- Qt 5.5
- Qt Widgets
- Menus Example
- mainwindow.cpp Example File
- Qt 5.5.1 Reference Documentation

# mainwindow.cpp Example File

mainwindows/menus/mainwindow.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    #include <QtWidgets>

    #include "mainwindow.h"

    MainWindow::MainWindow()
    {
        QWidget *widget = new QWidget;
        setCentralWidget(widget);

        QWidget *topFiller = new QWidget;
        topFiller->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

        infoLabel = new QLabel(tr("<i>Choose a menu option, or right-click to "
                                  "invoke a context menu</i>"));
        infoLabel->setFrameStyle(QFrame::StyledPanel | QFrame::Sunken);
        infoLabel->setAlignment(Qt::AlignCenter);

        QWidget *bottomFiller = new QWidget;
        bottomFiller->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

        QVBoxLayout *layout = new QVBoxLayout;
        layout->setMargin(5);
        layout->addWidget(topFiller);
        layout->addWidget(infoLabel);
        layout->addWidget(bottomFiller);
        widget->setLayout(layout);

        createActions();
        createMenus();

        QString message = tr("A context menu is available by right-clicking");
        statusBar()->showMessage(message);

        setWindowTitle(tr("Menus"));
        setMinimumSize(160, 160);
        resize(480, 320);
    }

    void MainWindow::contextMenuEvent(QContextMenuEvent *event)
    {
        QMenu menu(this);
        menu.addAction(cutAct);
        menu.addAction(copyAct);
        menu.addAction(pasteAct);
        menu.exec(event->globalPos());
    }

    void MainWindow::newFile()
    {
        infoLabel->setText(tr("Invoked <b>File|New</b>"));
    }

    void MainWindow::open()
    {
        infoLabel->setText(tr("Invoked <b>File|Open</b>"));
    }

    void MainWindow::save()
    {
        infoLabel->setText(tr("Invoked <b>File|Save</b>"));
    }

    void MainWindow::print()
    {
        infoLabel->setText(tr("Invoked <b>File|Print</b>"));
    }

    void MainWindow::undo()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Undo</b>"));
    }

    void MainWindow::redo()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Redo</b>"));
    }

    void MainWindow::cut()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Cut</b>"));
    }

    void MainWindow::copy()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Copy</b>"));
    }

    void MainWindow::paste()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Paste</b>"));
    }

    void MainWindow::bold()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Bold</b>"));
    }

    void MainWindow::italic()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Italic</b>"));
    }

    void MainWindow::leftAlign()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Left Align</b>"));
    }

    void MainWindow::rightAlign()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Right Align</b>"));
    }

    void MainWindow::justify()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Justify</b>"));
    }

    void MainWindow::center()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Center</b>"));
    }

    void MainWindow::setLineSpacing()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Set Line Spacing</b>"));
    }

    void MainWindow::setParagraphSpacing()
    {
        infoLabel->setText(tr("Invoked <b>Edit|Format|Set Paragraph Spacing</b>"));
    }

    void MainWindow::about()
    {
        infoLabel->setText(tr("Invoked <b>Help|About</b>"));
        QMessageBox::about(this, tr("About Menu"),
                tr("The <b>Menu</b> example shows how to create "
                   "menu-bar menus and context menus."));
    }

    void MainWindow::aboutQt()
    {
        infoLabel->setText(tr("Invoked <b>Help|About Qt</b>"));
    }

    void MainWindow::createActions()
    {
        newAct = new QAction(tr("&New"), this);
        newAct->setShortcuts(QKeySequence::New);
        newAct->setStatusTip(tr("Create a new file"));
        connect(newAct, SIGNAL(triggered()), this, SLOT(newFile()));

        openAct = new QAction(tr("&Open..."), this);
        openAct->setShortcuts(QKeySequence::Open);
        openAct->setStatusTip(tr("Open an existing file"));
        connect(openAct, SIGNAL(triggered()), this, SLOT(open()));

        saveAct = new QAction(tr("&Save"), this);
        saveAct->setShortcuts(QKeySequence::Save);
        saveAct->setStatusTip(tr("Save the document to disk"));
        connect(saveAct, SIGNAL(triggered()), this, SLOT(save()));

        printAct = new QAction(tr("&Print..."), this);
        printAct->setShortcuts(QKeySequence::Print);
        printAct->setStatusTip(tr("Print the document"));
        connect(printAct, SIGNAL(triggered()), this, SLOT(print()));

        exitAct = new QAction(tr("E&xit"), this);
        exitAct->setShortcuts(QKeySequence::Quit);
        exitAct->setStatusTip(tr("Exit the application"));
        connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

        undoAct = new QAction(tr("&Undo"), this);
        undoAct->setShortcuts(QKeySequence::Undo);
        undoAct->setStatusTip(tr("Undo the last operation"));
        connect(undoAct, SIGNAL(triggered()), this, SLOT(undo()));

        redoAct = new QAction(tr("&Redo"), this);
        redoAct->setShortcuts(QKeySequence::Redo);
        redoAct->setStatusTip(tr("Redo the last operation"));
        connect(redoAct, SIGNAL(triggered()), this, SLOT(redo()));

        cutAct = new QAction(tr("Cu&t"), this);
        cutAct->setShortcuts(QKeySequence::Cut);
        cutAct->setStatusTip(tr("Cut the current selection's contents to the "
                                "clipboard"));
        connect(cutAct, SIGNAL(triggered()), this, SLOT(cut()));

