在额外线程中运行 QML 方法

Question

I want to write a QML Item which can dynamically run functions + params in seperate threads.

I imagine it to look like so:

import QtQuick 2.0

Item {

    function runThread(fnc, params)
    {
        // run this fnc function with the given params in seperate thread without blocking ui
    }

}

The functions which are getting executed must be able to access any states from my main engine. Including connected cpp objects, item properties, ...

Answer 1

QtConcurrent might help. Try something like this:

void TestObj::testFct(int someParam, const QJSValue &callback){
    auto *watcher = new QFutureWatcher<int>(this);
    QObject::connect(watcher, &QFutureWatcher<int>::finished, this, [this, watcher, callback]() {
        int returnValue = watcher->result();
        QJSValue cbCopy(callback);
        QJSEngine *engine = qjsEngine(this);
        cbCopy.call(QJSValueList { engine->toScriptValue(returnValue) });
        watcher->deleteLater();
    }); 
    watcher->setFuture(QtConcurrent::run(this, &TestObj::testFctAsync, someParam));
}

Then call it from QML like this:

function testCall() {
    testObj.testFct(param, function(returnVal) {
        console.log("Asynchronous function returned: " + returnVal);
    })
}