mainwindow.cpp Example File

widgets/tablet/mainwindow.cpp 
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 #include <QtWidgets>

 #include "mainwindow.h"
 #include "tabletcanvas.h"

 MainWindow::MainWindow(TabletCanvas *canvas)
   : m_canvas(canvas), m_colorDialog(nullptr)
 {
     createMenus();
     setWindowTitle(tr("Tablet Example"));
     setCentralWidget(m_canvas);
     QCoreApplication::setAttribute(Qt::AA_CompressHighFrequencyEvents);
 }

 void MainWindow::setBrushColor()
 {
     if (!m_colorDialog) {
         m_colorDialog = new QColorDialog(this);
         m_colorDialog->setModal(false);
         m_colorDialog->setCurrentColor(m_canvas->color());
         connect(m_colorDialog, &QColorDialog::colorSelected, m_canvas, &TabletCanvas::setColor);
     }
     m_colorDialog->setVisible(true);
 }

 void MainWindow::setAlphaValuator(QAction *action)
 {
     m_canvas->setAlphaChannelValuator(action->data().value<TabletCanvas::Valuator>());
 }

 void MainWindow::setLineWidthValuator(QAction *action)
 {
     m_canvas->setLineWidthType(action->data().value<TabletCanvas::Valuator>());
 }

 void MainWindow::setSaturationValuator(QAction *action)
 {
     m_canvas->setColorSaturationValuator(action->data().value<TabletCanvas::Valuator>());
 }

 void MainWindow::setEventCompression(bool compress)
 {
     QCoreApplication::setAttribute(Qt::AA_CompressTabletEvents, compress);
 }

 bool MainWindow::save()
 {
     QString path = QDir::currentPath() + "/untitled.png";
     QString fileName = QFileDialog::getSaveFileName(this, tr("Save Picture"),
                              path);
     bool success = m_canvas->saveImage(fileName);
     if (!success)
         QMessageBox::information(this, "Error Saving Picture",
                                  "Could not save the image");
     return success;
 }

 void MainWindow::load()
 {
     QString fileName = QFileDialog::getOpenFileName(this, tr("Open Picture"),
                                                     QDir::currentPath());

     if (!m_canvas->loadImage(fileName))
         QMessageBox::information(this, "Error Opening Picture",
                                  "Could not open picture");
 }

 void MainWindow::clear()
 {
     if (QMessageBox::question(this, tr("Save changes"), tr("Do you want to save your changes?"),
                               QMessageBox::Save | QMessageBox::Discard | QMessageBox::Cancel,
                               QMessageBox::Save) != QMessageBox::Save || save())
         m_canvas->clear();
 }

 void MainWindow::about()
 {
     QMessageBox::about(this, tr("About Tablet Example"),
                        tr("This example shows how to use a graphics drawing tablet in Qt."));
 }

 void MainWindow::createMenus()
 {
     QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(tr("&Open..."), this, &MainWindow::load, QKeySequence::Open);
     fileMenu->addAction(tr("&Save As..."), this, &MainWindow::save, QKeySequence::SaveAs);
     fileMenu->addAction(tr("&New"), this, &MainWindow::clear, QKeySequence::New);
     fileMenu->addAction(tr("E&xit"), this, &MainWindow::close, QKeySequence::Quit);

     QMenu *brushMenu = menuBar()->addMenu(tr("&Brush"));
     brushMenu->addAction(tr("&Brush Color..."), this, &MainWindow::setBrushColor, tr("Ctrl+B"));

     QMenu *tabletMenu = menuBar()->addMenu(tr("&Tablet"));
     QMenu *lineWidthMenu = tabletMenu->addMenu(tr("&Line Width"));

     QAction *lineWidthPressureAction = lineWidthMenu->addAction(tr("&Pressure"));
     lineWidthPressureAction->setData(TabletCanvas::PressureValuator);
     lineWidthPressureAction->setCheckable(true);
     lineWidthPressureAction->setChecked(true);

     QAction *lineWidthTiltAction = lineWidthMenu->addAction(tr("&Tilt"));
     lineWidthTiltAction->setData(TabletCanvas::TiltValuator);
     lineWidthTiltAction->setCheckable(true);

