callout.cpp Example File | Qt Charts 5.12.9

- Qt 5.12
- Qt Charts
- Callout Example
- callout.cpp Example File
- Qt Charts | Commercial or GPLv3

# callout.cpp Example File

callout/callout.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2016 The Qt Company Ltd.
     ** Contact: https://www.qt.io/licensing/
     **
     ** This file is part of the Qt Charts module of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:GPL$
     ** Commercial License Usage
     ** Licensees holding valid commercial Qt licenses may use this file in
     ** accordance with the commercial license agreement provided with the
     ** Software or, alternatively, in accordance with the terms contained in
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     ** information use the contact form at https://www.qt.io/contact-us.
     **
     ** GNU General Public License Usage
     ** Alternatively, this file may be used under the terms of the GNU
     ** General Public License version 3 or (at your option) any later version
     ** approved by the KDE Free Qt Foundation. The licenses are as published by
     ** the Free Software Foundation and appearing in the file LICENSE.GPL3
     ** included in the packaging of this file. Please review the following
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     #include "callout.h"
     #include <QtGui/QPainter>
     #include <QtGui/QFontMetrics>
     #include <QtWidgets/QGraphicsSceneMouseEvent>
     #include <QtGui/QMouseEvent>
     #include <QtCharts/QChart>

     Callout::Callout(QChart *chart):
         QGraphicsItem(chart),
         m_chart(chart)
     {
     }

     QRectF Callout::boundingRect() const
     {
         QPointF anchor = mapFromParent(m_chart->mapToPosition(m_anchor));
         QRectF rect;
         rect.setLeft(qMin(m_rect.left(), anchor.x()));
         rect.setRight(qMax(m_rect.right(), anchor.x()));
         rect.setTop(qMin(m_rect.top(), anchor.y()));
         rect.setBottom(qMax(m_rect.bottom(), anchor.y()));
         return rect;
     }

     void Callout::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
     {
         Q_UNUSED(option)
         Q_UNUSED(widget)
         QPainterPath path;
         path.addRoundedRect(m_rect, 5, 5);

         QPointF anchor = mapFromParent(m_chart->mapToPosition(m_anchor));
         if (!m_rect.contains(anchor)) {
             QPointF point1, point2;

             // establish the position of the anchor point in relation to m_rect
             bool above = anchor.y() <= m_rect.top();
             bool aboveCenter = anchor.y() > m_rect.top() && anchor.y() <= m_rect.center().y();
             bool belowCenter = anchor.y() > m_rect.center().y() && anchor.y() <= m_rect.bottom();
             bool below = anchor.y() > m_rect.bottom();

             bool onLeft = anchor.x() <= m_rect.left();
             bool leftOfCenter = anchor.x() > m_rect.left() && anchor.x() <= m_rect.center().x();
             bool rightOfCenter = anchor.x() > m_rect.center().x() && anchor.x() <= m_rect.right();
             bool onRight = anchor.x() > m_rect.right();

             // get the nearest m_rect corner.
             qreal x = (onRight + rightOfCenter) * m_rect.width();
             qreal y = (below + belowCenter) * m_rect.height();
             bool cornerCase = (above && onLeft) || (above && onRight) || (below && onLeft) || (below && onRight);
             bool vertical = qAbs(anchor.x() - x) > qAbs(anchor.y() - y);

             qreal x1 = x + leftOfCenter * 10 - rightOfCenter * 20 + cornerCase * !vertical * (onLeft * 10 - onRight * 20);
             qreal y1 = y + aboveCenter * 10 - belowCenter * 20 + cornerCase * vertical * (above * 10 - below * 20);;
             point1.setX(x1);
             point1.setY(y1);

             qreal x2 = x + leftOfCenter * 20 - rightOfCenter * 10 + cornerCase * !vertical * (onLeft * 20 - onRight * 10);;
             qreal y2 = y + aboveCenter * 20 - belowCenter * 10 + cornerCase * vertical * (above * 20 - below * 10);;
             point2.setX(x2);
             point2.setY(y2);

             path.moveTo(point1);
             path.lineTo(anchor);
             path.lineTo(point2);
             path = path.simplified();
         }
         painter->setBrush(QColor(255, 255, 255));
         painter->drawPath(path);
         painter->drawText(m_textRect, m_text);
     }

     void Callout::mousePressEvent(QGraphicsSceneMouseEvent *event)
     {
         event->setAccepted(true);
     }

     void Callout::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
     {
         if (event->buttons() & Qt::LeftButton){
             setPos(mapToParent(event->pos() - event->buttonDownPos(Qt::LeftButton)));
             event->setAccepted(true);
         } else {
             event->setAccepted(false);
         }
     }

     void Callout::setText(const QString &text)
     {
         m_text = text;
         QFontMetrics metrics(m_font);
         m_textRect = metrics.boundingRect(QRect(0, 0, 150, 150), Qt::AlignLeft, m_text);
         m_textRect.translate(5, 5);
         prepareGeometryChange();
         m_rect = m_textRect.adjusted(-5, -5, 5, 5);
     }

     void Callout::setAnchor(QPointF point)
     {
         m_anchor = point;
     }

     void Callout::updateGeometry()
     {
         prepareGeometryChange();
         setPos(m_chart->mapToPosition(m_anchor) + QPoint(10, -50));
     }