QML two display problem

[artwaw]

Good afternoon.
I decided to dive into QML a bit.

I have a C++ backend that is properly communicating with the QML frontend. It all works just fine but one problem I can't figure out.

The idea is that the application has two screens available:

• the main screen, which is a touch screen - on it runs a stack view with controls and such (I started to code it, it runs just fine).
• the "display screen", where is just one fullscreen window with data display (again, I have that coded and works just fine).

Problem is that I would like to join those two in a single program. From the documentation I figure, that setting the screen option using Qt.application.screens array values is the way to go but when I set it all the views are on just one screen (array Qt.application.screens has two entries, as expected and both return expected screen sizes). My main.qml file:

import QtQuick 2.11
import QtQuick.Window 2.11
import QtQuick.Controls 2.4
import QtQuick.Controls.Material 2.3
import QtQuick.VirtualKeyboard 2.3
import BackEnd 1.0

ApplicationWindow {
    id: appwindow
    visible: true
    screen: Qt.application.screens[1]
    width: screen.width
    height: screen.height
    title: qsTr("Large")

    BackEnd {
        id: backend
    }

    Window {
        id: mainwindow
        screen: Qt.application.screens[0]
        width: screen.width
        height: screen.height
        visible: true
    }

    header: Text {
        Text {
            text: "Control panel"
            horizontalAlignment: Text.AlignHCenter
            verticalAlignment: Text.AlignVCenter
        }
    }

    footer: status

    StackView {
        id: cfg
        visible: true
        anchors.fill: parent
        initialItem: ConfigWindow

        Connections {
            target: backend
            onProgressStart: {
                push(progres);
                pHeaderText.text=backend.progressHeader;
                pFooterText.text=backend.progressFooter;
            }
            onProgressStop: pop(progres)
        }
    }

    Item {
        id: status
        Text {
            text: "Status: "+backend.status
            verticalAlignment: Text.AlignVCenter
            horizontalAlignment: Text.AlignHCenter
        }
    }

    Page {
        id: progres
        anchors.fill: parent
        header: Text {
            id: pHeaderText
            verticalAlignment: Text.AlignVCenter
            horizontalAlignment: Text.AlignHCenter
        }

        footer: Text {
            id: pFooterText
            verticalAlignment: Text.AlignVCenter
            horizontalAlignment: Text.AlignHCenter
        }

        ProgressBar {
            id: bar
            value: 0
            from: 0
            to: 100
        }

        Connections {
            target: backend
            onProgressChanged: bar.value=backend.progressValue
        }
    }

    Component.onCompleted: {
   //not important here
    }
}

[J.Hilk]

@artwaw what platform do you target ?

I assume you're using a version of Qt 5.11 (according to the imports)

I tried the following:

import QtQuick 2.12
import QtQuick.Window 2.12
import QtQuick.Controls 2.12

ApplicationWindow {
    id: appWindow

    screen: Qt.application.screens[1]
    visible: true
    width: 400
    height: 100

    Window {
            id: mainwindow
            screen: Qt.application.screens[0]
            width: screen.width
            height: screen.height
            visible: true
        }
}

on macOS (BigSur) with Qt 5.12.6 and I get both windows on different screens, one "full screen" and one not, like expected

[artwaw]

@J-Hilk Hi,
yes, I forgot to add platform... It is indeed 5.11, Raspberry Pi. I see the difference, will try it out later today and let you know the outcome.

Thanks a lot!

[artwaw]

@J-Hilk no joy. I don't understand why.
I think I'll try do do it with QtWidgets instead - less of a look I'd prefer but I feel more confident there.

[J.Hilk]

@artwaw you could try 5.12 maybe its a bug, and its fixed in this later Version ?

[artwaw]

@J-Hilk Unfortunately I can not - Raspi comes with 5.11. I tried to compile from source and it does compile however make install throws some errors about non-existing files in the build tree. I'll close this topic and try Qt Widgets instead...

[GrecKo]

Try using a QtObject as a root object and 2 child Window/ApplicationWindow in it.