helper.cpp Example File

2dpainting/helper.cpp
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#include "helper.h" #include <QPainter> #include <QPaintEvent> #include <QWidget> Helper::Helper() { QLinearGradient gradient(QPointF(50, -20), QPointF(80, 20)); gradient.setColorAt(0.0, Qt::white); gradient.setColorAt(1.0, QColor(0xa6, 0xce, 0x39)); background = QBrush(QColor(64, 32, 64)); circleBrush = QBrush(gradient); circlePen = QPen(Qt::black); circlePen.setWidth(1); textPen = QPen(Qt::white); textFont.setPixelSize(50); } void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed) { painter->fillRect(event->rect(), background); painter->translate(100, 100); painter->save(); painter->setBrush(circleBrush); painter->setPen(circlePen); painter->rotate(elapsed * 0.030); qreal r = elapsed / 1000.0; int n = 30; for (int i = 0; i < n; ++i) { painter->rotate(30); qreal factor = (i + r) / n; qreal radius = 0 + 120.0 * factor; qreal circleRadius = 1 + factor * 20; painter->drawEllipse(QRectF(radius, -circleRadius, circleRadius * 2, circleRadius * 2)); } painter->restore(); painter->setPen(textPen); painter->setFont(textFont); painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, QStringLiteral("Qt")); }