notepad.cpp Example File

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 #include <QFile>
 #include <QFileDialog>
 #include <QTextStream>
 #include <QMessageBox>
 #if defined(QT_PRINTSUPPORT_LIB)
 #include <QtPrintSupport/qtprintsupportglobal.h>
 #if QT_CONFIG(printer)
 #if QT_CONFIG(printdialog)
 #include <QPrintDialog>
 #endif // QT_CONFIG(printdialog)
 #include <QPrinter>
 #endif // QT_CONFIG(printer)
 #endif // QT_PRINTSUPPORT_LIB
 #include <QFont>
 #include <QFontDialog>

 #include "notepad.h"
 #include "ui_notepad.h"

 Notepad::Notepad(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::Notepad)
 {
     ui->setupUi(this);
     this->setCentralWidget(ui->textEdit);

     connect(ui->actionNew, &QAction::triggered, this, &Notepad::newDocument);
     connect(ui->actionOpen, &QAction::triggered, this, &Notepad::open);
     connect(ui->actionSave, &QAction::triggered, this, &Notepad::save);
     connect(ui->actionSave_as, &QAction::triggered, this, &Notepad::saveAs);
     connect(ui->actionPrint, &QAction::triggered, this, &Notepad::print);
     connect(ui->actionExit, &QAction::triggered, this, &Notepad::exit);
     connect(ui->actionCopy, &QAction::triggered, this, &Notepad::copy);
     connect(ui->actionCut, &QAction::triggered, this, &Notepad::cut);
     connect(ui->actionPaste, &QAction::triggered, this, &Notepad::paste);
     connect(ui->actionUndo, &QAction::triggered, this, &Notepad::undo);
     connect(ui->actionRedo, &QAction::triggered, this, &Notepad::redo);
     connect(ui->actionFont, &QAction::triggered, this, &Notepad::selectFont);
     connect(ui->actionBold, &QAction::triggered, this, &Notepad::setFontBold);
     connect(ui->actionUnderline, &QAction::triggered, this, &Notepad::setFontUnderline);
     connect(ui->actionItalic, &QAction::triggered, this, &Notepad::setFontItalic);
     connect(ui->actionAbout, &QAction::triggered, this, &Notepad::about);

 // Disable menu actions for unavailable features
 #if !QT_CONFIG(printer)
     ui->actionPrint->setEnabled(false);
 #endif

 #if !QT_CONFIG(clipboard)
     ui->actionCut->setEnabled(false);
     ui->actionCopy->setEnabled(false);
     ui->actionPaste->setEnabled(false);
 #endif
 }

 Notepad::~Notepad()
 {
     delete ui;
 }

 void Notepad::newDocument()
 {
     currentFile.clear();
     ui->textEdit->setText(QString());
 }

 void Notepad::open()
 {
     QString fileName = QFileDialog::getOpenFileName(this, "Open the file");
     QFile file(fileName);
     currentFile = fileName;
     if (!file.open(QIODevice::ReadOnly | QFile::Text)) {
         QMessageBox::warning(this, "Warning", "Cannot open file: " + file.errorString());
         return;
     }
     setWindowTitle(fileName);
     QTextStream in(&file);
     QString text = in.readAll();
     ui->textEdit->setText(text);
     file.close();
 }

 void Notepad::save()
 {
     QString fileName;
     // If we don't have a filename from before, get one.
     if (currentFile.isEmpty()) {
         fileName = QFileDialog::getSaveFileName(this, "Save");
         currentFile = fileName;
     } else {
         fileName = currentFile;
     }
     QFile file(fileName);
     if (!file.open(QIODevice::WriteOnly | QFile::Text)) {
         QMessageBox::warning(this, "Warning", "Cannot save file: " + file.errorString());
         return;
     }
     setWindowTitle(fileName);
     QTextStream out(&file);
     QString text = ui->textEdit->toPlainText();
     out << text;
     file.close();
 }

 void Notepad::saveAs()
 {
     QString fileName = QFileDialog::getSaveFileName(this, "Save as");
     QFile file(fileName);

     if (!file.open(QFile::WriteOnly | QFile::Text)) {
         QMessageBox::warning(this, "Warning", "Cannot save file: " + file.errorString());
         return;
     }
     currentFile = fileName;
     setWindowTitle(fileName);
     QTextStream out(&file);
     QString text = ui->textEdit->toPlainText();
     out << text;
     file.close();
 }

 void Notepad::print()
 {
 #if QT_CONFIG(printer)
     QPrinter printDev;
 #if QT_CONFIG(printdialog)
     QPrintDialog dialog(&printDev, this);
     if (dialog.exec() == QDialog::Rejected)
         return;
 #endif // QT_CONFIG(printdialog)
     ui->textEdit->print(&printDev);
 #endif // QT_CONFIG(printer)
 }

 void Notepad::exit()
 {
     QCoreApplication::quit();
 }

 void Notepad::copy()
 {
 #if QT_CONFIG(clipboard)
     ui->textEdit->copy();
 #endif
 }

 void Notepad::cut()
 {
 #if QT_CONFIG(clipboard)
     ui->textEdit->cut();
 #endif
 }

 void Notepad::paste()
 {
 #if QT_CONFIG(clipboard)
     ui->textEdit->paste();
 #endif
 }

 void Notepad::undo()
 {
      ui->textEdit->undo();
 }

 void Notepad::redo()
 {
     ui->textEdit->redo();
 }

 void Notepad::selectFont()
 {
     bool fontSelected;
     QFont font = QFontDialog::getFont(&fontSelected, this);
     if (fontSelected)
         ui->textEdit->setFont(font);
 }

 void Notepad::setFontUnderline(bool underline)
 {
     ui->textEdit->setFontUnderline(underline);
 }

 void Notepad::setFontItalic(bool italic)
 {
     ui->textEdit->setFontItalic(italic);
 }

 void Notepad::setFontBold(bool bold)
 {
     bold ? ui->textEdit->setFontWeight(QFont::Bold) :
            ui->textEdit->setFontWeight(QFont::Normal);
 }

 void Notepad::about()
 {
    QMessageBox::about(this, tr("About MDI"),
                 tr("The <b>Notepad</b> example demonstrates how to code a basic "
                    "text editor using QtWidgets"));

 }