mainwindow.cpp Example File

mainwindows/mdi/mainwindow.cpp
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#include <QtWidgets>

#include "mainwindow.h"
#include "mdichild.h"

MainWindow::MainWindow()
    : mdiArea(new QMdiArea)
{
    mdiArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    mdiArea->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    setCentralWidget(mdiArea);
    connect(mdiArea, &QMdiArea::subWindowActivated,
            this, &MainWindow::updateMenus);

    createActions();
    createStatusBar();
    updateMenus();

    readSettings();

    setWindowTitle(tr("MDI"));
    setUnifiedTitleAndToolBarOnMac(true);
}

void MainWindow::closeEvent(QCloseEvent *event)
{
    mdiArea->closeAllSubWindows();
    if (mdiArea->currentSubWindow()) {
        event->ignore();
    } else {
        writeSettings();
        event->accept();
    }
}

void MainWindow::newFile()
{
    MdiChild *child = createMdiChild();
    child->newFile();
    child->show();
}

void MainWindow::open()
{
    const QString fileName = QFileDialog::getOpenFileName(this);
    if (!fileName.isEmpty())
        openFile(fileName);
}

bool MainWindow::openFile(const QString &fileName)
{
    if (QMdiSubWindow *existing = findMdiChild(fileName)) {
        mdiArea->setActiveSubWindow(existing);
        return true;
    }
    const bool succeeded = loadFile(fileName);
    if (succeeded)
        statusBar()->showMessage(tr("File loaded"), 2000);
    return succeeded;
}

bool MainWindow::loadFile(const QString &fileName)
{
    MdiChild *child = createMdiChild();
    const bool succeeded = child->loadFile(fileName);
    if (succeeded)
        child->show();
    else
        child->close();
    MainWindow::prependToRecentFiles(fileName);
    return succeeded;
}

static inline QString recentFilesKey() { return QStringLiteral("recentFileList"); }
static inline QString fileKey() { return QStringLiteral("file"); }

static QStringList readRecentFiles(QSettings &settings)
{
    QStringList result;
    const int count = settings.beginReadArray(recentFilesKey());
    for (int i = 0; i < count; ++i) {
        settings.setArrayIndex(i);
        result.append(settings.value(fileKey()).toString());
    }
    settings.endArray();
    return result;
}

static void writeRecentFiles(const QStringList &files, QSettings &settings)
{
    const int count = files.size();
    settings.beginWriteArray(recentFilesKey());
    for (int i = 0; i < count; ++i) {
        settings.setArrayIndex(i);
        settings.setValue(fileKey(), files.at(i));
    }
    settings.endArray();
}

bool MainWindow::hasRecentFiles()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());
    const int count = settings.beginReadArray(recentFilesKey());
    settings.endArray();
    return count > 0;
}

void MainWindow::prependToRecentFiles(const QString &fileName)
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());

    const QStringList oldRecentFiles = readRecentFiles(settings);
    QStringList recentFiles = oldRecentFiles;
    recentFiles.removeAll(fileName);
    recentFiles.prepend(fileName);
    if (oldRecentFiles != recentFiles)
        writeRecentFiles(recentFiles, settings);

    setRecentFilesVisible(!recentFiles.isEmpty());
}

void MainWindow::setRecentFilesVisible(bool visible)
{
    recentFileSubMenuAct->setVisible(visible);
    recentFileSeparator->setVisible(visible);
}

void MainWindow::updateRecentFileActions()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());

    const QStringList recentFiles = readRecentFiles(settings);
    const int count = qMin(int(MaxRecentFiles), recentFiles.size());
    int i = 0;
    for ( ; i < count; ++i) {
        const QString fileName = QFileInfo(recentFiles.at(i)).fileName();
        recentFileActs[i]->setText(tr("&%1 %2").arg(i + 1).arg(fileName));
        recentFileActs[i]->setData(recentFiles.at(i));
        recentFileActs[i]->setVisible(true);
    }
    for ( ; i < MaxRecentFiles; ++i)
        recentFileActs[i]->setVisible(false);
}

void MainWindow::openRecentFile()
{
    if (const QAction *action = qobject_cast<const QAction *>(sender()))
        openFile(action->data().toString());
}

void MainWindow::save()
{
    if (activeMdiChild() && activeMdiChild()->save())
        statusBar()->showMessage(tr("File saved"), 2000);
}

void MainWindow::saveAs()
{
    MdiChild *child = activeMdiChild();
    if (child && child->saveAs()) {
        statusBar()->showMessage(tr("File saved"), 2000);
        MainWindow::prependToRecentFiles(child->currentFile());
    }
}

