mainwindow.cpp Example File

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#include <QtWidgets> #include "mainwindow.h" MainWindow::MainWindow() { init(); setCurrentFile(QString()); } MainWindow::MainWindow(const QString &fileName) { init(); loadFile(fileName); } void MainWindow::closeEvent(QCloseEvent *event) { if (maybeSave()) { writeSettings(); event->accept(); } else { event->ignore(); } } void MainWindow::newFile() { MainWindow *other = new MainWindow; other->tile(this); other->show(); } void MainWindow::open() { const QString fileName = QFileDialog::getOpenFileName(this); if (!fileName.isEmpty()) openFile(fileName); } void MainWindow::openFile(const QString &fileName) { MainWindow *existing = findMainWindow(fileName); if (existing) { existing->show(); existing->raise(); existing->activateWindow(); return; } if (isUntitled && textEdit->document()->isEmpty() && !isWindowModified()) { loadFile(fileName); return; } MainWindow *other = new MainWindow(fileName); if (other->isUntitled) { delete other; return; } other->tile(this); other->show(); } bool MainWindow::save() { return isUntitled ? saveAs() : saveFile(curFile); } bool MainWindow::saveAs() { QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"), curFile); if (fileName.isEmpty()) return false; return saveFile(fileName); } void MainWindow::about() { QMessageBox::about(this, tr("About SDI"), tr("The <b>SDI</b> example demonstrates how to write single " "document interface applications using Qt.")); } void MainWindow::documentWasModified() { setWindowModified(true); } void MainWindow::init() { setAttribute(Qt::WA_DeleteOnClose); isUntitled = true; textEdit = new QTextEdit; setCentralWidget(textEdit); createActions(); createStatusBar(); readSettings(); connect(textEdit->document(), &QTextDocument::contentsChanged, this, &MainWindow::documentWasModified); setUnifiedTitleAndToolBarOnMac(true); } void MainWindow::tile(const QMainWindow *previous) { if (!previous) return; int topFrameWidth = previous->geometry().top() - previous->pos().y(); if (!topFrameWidth) topFrameWidth = 40; const QPoint pos = previous->pos() + 2 * QPoint(topFrameWidth, topFrameWidth); if (QApplication::desktop()->availableGeometry(this).contains(rect().bottomRight() + pos)) move(pos); } 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")); QAction *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")); QAction *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); fileMenu->addAction(saveAct); fileToolBar->addAction(saveAct); const QIcon saveAsIcon = QIcon::fromTheme("document-save-as"); QAction *saveAsAct = fileMenu->addAction(saveAsIcon, tr("Save &As..."), this, &MainWindow::saveAs); saveAsAct->setShortcuts(QKeySequence::SaveAs); saveAsAct->setStatusTip(tr("Save the document under a new name")); 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()); QAction *closeAct = fileMenu->addAction(tr("&Close"), this, &QWidget::close); closeAct->setShortcut(tr("Ctrl+W")); closeAct->setStatusTip(tr("Close this window")); 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")); QMenu *editMenu = menuBar()->addMenu(tr("&Edit")); QToolBar *editToolBar = addToolBar(tr("Edit")); #ifndef QT_NO_CLIPBOARD const QIcon cutIcon = QIcon::fromTheme("edit-cut", QIcon(":/images/cut.png")); QAction *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, textEdit, &QTextEdit::cut); editMenu->addAction(cutAct); editToolBar->addAction(cutAct); const QIcon copyIcon = QIcon::fromTheme("edit-copy", QIcon(":/images/copy.png")); QAction *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, textEdit, &QTextEdit::copy); editMenu->addAction(copyAct); editToolBar->addAction(copyAct); const QIcon pasteIcon = QIcon::fromTheme("edit-paste", QIcon(":/images/paste.png")); QAction *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, textEdit, &QTextEdit::paste); editMenu->addAction(pasteAct); editToolBar->addAction(pasteAct); menuBar()->addSeparator(); #endif // !QT_NO_CLIPBOARD 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")); #ifndef QT_NO_CLIPBOARD cutAct->setEnabled(false); copyAct->setEnabled(false); connect(textEdit, &QTextEdit::copyAvailable, cutAct, &QAction::setEnabled); connect(textEdit, &QTextEdit::copyAvailable, copyAct, &QAction::setEnabled); #endif // !QT_NO_CLIPBOARD } 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()); } bool MainWindow::maybeSave() { if (!textEdit->document()->isModified()) return true; const QMessageBox::StandardButton ret = QMessageBox::warning(this, tr("SDI"), tr("The document has been modified.\n" "Do you want to save your changes?"), QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel); switch (ret) { case QMessageBox::Save: return save(); case QMessageBox::Cancel: return false; default: break; } return true; } void MainWindow::loadFile(const QString &fileName) { QFile file(fileName); if (! | QFile::Text)) { QMessageBox::warning(this, tr("SDI"), tr("Cannot read file %1:\n%2.") .arg(QDir::toNativeSeparators(fileName), file.errorString())); return; } QTextStream in(&file); QApplication::setOverrideCursor(Qt::WaitCursor); textEdit->setPlainText(in.readAll()); QApplication::restoreOverrideCursor(); setCurrentFile(fileName); statusBar()->showMessage(tr("File loaded"), 2000); } void MainWindow::setRecentFilesVisible(bool visible) { recentFileSubMenuAct->setVisible(visible); recentFileSeparator->setVisible(visible); } 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(),; } 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::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 = MainWindow::strippedName(; recentFileActs[i]->setText(tr("&%1 %2").arg(i + 1).arg(fileName)); recentFileActs[i]->setData(; 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()); } bool MainWindow::saveFile(const QString &fileName) { QFile file(fileName); if (! | QFile::Text)) { QMessageBox::warning(this, tr("SDI"), tr("Cannot write file %1:\n%2.") .arg(QDir::toNativeSeparators(fileName), file.errorString())); return false; } QTextStream out(&file); QApplication::setOverrideCursor(Qt::WaitCursor); out << textEdit->toPlainText(); QApplication::restoreOverrideCursor(); setCurrentFile(fileName); statusBar()->showMessage(tr("File saved"), 2000); return true; } void MainWindow::setCurrentFile(const QString &fileName) { static int sequenceNumber = 1; isUntitled = fileName.isEmpty(); if (isUntitled) { curFile = tr("document%1.txt").arg(sequenceNumber++); } else { curFile = QFileInfo(fileName).canonicalFilePath(); } textEdit->document()->setModified(false); setWindowModified(false); if (!isUntitled && windowFilePath() != curFile) MainWindow::prependToRecentFiles(curFile); setWindowFilePath(curFile); } QString MainWindow::strippedName(const QString &fullFileName) { return QFileInfo(fullFileName).fileName(); } MainWindow *MainWindow::findMainWindow(const QString &fileName) const { QString canonicalFilePath = QFileInfo(fileName).canonicalFilePath(); foreach (QWidget *widget, QApplication::topLevelWidgets()) { MainWindow *mainWin = qobject_cast<MainWindow *>(widget); if (mainWin && mainWin->curFile == canonicalFilePath) return mainWin; } return 0; }

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