// Copyright (C) 2017 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#include <QtCharts/QChartView>
#include <private/qchartview_p.h>
#include <private/qchart_p.h>
#include <QtWidgets/QGraphicsScene>
#include <QtWidgets/QRubberBand>
#include <QtWidgets/QGraphicsItem>

/*!
    \enum QChartView::RubberBand

    This enum describes the different types of rubber band effects that can
    be applied to the rectangular zooming area.

    \value NoRubberBand
           No zooming area is specified, and therefore zooming is not enabled.
    \value VerticalRubberBand
           The rubber band is locked to the size of the chart horizontally
           and can be pulled vertically to specify the zooming area.
    \value HorizontalRubberBand
           The rubber band is locked to the size of the chart vertically
           and can be pulled horizontally to specify the zooming area.
    \value RectangleRubberBand
           The rubber band is fixed to the point that was clicked and can be
           pulled both vertically and horizontally.
    \value ClickThroughRubberBand
           An option on the above rubber band choices that allows left clicks
           to be passed on to chart items if those chart items accept clicks.
           To select this, OR it with one of the rubber band selection modes.
           \since 6.2
*/

/*!
    \class QChartView
    \inmodule QtCharts
    \brief The QChartView is a standalone widget that can display charts.

    A chart view does not require a QGraphicsScene object to work. To display
    a chart in an existing QGraphicsScene, the QChart or QPolarChart class should
    be used instead.

    \sa QChart, QPolarChart
*/

QT_BEGIN_NAMESPACE

/*!
    Constructs a chart view object with the parent \a parent.
*/

QChartView::QChartView(QWidget *parent)
    : QGraphicsView(parent),
      d_ptr(new QChartViewPrivate(this))
{

}

/*!
    Constructs a chart view object with the parent \a parent to display the
    chart \a chart. The ownership of the chart is passed to the chart view.
*/

QChartView::QChartView(QChart *chart, QWidget *parent)
    : QGraphicsView(parent),
      d_ptr(new QChartViewPrivate(this, chart))
{

}


/*!
    Deletes the chart view object and the associated chart.
*/
QChartView::~QChartView()
{
}

/*!
    Returns the pointer to the associated chart.
*/
QChart *QChartView::chart() const
{
    return d_ptr->m_chart;
}

/*!
    Sets the current chart to \a chart. The ownership of the new chart is passed to
    the chart view and the ownership of the previous chart is released.

    To avoid memory leaks, the previous chart must be deleted.
*/

void QChartView::setChart(QChart *chart)
{
    d_ptr->setChart(chart);
}

/*!
    Sets the rubber band flags to \a rubberBand.
    The selected flags determine the way zooming is performed.

    \note Rubber band zooming is not supported for polar charts.
*/
void QChartView::setRubberBand(const RubberBands &rubberBand)
{
#ifndef QT_NO_RUBBERBAND
    d_ptr->m_rubberBandFlags = rubberBand;

    if (!(d_ptr->m_rubberBandFlags & ~RubberBands(ClickThroughRubberBand))) {
        delete d_ptr->m_rubberBand;
        d_ptr->m_rubberBand = nullptr;
        return;
    }

    if (!d_ptr->m_rubberBand) {
        d_ptr->m_rubberBand = new QRubberBand(QRubberBand::Rectangle, this);
        d_ptr->m_rubberBand->setEnabled(true);
    }
#else
    Q_UNUSED(rubberBand);
    qWarning("Unable to set rubber band because Qt is configured without it.");
#endif
}

/*!
    Returns the rubber band flags that are currently being used by the chart view.
*/
QChartView::RubberBands QChartView::rubberBand() const
{
    return d_ptr->m_rubberBandFlags;
}

/*!
    If the left mouse button is pressed and the rubber band is enabled, the event
    \a event is accepted and the rubber band is displayed on the screen. This
    enables the user to select the zoom area.