#ifndef QT_NO_CLIPBOARD
void MainWindow::cut()
{
    if (activeMdiChild())
        activeMdiChild()->cut();
}

void MainWindow::copy()
{
    if (activeMdiChild())
        activeMdiChild()->copy();
}

void MainWindow::paste()
{
    if (activeMdiChild())
        activeMdiChild()->paste();
}
#endif

void MainWindow::about()
{
   QMessageBox::about(this, tr("About MDI"),
            tr("The <b>MDI</b> example demonstrates how to write multiple "
               "document interface applications using Qt."));
}

void MainWindow::updateMenus()
{
    bool hasMdiChild = (activeMdiChild() != 0);
    saveAct->setEnabled(hasMdiChild);
    saveAsAct->setEnabled(hasMdiChild);
#ifndef QT_NO_CLIPBOARD
    pasteAct->setEnabled(hasMdiChild);
#endif
    closeAct->setEnabled(hasMdiChild);
    closeAllAct->setEnabled(hasMdiChild);
    tileAct->setEnabled(hasMdiChild);
    cascadeAct->setEnabled(hasMdiChild);
    nextAct->setEnabled(hasMdiChild);
    previousAct->setEnabled(hasMdiChild);
    windowMenuSeparatorAct->setVisible(hasMdiChild);

#ifndef QT_NO_CLIPBOARD
    bool hasSelection = (activeMdiChild() &&
                         activeMdiChild()->textCursor().hasSelection());
    cutAct->setEnabled(hasSelection);
    copyAct->setEnabled(hasSelection);
#endif
}

void MainWindow::updateWindowMenu()
{
    windowMenu->clear();
    windowMenu->addAction(closeAct);
    windowMenu->addAction(closeAllAct);
    windowMenu->addSeparator();
    windowMenu->addAction(tileAct);
    windowMenu->addAction(cascadeAct);
    windowMenu->addSeparator();
    windowMenu->addAction(nextAct);
    windowMenu->addAction(previousAct);
    windowMenu->addAction(windowMenuSeparatorAct);

    QList<QMdiSubWindow *> windows = mdiArea->subWindowList();
    windowMenuSeparatorAct->setVisible(!windows.isEmpty());

    for (int i = 0; i < windows.size(); ++i) {
        QMdiSubWindow *mdiSubWindow = windows.at(i);
        MdiChild *child = qobject_cast<MdiChild *>(mdiSubWindow->widget());

        QString text;
        if (i < 9) {
            text = tr("&%1 %2").arg(i + 1)
                               .arg(child->userFriendlyCurrentFile());
        } else {
            text = tr("%1 %2").arg(i + 1)
                              .arg(child->userFriendlyCurrentFile());
        }
        QAction *action = windowMenu->addAction(text, mdiSubWindow, [this, mdiSubWindow]() {
            mdiArea->setActiveSubWindow(mdiSubWindow);
        });
        action->setCheckable(true);
        action ->setChecked(child == activeMdiChild());
    }
}

MdiChild *MainWindow::createMdiChild()
{
    MdiChild *child = new MdiChild;
    mdiArea->addSubWindow(child);

#ifndef QT_NO_CLIPBOARD
    connect(child, &QTextEdit::copyAvailable, cutAct, &QAction::setEnabled);
    connect(child, &QTextEdit::copyAvailable, copyAct, &QAction::setEnabled);
#endif

    return child;
}

void MainWindow::createActions()
{
    QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
    QToolBar *fileToolBar = addToolBar(tr("File"));

    const QIcon newIcon = QIcon::fromTheme("document-new", QIcon(":/images/new.png"));
    newAct = new QAction(newIcon, tr("&New"), this);
    newAct->setShortcuts(QKeySequence::New);
    newAct->setStatusTip(tr("Create a new file"));
    connect(newAct, &QAction::triggered, this, &MainWindow::newFile);
    fileMenu->addAction(newAct);
    fileToolBar->addAction(newAct);

