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50
51#include "rasterwindow.h"
52
53//! [1]
54RasterWindow::RasterWindow(QWindow *parent)
55 : QWindow(parent)
56 , m_backingStore(new QBackingStore(this))
57{
58 setGeometry(posx: 100, posy: 100, w: 300, h: 200);
59}
60//! [1]
61
62
63//! [7]
64bool RasterWindow::event(QEvent *event)
65{
66 if (event->type() == QEvent::UpdateRequest) {
67 renderNow();
68 return true;
69 }
70 return QWindow::event(event);
71}
72//! [7]
73
74//! [6]
75void RasterWindow::renderLater()
76{
77 requestUpdate();
78}
79//! [6]
80
81
82//! [5]
83void RasterWindow::resizeEvent(QResizeEvent *resizeEvent)
84{
85 m_backingStore->resize(size: resizeEvent->size());
86}
87//! [5]
88
89//! [2]
90void RasterWindow::exposeEvent(QExposeEvent *)
91{
92 if (isExposed())
93 renderNow();
94}
95//! [2]
96
97
98//! [3]
99void RasterWindow::renderNow()
100{
101 if (!isExposed())
102 return;
103
104 QRect rect(0, 0, width(), height());
105 m_backingStore->beginPaint(rect);
106
107 QPaintDevice *device = m_backingStore->paintDevice();
108 QPainter painter(device);
109
110 painter.fillRect(x: 0, y: 0, w: width(), h: height(), p: QGradient::NightFade);
111 render(painter: &painter);
112 painter.end();
113
114 m_backingStore->endPaint();
115 m_backingStore->flush(region: rect);
116}
117//! [3]
118
119//! [4]
120void RasterWindow::render(QPainter *painter)
121{
122 painter->drawText(r: QRectF(0, 0, width(), height()), flags: Qt::AlignCenter, QStringLiteral("QWindow"));
123}
124//! [4]
125

source code of qtbase/examples/gui/rasterwindow/rasterwindow.cpp