how to change textbox data remotely by tcp socket in QT? - qt

Question

i would like to code a program by Qt tcp socket and QML together.
i am going to change a textbox variable that created by QML to the new data that get by remote client by tcp socket?
my snippet code is :
void Server::startRead()
{
client->waitForReadyRead(3000);
QString buf= client->readAll();
qDebug() << buf;
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
QObject *rootObject = engine.rootObjects().first();
QObject *qmlObject = rootObject->findChild<QObject*>("ttt");
qDebug() << "before change"
qDebug() << qmlObject->property("text");
qmlObject->setProperty("text", "new data");
qDebug() << "after change"
qDebug() << qmlObject->property("text");
}
main.qml
import QtQuick 2.0
import QtQuick 2.2
import QtQuick.Window 2.1
import QtQuick.Window 2.2
import QtQuick.Controls 1.2
Window{
width:400
height:400
visible:true
Item {
id: rootItem
property string text
Text {
id: message
text: rootItem.text
}
}
}
I really appreciate it.

Answer 1

There are many ways to do that. Next examples demonstrate how to change qml element properties from cpp. If you need to change visibility just use bool properties instead of string that i used in examples.
1. This is good solution i think.
You could create qml adapter
class ServerQMLAdapter : public QQuickItem
{
Q_OBJECT
Q_PROPERTY(QString data READ data WRITE setData NOTIFY dataChanged)
public:
explicit ServerQMLAdapter(QQuickItem *parent = nullptr) : QQuickItem(parent){}
QString data() const {
return mData;
}
void setData(const QString &data) {
if(mData == data)
return;
mData = data;
emit dataChanged();
}
private slots:
/**
this slots called on data read
*/
void onDataRead(const QString &data) {
setData(data);
}
private:
QString mData = QString();
};
in application class you sould register your adapter
qmlRegisterType<ServerQMLAdapter>("ServerQMLAdapter", 1, 0, "ServerQMLAdapter");
After that you can use it in your qml file
import ServerQMLAdapter 1.0
Item {
ServerQMLAdapter {
id: myAdapter
}
Text {
id: message
text: myAdapter.data
}
}
2. You can change properties from cpp.
Just like you do in your snippet
auto rootObject = engine.rootObjects().first();
rootObject->setProperty("text", "new data");
and add this propetry to your qml file
Item {
id: rootItem
property string text
Text {
id: message
text: rootItem.text
}
}
3. Use invoked methods
From you cpp file
auto rootObject = engine.rootObjects().first();
QMetaObject::invokeMethod(rootObject, "setText",
Q_ARG(QVariant, QVariant::fromValue(data)));
and add function to your qml file
Item {
id: rootItem
function setText(data) {
message.text = data;
}
Text {
id: message
}
}