    const QIcon openIcon = QIcon::fromTheme("document-open", QIcon(":/images/open.png"));
    QAction *openAct = new QAction(openIcon, tr("&Open..."), this);
    openAct->setShortcuts(QKeySequence::Open);
    openAct->setStatusTip(tr("Open an existing file"));
    connect(openAct, &QAction::triggered, this, &MainWindow::open);
    fileMenu->addAction(openAct);
    fileToolBar->addAction(openAct);

    const QIcon saveIcon = QIcon::fromTheme("document-save", QIcon(":/images/save.png"));
    saveAct = new QAction(saveIcon, tr("&Save"), this);
    saveAct->setShortcuts(QKeySequence::Save);
    saveAct->setStatusTip(tr("Save the document to disk"));
    connect(saveAct, &QAction::triggered, this, &MainWindow::save);
    fileToolBar->addAction(saveAct);

    const QIcon saveAsIcon = QIcon::fromTheme("document-save-as");
    saveAsAct = new QAction(saveAsIcon, tr("Save &As..."), this);
    saveAsAct->setShortcuts(QKeySequence::SaveAs);
    saveAsAct->setStatusTip(tr("Save the document under a new name"));
    connect(saveAsAct, &QAction::triggered, this, &MainWindow::saveAs);
    fileMenu->addAction(saveAsAct);

    fileMenu->addSeparator();

    QMenu *recentMenu = fileMenu->addMenu(tr("Recent..."));
    connect(recentMenu, &QMenu::aboutToShow, this, &MainWindow::updateRecentFileActions);
    recentFileSubMenuAct = recentMenu->menuAction();

    for (int i = 0; i < MaxRecentFiles; ++i) {
        recentFileActs[i] = recentMenu->addAction(QString(), this, &MainWindow::openRecentFile);
        recentFileActs[i]->setVisible(false);
    }

    recentFileSeparator = fileMenu->addSeparator();

    setRecentFilesVisible(MainWindow::hasRecentFiles());

    fileMenu->addAction(tr("Switch layout direction"), this, &MainWindow::switchLayoutDirection);

    fileMenu->addSeparator();

    const QIcon exitIcon = QIcon::fromTheme("application-exit");
    QAction *exitAct = fileMenu->addAction(exitIcon, tr("E&xit"), qApp, &QApplication::closeAllWindows);
    exitAct->setShortcuts(QKeySequence::Quit);
    exitAct->setStatusTip(tr("Exit the application"));
    fileMenu->addAction(exitAct);

#ifndef QT_NO_CLIPBOARD
    QMenu *editMenu = menuBar()->addMenu(tr("&Edit"));
    QToolBar *editToolBar = addToolBar(tr("Edit"));

    const QIcon cutIcon = QIcon::fromTheme("edit-cut", QIcon(":/images/cut.png"));
    cutAct = new QAction(cutIcon, tr("Cu&t"), this);
    cutAct->setShortcuts(QKeySequence::Cut);
    cutAct->setStatusTip(tr("Cut the current selection's contents to the "
                            "clipboard"));
    connect(cutAct, &QAction::triggered, this, &MainWindow::cut);
    editMenu->addAction(cutAct);
    editToolBar->addAction(cutAct);

    const QIcon copyIcon = QIcon::fromTheme("edit-copy", QIcon(":/images/copy.png"));
    copyAct = new QAction(copyIcon, tr("&Copy"), this);
    copyAct->setShortcuts(QKeySequence::Copy);
    copyAct->setStatusTip(tr("Copy the current selection's contents to the "
                             "clipboard"));
    connect(copyAct, &QAction::triggered, this, &MainWindow::copy);
    editMenu->addAction(copyAct);
    editToolBar->addAction(copyAct);

    const QIcon pasteIcon = QIcon::fromTheme("edit-paste", QIcon(":/images/paste.png"));
    pasteAct = new QAction(pasteIcon, tr("&Paste"), this);
    pasteAct->setShortcuts(QKeySequence::Paste);
    pasteAct->setStatusTip(tr("Paste the clipboard's contents into the current "
                              "selection"));
    connect(pasteAct, &QAction::triggered, this, &MainWindow::paste);
    editMenu->addAction(pasteAct);
    editToolBar->addAction(pasteAct);
#endif

