qquickfusionknob.cpp

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// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickfusionknob_p.h"
 
#include <QtCore/qmath.h>
#include <QtGui/qpainter.h>
#include <QtQuick/private/qquickpalette_p.h>
#include <QtQuick/private/qquickitem_p.h>
 
QT_BEGIN_NAMESPACE
 
QQuickFusionKnob::QQuickFusionKnob(QQuickItem *parent)
    : QQuickPaintedItem(parent)
{
    connect(this, &QQuickItem::paletteChanged, this, [this](){ update(); });
}
 
// extracted from QStyleHelper::drawDial()
void QQuickFusionKnob::paint(QPainter *painter)
{
    const qreal w = width();
    const qreal h = height();
    if (w <= 0 || h <= 0)
        return;
 
    QColor color = QQuickItemPrivate::get(this)->palette()->button().toHsv();
    color.setHsv(color.hue(),
                 qMin(140, color .saturation()),
                 qMax(180, color.value()));
    color = color.lighter(104);
    color.setAlphaF(0.8f);
 
    const qreal sz = qMin(w, h);
    QRectF rect(0, 0, sz, sz);
    rect.moveCenter(QPointF(w / 2.0, h / 2.0));
    const QPointF center = rect.center();
 
    QRadialGradient gradient(center.x() + rect.width() / 2,
                             center.y() + rect.width(),
                             rect.width() * 2,
                             center.x(), center.y());
    gradient.setColorAt(1, color.darker(140));
    gradient.setColorAt(qreal(0.4), color.darker(120));
    gradient.setColorAt(0, color.darker(110));
 
    painter->setRenderHint(QPainter::Antialiasing);
    painter->setBrush(gradient);
    painter->setPen(QColor(255, 255, 255, 150));
    painter->drawEllipse(rect);
    painter->setPen(QColor(0, 0, 0, 80));
    painter->drawEllipse(rect.adjusted(1, 1, -1, -1));
}
 
QT_END_NAMESPACE
 
#include "moc_qquickfusionknob_p.cpp"