    If some other mouse button is pressed or the rubber band is disabled, the event
    is passed to QGraphicsView::mousePressEvent().
*/
void QChartView::mousePressEvent(QMouseEvent *event)
{
#ifndef QT_NO_RUBBERBAND
    QGraphicsItem *itemUnderCursor = itemAt(event->pos());
    bool itemUnderCursorAcceptsLMB = itemUnderCursor && (itemUnderCursor->acceptedMouseButtons() & Qt::LeftButton);
    bool clickThrough = d_ptr->m_rubberBandFlags.testFlag(ClickThroughRubberBand);
    QRectF plotArea = d_ptr->m_chart->plotArea();
    if (d_ptr->m_rubberBand && d_ptr->m_rubberBand->isEnabled()
            && event->button() == Qt::LeftButton
            && plotArea.contains(event->pos())
            && !(clickThrough && itemUnderCursorAcceptsLMB)) {
        d_ptr->m_rubberBandOrigin = event->pos();
        d_ptr->m_rubberBand->setGeometry(QRect(d_ptr->m_rubberBandOrigin, QSize()));
        d_ptr->m_rubberBand->show();
        event->accept();
    } else {
#endif
        QGraphicsView::mousePressEvent(event);
#ifndef QT_NO_RUBBERBAND
    }
#endif
}

/*!
    If the rubber band rectangle is displayed in the press event specified by
    \a event, the event data is used to update the rubber band geometry.
    Otherwise, the default QGraphicsView::mouseMoveEvent() implementation is called.
*/
void QChartView::mouseMoveEvent(QMouseEvent *event)
{
#ifndef QT_NO_RUBBERBAND
    if (d_ptr->m_rubberBand && d_ptr->m_rubberBand->isVisible()) {
        QRect rect = d_ptr->m_chart->plotArea().toRect();
        int width = event->pos().x() - d_ptr->m_rubberBandOrigin.x();
        int height = event->pos().y() - d_ptr->m_rubberBandOrigin.y();
        if (!d_ptr->m_rubberBandFlags.testFlag(VerticalRubberBand)) {
            d_ptr->m_rubberBandOrigin.setY(rect.top());
            height = rect.height();
        }
        if (!d_ptr->m_rubberBandFlags.testFlag(HorizontalRubberBand)) {
            d_ptr->m_rubberBandOrigin.setX(rect.left());
            width = rect.width();
        }
        d_ptr->m_rubberBand->setGeometry(QRect(d_ptr->m_rubberBandOrigin.x(), d_ptr->m_rubberBandOrigin.y(), width, height).normalized());
    } else {
#endif
        QGraphicsView::mouseMoveEvent(event);
#ifndef QT_NO_RUBBERBAND
    }
#endif
}

/*!
    If the left mouse button is released and the rubber band is enabled, the
    event \a event is accepted and the view is zoomed into the rectangle
    specified by the rubber band. If releasing the right mouse button triggered
    the event, the view is zoomed out.
*/
void QChartView::mouseReleaseEvent(QMouseEvent *event)
{
#ifndef QT_NO_RUBBERBAND
    if (d_ptr->m_rubberBand && d_ptr->m_rubberBand->isVisible()) {
        if (event->button() == Qt::LeftButton) {
            d_ptr->m_rubberBand->hide();
            QRectF rect = d_ptr->m_rubberBand->geometry();
            // Since plotArea uses QRectF and rubberband uses QRect, we can't just blindly use
            // rubberband's dimensions for vertical and horizontal rubberbands, where one
            // dimension must match the corresponding plotArea dimension exactly.
            if (!d_ptr->m_rubberBandFlags.testFlag(RectangleRubberBand)) {
                if (d_ptr->m_rubberBandFlags.testFlag(VerticalRubberBand)) {
                    rect.setX(d_ptr->m_chart->plotArea().x());
                    rect.setWidth(d_ptr->m_chart->plotArea().width());
                } else if (d_ptr->m_rubberBandFlags.testFlag(HorizontalRubberBand)) {
                    rect.setY(d_ptr->m_chart->plotArea().y());
                    rect.setHeight(d_ptr->m_chart->plotArea().height());
                }
            }
            d_ptr->m_chart->zoomIn(rect);
            event->accept();
        }
    } else if (d_ptr->m_rubberBand && event->button() == Qt::RightButton) {
            // If vertical or horizontal rubberband mode, restrict zoom out to specified axis.
            // Since there is no suitable API for that, use zoomIn with rect bigger than the
            // plot area.
            if (d_ptr->m_rubberBandFlags.testFlag(VerticalRubberBand)
                || d_ptr->m_rubberBandFlags.testFlag(HorizontalRubberBand)) {
                QRectF rect = d_ptr->m_chart->plotArea();
                if (d_ptr->m_rubberBandFlags.testFlag(VerticalRubberBand)) {
                    qreal adjustment = rect.height() / 2;
                    rect.adjust(0, -adjustment, 0, adjustment);
                }
                if (d_ptr->m_rubberBandFlags.testFlag(HorizontalRubberBand)) {
                    qreal adjustment = rect.width() / 2;
                    rect.adjust(-adjustment, 0, adjustment, 0);
                }
                d_ptr->m_chart->zoomIn(rect);
            }
            event->accept();
    } else {
#endif
        QGraphicsView::mouseReleaseEvent(event);
#ifndef QT_NO_RUBBERBAND
    }
#endif
}

