Where is the mistake in my code?

Question

Hi..

I want to make a customized list view, in that I will add items dynamically, I have written code for the same, but it's giving me some problems,

1. code is compiling fine but it will give some linker error,
2. I tried the same code by keeping different header files, it runs well, but i am not getting control to my delegate class only.

Please can you suggest what the mistake(s) might be?

#include <QtGui>
#include <QApplication>
#include <QtGui/QMainWindow>


class ItemDeligate:public QStyledItemDelegate
    {
public:
    ItemDeligate(QObject *parent = 0):QStyledItemDelegate(parent)
    {}
    ~ItemDeligate(){}

public:
    enum ItemDataRole { SubTextRole = Qt::UserRole + 100};

    QSize sizeHint(const QStyleOptionViewItem& option, const QModelIndex& index) const;
    void paint(QPainter* painter, const QStyleOptionViewItem& option, const QModelIndex& index) const;

    };

QSize ItemDeligate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    //here i know implimentation

}

void ItemDeligate::paint(QPainter *p, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    //here i know the implimentation
    QStyledItemDelegate::paint(p,option,index);
}


class Test : public QMainWindow
{
    Q_OBJECT

public:
    Test(QWidget *parent = 0);
    ~Test(){};

    QPixmap GreenPixmap;
    QList<QStandardItem *> ItemList;
    QStandardItemModel *ListModel;    
    QVBoxLayout Listlayout;    
    QListView *MylistView;    
    QAction *AddItemMenu;

public slots:
    void addItem();
};


Test::Test(QWidget *parent)
    : QMainWindow(parent)
{
         MylistView = new QListView();
             QDesktopWidget* desktopWidget = QApplication::desktop();
         QRect clientRect = desktopWidget->geometry();

         MylistView->setMinimumSize(QSize(clientRect.width()-7,clientRect.height()-1));

         MylistView->setViewMode(QListView::ListMode);
         MylistView->setMovement(QListView::Free);
         MylistView->setItemDelegate(new ItemDeligate(MylistView));
         MylistView->setSelectionMode(QAbstractItemView::SingleSelection);
         bool val =GreenPixmap.load(":/new/prefix1/temp/test.png");

         ListModel = new QStandardItemModel();
         ListModel->appendColumn(ItemList);    
         MylistView->setModel(ListModel); 
             Listlayout.addWidget(MylistView);
          Listlayout.addWidget(MylistView);  
          this->setLayout(&Listlayout);
          AddItemMenu = new QAction("Add",this);      
         menuBar()->addAction(AddItemMenu); 
         val = connect(AddItemMenu,SIGNAL(triggered()),this,SLOT(addItem()));

}

void Test::addItem()
    {
            QStandardItem *Items = new QStandardItem(QIcon(GreenPixmap),"Avatar");
        Items->setData("WAKE UP",ItemDeligate::SubTextRole);
        ItemList.append(Items);
        ListModel->appendColumn(ItemList);

    }

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Test test;
    test.showMaximized();
    test.showMaximized();

    return a.exec();
}

Errors caused tool to abort.

mwldsym2.exe: Undefined symbol: 'void * Test::qt_metacast(char const *) (?qt_metacast@Test@@UAEPAXPBD@Z)'
mwldsym2.exe: referenced from 'const Test::`vftable' (??_7Test@@6B@~)' in main.o
mwldsym2.exe: Undefined symbol: 'struct QMetaObject const * Test::metaObject(void) const (?metaObject@Test@@UBEPBUQMetaObject@@XZ)'
mwldsym2.exe: referenced from 'const Test::`vftable' (??_7Test@@6B@~)' in main.o

Answer 1

Judging from the error messages I would have to guess that you forgot to run moc.

Answer 2

Make sure the header where the Test class is, is added to the HEADERS variable in the project file. Like this:

HEADERS += Test.h

Rerun qmake and make.

Godspeed

Answer 3

You didn't specify what platform you're developing on.

If you're using Linux or Mac, are you generating your Makefile using qmake? If not, you're probably missing some important Qt-specific steps. For instance, all Qt-derived classes need to be run through the meta-object compiler (moc.) This provides the class with the specific functionality that Qt provides that isn't a part of C++ (such as slots, signals, etc,) if I recall correctly.

Make sure you have a Qt project (.pro) file. From this, you can generate a GNU make file using QMake.

Typically, you'll want to run:

qmake make

to build your application whenever you add new source files. Otherwise you can just run "make."