mainwindow.cpp Example File

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 #include "pieview.h"
 #include "mainwindow.h"

 #include <QtWidgets>

 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
 {
     QMenu *fileMenu = new QMenu(tr("&File"), this);
     QAction *openAction = fileMenu->addAction(tr("&Open..."));
     openAction->setShortcuts(QKeySequence::Open);
     QAction *saveAction = fileMenu->addAction(tr("&Save As..."));
     saveAction->setShortcuts(QKeySequence::SaveAs);
     QAction *quitAction = fileMenu->addAction(tr("E&xit"));
     quitAction->setShortcuts(QKeySequence::Quit);

     setupModel();
     setupViews();

     connect(openAction, &QAction::triggered, this, &MainWindow::openFile);
     connect(saveAction, &QAction::triggered, this, &MainWindow::saveFile);
     connect(quitAction, &QAction::triggered, qApp, &QCoreApplication::quit);

     menuBar()->addMenu(fileMenu);
     statusBar();

     loadFile(":/Charts/qtdata.cht");

     setWindowTitle(tr("Chart"));
     resize(870, 550);
 }

 void MainWindow::setupModel()
 {
     model = new QStandardItemModel(8, 2, this);
     model->setHeaderData(0, Qt::Horizontal, tr("Label"));
     model->setHeaderData(1, Qt::Horizontal, tr("Quantity"));
 }

 void MainWindow::setupViews()
 {
     QSplitter *splitter = new QSplitter;
     QTableView *table = new QTableView;
     pieChart = new PieView;
     splitter->addWidget(table);
     splitter->addWidget(pieChart);
     splitter->setStretchFactor(0, 0);
     splitter->setStretchFactor(1, 1);

     table->setModel(model);
     pieChart->setModel(model);

     QItemSelectionModel *selectionModel = new QItemSelectionModel(model);
     table->setSelectionModel(selectionModel);
     pieChart->setSelectionModel(selectionModel);

     QHeaderView *headerView = table->horizontalHeader();
     headerView->setStretchLastSection(true);

     setCentralWidget(splitter);
 }

 void MainWindow::openFile()
 {
     const QString fileName =
         QFileDialog::getOpenFileName(this, tr("Choose a data file"), "", "*.cht");
     if (!fileName.isEmpty())
         loadFile(fileName);
 }

 void MainWindow::loadFile(const QString &fileName)
 {
     QFile file(fileName);
     if (!file.open(QFile::ReadOnly | QFile::Text))
         return;

     QTextStream stream(&file);

     model->removeRows(0, model->rowCount(QModelIndex()), QModelIndex());

     int row = 0;
     while (!stream.atEnd()) {
         const QString line = stream.readLine();
         if (!line.isEmpty()) {
             model->insertRows(row, 1, QModelIndex());

             const QStringList pieces = line.split(',', QString::SkipEmptyParts);
             if (pieces.size() < 3)
                 continue;
             model->setData(model->index(row, 0, QModelIndex()),
                            pieces.value(0));
             model->setData(model->index(row, 1, QModelIndex()),
                            pieces.value(1));
             model->setData(model->index(row, 0, QModelIndex()),
                            QColor(pieces.value(2)), Qt::DecorationRole);
             row++;
         }
     };

     file.close();
     statusBar()->showMessage(tr("Loaded %1").arg(fileName), 2000);
 }

 void MainWindow::saveFile()
 {
     QString fileName = QFileDialog::getSaveFileName(this,
         tr("Save file as"), "", "*.cht");

     if (fileName.isEmpty())
         return;

     QFile file(fileName);
     if (!file.open(QFile::WriteOnly | QFile::Text))
         return;

     QTextStream stream(&file);
     for (int row = 0; row < model->rowCount(QModelIndex()); ++row) {

         QStringList pieces;

         pieces.append(model->data(model->index(row, 0, QModelIndex()),
                                   Qt::DisplayRole).toString());
         pieces.append(model->data(model->index(row, 1, QModelIndex()),
                                   Qt::DisplayRole).toString());
         pieces.append(model->data(model->index(row, 0, QModelIndex()),
                                   Qt::DecorationRole).toString());

         stream << pieces.join(',') << "\n";
     }

     file.close();
     statusBar()->showMessage(tr("Saved %1").arg(fileName), 2000);
 }