#ifdef Q_OS_MACOS
#if QT_CONFIG(wheelevent)
void QChartView::wheelEvent(QWheelEvent *event)
{
    Q_UNUSED(event);
    // We just need to override wheelEvent, or scrolling won't work correctly on macOS trackpad
    // (QTBUG-77403)
}
#endif
#endif

/*!
    Resizes and updates the chart area using the data specified by \a event.
*/
void QChartView::resizeEvent(QResizeEvent *event)
{
    QGraphicsView::resizeEvent(event);
    d_ptr->resize();
}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

QChartViewPrivate::QChartViewPrivate(QChartView *q, QChart *chart)
    : q_ptr(q),
      m_scene(new QGraphicsScene(q)),
      m_chart(chart),
#ifndef QT_NO_RUBBERBAND
      m_rubberBand(nullptr),
#endif
      m_rubberBandFlags(QChartView::NoRubberBand)
{
    q_ptr->setFrameShape(QFrame::NoFrame);
    q_ptr->setBackgroundRole(QPalette::Window);
    q_ptr->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    q_ptr->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    q_ptr->setScene(m_scene);
    q_ptr->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    if (!m_chart)
        m_chart = new QChart();
    m_scene->addItem(m_chart);
}

QChartViewPrivate::~QChartViewPrivate()
{
}

void QChartViewPrivate::setChart(QChart *chart)
{
    Q_ASSERT(chart);

    if (m_chart == chart)
        return;

    if (m_chart)
        m_scene->removeItem(m_chart);

    m_chart = chart;
    m_scene->addItem(m_chart);

    resize();
}

void QChartViewPrivate::resize()
{
    // Fit the chart into view if it has been rotated
    qreal sinA = qAbs(q_ptr->transform().m21());
    qreal cosA = qAbs(q_ptr->transform().m11());
    QSize chartSize = q_ptr->size();

    if (sinA == 1.0) {
        chartSize.setHeight(q_ptr->size().width());
        chartSize.setWidth(q_ptr->size().height());
    } else if (sinA != 0.0) {
        // Non-90 degree rotation, find largest square chart that can fit into the view.
        qreal minDimension = qMin(q_ptr->size().width(), q_ptr->size().height());
        qreal h = (minDimension - (minDimension / ((sinA / cosA) + 1.0))) / sinA;
        chartSize.setHeight(h);
        chartSize.setWidth(h);
    }

    m_chart->resize(chartSize);
    q_ptr->setMinimumSize(m_chart->minimumSize().toSize().expandedTo(q_ptr->minimumSize()));
    q_ptr->setMaximumSize(q_ptr->maximumSize().boundedTo(m_chart->maximumSize().toSize()));
    q_ptr->setSceneRect(m_chart->geometry());
}

QT_END_NAMESPACE

#include "moc_qchartview.cpp"
