在带有多个y轴的Qt图表中显示工具提示

C/C++问题 得得之家
Showing tooltip in a Qt chart with multiple y axes(在带有多个y轴的Qt图表中显示工具提示)
本文介绍了在带有多个y轴的Qt图表中显示工具提示的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在努力实现永久工具提示功能，即，在悬停时显示工具提示，并在我的图表中单击我有线条系列和样条系列的图表时使工具提示永久停留。这基本上是Qt标注示例的不同版本，这里是the link。我实现的唯一更改是使用QValueAxis在左侧添加了两个y轴，每个系列一个。它们共享同一个x轴。现在，当我尝试运行该程序时，直线曲线的工具提示显示正确，但是在样条曲线的情况下，它被放错了位置。它出现在曲线上我悬停鼠标指针的点的垂直下方的某个距离处。

当我通过使用createdefaulTax()使用单个y轴时，不会出现此问题。

具有单个y轴的结果

多个y轴的结果

我已经在下面发布了与单击和悬停功能相关的代码。此代码中使用了"Callout"类的对象，因此这里是code for Callout(与我之前发布的链接相同)。我找不出哪些标注代码片段与此问题最相关，因此我必须发布该链接。

// chart
    m_chart = new QChart;

    QLineSeries *series = new QLineSeries;
    //appended some (x,y) values to series and added to chart
    m_chart->addSeries(series);

    QSplineSeries *series2 = new QSplineSeries;
    //appended some (x,y) values to series2 and added to chart
    m_chart->addSeries(series2);

    //m_chart->createDefaultAxes(); for single y axis
    QValueAxis *axisX = new QValueAxis; 
    QValueAxis *axisY1 = new QValueAxis;  //for multiple y axes
    QValueAxis *axisY2 = new QValueAxis;

    m_chart->addAxis(axisX, Qt::AlignBottom);
    m_chart->addAxis(axisY1, Qt::AlignLeft);
    m_chart->addAxis(axisY2, Qt::AlignLeft);

    series->attachAxis(axisX);
    series->attachAxis(axisY1);
    series2->attachAxis(axisX);
    series2->attachAxis(axisY2);

    m_chart->setAcceptHoverEvents(true);

    setRenderHint(QPainter::Antialiasing);
    scene()->addItem(m_chart);

    connect(series, &QLineSeries::clicked, this, &View::keepCallout);
    connect(series, &QLineSeries::hovered, this, &View::tooltip);

    connect(series2, &QSplineSeries::clicked, this, &View::keepCallout);
    connect(series2, &QSplineSeries::hovered, this, &View::tooltip);

    this->setMouseTracking(true);

// keepCallout() function
    {
     m_callouts.append(m_tooltip);//m_callouts is a QList of "Callout" class type
     m_tooltip = new Callout(m_chart);
    }

//tooltip(QPointF point, bool state) function
{
    if (m_tooltip == 0)
        m_tooltip = new Callout(m_chart);

    if (state) {
        m_tooltip->setText(QString("X: %1 
Y: %2").arg(point.x()).arg(point.y()));
        m_tooltip->setAnchor(point);
        m_tooltip->setZValue(11);
        m_tooltip->updateGeometry();
        m_tooltip->show();
  } else {
        m_tooltip->hide();
  }
}

推荐答案

mapToPosition()返回给定位置一个值，该值取决于它们所属的系列，在您的示例中，如果该值有2个轴，则需要显式指示该系列。为此，callout必须具有存储系列的属性。

view.cpp

...
void View::keepCallout()
{
    QAbstractSeries *series = qobject_cast<QAbstractSeries *>(sender());
    m_callouts.append(m_tooltip);

    m_tooltip = new Callout(m_chart, series);
    m_tooltip->hide();
}

void View::tooltip(QPointF point, bool state)
{
    QAbstractSeries *series = qobject_cast<QAbstractSeries *>(sender());
    if (m_tooltip == 0){
        m_tooltip = new Callout(m_chart, series);
    }
    if (state) {
        m_tooltip->setSeries(series);
        m_tooltip->setText(QString("X: %1 
Y: %2 ").arg(point.x()).arg(point.y()));
        m_tooltip->setAnchor(point);
        m_tooltip->setZValue(11);
        m_tooltip->updateGeometry();
        m_tooltip->show();
    } else {
        m_tooltip->hide();
    }
}

callout.h

#ifndef CALLOUT_H
#define CALLOUT_H

#include <QtCharts/QChartGlobal>
#include <QtWidgets/QGraphicsItem>
#include <QtGui/QFont>
QT_BEGIN_NAMESPACE
class QGraphicsSceneMouseEvent;
QT_END_NAMESPACE

QT_CHARTS_BEGIN_NAMESPACE
class QChart;
class QAbstractSeries;
QT_CHARTS_END_NAMESPACE

QT_CHARTS_USE_NAMESPACE

class Callout : public QGraphicsItem
{
public:
    Callout(QChart *chart, QAbstractSeries *series);

    void setText(const QString &text);
    void setAnchor(QPointF point);
    void updateGeometry();

    QRectF boundingRect() const;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,QWidget *widget);
    void setSeries(QAbstractSeries *series);

protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *event);
    void mouseMoveEvent(QGraphicsSceneMouseEvent *event);

private:
    QString m_text;
    QRectF m_textRect;
    QRectF m_rect;
    QPointF m_anchor;
    QFont m_font;
    QChart *m_chart;
    QAbstractSeries *m_series;
};

#endif // CALLOUT_H

callout.cpp

#include "callout.h"
#include <QtGui/QPainter>
#include <QtGui/QFontMetrics>
#include <QtWidgets/QGraphicsSceneMouseEvent>
#include <QtGui/QMouseEvent>
#include <QtCharts/QChart>

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

QRectF Callout::boundingRect() const
{
    QPointF anchor = mapFromParent(m_chart->mapToPosition(m_anchor, m_series));
    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, m_series));
    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::setSeries(QAbstractSeries *series)
{
    m_series = series;
}

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, m_series) + QPoint(10, -50));
}

您可以在以下link

中找到完整的代码

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