how do i UpdateUI in a Callback which is non-mainThread & non-QtThread?

Kent-Dorfman

May or may not be a more direct way to handle it but create a function under a QObject class that looks for some non-Qt syncronization signal (POSIX methods: signal, semaphore state chagne, etc) and when it receives the appropriate event, emit the Qt signal necessary to do your update.

opengpu

all i have in exe code it that callback func.
and i plan to create inhrite a class from QObject.
and let it MyObject* g_pMy; it global.
and then in that callback fun, just use g_pMy->emit

is this method ok?

SGaist

Hi,

What parameters can you pass to that callback ?

opengpu

@SGaist nothing, the callback is returnedn by a DLL from 3rdParty

aha_1980

@opengpu can you please provide a bit more information? how does the callbacks function signature look like?

opengpu

@aha_1980 just a callback funtion in windows dev, but that callback is returned from a 3rdParty DLL which use COM

aha_1980

@opengpu

you didn't answer my question.

how does the callbacks function signature look like?

opengpu

@aha_1980
WINAPI Callback(const Data& data)
{
//here is not mainThread; so i have to pass the data by value to the slot which is in mainThread; or i use mutex & save data to m_data, and then in slot mainThread getData also with mutex protect thread-safety
}

opengpu

is this a good way to emit signal in the non-thread non-qt Callback function?

WINAPI Callback(const Data& data)
{//here is not mainThread; so i have to pass the data by value to the slot which is in mainThread; or i use mutex & save data to m_data, and then in slot mainThread getData also with mutex protect thread-safety
    emit g_qtObj->mySignal();
}

class QtObj : public QObject
{
Q_OBJECT
signals:
    void mySignal();
}
QtObj g_obj;
QtObj* g_qtObj = &g_obj;

SGaist

Use QMetaObject::invokeMethod

jsulm

@opengpu said in how do i UpdateUI in a Callback which is non-mainThread & non-QtThread?:

g_qtObj->emit mySignal();

should be

g_qtObj->mySignal();

opengpu

@jsulm thanks

opengpu

@SGaist ```
WINAPI Callback(const Data& data)
{//here is not mainThread; so i have to pass the data by value to the slot which is in mainThread; or i use mutex & save data to m_data, and then in slot mainThread getData also with mutex protect thread-safety
//emit g_qtObj->mySignal();
QMetaObject::invokeMethod(g_pQtMainWindow, slotDoSth, Qt::QueuedConnection);
}

like this? use invokeMethod instead of emit signal ?

SGaist

Why do you have a global Qt object ?
What makes you define your Callback method like that ?

opengpu

why QMetaObject::invokeMethod pass custom-type called Twice custom-type's copy constructor...
https://forum.qt.io/topic/102915/qmetaobject-invokemethod-pass-custom-type-called-twice-custom-type-s-copy-constructor