Qt 5.9 | Qt Charts | Callout Example | callout.cpp Example File

Qt 5.9.3 Reference Documentation

# 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.
      **
      ** $QT_BEGIN_LICENSE:GPL$
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      ** Alternatively, this file may be used under the terms of the GNU
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      ** the Free Software Foundation and appearing in the file LICENSE.GPL3
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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));
      }