Syntax Highlighter Example

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#include <QtWidgets>

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    setupFileMenu();
    setupHelpMenu();
    setupEditor();

    setCentralWidget(editor);
    setWindowTitle(tr("Syntax Highlighter"));
}

void MainWindow::about()
{
    QMessageBox::about(this, tr("About Syntax Highlighter"),
                tr("<p>The <b>Syntax Highlighter</b> example shows how " \
                   "to perform simple syntax highlighting by subclassing " \
                   "the QSyntaxHighlighter class and describing " \
                   "highlighting rules using regular expressions.</p>"));
}

void MainWindow::newFile()
{
    editor->clear();
}

void MainWindow::openFile(const QString &path)
{
    QString fileName = path;

    if (fileName.isNull())
        fileName = QFileDialog::getOpenFileName(this, tr("Open File"), "", "C++ Files (*.cpp *.h)");

    if (!fileName.isEmpty()) {
        QFile file(fileName);
        if (file.open(QFile::ReadOnly | QFile::Text))
            editor->setPlainText(file.readAll());
    }
}

void MainWindow::setupEditor()
{
    QFont font;
    font.setFamily("Courier");
    font.setFixedPitch(true);
    font.setPointSize(10);

    editor = new QTextEdit;
    editor->setFont(font);

    highlighter = new Highlighter(editor->document());

    QFile file("mainwindow.h");
    if (file.open(QFile::ReadOnly | QFile::Text))
        editor->setPlainText(file.readAll());
}

void MainWindow::setupFileMenu()
{
    QMenu *fileMenu = new QMenu(tr("&File"), this);
    menuBar()->addMenu(fileMenu);

    fileMenu->addAction(tr("&New"), this, SLOT(newFile()), QKeySequence::New);
    fileMenu->addAction(tr("&Open..."), this, SLOT(openFile()), QKeySequence::Open);
    fileMenu->addAction(tr("E&xit"), qApp, SLOT(quit()), QKeySequence::Quit);
}

void MainWindow::setupHelpMenu()
{
    QMenu *helpMenu = new QMenu(tr("&Help"), this);
    menuBar()->addMenu(helpMenu);

    helpMenu->addAction(tr("&About"), this, SLOT(about()));
    helpMenu->addAction(tr("About &Qt"), qApp, SLOT(aboutQt()));
}