examples/charts/chartsgallery/scatterinteractionswidget.cpp


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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#include "scatterinteractionswidget.h"

#include <QChart>
#include <QtMath>
#include <QScatterSeries>

ScatterInteractionsWidget::ScatterInteractionsWidget(QWidget *parent)
    : ContentWidget(parent)
{
    m_scatter = new QScatterSeries;
    m_scatter->setName("scatter1");
    for (qreal x(0.5); x <= 4.0; x += 0.5) {
        for (qreal y(0.5); y <= 4.0; y += 0.5)
            *m_scatter << QPointF(x, y);
    }
    m_scatter2 = new QScatterSeries;
    m_scatter2->setName("scatter2");

    auto *chart = new QChart;
    chart->setTitle("Click to interact with scatter points");
    chart->addSeries(m_scatter2);
    chart->addSeries(m_scatter);
    chart->createDefaultAxes();
    chart->axes(Qt::Horizontal).first()->setRange(0, 4.5);
    chart->axes(Qt::Vertical).first()->setRange(0, 4.5);

    connect(m_scatter, &QScatterSeries::clicked,
            this, &ScatterInteractionsWidget::handleClickedPoint);

    createDefaultChartView(chart);
}

void ScatterInteractionsWidget::handleClickedPoint(const QPointF &point)
{
    QPointF clickedPoint = point;

    // Find the closest point from series 1
    QPointF closest(INT_MAX, INT_MAX);
    qreal distance(INT_MAX);
    const auto points = m_scatter->points();
    for (const QPointF &currentPoint : points) {
        qreal currentDistance = qSqrt((currentPoint.x() - clickedPoint.x())
                                      * (currentPoint.x() - clickedPoint.x())
                                      + (currentPoint.y() - clickedPoint.y())
                                      * (currentPoint.y() - clickedPoint.y()));
        if (currentDistance < distance) {
            distance = currentDistance;
            closest = currentPoint;
        }
    }

    // Remove the closest point from series 1 and append it to series 2
    m_scatter->remove(closest);
    m_scatter2->append(closest);
}