callout.cpp Example File

callout/callout.cpp
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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)); }