     QAction *lineWidthFixedAction = lineWidthMenu->addAction(tr("&Fixed"));
     lineWidthFixedAction->setData(TabletCanvas::NoValuator);
     lineWidthFixedAction->setCheckable(true);

     QActionGroup *lineWidthGroup = new QActionGroup(this);
     lineWidthGroup->addAction(lineWidthPressureAction);
     lineWidthGroup->addAction(lineWidthTiltAction);
     lineWidthGroup->addAction(lineWidthFixedAction);
     connect(lineWidthGroup, &QActionGroup::triggered, this,
             &MainWindow::setLineWidthValuator);

     QMenu *alphaChannelMenu = tabletMenu->addMenu(tr("&Alpha Channel"));
     QAction *alphaChannelPressureAction = alphaChannelMenu->addAction(tr("&Pressure"));
     alphaChannelPressureAction->setData(TabletCanvas::PressureValuator);
     alphaChannelPressureAction->setCheckable(true);

     QAction *alphaChannelTangentialPressureAction = alphaChannelMenu->addAction(tr("T&angential Pressure"));
     alphaChannelTangentialPressureAction->setData(TabletCanvas::TangentialPressureValuator);
     alphaChannelTangentialPressureAction->setCheckable(true);
     alphaChannelTangentialPressureAction->setChecked(true);

     QAction *alphaChannelTiltAction = alphaChannelMenu->addAction(tr("&Tilt"));
     alphaChannelTiltAction->setData(TabletCanvas::TiltValuator);
     alphaChannelTiltAction->setCheckable(true);

     QAction *noAlphaChannelAction = alphaChannelMenu->addAction(tr("No Alpha Channel"));
     noAlphaChannelAction->setData(TabletCanvas::NoValuator);
     noAlphaChannelAction->setCheckable(true);

     QActionGroup *alphaChannelGroup = new QActionGroup(this);
     alphaChannelGroup->addAction(alphaChannelPressureAction);
     alphaChannelGroup->addAction(alphaChannelTangentialPressureAction);
     alphaChannelGroup->addAction(alphaChannelTiltAction);
     alphaChannelGroup->addAction(noAlphaChannelAction);
     connect(alphaChannelGroup, &QActionGroup::triggered,
             this, &MainWindow::setAlphaValuator);

     QMenu *colorSaturationMenu = tabletMenu->addMenu(tr("&Color Saturation"));

     QAction *colorSaturationVTiltAction = colorSaturationMenu->addAction(tr("&Vertical Tilt"));
     colorSaturationVTiltAction->setData(TabletCanvas::VTiltValuator);
     colorSaturationVTiltAction->setCheckable(true);

     QAction *colorSaturationHTiltAction = colorSaturationMenu->addAction(tr("&Horizontal Tilt"));
     colorSaturationHTiltAction->setData(TabletCanvas::HTiltValuator);
     colorSaturationHTiltAction->setCheckable(true);

     QAction *colorSaturationPressureAction = colorSaturationMenu->addAction(tr("&Pressure"));
     colorSaturationPressureAction->setData(TabletCanvas::PressureValuator);
     colorSaturationPressureAction->setCheckable(true);

     QAction *noColorSaturationAction = colorSaturationMenu->addAction(tr("&No Color Saturation"));
     noColorSaturationAction->setData(TabletCanvas::NoValuator);
     noColorSaturationAction->setCheckable(true);
     noColorSaturationAction->setChecked(true);

     QActionGroup *colorSaturationGroup = new QActionGroup(this);
     colorSaturationGroup->addAction(colorSaturationVTiltAction);
     colorSaturationGroup->addAction(colorSaturationHTiltAction);
     colorSaturationGroup->addAction(colorSaturationPressureAction);
     colorSaturationGroup->addAction(noColorSaturationAction);
     connect(colorSaturationGroup, &QActionGroup::triggered,
             this, &MainWindow::setSaturationValuator);

     QAction *compressAction = tabletMenu->addAction(tr("Co&mpress events"));
     compressAction->setCheckable(true);
     connect(compressAction, &QAction::toggled, this, &MainWindow::setEventCompression);

     QMenu *helpMenu = menuBar()->addMenu("&Help");
     helpMenu->addAction(tr("A&bout"), this, &MainWindow::about);
     helpMenu->addAction(tr("About &Qt"), qApp, &QApplication::aboutQt);
 }

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