rasterwindow.cpp Example File

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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"));
 }