Using C++ model in QML, white page - c++

Question

I'am trying to send a object Cloud from C++ to QML. I want to show the name of my cloud in the QML using the model property.
I have no compilation error but when I execute the code severals infos are wrote :
QQUickView only supports loading of root objects that derive from
QuickItem
for this one i've tried to change all my QObject in QuickItem, without success.
If your example is using QML2, and the .qml file you loaded has 'import QTquick1,0' or 'import QT 4,7', this error will occur
I look for the import signaled, but I can't find any QtQuick1,0 or QT4
7 in my code.
Here my Cloud.h:
#ifndef CLOUD_H
#define CLOUD_H
#include <QObject>
class Cloud: public QObject
{
Q_OBJECT
Q_PROPERTY(QString name READ name WRITE setName NOTIFY nameChanged)
Q_PROPERTY(QString description READ description WRITE setDescription NOTIFY descriptionChanged)
public:
Cloud(QObject *parent=0);
Cloud(const QString &name, const QString &description, QObject *parent=0);
QString name() const;
void setName(const QString &name);
QString description() const;
void setDescription(const QString &name);
signals:
void nameChanged();
void descriptionChanged();
private:
QString m_name;
QString m_description;
};
#endif // CLOUD_H
My Cloud.cpp
#include "cloud.h"
#include <QDebug>
Cloud::Cloud(QObject *parent)
:QObject(parent)
{
}
Cloud::Cloud(const QString &name, const QString &description, QObject *parent)
:QObject(parent), m_name(name), m_description(description)
{
}
QString Cloud::name() const{
return m_name;
}
void Cloud::setName(const QString &name){
if(name != m_name){
m_name = name;
emit nameChanged();
}
}
QString Cloud::description() const{
return m_description;
}
void Cloud::setDescription(const QString &description){
if(description != m_description){
m_description = description;
emit descriptionChanged();
}
}
My main.cpp
#include <QGuiApplication>
#include <qqml.h>
#include <QtQuick/qquickitem.h>
#include <QtQuick/qquickview.h>
#include <QQmlContext>
#include "cloud.h"
int main(int argc, char *argv[])
{
QGuiApplication app(argc, argv);
qmlRegisterType<Cloud>("Sky", 1,0,"Cloud");
QList<Cloud*> cloudList;
cloudList.append(new Cloud("Cumulus Mediocris", "super nuage brocoli"));
cloudList.append(new Cloud("Cumulus Towering", "super nuage tour"));
cloudList.append(new Cloud("Cumulonimbus", "Gros nuage pas content"));
QQuickView view;
view.setResizeMode(QQuickView::SizeRootObjectToView);
QQmlContext *ctxt = view.rootContext();
ctxt->setContextProperty("myModel", QVariant::fromValue(cloudList));
view.setSource(QUrl("qrc:main.qml"));
view.show();
return app.exec();
}
And finally my main.qml:
import QtQuick 2.4
import QtQuick.Controls 1.3
import QtQuick.Window 2.2
import QtQuick.Dialogs 1.2
ApplicationWindow {
title: qsTr("Hello World")
width: 640
height: 480
visible: true
Rectangle{
width:10;height:10
color:"red"
anchors.left : parent.left
anchors.top:parent.top
}
ListView{
width:100;height:100
model: myModel
delegate:Rectangle{
height:25
width:100
color:"pink"
Text{text:model.modelData.name}
}
}
}
To write this code I took a look to Models and views in QtQuick and Using C++ Models with QtQUick View
Thank you in advance for your help :)

Answer 1

The problem is in your main function. QQuickView is a quick way to display a QML scene in a window (QQuickView is itself a subclass of QQuickWindow). In your QML, the root object is ApplicationWindow. You cannot display a window inside a window.
The solution is to switch to QQmlApplicationEngine:
QQmlApplicationEngine view;
QQmlContext *ctxt = view.rootContext();
ctxt->setContextProperty("myModel", QVariant::fromValue(cloudList));
view.load(QUrl("qrc:main.qml"));
The second problem is with your model. ListView would understand a QList<QObject*>, but not a QList<Cloud*>. Just change the declaration to:
QList<QObject*> cloudList;