Add ability to customize labels for specific points

[ChangeLog][QXYSeries] Add LabelFormat to PointConfiguration,
allowing the user to set a custom label to specific points.

This follows setPointLabelsFormat, allowing the user to substitute the
x position, y position, or index in the label.

Adds @index to formats to allow substituting the index of the point in
the label.

Task-number: QTBUG-89452
Change-Id: If58e50357ca3275f3479b4ade44b789c568564ec
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

12 files changed, 415 insertions, 24 deletions

diff --git a/examples/charts/CMakeLists.txt b/examples/charts/CMakeLists.txt
index cc107889..f630f3c6 100644
--- a/examples/charts/CMakeLists.txt
+++ b/examples/charts/CMakeLists.txt
@@ -14,6 +14,7 @@ if(QT_FEATURE_charts_line_chart)
     qt_internal_add_example(logvalueaxis)
     qt_internal_add_example(modeldata)
     qt_internal_add_example(zoomlinechart)
+    qt_internal_add_example(pointconfiguration)
 endif()
 if(QT_FEATURE_charts_spline_chart)
     qt_internal_add_example(dynamicspline)
diff --git a/examples/charts/pointconfiguration/CMakeLists.txt b/examples/charts/pointconfiguration/CMakeLists.txt
new file mode 100644
index 00000000..5fc8042f
--- /dev/null
+++ b/examples/charts/pointconfiguration/CMakeLists.txt
@@ -0,0 +1,38 @@
+# Copyright (C) 2022 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+cmake_minimum_required(VERSION 3.14)
+project(pointconfiguration LANGUAGES CXX)
+
+set(CMAKE_AUTOMOC ON)
+
+if(NOT DEFINED INSTALL_EXAMPLESDIR)
+    set(INSTALL_EXAMPLESDIR "examples")
+endif()
+
+set(INSTALL_EXAMPLEDIR "${INSTALL_EXAMPLESDIR}/charts/pointconfiguration")
+
+find_package(Qt6 REQUIRED COMPONENTS Charts Core Gui)
+
+qt_add_executable(pointconfiguration
+    chartwindow.cpp
+    chartwindow.h
+    main.cpp
+)
+
+set_target_properties(pointconfiguration PROPERTIES
+    WIN32_EXECUTABLE TRUE
+    MACOSX_BUNDLE TRUE
+)
+
+target_link_libraries(pointconfiguration PUBLIC
+    Qt::Charts
+    Qt::Core
+    Qt::Gui
+)
+
+install(TARGETS pointconfiguration
+    RUNTIME DESTINATION "${INSTALL_EXAMPLEDIR}"
+    BUNDLE DESTINATION "${INSTALL_EXAMPLEDIR}"
+    LIBRARY DESTINATION "${INSTALL_EXAMPLEDIR}"
+)
diff --git a/examples/charts/pointconfiguration/chartwindow.cpp b/examples/charts/pointconfiguration/chartwindow.cpp
new file mode 100644
index 00000000..a19c4867
--- /dev/null
+++ b/examples/charts/pointconfiguration/chartwindow.cpp
@@ -0,0 +1,159 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "chartwindow.h"
+
+#include <QChart>
+#include <QColor>
+#include <QGridLayout>
+#include <QHBoxLayout>
+#include <QIcon>
+#include <QLabel>
+#include <QLineSeries>
+#include <QMainWindow>
+
+//![1]
+ChartWindow::ChartWindow(QWidget *parent)
+    : QMainWindow(parent)
+{
+//![1]
+    //![2]
+    setWindowTitle(tr("Chart"));
+
+    m_series = new QLineSeries(this);
+    m_series->setName(tr("Customized series"));
+    m_series->setPointsVisible(true);
+    m_series->append({QPointF(0, 7),  QPointF(2, 4),
+                    QPointF(3, 5),  QPointF(7, 4),
+                    QPointF(10, 5), QPointF(11, 1),
+                    QPointF(13, 3), QPointF(17, 6),
+                    QPointF(18, 3), QPointF(20, 2)});
+    //![2]
+
+    //![3]
+    QLabel *selectedPointIndexLabel = new QLabel(tr("Selected Point: "));
+    m_selectedPointIndexLineEdit = new QLineEdit();
+    m_selectedPointIndexLineEdit->setReadOnly(true);
+
+    QLabel *colorLabel = new QLabel(tr("Color: "));
+    m_colorCombobox = new QComboBox();
