Use Signal in QML from C++

Nio74

Good morning, I have to use signal emited at call in the function c++ in to qml:

void Backend::smbConnectedToServer()
{
    emit smbConnected();
}

I have declared my backend.cpp as a context:

 QQmlContext *context = engine.rootContext();
    context->setContextProperty("backend",&backend);

while on the tutorial why I am following it is declared on this way:

qmlRegisterType<Backend>("io.qt.Backend", 1, 0, "Backend");

and thi is his qml:

Window {
    visible: true
    width: 700
    minimumWidth: 500
    height: 450
    minimumHeight: 200
    title: "Server"
    color: "#CED0D4"

    Backend {
        id: backend
        onSmbConnected: {
            ti.append(addMsg("Somebody has connected"));
        }
        onSmbDisconnected: {
            ti.append(addMsg("Somebody has disconnected"));
        }
        onNewMessage: {
            ti.append(addMsg("New message: " + msg));
        }




    }

    ColumnLayout
    {
        anchors.fill: parent
        anchors.margins: 10

        RowLayout {
            anchors.horizontalCenter: parent.horizontalCenter

            BetterButton {
                id: btn_start
                anchors.left: parent.left
                text: "Start server"
                color: enabled ? this.down ? "#78C37F" : "#87DB8D" : "gray"
                border.color: "#78C37F"
                onClicked: {
                    ti.append(addMsg(backend.startClicked()));
                    this.enabled = false;
                }
            }
            BetterButton {
                enabled: !btn_start.enabled
                anchors.right: parent.right
                text: "Stop server"
                color: enabled ? this.down ? "#DB7A74" : "#FF7E79" : "gray"
                border.color: "#DB7A74"
                onClicked: {
                    ti.append(addMsg(backend.stopClicked()));
                    btn_start.enabled = true;
                    ti.append(add)
                }
            }
        }

        LayoutSection {
            Layout.fillHeight: true

            ScrollView {
                id: scrollView
                anchors.fill: parent

                TextArea {
                    id: ti
                    readOnly: true
                    selectByMouse : true
                    font.pixelSize: 14
                    wrapMode: TextInput.WrapAnywhere
                }
            }
        }

        BetterButton {
            anchors.horizontalCenter: parent.horizontalCenter
            text: "Test connection"
            color: this.down ? "#6FA3D2" : "#7DB7E9"
            border.color: "#6FA3D2"
            onClicked: {
                ti.append(addMsg(backend.testClicked()));
            }
        }
    }


Component.onCompleted: {
    ti.text = addMsg("Application started\n- - - - - -");
}

function addMsg(someText)
{
    return "[" + currentTime() + "] " + someText;
}

function currentTime()
{
    var now = new Date();
    var nowString = ("0" + now.getHours()).slice(-2) + ":"
            + ("0" + now.getMinutes()).slice(-2) + ":"
            + ("0" + now.getSeconds()).slice(-2);
    return nowString;
}

}

I can not understand how to do the same thing.

SGaist

Hi,

You are creating a new Backend object in your QML code so it's not going to be the same as the one you put in the context.

I think you are looking for the Connections type.

Hope it helps