rasterwindow.cpp Example File | Qt GUI 5.12.11

- Qt 5.12
- Qt GUI
- Raster Window Example
- rasterwindow.cpp Example File
- Qt 5.12.11 Reference Documentation

# rasterwindow.cpp Example File

rasterwindow/rasterwindow.cpp

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     #include "rasterwindow.h"

     RasterWindow::RasterWindow(QWindow *parent)
         : QWindow(parent)
         , m_backingStore(new QBackingStore(this))
     {
         setGeometry(100, 100, 300, 200);
     }

     bool RasterWindow::event(QEvent *event)
     {
         if (event->type() == QEvent::UpdateRequest) {
             renderNow();
             return true;
         }
         return QWindow::event(event);
     }

     void RasterWindow::renderLater()
     {
         requestUpdate();
     }

     void RasterWindow::resizeEvent(QResizeEvent *resizeEvent)
     {
         m_backingStore->resize(resizeEvent->size());
     }

     void RasterWindow::exposeEvent(QExposeEvent *)
     {
         if (isExposed())
             renderNow();
     }

     void RasterWindow::renderNow()
     {
         if (!isExposed())
             return;

         QRect rect(0, 0, width(), height());
         m_backingStore->beginPaint(rect);

         QPaintDevice *device = m_backingStore->paintDevice();
         QPainter painter(device);

         painter.fillRect(0, 0, width(), height(), QGradient::NightFade);
         render(&painter);
         painter.end();

         m_backingStore->endPaint();
         m_backingStore->flush(rect);
     }

     void RasterWindow::render(QPainter *painter)
     {
         painter->drawText(QRectF(0, 0, width(), height()), Qt::AlignCenter, QStringLiteral("QWindow"));
     }