mainwindow.cpp Example File

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#include <QtWidgets> #include "mainwindow.h" #include "scribblearea.h" MainWindow::MainWindow() { scribbleArea = new ScribbleArea; setCentralWidget(scribbleArea); createActions(); createMenus(); setWindowTitle(tr("Scribble")); resize(500, 500); } void MainWindow::closeEvent(QCloseEvent *event) { if (maybeSave()) { event->accept(); } else { event->ignore(); } } void MainWindow::open() { if (maybeSave()) { QString fileName = QFileDialog::getOpenFileName(this, tr("Open File"), QDir::currentPath()); if (!fileName.isEmpty()) scribbleArea->openImage(fileName); } } void MainWindow::save() { QAction *action = qobject_cast<QAction *>(sender()); QByteArray fileFormat = action->data().toByteArray(); saveFile(fileFormat); } void MainWindow::penColor() { QColor newColor = QColorDialog::getColor(scribbleArea->penColor()); if (newColor.isValid()) scribbleArea->setPenColor(newColor); } void MainWindow::penWidth() { bool ok; int newWidth = QInputDialog::getInt(this, tr("Scribble"), tr("Select pen width:"), scribbleArea->penWidth(), 1, 50, 1, &ok); if (ok) scribbleArea->setPenWidth(newWidth); } void MainWindow::about() { QMessageBox::about(this, tr("About Scribble"), tr("<p>The <b>Scribble</b> example shows how to use QMainWindow as the " "base widget for an application, and how to reimplement some of " "QWidget's event handlers to receive the events generated for " "the application's widgets:</p><p> We reimplement the mouse event " "handlers to facilitate drawing, the paint event handler to " "update the application and the resize event handler to optimize " "the application's appearance. In addition we reimplement the " "close event handler to intercept the close events before " "terminating the application.</p><p> The example also demonstrates " "how to use QPainter to draw an image in real time, as well as " "to repaint widgets.</p>")); } void MainWindow::createActions() { openAct = new QAction(tr("&Open..."), this); openAct->setShortcuts(QKeySequence::Open); connect(openAct, SIGNAL(triggered()), this, SLOT(open())); foreach (QByteArray format, QImageWriter::supportedImageFormats()) { QString text = tr("%1...").arg(QString(format).toUpper()); QAction *action = new QAction(text, this); action->setData(format); connect(action, SIGNAL(triggered()), this, SLOT(save())); saveAsActs.append(action); } printAct = new QAction(tr("&Print..."), this); connect(printAct, SIGNAL(triggered()), scribbleArea, SLOT(print())); exitAct = new QAction(tr("E&xit"), this); exitAct->setShortcuts(QKeySequence::Quit); connect(exitAct, SIGNAL(triggered()), this, SLOT(close())); penColorAct = new QAction(tr("&Pen Color..."), this); connect(penColorAct, SIGNAL(triggered()), this, SLOT(penColor())); penWidthAct = new QAction(tr("Pen &Width..."), this); connect(penWidthAct, SIGNAL(triggered()), this, SLOT(penWidth())); clearScreenAct = new QAction(tr("&Clear Screen"), this); clearScreenAct->setShortcut(tr("Ctrl+L")); connect(clearScreenAct, SIGNAL(triggered()), scribbleArea, SLOT(clearImage())); aboutAct = new QAction(tr("&About"), this); connect(aboutAct, SIGNAL(triggered()), this, SLOT(about())); aboutQtAct = new QAction(tr("About &Qt"), this); connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt())); } void MainWindow::createMenus() { saveAsMenu = new QMenu(tr("&Save As"), this); foreach (QAction *action, saveAsActs) saveAsMenu->addAction(action); fileMenu = new QMenu(tr("&File"), this); fileMenu->addAction(openAct); fileMenu->addMenu(saveAsMenu); fileMenu->addAction(printAct); fileMenu->addSeparator(); fileMenu->addAction(exitAct); optionMenu = new QMenu(tr("&Options"), this); optionMenu->addAction(penColorAct); optionMenu->addAction(penWidthAct); optionMenu->addSeparator(); optionMenu->addAction(clearScreenAct); helpMenu = new QMenu(tr("&Help"), this); helpMenu->addAction(aboutAct); helpMenu->addAction(aboutQtAct); menuBar()->addMenu(fileMenu); menuBar()->addMenu(optionMenu); menuBar()->addMenu(helpMenu); } bool MainWindow::maybeSave() { if (scribbleArea->isModified()) { QMessageBox::StandardButton ret; ret = QMessageBox::warning(this, tr("Scribble"), tr("The image has been modified.\n" "Do you want to save your changes?"), QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel); if (ret == QMessageBox::Save) { return saveFile("png"); } else if (ret == QMessageBox::Cancel) { return false; } } return true; } bool MainWindow::saveFile(const QByteArray &fileFormat) { QString initialPath = QDir::currentPath() + "/untitled." + fileFormat; QString fileName = QFileDialog::getSaveFileName(this, tr("Save As"), initialPath, tr("%1 Files (*.%2);;All Files (*)") .arg(QString::fromLatin1(fileFormat.toUpper())) .arg(QString::fromLatin1(fileFormat))); if (fileName.isEmpty()) { return false; } else { return scribbleArea->saveImage(fileName, fileFormat.constData()); } }

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