QTimer::singleShot equivalent for QML - qt

Question

Consider this C++ statement (example from docs):
QTimer::singleShot(600000, &app, SLOT(quit()));
How to do the same in .qml JavaScript, something like this QML:
Rectangle {
property int counter: 0
onCounterChanged: {
if (counter > 42) {
// do equivalent of above C++ statement here
}
}
// more code, which actually manipulates counter
}
There's the obvious solution of having separate Timer, which is then started by this JavaScript code, and I'll accept that as an answer if a one-liner is not possible. Is it?

Answer 1

I ended up adding this to my main.qml:
Component {
id: delayCallerComponent
Timer {
}
}
function delayCall( interval, callback ) {
var delayCaller = delayCallerComponent.createObject( null, { "interval": interval } );
delayCaller.triggered.connect( function () {
callback();
delayCaller.destroy();
} );
delayCaller.start();
}
Which can be used like this:
delayCall( 1000, function () { ... } );

Answer 2

Change "repeat" property to false for Timer object.
import QtQuick 1.0
Item {
Timer {
id: timer
interval: 600000
running: false
repeat: false
onTriggered: Qt.quit()
}
Rectangle {
property int counter: 0
onCounterChanged: {
if (counter > 42) {
timer.running = true
}
}
}
}

Answer 3

Here is how to do it using a SequentialAnimation element:
SequentialAnimation {
id: quitTimer
PauseAnimation { duration: 60000 }
ScriptAction { script: Qt.quit() }
}
Rectangle {
property int counter: 0
onCounterChanged: {
if (counter > 42) {
quitTimer.start()
}
}
}
If that's too ugly, make a component out of it:
// SingleshotTimer.qml
import QtQuick 2.0
SequentialAnimation {
property alias delay: delayAnim.duration
property alias script: scriptAction.script
PauseAnimation { id: delayAnim; duration: 10000 }
ScriptAction { id: scriptAction }
}
Using this new component gives what you want:
SingleshotTimer { id: timer; delay: 60000; script: Qt.quit() }
Rectangle {
property int counter: 0
onCounterChanged: {
if (counter > 42) {
timer.start()
}
}
}

Answer 4

Another option I came up with is to simply define a function like this in C++:
void QmlUtils::singleShot(int msec, QJSValue callback)
{
QTimer::singleShot(msec, this, [callback] () mutable {
if (callback.isCallable())
callback.call();
});
}
and I call it from QML with:
lqtUtils.singleShot(5000, () => console.log("Hello!"))
I then added that C++ function to my collection of "must-have" here: https://github.com/carlonluca/lqtutils/blob/master/lqtutils_ui.h#L53.

Answer 5

there is a timer component in QML
import QtQuick 2.0
Item {
Timer {
interval: 500; running: true; repeat: true
onTriggered: time.text = Date().toString()
}
Text { id: time }
}
for more details see the documentation

Answer 6

I set properties like this running: true; repeat: false;
Timer {
interval: 5000
running: true
repeat: false
onTriggered:console.log("Test");
}