Signal between QML with Repeater - connection

Question

I have the following qml files, the main.qml creates TestWindow.qml elements.
I would like to connect a signal in TestWindow.qml (click on a button mySignalToMainWindow() ) to a function in main.qml, testConnection().
main.qml
Window {
id: _component
property int instances: 3
width: 200
height: Screen.height / 2
visible: true
Component.onCompleted: {
x = 40
y = 40
}
Repeater {
id: _windows
model: instances
TestWindow {
index: model.index
leftOffset: _component.width
}
}
Column {
Repeater {
model: instances
Button {
text: "Window " + index
onClicked:{ _windows.itemAt(index).window.raise();
}
}
}
}
function testConnection(){console.log("Subwindow To Main Window")}
}
And TestWindow.qml :
Item {
id: _windowItem
property int index
property int leftOffset
property alias window: _window
signal mySignalToMainWindow()
Window {
id: _window
visible: true
title: "SubWindowText " + index
Component.onCompleted: {
x = leftOffset
y = 40
width = Screen.width - leftOffset
height = Screen.height / 2
}
Text {
id: windowText
text: qsTr("SubWindowText")
}
Button {
text: "SubWindow " + index
onClicked: {console.log("TestWindow::Button onClicked "+_window);
_windowItem.mySignalToMainWindow();
}
}
}
}
I tested those two :
How to bind to a signal from a delegate component within a ListView in QML
and
How to access dynamically/randomly loaded Repeater items in QML?
with no success.
So, how to do that?
Thanks

Answer 1

You have multiple options there. The first is to define the binding, when creating the Component for the delegate:
Repeater {
id: _windows
model: instances
TestWindow {
index: model.index
leftOffset: _component.width
onMySignalToMainWindow: testConnection() <--- Here you can connect it.
}
}
Another option is to use the onItemAdded and onItemRemoved-Handlers and connect the function there (mySignalToMainWindow.connect(functionToConnect)) and the respective disconnect, when it gets destroyed.
I'd recommend the former, if you want the connection to be permanent, and the latter if you might want to disconnect at some time.
The onItemAdded/onRemoved handlers are especially important if you don't declare a delegate for the Repeater. This happens for example if you use a DelegateModel or an ObjectModel. As with those models, you can't be sure, the objects are instantiated or destroyed when the Repeater adds or removes them, you could not use the often mentioned: Component.onCompleted/onDestruction, so I consider the itemAdded/Removed-signals superior/more general for the use with a Repeater.