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50
51#include "helper.h"
52
53#include <QPainter>
54#include <QPaintEvent>
55#include <QWidget>
56
57//! [0]
58Helper::Helper()
59{
60 QLinearGradient gradient(QPointF(50, -20), QPointF(80, 20));
61 gradient.setColorAt(0.0, Qt::white);
62 gradient.setColorAt(1.0, QColor(0xa6, 0xce, 0x39));
63
64 background = QBrush(QColor(64, 32, 64));
65 circleBrush = QBrush(gradient);
66 circlePen = QPen(Qt::black);
67 circlePen.setWidth(1);
68 textPen = QPen(Qt::white);
69 textFont.setPixelSize(50);
70}
71//! [0]
72
73//! [1]
74void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed)
75{
76 painter->fillRect(event->rect(), background);
77 painter->translate(100, 100);
78//! [1]
79
80//! [2]
81 painter->save();
82 painter->setBrush(circleBrush);
83 painter->setPen(circlePen);
84 painter->rotate(elapsed * 0.030);
85
86 qreal r = elapsed / 1000.0;
87 int n = 30;
88 for (int i = 0; i < n; ++i) {
89 painter->rotate(30);
90 qreal factor = (i + r) / n;
91 qreal radius = 0 + 120.0 * factor;
92 qreal circleRadius = 1 + factor * 20;
93 painter->drawEllipse(QRectF(radius, -circleRadius,
94 circleRadius * 2, circleRadius * 2));
95 }
96 painter->restore();
97//! [2]
98
99//! [3]
100 painter->setPen(textPen);
101 painter->setFont(textFont);
102 painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, QStringLiteral("Qt"));
103}
104//! [3]
105