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// Copyright (C) 2025 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
#include "helper.h"
#include <QPainter>
#include <QPaintEvent>
#include <QWidget>
//! [0]
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);
}
//! [0]
//! [1]
void Helper::paint(QPainter *painter, QPaintEvent *event, int elapsed)
{
painter->fillRect(event->rect(), background);
painter->translate(100, 100);
//! [1]
//! [2]
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();
//! [2]
//! [3]
painter->setPen(textPen);
painter->setFont(textFont);
painter->drawText(QRect(-50, -50, 100, 100), Qt::AlignCenter, QStringLiteral("Qt"));
}
//! [3]
void Helper::canvasInit(QCanvasPainter *painter)
{
qcCircleBrush = QCanvasLinearGradient(QPointF(50, -20), QPointF(80, 20));
qcCircleBrush.setColorAt(0.0, Qt::white);
qcCircleBrush.setColorAt(1.0, QColor(0xa6, 0xce, 0x39));
qcTextFont.setPixelSize(50);
}
void Helper::paint(QCanvasPainter *painter, const QRect &rect, int elapsed)
{
painter->setFillStyle(QColor(64, 32, 64));
painter->fillRect(rect);
painter->translate(100, 100);
painter->save();
painter->rotate(qDegreesToRadians(elapsed * 0.030));
painter->setFillStyle(qcCircleBrush);
painter->setStrokeStyle(Qt::black);
qreal r = elapsed / 1000.0;
int n = 30;
for (int i = 0; i < n; ++i) {
painter->rotate(qDegreesToRadians(30));
qreal factor = (i + r) / n;
qreal radius = 0 + 120.0 * factor;
qreal circleRadius = 1 + factor * 20;
painter->beginPath();
painter->ellipse(QRectF(radius, -circleRadius, circleRadius * 2, circleRadius * 2));
painter->stroke();
painter->fill();
}
painter->restore();
painter->setFont(qcTextFont);
painter->setTextAlign(QCanvasPainter::TextAlign::Center);
painter->setTextBaseline(QCanvasPainter::TextBaseline::Middle);
painter->setFillStyle(Qt::white);
painter->fillText(QStringLiteral("Qt"), QRect(-50, -50, 100, 100));
}