Tree Model Completer Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Tree Model Completer Example

Qt 5.13.0 Reference Documentation

# Tree Model Completer Example

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      #include <QtWidgets>
      #include "treemodelcompleter.h"
      #include "mainwindow.h"

      MainWindow::MainWindow(QWidget *parent)
          : QMainWindow(parent), completer(0), lineEdit(0)
      {
          createMenu();

          completer = new TreeModelCompleter(this);
          completer->setModel(modelFromFile(":/resources/treemodel.txt"));
          completer->setSeparator(QLatin1String("."));
          QObject::connect(completer, QOverload<const QModelIndex &>::of(&TreeModelCompleter::highlighted),
                           this, &MainWindow::highlight);

          QWidget *centralWidget = new QWidget;

          QLabel *modelLabel = new QLabel;
          modelLabel->setText(tr("Tree Model<br>(Double click items to edit)"));

          QLabel *modeLabel = new QLabel;
          modeLabel->setText(tr("Completion Mode"));
          modeCombo = new QComboBox;
          modeCombo->addItem(tr("Inline"));
          modeCombo->addItem(tr("Filtered Popup"));
          modeCombo->addItem(tr("Unfiltered Popup"));
          modeCombo->setCurrentIndex(1);

          QLabel *caseLabel = new QLabel;
          caseLabel->setText(tr("Case Sensitivity"));
          caseCombo = new QComboBox;
          caseCombo->addItem(tr("Case Insensitive"));
          caseCombo->addItem(tr("Case Sensitive"));
          caseCombo->setCurrentIndex(0);

          QLabel *separatorLabel = new QLabel;
          separatorLabel->setText(tr("Tree Separator"));

          QLineEdit *separatorLineEdit = new QLineEdit;
          separatorLineEdit->setText(completer->separator());
          connect(separatorLineEdit, &QLineEdit::textChanged,
                  completer, &TreeModelCompleter::setSeparator);

          QCheckBox *wrapCheckBox = new QCheckBox;
          wrapCheckBox->setText(tr("Wrap around completions"));
          wrapCheckBox->setChecked(completer->wrapAround());
          connect(wrapCheckBox, &QAbstractButton::clicked, completer, &QCompleter::setWrapAround);

          contentsLabel = new QLabel;
          contentsLabel->setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
          connect(separatorLineEdit, &QLineEdit::textChanged,
                  this, &MainWindow::updateContentsLabel);

          treeView = new QTreeView;
          treeView->setModel(completer->model());
          treeView->header()->hide();
          treeView->expandAll();

          connect(modeCombo, QOverload<int>::of(&QComboBox::activated),
                  this, &MainWindow::changeMode);
          connect(caseCombo, QOverload<int>::of(&QComboBox::activated),
                  this, &MainWindow::changeMode);

          lineEdit = new QLineEdit;
          lineEdit->setCompleter(completer);

          QGridLayout *layout = new QGridLayout;
          layout->addWidget(modelLabel, 0, 0); layout->addWidget(treeView, 0, 1);
          layout->addWidget(modeLabel, 1, 0);  layout->addWidget(modeCombo, 1, 1);
          layout->addWidget(caseLabel, 2, 0);  layout->addWidget(caseCombo, 2, 1);
          layout->addWidget(separatorLabel, 3, 0); layout->addWidget(separatorLineEdit, 3, 1);
          layout->addWidget(wrapCheckBox, 4, 0);
          layout->addWidget(contentsLabel, 5, 0, 1, 2);
          layout->addWidget(lineEdit, 6, 0, 1, 2);
          centralWidget->setLayout(layout);
          setCentralWidget(centralWidget);

          changeCase(caseCombo->currentIndex());
          changeMode(modeCombo->currentIndex());

          setWindowTitle(tr("Tree Model Completer"));
          lineEdit->setFocus();
      }

      void MainWindow::createMenu()
      {
          QAction *exitAction = new QAction(tr("Exit"), this);
          QAction *aboutAct = new QAction(tr("About"), this);
          QAction *aboutQtAct = new QAction(tr("About Qt"), this);

          connect(exitAction, &QAction::triggered, qApp, &QApplication::quit);
          connect(aboutAct, &QAction::triggered, this, &MainWindow::about);
          connect(aboutQtAct, &QAction::triggered, qApp, &QApplication::aboutQt);

          QMenu* fileMenu = menuBar()->addMenu(tr("File"));
          fileMenu->addAction(exitAction);

          QMenu* helpMenu = menuBar()->addMenu(tr("About"));
          helpMenu->addAction(aboutAct);
          helpMenu->addAction(aboutQtAct);
      }

      void MainWindow::changeMode(int index)
      {
          QCompleter::CompletionMode mode;
          if (index == 0)
              mode = QCompleter::InlineCompletion;
          else if (index == 1)
              mode = QCompleter::PopupCompletion;
          else
              mode = QCompleter::UnfilteredPopupCompletion;

          completer->setCompletionMode(mode);
      }

      QAbstractItemModel *MainWindow::modelFromFile(const QString& fileName)
      {
          QFile file(fileName);
          if (!file.open(QFile::ReadOnly))
              return new QStringListModel(completer);

      #ifndef QT_NO_CURSOR
          QGuiApplication::setOverrideCursor(QCursor(Qt::WaitCursor));
      #endif
          QStringList words;

          QStandardItemModel *model = new QStandardItemModel(completer);
          QVector<QStandardItem *> parents(10);
          parents[0] = model->invisibleRootItem();

          while (!file.atEnd()) {
              QString line = file.readLine();
              QString trimmedLine = line.trimmed();
              if (line.isEmpty() || trimmedLine.isEmpty())
                  continue;

              QRegularExpression re("^\\s+");
              QRegularExpressionMatch match = re.match(line);
              int nonws = match.capturedStart();
              int level = 0;
              if (nonws == -1) {
                  level = 0;
              } else {
                  if (line.startsWith("\t")) {
                      level = match.capturedLength();
                  } else {
                      level = match.capturedLength()/4;
                  }
              }

              if (level+1 >= parents.size())
                  parents.resize(parents.size()*2);

              QStandardItem *item = new QStandardItem;
              item->setText(trimmedLine);
              parents[level]->appendRow(item);
              parents[level+1] = item;
          }

      #ifndef QT_NO_CURSOR
          QGuiApplication::restoreOverrideCursor();
      #endif

          return model;
      }

      void MainWindow::highlight(const QModelIndex &index)
      {
          QAbstractItemModel *completionModel = completer->completionModel();
          QAbstractProxyModel *proxy = qobject_cast<QAbstractProxyModel *>(completionModel);
          if (!proxy)
              return;
          QModelIndex sourceIndex = proxy->mapToSource(index);
          treeView->selectionModel()->select(sourceIndex, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
          treeView->scrollTo(sourceIndex);
      }

      void MainWindow::about()
      {
          QMessageBox::about(this, tr("About"), tr("This example demonstrates how "
              "to use a QCompleter with a custom tree model."));
      }

      void MainWindow::changeCase(int cs)
      {
          completer->setCaseSensitivity(cs ? Qt::CaseSensitive : Qt::CaseInsensitive);
      }

      void MainWindow::updateContentsLabel(const QString& sep)
      {
          contentsLabel->setText(tr("Type path from model above with items at each level separated by a '%1'").arg(sep));
      }