January 3, 2011

YetAnotherNick YetAnotherNi..
Lab Rat
10 posts

Using a QML model from a QDeclarativeItem subclass

 

Hi! I’m creating a QDeclarativeItem subclass:

  1. class MyGraphic : public QDeclarativeItem
  2. {
  3.     Q_OBJECT
  4.     Q_PROPERTY(????? model READ model SET model)
  5.  
  6. public:
  7.     MyGraphic(QDeclarativeItem *parent = 0);
  8.     void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = 0);
  9.     ...
  10. };

I would like to use it in QML like this:

  1. Rectangle {
  2.     ListModel {
  3.         id: mymodel
  4.         ListElement { type: "Oranges"; amount: 35 }
  5.         ListElement { type: "Apples"; amount: 27 }
  6.         ListElement { type: "Peaches"; amount: 12 }
  7.     }
  8.  
  9.     MyGraphic {
  10.         width: 300; height: 200
  11.         model: mymodel
  12.     }
  13. }

There are plenty of examples on how to make a C++ model available in the QML world but I have found nothing on how to access a QML model from C++.

How can I access mymodel from MyGraphic (the C++ class)? Should I use QAbstractItemModel* directly in the Q_PROPERTY?

I mean something like:

  1. void MyGraphic::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
  2. {
  3.     QString type = model->data(...);    // model would be "mymodel" from QML
  4.     int amount = model->data(...);
  5.     // paint a graphic using the "type" and "amount" variables
  6. }

4 replies

January 3, 2011

Andre Andre
Area 51 Engineer
6031 posts
  • Certified Specialist
  • Qt DevNet Moderator

Sounds like the same question as this [developer.qt.nokia.com].

Short answer: AFAIK, this is not yet possible*, as the QML model API is private API.

*) in a supported way.

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January 3, 2011

YetAnotherNick YetAnotherNi..
Lab Rat
10 posts

Thanks! Seems like I will have to use a QAbstractItemModel and set it in C++. Doesn’t look so pretty either but that’s life.

January 3, 2011

xsacha xsacha
Lab Rat
517 posts
  • Groupie L1
  • Qt DevNet Moderator

This is something that would be very useful.
The workaround would be too complicated.
For now, do it (i mean the model) in the C++ and then it is much easier to manipulate both in QML and C++.

 Signature 

- Sacha

January 3, 2011

syrianzoro syrianzoro
Lab Rat
63 posts

I have did the same as in this example, I replaced the qlist with standard model but in vain

  1. #include <QAbstractListModel>
  2. #include <QStringList>
  3.  
  4. //![0]
  5. class Animal
  6. {
  7. public:
  8.     Animal(const QString &type, const QString &size);
  9. //![0]
  10.  
  11.     QString type() const;
  12.     QString size() const;
  13.  
  14. private:
  15.     QString m_type;
  16.     QString m_size;
  17. //![1]
  18. };
  19.  
  20. class AnimalModel : public QAbstractListModel
  21. {
  22.     Q_OBJECT
  23. public:
  24.     enum AnimalRoles {
  25.         TypeRole = Qt::UserRole + 1,
  26.         SizeRole
  27.     };
  28.  
  29.     AnimalModel(QObject *parent = 0);
  30. //![1]
  31.  
  32.     void addAnimal(const Animal &animal);
  33.  
  34.     int rowCount(const QModelIndex & parent = QModelIndex()) const;
  35.  
  36.     QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;
  37.  
  38. private:
  39.     QList<Animal> m_animals;
  40. //![2]
  41. };

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Qt is the future

 
  ‹‹ QML Text item + OSX      [SOLVED]Undocumented features ››

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