On 01/17/2011 08:04 AM, [email protected] wrote:
You can find an example of using QAbstractListModel with QML under
examples/declarative/modelviews/abstractitemmodel. The example is also online
at
http://doc.qt.nokia.com/4.7-snapshot/declarative-modelviews-abstractitemmodel.html.
The example doesn't modify the model from QML, but you could for example add a
method to the model class like this:
Q_INVOKABLE void updateModel(int index, const QVariant&value);
and then you can call this from QML to modify the model data.
The example shows some of the signals that needs to be emitted from a Qt model
in order to update the view (e.g. QAbstractItemModel::beginInsertRows() ). If
you are simply changing the data in an existing row, then emit dataChanged().
See
http://doc.qt.nokia.com/4.7-snapshot/model-view-programming.html#model-subclassing-reference.
I've been playing with this example, to try adding a thread that
randomly adds new items to an Abstract model, using a separate thread.
It seems the abstractmodel+QML cannot cope with updating. I'm hoping its
something wrong with the model implementation, i guess it needs to send
a dataChanged signal or something? The error it generates when
attempting to add the second new item is:
QObject::connect: Cannot queue arguments of type 'QModelIndex'
(Make sure 'QModelIndex' is registered using qRegisterMetaType().)
How do i fix this?
The changed main.cpp is attached, the rest of the source for the example
is here:
http://qt.gitorious.org/qt/qt/trees/4.7/examples/declarative/modelviews/abstractitemmodel
regards,
Tim.
regards,
Bea
On 15/01/2011, at 6:38 PM, ext Pelle Johnsen wrote:
Hi,
I can recommend subclassing QAbstractListModel
(http://doc.trolltech.com/4.7/qabstractlistmodel.html). You can use a normal
QList, but it only has a single change signal, so if e.g. you insert an item
then QML thinks the whole list has changed, which can cause performance
problems. The whole Qt model/view classes are rather complex (compared to
QList), but in my experience it's worth the effort to use it.
-pjoe
On Fri, Jan 14, 2011 at 6:26 PM, Jamil Naja<[email protected]> wrote:
Hi guys,
As the title suggests, I am looking for an example with a C++ model and QML
view where the QML view (or other QML elements within the QML code) doing
modification on the c++ model data.
Any suggestions ?
Thanks
Jamil
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#include "model.h"
#include <QDeclarativeContext>
#include <QDeclarativeView>
#include <QApplication>
#include <QtCore>
QMutex paws;
QWaitCondition newAnimal;
QDeclarativeContext *ctxt;
const int maxTime = 1000;
AnimalModel model;
class MyThread : public QThread
{
public:
void run();
};
void MyThread::run()
{
// reset random seed
qsrand(QTime(0,0,0).secsTo(QTime::currentTime()));
int randomTime;
forever {
// calculate a random nonzero time.
do {
randomTime=qrand() % maxTime;
} while (randomTime == 0);
QString lengthMessage = QString::number(randomTime) + " cm long";
qDebug() << lengthMessage;
// add new snake to the abstract model
model.addAnimal(Animal("Snake", lengthMessage));
// wait randomTime before adding another snake
paws.lock();
newAnimal.wait(&paws,randomTime);
paws.unlock();
}
}
int main(int argc, char ** argv)
{
QApplication app(argc, argv);
model.addAnimal(Animal("Wolf", "Medium"));
model.addAnimal(Animal("Polar bear", "Large"));
model.addAnimal(Animal("Quoll", "Small"));
QDeclarativeView view;
ctxt = view.rootContext();
ctxt->setContextProperty("myModel", &model);
// begin adding snakes
MyThread snakes;
snakes.start();
view.setSource(QUrl("qrc:view.qml"));
view.show();
return app.exec();
}
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