mainwindow.cpp Example File
opengl/grabber/mainwindow.cpp

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 #include <QtGui>
 #include <QtOpenGL>

 #include "glwidget.h"
 #include "mainwindow.h"

 MainWindow::MainWindow()
 {
     centralWidget = new QWidget;
     setCentralWidget(centralWidget);

     glWidget = new GLWidget;
     pixmapLabel = new QLabel;

     glWidgetArea = new QScrollArea;
     glWidgetArea->setWidget(glWidget);
     glWidgetArea->setWidgetResizable(true);
     glWidgetArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     glWidgetArea->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     glWidgetArea->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
     glWidgetArea->setMinimumSize(50, 50);

     pixmapLabelArea = new QScrollArea;
     pixmapLabelArea->setWidget(pixmapLabel);
     pixmapLabelArea->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Ignored);
     pixmapLabelArea->setMinimumSize(50, 50);

     xSlider = createSlider(SIGNAL(xRotationChanged(int)),
                            SLOT(setXRotation(int)));
     ySlider = createSlider(SIGNAL(yRotationChanged(int)),
                            SLOT(setYRotation(int)));
     zSlider = createSlider(SIGNAL(zRotationChanged(int)),
                            SLOT(setZRotation(int)));

     createActions();
     createMenus();

     QGridLayout *centralLayout = new QGridLayout;
     centralLayout->addWidget(glWidgetArea, 0, 0);
     centralLayout->addWidget(pixmapLabelArea, 0, 1);
     centralLayout->addWidget(xSlider, 1, 0, 1, 2);
     centralLayout->addWidget(ySlider, 2, 0, 1, 2);
     centralLayout->addWidget(zSlider, 3, 0, 1, 2);
     centralWidget->setLayout(centralLayout);

     xSlider->setValue(15 * 16);
     ySlider->setValue(345 * 16);
     zSlider->setValue(0 * 16);

     setWindowTitle(tr("Grabber"));
     resize(400, 300);
 }

 void MainWindow::renderIntoPixmap()
 {
     QSize size = getSize();
     if (size.isValid()) {
         QPixmap pixmap = glWidget->renderPixmap(size.width(), size.height());
         setPixmap(pixmap);
     }
 }

 void MainWindow::grabFrameBuffer()
 {
     QImage image = glWidget->grabFrameBuffer();
     setPixmap(QPixmap::fromImage(image));
 }

 void MainWindow::clearPixmap()
 {
     setPixmap(QPixmap());
 }

 void MainWindow::about()
 {
     QMessageBox::about(this, tr("About Grabber"),
             tr("The <b>Grabber</b> example demonstrates two approaches for "
                "rendering OpenGL into a Qt pixmap."));
 }

 void MainWindow::createActions()
 {
     renderIntoPixmapAct = new QAction(tr("&Render into Pixmap..."), this);
     renderIntoPixmapAct->setShortcut(tr("Ctrl+R"));
     connect(renderIntoPixmapAct, SIGNAL(triggered()),
             this, SLOT(renderIntoPixmap()));

     grabFrameBufferAct = new QAction(tr("&Grab Frame Buffer"), this);
     grabFrameBufferAct->setShortcut(tr("Ctrl+G"));
     connect(grabFrameBufferAct, SIGNAL(triggered()),
             this, SLOT(grabFrameBuffer()));

     clearPixmapAct = new QAction(tr("&Clear Pixmap"), this);
     clearPixmapAct->setShortcut(tr("Ctrl+L"));
     connect(clearPixmapAct, SIGNAL(triggered()), this, SLOT(clearPixmap()));

     exitAct = new QAction(tr("E&xit"), this);
     exitAct->setShortcut(tr("Ctrl+Q"));
     connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));

     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()
 {
     fileMenu = menuBar()->addMenu(tr("&File"));
     fileMenu->addAction(renderIntoPixmapAct);
     fileMenu->addAction(grabFrameBufferAct);
     fileMenu->addAction(clearPixmapAct);
     fileMenu->addSeparator();
     fileMenu->addAction(exitAct);

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

 QSlider *MainWindow::createSlider(const char *changedSignal,
                                   const char *setterSlot)
 {
     QSlider *slider = new QSlider(Qt::Horizontal);
     slider->setRange(0, 360 * 16);
     slider->setSingleStep(16);
     slider->setPageStep(15 * 16);
     slider->setTickInterval(15 * 16);
     slider->setTickPosition(QSlider::TicksRight);
     connect(slider, SIGNAL(valueChanged(int)), glWidget, setterSlot);
     connect(glWidget, changedSignal, slider, SLOT(setValue(int)));
     return slider;
 }

 void MainWindow::setPixmap(const QPixmap &pixmap)
 {
     pixmapLabel->setPixmap(pixmap);
     QSize size = pixmap.size();
     if (size - QSize(1, 0) == pixmapLabelArea->maximumViewportSize())
         size -= QSize(1, 0);
     pixmapLabel->resize(size);
 }

 QSize MainWindow::getSize()
 {
     bool ok;
     QString text = QInputDialog::getText(this, tr("Grabber"),
                                          tr("Enter pixmap size:"),
                                          QLineEdit::Normal,
                                          tr("%1 x %2").arg(glWidget->width())
                                                       .arg(glWidget->height()),
                                          &ok);
     if (!ok)
         return QSize();

     QRegExp regExp(tr("([0-9]+) *x *([0-9]+)"));
     if (regExp.exactMatch(text)) {
         int width = regExp.cap(1).toInt();
         int height = regExp.cap(2).toInt();
         if (width > 0 && width < 2048 && height > 0 && height < 2048)
             return QSize(width, height);
     }

     return glWidget->size();
 }