So this may seem like a strange setup. I have a C++ object that inherits from QObject called "MasterGuiLogic" for simplicity. It is created with a pointer to another object called "MainEventBroker" which as you might guess handles all of my applications events. The MasterGuiLogic object is registered with qml as a context property so that it's properties can be used anywhere in my qml. So main.cpp looks like this:
int main(int argc, char *argv[])
{
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
MasterEventBroker *MainEventBroker = new MasterEventBroker();
MasterGuiLogic *MainGuiLogic = new MasterGuiLogic(*MainEventBroker);
qmlRegisterUncreatableType<MasterGuiLogic>("GrblCom", 1, 0, "MasterGuiLogic", "");
qmlRegisterUncreatableType<GuiLogic_SerialCom>("GrblCom", 1, 0, "GuiLogic_SerialCom", "");
QQmlApplicationEngine engine;
QQmlContext* context = engine.rootContext();
context->setContextProperty("MasterGuiLogic", &(*MainGuiLogic));
engine.load(QUrl(QLatin1String("qrc:/QmlGui/main.qml")));
if (engine.rootObjects().isEmpty())
return -1;
return app.exec();
}
MasterGuiLogic creates an instance of another class called SerialCom, which is set as a Q_PROPERTY so that it's properties and public slots can be reached in qml through the MasterGuiLogic property.
MasterGuiLogic.h:
class MasterGuiLogic : public QObject
{
Q_OBJECT
Q_PROPERTY(GuiLogic_SerialCom* serialCom READ serialCom CONSTANT)
public:
MasterEventBroker *eventBroker;
explicit MasterGuiLogic(MasterEventBroker &ev, QObject *parent = nullptr);
GuiLogic_SerialCom* serialCom() const {
return Gui_SerialCom;
}
private:
GuiLogic_SerialCom *Gui_SerialCom;
MasterGuiLogic.cpp:
MasterGuiLogic::MasterGuiLogic(MasterEventBroker &ev, QObject *parent) : QObject(parent)
{
this->eventBroker = &ev;
this->Gui_SerialCom = new GuiLogic_SerialCom(this);
}
SerialCom.h:
//Forward Declare our parent
class MasterGuiLogic;
class GuiLogic_SerialCom : public QObject
{
Q_OBJECT
Q_PROPERTY(QStringList portNames READ portNames NOTIFY portNamesChanged)
Q_PROPERTY(bool connectedToPort READ connectedToPort NOTIFY connectedToPortChanged)
public:
MasterGuiLogic *parent;
explicit GuiLogic_SerialCom(MasterGuiLogic *parent = nullptr);
std::map<QString, QSerialPortInfo> portsMap;
QStringList portNames() {
return _portNames;
}
bool connectedToPort() {
return _connectedToPort;
}
private:
QStringList _portNames;
bool _connectedToPort = false;
signals:
void portNamesChanged(const QStringList &);
void connectedToPortChanged(const bool &);
public slots:
void connectToPort(const QString portName);
void disconnectFromPort(const QString portName);
};
SerialCom.cpp:
GuiLogic_SerialCom::GuiLogic_SerialCom(MasterGuiLogic *parent) : QObject(qobject_cast<QObject *>(parent))
{
this->parent = parent;
QList<QSerialPortInfo> allPorts = QSerialPortInfo::availablePorts();
for (int i = 0; i < allPorts.size(); ++i) {
this->_portNames.append(allPorts.at(i).portName());
this->portsMap[allPorts.at(i).portName()] = allPorts.at(i);
}
emit portNamesChanged(_portNames);
}
void GuiLogic_SerialCom::connectToPort(const QString portName) {
//TODO: Connect To Port Logic Here;
//Set Connected
this->_connectedToPort = true;
emit connectedToPortChanged(this->_connectedToPort);
qDebug() << portName;
}
void GuiLogic_SerialCom::disconnectFromPort(const QString portName) {
//TODO: DisConnect To Port Logic Here;
//Set DisConnected
this->_connectedToPort = false;
emit connectedToPortChanged(this->_connectedToPort);
qDebug() << portName;
}
So from qml it's pretty easy to read any of these properties and even send signals from qml to c++
For example, this works just fine:
connectCom.onClicked: {
if (MasterGuiLogic.serialCom.connectedToPort === false) {
MasterGuiLogic.serialCom.connectToPort(comPort.currentText);
} else {
MasterGuiLogic.serialCom.disconnectFromPort(comPort.currentText);
}
}
The problem is, I can't seem to find a way to connect to signals that are emitted from SerialCom. I thought I would be able to do something like this:
Connections: {
target: MasterGuiLogic.serialCom;
onConnectedToPortChanged: {
if (MasterGuiLogic.serialCom.connectedToPort === false) {
connectCom.text = "Disconnect";
comPort.enabled = false;
} else {
connectCom.text = "Connect";
comPort.enabled = true;
}
}
}
This should listen to the boolean property on SerialCom to change, but I get the following error:
QQmlApplicationEngine failed to load component
qrc:/QmlGui/main.qml:21 Type Page1 unavailable
qrc:/QmlGui/Page1.qml:49 Invalid attached object assignment
This just means that I can't "connect" using the target line above. Is there any other way I can connect to signals from a Q_PROPERTY of type QObject inside a ContextProperty?
Ok, I found the problem... The provided answers, while indeed helpful for other reasons, were not the correct solution. After going over the code by @Xplatforms, I couldn't figure out what the difference was between what I was doing and what he did.... until I saw this in my own code:
Connections: {
target: MasterGuiLogic.serialCom;
onConnectedToPortChanged: {
...
}
}
There isn't supposed to be a colon(:) there...
Connections {
target: MasterGuiLogic.serialCom;
onConnectedToPortChanged: {
...
}
}
Never try programming while sleepy...lol