QAbstractListModel derive from interface: SIGFAULT

bkamps

Hi,

I have the following class:

@
class ListModel : public QAbstractListModel, public IDataModel
{
Q_OBJECT
Q_INTERFACES(IDataModel)
Q_PROPERTY(int count READ count NOTIFY countChanged)
Q_PROPERTY(int currentIndex READ CurrentIndex NOTIFY currentIndexChanged)

public:
//model API
enum Roles { ObjectRole = Qt::UserRole+1 };

ListModel(QObject * aParent = 0);

virtual ~ListModel();

.................
@

This is the IDataModel interface:

@
class IDataModel
{
public:
virtual ~IDataModel() {}

virtual void AddItem(const ModelItemSharedPtr & aItem) = 0;

virtual void Clear() = 0;

virtual bool GetSelectedItem(ModelItemSharedPtr & aItem) = 0;

virtual void SetPreviousItem() = 0;

// To navigate through DataModel
virtual void GoUp() = 0;
virtual void GoDown() = 0;
virtual void GoLeft() = 0;
virtual void GoRight() = 0;

};

Q_DECLARE_INTERFACE(IDataModel, "IDataModel")
@

When I run this code I always get a sigfault in the ScriptValueEngine of QML... If I do not use the ListModel (my derived class) there is no problem.

Does anyone have a suggestion, could this be a bug?

dialingo

It depends on the implementation. Or is there a reason to think that the part you have shown is enough to find the problem?

vsorokin

I'm not sure, but I think name ListModel conflicting with qml ListModel component name
For QAbstractListModel inheritor you should define few virtual method, such as:
rowCount, columnCount, data, etc.

bkamps

Sorry for my late reply! I'll give some more information:

I used my ListModel before (without deriving it from an interface) without any troubles. I use ListModel as follows:

Header:
@
class ListModel : public QAbstractListModel, public IDataModel
{
Q_OBJECT
Q_INTERFACES(IDataModel)
Q_PROPERTY(int count READ count NOTIFY countChanged)
Q_PROPERTY(int currentIndex READ CurrentIndex NOTIFY currentIndexChanged)

public:
//model API
enum Roles { ObjectRole = Qt::UserRole+1 };

ListModel(QObject * aParent = 0);

virtual ~ListModel();

int rowCount(const QModelIndex &parent;) const;
QVariant data(const QModelIndex &index;, int role) const;

virtual void AddItem(const ModelItemSharedPtr & aItem); // >>>>IMPLEMENTED FROM IDATAMODEL
virtual void SetPreviousItem();  // >>>>IMPLEMENTED FROM IDATAMODEL
virtual void Clear(); // >>>>IMPLEMENTED FROM IDATAMODEL 
virtual bool GetSelectedItem(ModelItemSharedPtr & aItem); // >>>>IMPLEMENTED FROM IDATAMODEL

virtual void GoUp(); // >>>>IMPLEMENTED FROM IDATAMODEL
virtual void GoDown(); // >>>>IMPLEMENTED FROM IDATAMODEL
virtual void GoLeft() {} // >>>>IMPLEMENTED FROM IDATAMODEL
virtual void GoRight() {} // >>>>IMPLEMENTED FROM IDATAMODEL

int CurrentIndex() const;
void SetIndex(int aIndex);

inline int count() const { return mItems.count(); }

signals:
void countChanged();
void currentIndexChanged();

private:
int mCurrentIndex;
int mPrevIndex;
ItemList mItems;
};
@

Source file:
@
#include "ListModel.h"

ListModel::ListModel(QObject* aParent):
QAbstractListModel(aParent),
mCurrentIndex(START_POS), // Position in list starts from 0
mPrevIndex(START_POS)
{
QHash<int, QByteArray> roles;
roles[ObjectRole] = "object";
setRoleNames(roles);
}

ListModel::~ListModel()
{
}

bool ListModel::GetSelectedItem(ModelItemSharedPtr & aItem)
{
bool lFound = false;

if (ValidIndex(mCurrentIndex))
{
aItem = mItems[mCurrentIndex];
lFound = true;
}

return lFound;
}

void ListModel::AddItem(const ModelItemSharedPtr & aItem)
{
beginInsertRows(QModelIndex(), count(), count());
mItems.push_back(aItem);
endInsertRows();
emit countChanged();
}

QVariant ListModel::data(const QModelIndex &index;, int role) const
{
if (index.row() < 0 || index.row() >= count())
return QVariant();

if (role == ObjectRole)
 return QVariant::fromValue((QObject*)(mItems.at(index.row()).data()));

return QVariant();

}

int ListModel::rowCount(const QModelIndex &parent;) const
{
Q_UNUSED(parent);
return count();
}

int ListModel::CurrentIndex() const
{
return mCurrentIndex;
}

void ListModel::GoUp()
{
}

void ListModel::GoDown()
{
}

void ListModel::Clear()
{
// Goto first element in list
mItems.clear();
GoFirst();
reset();
}
@

bkamps

Interface IDataModel:
@

#pragma once

#include "ModelItem.h"

class IDataModel
{
public:
virtual ~IDataModel() {}

virtual void AddItem(const ModelItemSharedPtr & aItem) = 0;

virtual void Clear() = 0;

virtual bool GetSelectedItem(ModelItemSharedPtr & aItem) = 0;

virtual void SetPreviousItem() = 0;

// To navigate through DataModel
virtual void GoUp() = 0;
virtual void GoDown() = 0;
virtual void GoLeft() = 0;
virtual void GoRight() = 0;

};

Q_DECLARE_INTERFACE(IDataModel, "mmi.IDataModel")
@

I map ListModel to a QML listview:

@
ListView {
id: list
highlight: Rectangle {color: "darkgrey"; radius: 5}
y: 27
spacing: 2
width: parent.width
height: 196

Component {
id: listDelegate
Item {
width: parent.width; height: listItem.height; x: 5

Column {
 ListItem {
  id: listItem 
  text: modelData.text
  subtext: modelData.subtext
  item_enabled: modelData.item_enabled       
 }
}

}
}

delegate: listDelegate
}
@

If I use this code (ListModel derived from IDataModel) the scriptengine of QML crashes! If I ONLY remove the interface there is no problem at all...

bkamps

[quote author="Vass" date="1310546861"]1. I'm not sure, but I think name ListModel conflicting with qml ListModel component name 2. For QAbstractListModel inheritor you should define few virtual method, such as: rowCount, columnCount, data, etc.[/quote]

I tried to change ListModel to ListDataModel but that didn't help. Those virtual methods you are talking about I have implemented..

bkamps

I fixed the problem myself.

When I mapped the ListModel to QML using setContextProperty I used a static cast to cast the IDataModel* to a QObject. This was wrong, now I use dynamic_cast and no more crash!