I am using Qt 5.9.3. I have following property declared in my app's main.qml
Code:
//main.qml
MyQuickItem {
property color nextColor
onNextColorChanged: {
console.log("The next color will be: " + nextColor.toString())
}
}
// MyQuickItem.h
class MyQuickItem : public QQuickItem {
}
Question:
How can I make onNextColorChanged
be defined in the C++ side?
I know that I can also make nextColor
as a property inside C++ class MyQuickItem
. like so
// MyQuickItem.h
class MyQuickItem : public QQuickItem {
Q_PROPERTY(QColor nextColor READ nextColor WRITE setNextColor NOTIFY nextColorChanged)
}
Is it possible to monitor OnNextColorChanged
inside MyQuickItem
?
We can use the QMetaObject to obtain the property and the signal, then we connect it through the old style:
#ifndef MYQUICKITEM_H
#define MYQUICKITEM_H
#include <QQuickItem>
#include <QDebug>
class MyQuickItem : public QQuickItem
{
Q_OBJECT
public:
MyQuickItem(QQuickItem *parent = Q_NULLPTR): QQuickItem(parent){}
protected:
void componentComplete(){
int index =metaObject()->indexOfProperty("nextColor");
const QMetaProperty property = metaObject()->property(index);
if (property.hasNotifySignal()){
const QMetaMethod s = property.notifySignal();
QString sig = QString("2%1").arg(QString(s.methodSignature()));
connect(this, sig.toStdString().c_str() , this, SLOT(onNextColorChanged()));
}
}
private slots:
void onNextColorChanged(){
int index =metaObject()->indexOfProperty("nextColor");
const QMetaProperty property = metaObject()->property(index);
qDebug()<<"color" << property.read(this);
}
};
#endif // MYQUICKITEM_H
The complete example can be found in the following link.