How to keep a single instance of the window? - qt

Question

I have the next QML:
import Qt.labs.platform 1.0
SystemTrayIcon {
visible: true
iconSource: "qrc:/icons/ic_tray.png"
menu: Menu {
MenuItem {
text: qsTr("Settings")
onTriggered: {
// Don't create a new object if it exists, just show
var settings = Qt.createComponent("main.qml")
var form = settings.createObject(this)
form.show()
}
}
MenuItem {
text: qsTr("Quit")
onTriggered: Qt.quit() // Just hide an existing
}
}
}
How to create main.qml one time only and after just show/hide?
P.S. I'm learning Qt including QtQuick 2 only

Answer 1

Depending on how your application is structured, the best way could be to pass in the window that the tray icon shall control as a property from "further up" your user interface structure.
First, extend your tray icon component and add a "window" property to it:
import QtQuick 2.9
import QtQuick.Window 2.2
import Qt.labs.platform 1.0
SystemTrayIcon {
id: trayIcon
// this property holds the window the tray icon controls:
property Window window
visible: true
iconSource: "qrc:/icons/ic_tray.png"
menu: Menu {
MenuItem {
text: qsTr("Settings")
onTriggered: {
trayIcon.window.show();
}
}
MenuItem {
text: qsTr("Quit")
onTriggered: Qt.quit() // Just hide an existing
}
}
}
Now, you could instantiate your tray icon e.g. in your main window like this:
import QtQuick 2.9
import QtQuick.Window 2.2
Window {
id: mainWindow
width: 800
height: 600
TrayIcon { window: mainWindow }
}
In this case, the tray icon would control the main window itself; however, you can easily create a single instance of a settings window within the main window and pass that one to the tray icon.

Answer 2

You can create the component in the onCompleted.
SystemTrayIcon {
visible: true
iconSource: "qrc:/icons/ic_tray.png"
menu: Menu {
MenuItem {
text: qsTr("Settings")
property var form
onTriggered: {
form.show()
}
Component.onCompleted: {
// Don't create a new object if it exists, just show
var settings = Qt.createComponent("Test.qml")
form = settings.createObject(this)
}
}
MenuItem {
text: qsTr("Quit")
onTriggered: Qt.quit() // Just hide an existing
}
}
}