    windowMenu = menuBar()->addMenu(tr("&Window"));
    connect(windowMenu, &QMenu::aboutToShow, this, &MainWindow::updateWindowMenu);

    closeAct = new QAction(tr("Cl&ose"), this);
    closeAct->setStatusTip(tr("Close the active window"));
    connect(closeAct, &QAction::triggered,
            mdiArea, &QMdiArea::closeActiveSubWindow);

    closeAllAct = new QAction(tr("Close &All"), this);
    closeAllAct->setStatusTip(tr("Close all the windows"));
    connect(closeAllAct, &QAction::triggered, mdiArea, &QMdiArea::closeAllSubWindows);

    tileAct = new QAction(tr("&Tile"), this);
    tileAct->setStatusTip(tr("Tile the windows"));
    connect(tileAct, &QAction::triggered, mdiArea, &QMdiArea::tileSubWindows);

    cascadeAct = new QAction(tr("&Cascade"), this);
    cascadeAct->setStatusTip(tr("Cascade the windows"));
    connect(cascadeAct, &QAction::triggered, mdiArea, &QMdiArea::cascadeSubWindows);

    nextAct = new QAction(tr("Ne&xt"), this);
    nextAct->setShortcuts(QKeySequence::NextChild);
    nextAct->setStatusTip(tr("Move the focus to the next window"));
    connect(nextAct, &QAction::triggered, mdiArea, &QMdiArea::activateNextSubWindow);

    previousAct = new QAction(tr("Pre&vious"), this);
    previousAct->setShortcuts(QKeySequence::PreviousChild);
    previousAct->setStatusTip(tr("Move the focus to the previous "
                                 "window"));
    connect(previousAct, &QAction::triggered, mdiArea, &QMdiArea::activatePreviousSubWindow);

    windowMenuSeparatorAct = new QAction(this);
    windowMenuSeparatorAct->setSeparator(true);

    updateWindowMenu();

    menuBar()->addSeparator();

    QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));

    QAction *aboutAct = helpMenu->addAction(tr("&About"), this, &MainWindow::about);
    aboutAct->setStatusTip(tr("Show the application's About box"));

    QAction *aboutQtAct = helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
    aboutQtAct->setStatusTip(tr("Show the Qt library's About box"));
}

void MainWindow::createStatusBar()
{
    statusBar()->showMessage(tr("Ready"));
}

void MainWindow::readSettings()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());
    const QByteArray geometry = settings.value("geometry", QByteArray()).toByteArray();
    if (geometry.isEmpty()) {
        const QRect availableGeometry = QApplication::desktop()->availableGeometry(this);
        resize(availableGeometry.width() / 3, availableGeometry.height() / 2);
        move((availableGeometry.width() - width()) / 2,
             (availableGeometry.height() - height()) / 2);
    } else {
        restoreGeometry(geometry);
    }
}

void MainWindow::writeSettings()
{
    QSettings settings(QCoreApplication::organizationName(), QCoreApplication::applicationName());
    settings.setValue("geometry", saveGeometry());
}

MdiChild *MainWindow::activeMdiChild() const
{
    if (QMdiSubWindow *activeSubWindow = mdiArea->activeSubWindow())
        return qobject_cast<MdiChild *>(activeSubWindow->widget());
    return 0;
}

QMdiSubWindow *MainWindow::findMdiChild(const QString &fileName) const
{
    QString canonicalFilePath = QFileInfo(fileName).canonicalFilePath();

    foreach (QMdiSubWindow *window, mdiArea->subWindowList()) {
        MdiChild *mdiChild = qobject_cast<MdiChild *>(window->widget());
        if (mdiChild->currentFile() == canonicalFilePath)
            return window;
    }
    return 0;
}

void MainWindow::switchLayoutDirection()
{
    if (layoutDirection() == Qt::LeftToRight)
        QGuiApplication::setLayoutDirection(Qt::RightToLeft);
    else
        QGuiApplication::setLayoutDirection(Qt::LeftToRight);
}

© 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.