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# 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();
     }