persistent indexes
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#ifndef MODEL_H
#define MODEL_H
#include <QAbstractListModel>
#include <QObject>
#include <QStringList>
class StringListModel : public QAbstractListModel
{
Q_OBJECT
public:
StringListModel(const QStringList &strings, QObject *parent = 0)
: QAbstractListModel(parent), stringList(strings) {}
int rowCount(const QModelIndex &parent = QModelIndex()) const;
QVariant data(const QModelIndex &index, int role) const;
QVariant headerData(int section, Qt::Orientation orientation,
int role = Qt::DisplayRole) const;
Qt::ItemFlags flags(const QModelIndex &index) const;
bool setData(const QModelIndex &index, const QVariant &value,
int role = Qt::EditRole);
bool insertRows(int position, int rows, const QModelIndex &index = QModelIndex());
bool removeRows(int position, int rows, const QModelIndex &index = QModelIndex());
private:
QStringList stringList;
};
#endif
/*
model.cpp
A simple model that uses a QStringList as its data source.
*/
#include <qdebug.h>
#include "model.h"
/*!
Returns the number of items in the string list as the number of rows
in the model.
*/
int StringListModel::rowCount(const QModelIndex &parent) const
{
return stringList.count();
}
/*!
Returns an appropriate value for the requested data.
If the view requests an invalid index, an invalid variant is returned.
If a header is requested then we just return the column or row number,
depending on the orientation of the header.
Any valid index that corresponds to a string in the list causes that
string to be returned.
*/
QVariant StringListModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
return QVariant();
if (index.row() < 0 || index.row() >= stringList.size())
return QVariant();
if (role == Qt::DisplayRole)
return stringList.at(index.row());
else
return QVariant();
}
/*!
Returns the appropriate header string depending on the orientation of
the header and the section. If anything other than the display role is
requested, we return an invalid variant.
*/
QVariant StringListModel::headerData(int section, Qt::Orientation orientation,
int role) const
{
if (role != Qt::DisplayRole)
return QVariant();
if (orientation == Qt::Horizontal)
return QString("Column %1").arg(section);
else
return QString("Row %1").arg(section);
}
/*!
Returns an appropriate value for the item's flags. Valid items are
enabled, selectable, and editable.
*/
Qt::ItemFlags StringListModel::flags(const QModelIndex &index) const
{
if (!index.isValid())
return Qt::ItemIsEnabled;
return QAbstractItemModel::flags(index) | Qt::ItemIsEditable;
}
/*!
Changes an item in the string list, but only if the following conditions
are met:
* The index supplied is valid.
* The index corresponds to an item to be shown in a view.
* The role associated with editing text is specified.
The dataChanged() signal is emitted if the item is changed.
*/
bool StringListModel::setData(const QModelIndex &index,
const QVariant &value, int role)
{
if (index.isValid() && role == Qt::EditRole) {
stringList.replace(index.row(), value.toString());
emit dataChanged(index, index);
return true;
}
return false;
}
/*!
Inserts a number of rows into the model at the specified position.
*/
bool StringListModel::insertRows(int position, int rows, const QModelIndex &parent)
{
beginInsertRows(parent, position, position + rows - 1);
for (int row = 0; row < rows; ++row) {
stringList.insert(position, "");
}
endInsertRows();
return true;
}
/*!
Removes a number of rows from the model at the specified position.
*/
bool StringListModel::removeRows(int position, int rows, const QModelIndex &parent)
{
beginRemoveRows(parent, position, position + rows - 1);
for (int row = 0; row < rows; ++row) {
stringList.removeAt(position);
}
endRemoveRows();
return true;
}
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QModelIndex>
class QAbstractItemModel;
class QAction;
class QItemSelectionModel;
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
private slots:
void insertItem();
void removeItem();
void updateMenus(const QModelIndex ¤tIndex);
private:
QAbstractItemModel *model;
QAction *insertAction;
QAction *removeAction;
QItemSelectionModel *selectionModel;
};
#endif
#include <QtGui>
#include "mainwindow.h"
#include "model.h"
/*!
The main window constructor creates and populates a model with values
from a string list then displays the contents of the model using a
QListView widget.
*/
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
{
QMenu *fileMenu = new QMenu(tr("&File"));
QAction *quitAction = fileMenu->addAction(tr("E&xit"));
quitAction->setShortcut(tr("Ctrl+Q"));
QMenu *itemsMenu = new QMenu(tr("&Items"));
insertAction = itemsMenu->addAction(tr("&Insert Item"));
removeAction = itemsMenu->addAction(tr("&Remove Item"));
menuBar()->addMenu(fileMenu);
menuBar()->addMenu(itemsMenu);
QStringList numbers;
numbers << tr("One") << tr("Two") << tr("Three") << tr("Four") << tr("Five")
<< tr("Six") << tr("Seven") << tr("Eight") << tr("Nine") << tr("Ten");
model = new StringListModel(numbers);
QListView *view = new QListView(this);
view->setModel(model);
selectionModel = view->selectionModel();
connect(quitAction, SIGNAL(triggered()), qApp, SLOT(quit()));
connect(insertAction, SIGNAL(triggered()), this, SLOT(insertItem()));
connect(removeAction, SIGNAL(triggered()), this, SLOT(removeItem()));
connect(selectionModel,
SIGNAL(currentChanged(const QModelIndex &, const QModelIndex &)),
this, SLOT(updateMenus(const QModelIndex &)));
setCentralWidget(view);
setWindowTitle("View onto a string list model");
}
void MainWindow::insertItem()
{
if (!selectionModel->currentIndex().isValid())
return;
QString itemText = QInputDialog::getText(this, tr("Insert Item"),
tr("Input text for the new item:"));
if (itemText.isNull())
return;
int row = selectionModel->currentIndex().row();
if (model->insertRows(row, 1))
model->setData(model->index(row, 0), itemText, Qt::EditRole);
}
void MainWindow::removeItem()
{
if (!selectionModel->currentIndex().isValid())
return;
int row = selectionModel->currentIndex().row();
model->removeRows(row, 1);
}
void MainWindow::updateMenus(const QModelIndex ¤tIndex)
{
insertAction->setEnabled(currentIndex.isValid());
removeAction->setEnabled(currentIndex.isValid());
}
#include <QApplication>
#include "mainwindow.h"
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
MainWindow *window = new MainWindow;
window->show();
return app.exec();
}
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