+    QStringList colorStrings = {"red", "orange", "yellow", "green", "blue",
+                                "indigo", "violet", "black"};
+    QStringList trColorStrings = {tr("red"), tr("orange"), tr("yellow"),
+                                  tr("green"), tr("blue"), tr("indigo"),
+                                  tr("violet"), tr("black")};
+    for (int i = 0; i < colorStrings.size(); i++)
+        m_colorCombobox->addItem(QIcon(), trColorStrings[i], QColor(colorStrings[i]));
+
+    QLabel *sizeLabel = new QLabel(tr("Size: "));
+    m_sizeCombobox = new QComboBox();
+    for (auto size : { 2, 3, 4, 6, 8, 10, 12, 15 })
+        m_sizeCombobox->addItem(QIcon(), QString::number(size), size);
+
+    QLabel *labelVisibilityLabel = new QLabel(tr("Label Visibility: "));
+    m_labelVisibilityCheckbox = new QCheckBox();
+
+    QLabel *customLabelLabel = new QLabel(tr("Custom Label: "));
+    m_customLabelLineEdit = new QLineEdit();
+    //![3]
+
+    //![4]
+    QObject::connect(m_series, &QXYSeries::clicked, m_series, [&](const QPointF &point) {
+        int index = m_series->points().indexOf(point.toPoint());
+        if (index != -1) {
+            m_series->deselectAllPoints();
+            m_series->selectPoint(index);
+            m_selectedPointIndex = index;
+            m_selectedPointConfig = m_series->pointConfiguration(index);
+            const QPointF selectedPoint(m_series->at(index));
+            m_selectedPointIndexLineEdit->setText("(" + QString::number(selectedPoint.x()) + ", " +
+                                                  QString::number(selectedPoint.y()) + ")");
+            PointConfigurations config = m_series->pointConfiguration(index);
+
+            QVariant colorVar = config[QXYSeries::PointConfiguration::Color];
+            QColor color = colorVar.isValid() ? colorVar.value<QColor>() : m_series->color();
+            if (m_colorCombobox->findData(color) < 0)
+                m_colorCombobox->addItem(color.name(), color);
+            m_colorCombobox->setCurrentIndex(m_colorCombobox->findData(color));
+
+            QVariant sizeVar = config[QXYSeries::PointConfiguration::Size];
+            qreal size = sizeVar.isValid() ? sizeVar.toReal() : m_series->markerSize();
+            if (m_sizeCombobox->findData(size) < 0)
+                m_sizeCombobox->addItem(QString::number(size), size);
+            m_sizeCombobox->setCurrentIndex(m_sizeCombobox->findData(size));
+
+            QVariant labelVisibilityVar = config[QXYSeries::PointConfiguration::LabelVisibility];
+            bool labelVisibility = labelVisibilityVar.isValid() ? labelVisibilityVar.toBool() :
+                                                                  m_series->pointLabelsVisible();
+            m_labelVisibilityCheckbox->setChecked(labelVisibility);
+
+            QVariant customLabelVar = config[QXYSeries::PointConfiguration::LabelFormat];
+            QString customLabel = customLabelVar.isValid() ? customLabelVar.toString() : "";
+            m_customLabelLineEdit->setText(customLabel);
+        }
+    });
+    //![4]
+
+    //![5]
+    QObject::connect(m_colorCombobox, &QComboBox::activated, m_series, [&](const int index) {
+        m_selectedPointConfig[QXYSeries::PointConfiguration::Color] = m_colorCombobox->currentData();
+        m_series->setPointConfiguration(m_selectedPointIndex, m_selectedPointConfig);
+    });
+    QObject::connect(m_sizeCombobox, &QComboBox::activated, m_series, [&](const int index) {