        copyAct = new QAction(tr("&Copy"), this);
        copyAct->setShortcuts(QKeySequence::Copy);
        copyAct->setStatusTip(tr("Copy the current selection's contents to the "
                                 "clipboard"));
        connect(copyAct, SIGNAL(triggered()), this, SLOT(copy()));

        pasteAct = new QAction(tr("&Paste"), this);
        pasteAct->setShortcuts(QKeySequence::Paste);
        pasteAct->setStatusTip(tr("Paste the clipboard's contents into the current "
                                  "selection"));
        connect(pasteAct, SIGNAL(triggered()), this, SLOT(paste()));

        boldAct = new QAction(tr("&Bold"), this);
        boldAct->setCheckable(true);
        boldAct->setShortcut(QKeySequence::Bold);
        boldAct->setStatusTip(tr("Make the text bold"));
        connect(boldAct, SIGNAL(triggered()), this, SLOT(bold()));

        QFont boldFont = boldAct->font();
        boldFont.setBold(true);
        boldAct->setFont(boldFont);

        italicAct = new QAction(tr("&Italic"), this);
        italicAct->setCheckable(true);
        italicAct->setShortcut(QKeySequence::Italic);
        italicAct->setStatusTip(tr("Make the text italic"));
        connect(italicAct, SIGNAL(triggered()), this, SLOT(italic()));

        QFont italicFont = italicAct->font();
        italicFont.setItalic(true);
        italicAct->setFont(italicFont);

        setLineSpacingAct = new QAction(tr("Set &Line Spacing..."), this);
        setLineSpacingAct->setStatusTip(tr("Change the gap between the lines of a "
                                           "paragraph"));
        connect(setLineSpacingAct, SIGNAL(triggered()), this, SLOT(setLineSpacing()));

        setParagraphSpacingAct = new QAction(tr("Set &Paragraph Spacing..."), this);
        setParagraphSpacingAct->setStatusTip(tr("Change the gap between paragraphs"));
        connect(setParagraphSpacingAct, SIGNAL(triggered()),
                this, SLOT(setParagraphSpacing()));

        aboutAct = new QAction(tr("&About"), this);
        aboutAct->setStatusTip(tr("Show the application's About box"));
        connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));

        aboutQtAct = new QAction(tr("About &Qt"), this);
        aboutQtAct->setStatusTip(tr("Show the Qt library's About box"));
        connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
        connect(aboutQtAct, SIGNAL(triggered()), this, SLOT(aboutQt()));

        leftAlignAct = new QAction(tr("&Left Align"), this);
        leftAlignAct->setCheckable(true);
        leftAlignAct->setShortcut(tr("Ctrl+L"));
        leftAlignAct->setStatusTip(tr("Left align the selected text"));
        connect(leftAlignAct, SIGNAL(triggered()), this, SLOT(leftAlign()));

        rightAlignAct = new QAction(tr("&Right Align"), this);
        rightAlignAct->setCheckable(true);
        rightAlignAct->setShortcut(tr("Ctrl+R"));
        rightAlignAct->setStatusTip(tr("Right align the selected text"));
        connect(rightAlignAct, SIGNAL(triggered()), this, SLOT(rightAlign()));

        justifyAct = new QAction(tr("&Justify"), this);
        justifyAct->setCheckable(true);
        justifyAct->setShortcut(tr("Ctrl+J"));
        justifyAct->setStatusTip(tr("Justify the selected text"));
        connect(justifyAct, SIGNAL(triggered()), this, SLOT(justify()));

        centerAct = new QAction(tr("&Center"), this);
        centerAct->setCheckable(true);
        centerAct->setShortcut(tr("Ctrl+E"));
        centerAct->setStatusTip(tr("Center the selected text"));
        connect(centerAct, SIGNAL(triggered()), this, SLOT(center()));

        alignmentGroup = new QActionGroup(this);
        alignmentGroup->addAction(leftAlignAct);
        alignmentGroup->addAction(rightAlignAct);
        alignmentGroup->addAction(justifyAct);
        alignmentGroup->addAction(centerAct);
        leftAlignAct->setChecked(true);
    }

    void MainWindow::createMenus()
    {
        fileMenu = menuBar()->addMenu(tr("&File"));
        fileMenu->addAction(newAct);
        fileMenu->addAction(openAct);
        fileMenu->addAction(saveAct);
        fileMenu->addAction(printAct);
        fileMenu->addSeparator();
        fileMenu->addAction(exitAct);

        editMenu = menuBar()->addMenu(tr("&Edit"));
        editMenu->addAction(undoAct);
        editMenu->addAction(redoAct);
        editMenu->addSeparator();
        editMenu->addAction(cutAct);
        editMenu->addAction(copyAct);
        editMenu->addAction(pasteAct);
        editMenu->addSeparator();

        helpMenu = menuBar()->addMenu(tr("&Help"));
        helpMenu->addAction(aboutAct);
        helpMenu->addAction(aboutQtAct);

        formatMenu = editMenu->addMenu(tr("&Format"));
        formatMenu->addAction(boldAct);
        formatMenu->addAction(italicAct);
        formatMenu->addSeparator()->setText(tr("Alignment"));
        formatMenu->addAction(leftAlignAct);
        formatMenu->addAction(rightAlignAct);
        formatMenu->addAction(justifyAct);
        formatMenu->addAction(centerAct);
        formatMenu->addSeparator();
        formatMenu->addAction(setLineSpacingAct);
        formatMenu->addAction(setParagraphSpacingAct);
    }