCallObject()
new_args = tuple([inter_call_object] + list(args)[:])
CuraApplication.getInstance().callLater(_handle_call, *new_args, **kwargs)
inter_call_object.finish_event.wait()
return inter_call_object.result
return _call_on_qt_thread_wrapper