Make BusyIndicator run when click on button (signal to C++) - qt

Question

I created an interface has a ListView and two Buttons. When click on Scan button it will call to C++ and make change to the model of ListView. After that C++ will emit signal to inform model is changed therefore ListView in QML will update with new model. I want to make BusyIndicator running during that process. How can i do that ?.
I saw a few solutions on stackoverflow like this one: BusyIndicator does not show up but none of them worked for my case.
Can anyone help me ? Thanks.
Here is my qml code:
import QtQuick 2.5
import QtQuick.Layouts 1.3
import Qt.labs.controls 1.0
Rectangle
{
objectName: "bluetoothPage"
anchors.fill: parent
property var bluetoothDataModel: messageFromApp.bluetoothData
onBluetoothDataModelChanged: listView.update()
signal qmlScanButtonSignal()
signal qmlDisconnectButtonSignal()
ColumnLayout
{
anchors.fill: parent
spacing: 6
RowLayout
{
Layout.fillWidth: true
Text
{
Layout.fillWidth: true
text: "Connect with ECU"
font.bold: true
font.pixelSize: 20
}
BusyIndicator
{
id: busyIndicator
Layout.preferredWidth: 30
Layout.preferredHeight: 30
running: false
visible: false
}
}
GroupBox
{
Layout.fillHeight: true
Layout.fillWidth: true
title: qsTr("Available device:")
ListView
{
id: listView
anchors.fill: parent
model: bluetoothDataModel
delegate: Component
{
Item
{
width: parent.width
height: 40
Column
{
Text { text: "Name:" + model.modelData.name }
Text { text: "Number:" + model.modelData.macAddress }
}
MouseArea
{
anchors.fill: parent
onClicked: listView.currentIndex = index
}
}
}
highlight: Rectangle
{
color: "blue"
}
}
}
RowLayout
{
Layout.fillWidth: true
Layout.preferredHeight: 10
Button
{
Layout.fillHeight: true
Layout.fillWidth: true
text: "Scan"
onClicked: qmlScanButtonSignal()
}
Button
{
Layout.fillHeight: true
Layout.fillWidth: true
text: "Disconnect"
onClicked: qmlDisconnectButtonSignal()
}
}
}
}

Answer 1

Only this solution worked for me in my case. However, like everybody said using QCoreApplication::processEvents()
is really bad practice. I also try to using QThread but it got crash when emitted signal inside thread. If you guy have any futher solutions, please let me now. I'm really appreciate. Thanks.
QML
BusyIndicator {
running: CPPModule.busy
}
CPP
void CPPModule::setBusy(const bool &busy)
{
m_busy = busy;
emit busyChanged();
}
void CPPModule::InsertIntoDB()
{
setBusy(true);
QThread::msleep(50);
QCoreApplication::processEvents();
/*
very Long Operation
*/
setBusy(false);
}
Another solution is this:
Timer {
id: myTimer
interval: 1
onTriggered: {
app.someLongRunningFunction();
myActivityIndicator.visible = false;
}
}
Butoon{
....
onClicked: {
myActivityIndicator.visible=true;
myTimer.start();
}
}