在QtCharts上显示文本

Question

我正在使用QtCharts类制作折线图。我希望能够在图形本身上添加注释/文本。我该怎么做呢？我找到了一个类似于我想要的“https://doc.qt.io/qt-5/qtcharts-callout-example.html”的例子，有没有更简单的方法？

Answer 1

这是我的版本。可能存在错误

textitem.h

#pragma once

#include <QtCharts/QChartGlobal>
#include <QtWidgets/QGraphicsItem>

QT_CHARTS_BEGIN_NAMESPACE
class QChart;
class QAbstractSeries;
QT_CHARTS_END_NAMESPACE

QT_CHARTS_USE_NAMESPACE


class TextItem : public QGraphicsItem {
public:
    TextItem(QString text, QPoint pos, QChart *chart, QAbstractSeries *series);
    QRectF boundingRect() const override;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;

    void setText(const QString &text);
    void setAnchor(QPointF point);
private:
    QChart *_chart;
    QAbstractSeries *_series;
    QString _text;
    QRectF _textRect;
    QPointF _anchor;
};

textitem.cpp

#include "textitem.h"
#include <QtCharts/QChart>
#include <QPainter>
#include <QRect>

TextItem::TextItem(QString text, QPoint pos, QChart *chart, QAbstractSeries *series)
    : QGraphicsItem(chart), _chart(chart), _series(series), _anchor(pos) {
    setText(text);
}

QRectF TextItem::boundingRect() const {
    QPointF anchor = mapFromParent(_chart->mapToPosition(_anchor, _series));
    QRectF rect;
    rect.setLeft(qMin(_textRect.left(), anchor.x()));
    rect.setRight(qMax(_textRect.right(), anchor.x()));
    rect.setTop(qMin(_textRect.top(), anchor.y()));
    rect.setBottom(qMax(_textRect.bottom(), anchor.y()));
    return rect;
}

void TextItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) {
    Q_UNUSED(option)
    Q_UNUSED(widget)
    QPointF anchor = mapFromParent(_chart->mapToPosition(_anchor, _series));
    painter->drawText(anchor, _text);
}

void TextItem::setText(const QString &text) {
  _text = text;
  QFontMetrics metrics((QFont()));
  _textRect = metrics.boundingRect(QRect(0, 0, 150, 150),
                                   Qt::AlignLeft, _text);
  _textRect.translate(5, 5);
  prepareGeometryChange();
}

void TextItem::setAnchor(QPointF point) { _anchor = point; }