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在QtCharts上显示文本

c++qtuser-interfaceqtwidgets
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2个回答
0
这是我的版本。可能会有错误。

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; }
0

我知道这是一个晚回复，对你来说已经不再相关了，但对其他人可能有用：

就我所见，他们已经使用了一种非常简单的方法来实现这一点。 在他们的示例中，他们使用 QGraphicsTextItem 在图表中的特定位置添加文本。

假设您有一个系列，并希望向该系列中在图表中可见的每个点添加文本。 以下是一个（Python PySide6）示例，演示如何实现此目的（您可以以相同的方式在C++中实现）：

chart = QChart()  # some chart
series = QScatterSeries()  # some series which has been added to the chart

# create text items and add to chart
my_text_items = []
for i in range(series.count()):
    text_item = QGraphicsTextItem("point with idx: {}".format(i), parent=chart)
    my_text_items.append(text_item)


# define function to set/update the position of the text items (has to be called during resize)
def update_position_of_text_items(text_items, series):
    for i, text_item in enumerate(text_items):
        # get point at index i
        point = series.at(i)

        # map its position of the series to the position in the chart
        position_in_chart = series.chart().mapToPosition(point, series)

        # set the position of the text item at index i accordingly
        text_item.setPos(position_in_chart)


update_position_of_text_items(my_text_items, series)

确保在调整小部件大小时调用update_position_of_text_items(..)函数。
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