mainwindow.cpp Example File | Qt Widgets 5.12.9

- Qt 5.12
- Qt Widgets
- Text Codecs Example
- mainwindow.cpp Example File
- Qt 5.12.9 Reference Documentation

# mainwindow.cpp Example File

tools/codecs/mainwindow.cpp

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     #include <QtWidgets>

     #include "mainwindow.h"
     #include "encodingdialog.h"
     #include "previewform.h"

     MainWindow::MainWindow()
     {
         textEdit = new QPlainTextEdit;
         textEdit->setLineWrapMode(QPlainTextEdit::NoWrap);
         setCentralWidget(textEdit);

         findCodecs();

         previewForm = new PreviewForm(this);
         previewForm->setCodecList(codecs);

         createMenus();

         setWindowTitle(tr("Codecs"));

         const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
         resize(screenGeometry.width() / 2, screenGeometry.height() * 2 / 3);
     }

     void MainWindow::open()
     {
         const QString fileName = QFileDialog::getOpenFileName(this);
         if (fileName.isEmpty())
             return;
         QFile file(fileName);
         if (!file.open(QFile::ReadOnly)) {
             QMessageBox::warning(this, tr("Codecs"),
                                  tr("Cannot read file %1:\n%2")
                                  .arg(QDir::toNativeSeparators(fileName),
                                       file.errorString()));
             return;
         }

         const QByteArray data = file.readAll();

         previewForm->setWindowTitle(tr("Choose Encoding for %1").arg(QFileInfo(fileName).fileName()));
         previewForm->setEncodedData(data);
         if (previewForm->exec())
             textEdit->setPlainText(previewForm->decodedString());
     }

     void MainWindow::save()
     {
         const QAction *action = qobject_cast<const QAction *>(sender());
         const QByteArray codecName = action->data().toByteArray();
         const QString title = tr("Save As (%1)").arg(QLatin1String(codecName));

         QString fileName = QFileDialog::getSaveFileName(this, title);
         if (fileName.isEmpty())
             return;
         QFile file(fileName);
         if (!file.open(QFile::WriteOnly | QFile::Text)) {
             QMessageBox::warning(this, tr("Codecs"),
                                  tr("Cannot write file %1:\n%2")
                                  .arg(QDir::toNativeSeparators(fileName),
                                       file.errorString()));
             return;
         }

         QTextStream out(&file);
         out.setCodec(codecName.constData());
         out << textEdit->toPlainText();
     }

     void MainWindow::about()
     {
         QMessageBox::about(this, tr("About Codecs"),
                 tr("The <b>Codecs</b> example demonstrates how to read and write "
                    "files using various encodings."));
     }

     void MainWindow::aboutToShowSaveAsMenu()
     {
         QString currentText = textEdit->toPlainText();

         foreach (QAction *action, saveAsActs) {
             QByteArray codecName = action->data().toByteArray();
             QTextCodec *codec = QTextCodec::codecForName(codecName);
             action->setVisible(codec && codec->canEncode(currentText));
         }
     }

     void MainWindow::findCodecs()
     {
         QMap<QString, QTextCodec *> codecMap;
         QRegularExpression iso8859RegExp("^ISO[- ]8859-([0-9]+).*$");
         QRegularExpressionMatch match;

         foreach (int mib, QTextCodec::availableMibs()) {
             QTextCodec *codec = QTextCodec::codecForMib(mib);

             QString sortKey = codec->name().toUpper();
             int rank;

             if (sortKey.startsWith(QLatin1String("UTF-8"))) {
                 rank = 1;
             } else if (sortKey.startsWith(QLatin1String("UTF-16"))) {
                 rank = 2;
             } else if ((match = iso8859RegExp.match(sortKey)).hasMatch()) {
                 if (match.captured(1).size() == 1)
                     rank = 3;
                 else
                     rank = 4;
             } else {
                 rank = 5;
             }
             sortKey.prepend(QLatin1Char('0' + rank));

             codecMap.insert(sortKey, codec);
         }
         codecs = codecMap.values();
     }

     void MainWindow::createMenus()
     {
         QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
         QAction *openAct =
             fileMenu->addAction(tr("&Open..."), this, &MainWindow::open);
         openAct->setShortcuts(QKeySequence::Open);

         QMenu *saveAsMenu = fileMenu->addMenu(tr("&Save As"));
         connect(saveAsMenu, &QMenu::aboutToShow,
                 this, &MainWindow::aboutToShowSaveAsMenu);
         foreach (const QTextCodec *codec, codecs) {
             const QByteArray name = codec->name();
             QAction *action = saveAsMenu->addAction(tr("%1...").arg(QLatin1String(name)));
             action->setData(QVariant(name));
             connect(action, &QAction::triggered, this, &MainWindow::save);
             saveAsActs.append(action);
         }

         fileMenu->addSeparator();
         QAction *exitAct = fileMenu->addAction(tr("E&xit"), this, &QWidget::close);
         exitAct->setShortcuts(QKeySequence::Quit);

         auto toolMenu =  menuBar()->addMenu(tr("&Tools"));
         auto encodingAction = toolMenu->addAction(tr("Encodings"), this, &MainWindow::encodingDialog);
         encodingAction->setShortcut(Qt::CTRL + Qt::Key_E);
         encodingAction->setToolTip(tr("Shows a dialog allowing to convert to common encoding in programming languages."));

         menuBar()->addSeparator();

         QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
         helpMenu->addAction(tr("&About"), this, &MainWindow::about);
         helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
     }

     void MainWindow::encodingDialog()
     {
         if (!m_encodingDialog) {
             m_encodingDialog = new EncodingDialog(this);
             const QRect screenGeometry = QApplication::desktop()->screenGeometry(this);
             m_encodingDialog->setMinimumWidth(screenGeometry.width() / 4);
         }
         m_encodingDialog->show();
         m_encodingDialog->raise();

     }