api.py

import inspect
import asyncio
from imswitch import IS_HEADLESS
from imswitch.imcommon.framework import Mutex, Signal, SignalInterface


class APIExport:
    """ Decorator for methods that should be exported to API. """

    def __init__(self, *, runOnUIThread=False, asyncExecution=False):
        self._APIExport = True
        self._APIRunOnUIThread = runOnUIThread
        self._APIAsyncExecution = asyncExecution

    def __call__(self, func):
        func._APIExport = self._APIExport
        func._APIRunOnUIThread = self._APIRunOnUIThread
        func._APIAsyncExecution = self._APIAsyncExecution
        return func


def generateAPI(objs, *, missingAttributeErrorMsg=None):
    """ Generates an API from APIExport-decorated methods in the objects in the
    passed array objs. Must be called from the main thread. """

    from imswitch.imcommon.model import pythontools

    exportedFuncs = {}
    for obj in objs:
        for subObjName in dir(obj):
            subObj = getattr(obj, subObjName)
            if not callable(subObj):
                continue

            if not hasattr(subObj, '_APIExport') or not subObj._APIExport:
                continue

            if subObjName in exportedFuncs:
                raise NameError(f'API method name "{subObjName}" is already in use')

            runOnUIThread = hasattr(subObj, '_APIRunOnUIThread') and subObj._APIRunOnUIThread

            if runOnUIThread and not IS_HEADLESS:
                wrapper = _UIThreadExecWrapper(subObj)
                exportedFuncs[subObjName] = wrapper
                wrapper.module = subObj.__module__.split('.')[-1]
            else:
                exportedFuncs[subObjName] = subObj

    return pythontools.dictToROClass(exportedFuncs,
                                     missingAttributeErrorMsg=missingAttributeErrorMsg)


class _UIThreadExecWrapper(SignalInterface):
    """ Wrapper for executing the specified function on the UI thread. """

    wrappingSignal = Signal()

    def __init__(self, apiFunc):
        super().__init__()

        self.__name__ = apiFunc.__name__
        self.__signature__ = inspect.signature(apiFunc)
        self.__doc__ = apiFunc.__doc__

        self._apiFunc = apiFunc
        self._execMutex = Mutex()
        self.wrappingSignal.connect(self._apiCall)

    def __call__(self, *args, **kwargs):
        self._execMutex.lock()
        self._args = args
        self._kwargs = kwargs
        self.wrappingSignal.emit()

    def _apiCall(self):
        try:
            if asyncio.iscoroutinefunction(self._apiFunc):
                self._execAsync()
            else:
                self._apiFunc(*self._args, **self._kwargs)
        finally:
            self._execMutex.unlock()

    async def _execAsync(self):
        await self._apiFunc(*self._args, **self._kwargs)
        

# Copyright (C) 2020-2023 ImSwitch developers
# This file is part of ImSwitch.
#
# ImSwitch is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# ImSwitch is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.