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modelmenu.cpp Example File
demos/browser/modelmenu.cpp

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 #include "modelmenu.h"

 #include <QtCore/QAbstractItemModel>
 #include <qdebug.h>

 ModelMenu::ModelMenu(QAbstractItemModel *model, QWidget * parent): QMenu(parent),
     m_maxRows(7),
     m_maxWidth(-1),
     m_model(model)
 {
     connect(this, SIGNAL(aboutToShow()), this, SLOT(aboutToShow()));
 }

 bool ModelMenu::prePopulated()
 {
     return false;
 }

 void ModelMenu::postPopulated()
 {
 }

 QAbstractItemModel *ModelMenu::model() const
 {
     return m_model;
 }

 void ModelMenu::setMaxRows(int max)
 {
     m_maxRows = max;
 }

 int ModelMenu::maxRows() const
 {
     return m_maxRows;
 }

 Q_DECLARE_METATYPE(QModelIndex)
 void ModelMenu::aboutToShow()
 {
     if (QMenu *menu = qobject_cast<QMenu*>(sender())) {
         QVariant v = menu->menuAction()->data();
         if (v.canConvert<int>()) {
             int row = v.toInt();
             QModelIndex idx = m_model->index(row, 0);
             createMenu(idx, -1, menu);
             disconnect(menu, SIGNAL(aboutToShow()), this, SLOT(aboutToShow()));
             return;
         }
     }

     clear();
     if (prePopulated())
         addSeparator();
     createMenu(QModelIndex(), m_maxRows, this);
     postPopulated();
 }

 void ModelMenu::createMenu(const QModelIndex &parent, int max, QMenu *menu)
 {
     // for history, remove somehow
     if (parent.row() == 0 && !menu && m_model->rowCount(parent) < 20)
         return;

     if (!menu) {
         QString title = parent.data().toString();
         menu = new QMenu(title, this);
         addMenu(menu);
         menu->menuAction()->setData(parent.row());
         connect(menu, SIGNAL(aboutToShow()), this, SLOT(aboutToShow()));
         return;
     }

     int end = m_model->rowCount(parent);
     if (max != -1)
         end = qMin(max, end);

     connect(menu, SIGNAL(triggered(QAction*)), this, SLOT(triggered(QAction*)));

     // for history, remove somehow
     int start = 0;
     if (parent.row() == 0 && menu != this)
         start = 20;

     for (int i = start; i < end; ++i) {
         QModelIndex idx = m_model->index(i, 0, parent);
         if (m_model->hasChildren(idx))
             createMenu(idx, -1);
         else
             menu->addAction(makeAction(idx));
     }
 }

 QAction *ModelMenu::makeAction(const QModelIndex &index)
 {
     QIcon icon = qvariant_cast<QIcon>(index.data(Qt::DecorationRole));
     QAction *action = makeAction(icon, index.data().toString(), this);
     QVariant v;
     v.setValue(index);
     action->setData(v);
     return action;
 }

 QAction *ModelMenu::makeAction(const QIcon &icon, const QString &text, QObject *parent)
 {
     QFontMetrics fm(font());
     if (-1 == m_maxWidth)
         m_maxWidth = fm.width("m") * 30;
     QString smallText = fm.elidedText(text, Qt::ElideMiddle, m_maxWidth);
     return new QAction(icon, smallText, parent);
 }

 void ModelMenu::triggered(QAction *action)
 {
     QVariant v = action->data();
     if (v.canConvert<QModelIndex>()) {
         QModelIndex idx = qvariant_cast<QModelIndex>(v);
         emit activated(idx);
     }
 }


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Qt 4.4.0-beta1