+        m_selectedPointConfig[QXYSeries::PointConfiguration::Size] = m_sizeCombobox->currentData();
+        m_series->setPointConfiguration(m_selectedPointIndex, m_selectedPointConfig);
+    });
+    QObject::connect(m_labelVisibilityCheckbox, &QAbstractButton::clicked, m_series, [&](const bool checked) {
+        m_selectedPointConfig[QXYSeries::PointConfiguration::LabelVisibility] = checked;
+        m_series->setPointConfiguration(m_selectedPointIndex, m_selectedPointConfig);
+    });
+    QObject::connect(m_customLabelLineEdit, &QLineEdit::editingFinished, m_series, [&]() {
+        m_selectedPointConfig[QXYSeries::PointConfiguration::LabelFormat] = m_customLabelLineEdit->text();
+        m_series->setPointConfiguration(m_selectedPointIndex, m_selectedPointConfig);
+    });
+    //![5]
+
+    //![6]
+    m_chart = new QChart();
+    m_chart->addSeries(m_series);
+    m_chart->createDefaultAxes();
+
+    m_selectInitialPointConnection = QObject::connect(m_chart, &QChart::geometryChanged, m_chart, [&]() {
+        m_series->selectPoint(4);
+        m_series->clicked(m_series->at(m_series->selectedPoints()[0]));
+        disconnect(m_selectInitialPointConnection);
+    });
+
+    QChartView *chartView = new QChartView(m_chart);
+    chartView->setRenderHint(QPainter::Antialiasing);
+
+    QWidget *controlWidget = new QWidget(this);
+    QGridLayout *controlLayout = new QGridLayout(controlWidget);
+    controlLayout->setColumnStretch(1, 1);
+
+    controlLayout->addWidget(selectedPointIndexLabel, 0, 0);
+    controlLayout->addWidget(m_selectedPointIndexLineEdit, 0, 1);
+
+    controlLayout->addWidget(colorLabel, 1, 0);
+    controlLayout->addWidget(m_colorCombobox, 1, 1);
+
+    controlLayout->addWidget(sizeLabel, 2, 0);
+    controlLayout->addWidget(m_sizeCombobox, 2, 1);
+
+    controlLayout->addWidget(labelVisibilityLabel, 3, 0);
+    controlLayout->addWidget(m_labelVisibilityCheckbox, 3, 1, 1, 2);
+
+    controlLayout->addWidget(customLabelLabel, 4, 0);
+    controlLayout->addWidget(m_customLabelLineEdit, 4, 1);
+
+    QWidget *mainWidget = new QWidget(this);
+    QHBoxLayout *mainLayout = new QHBoxLayout(mainWidget);
+    mainLayout->addWidget(chartView);
+    mainLayout->setStretch(0, 1);
+    mainLayout->addWidget(controlWidget);
+
+    setCentralWidget(mainWidget);
+    //![6]
+//![7]
+}
+//![7]
diff --git a/examples/charts/pointconfiguration/chartwindow.h b/examples/charts/pointconfiguration/chartwindow.h
new file mode 100644
index 00000000..da01e9ad
--- /dev/null
+++ b/examples/charts/pointconfiguration/chartwindow.h
@@ -0,0 +1,36 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include <QChartView>
+#include <QCheckBox>
+#include <QComboBox>
+#include <QLineEdit>
+#include <QMainWindow>
+#include <QXYSeries>
+
+typedef QHash<QXYSeries::PointConfiguration, QVariant> PointConfigurations;
+
+//![1]
+class ChartWindow : public QMainWindow
+{
+    Q_OBJECT
+
+public:
+    explicit ChartWindow(QWidget *parent = nullptr);
+    ~ChartWindow() {};
+
+private:
+    QChart *m_chart = nullptr;
+    QXYSeries *m_series = nullptr;
+
+    QMetaObject::Connection m_selectInitialPointConnection;
+    int m_selectedPointIndex = -1;
+    PointConfigurations m_selectedPointConfig;
+
+    QLineEdit *m_selectedPointIndexLineEdit = nullptr;
+    QComboBox *m_colorCombobox = nullptr;
+    QComboBox *m_sizeCombobox = nullptr;
+    QCheckBox *m_labelVisibilityCheckbox = nullptr;
+    QLineEdit *m_customLabelLineEdit = nullptr;
+};
+//![1]
diff --git a/examples/charts/pointconfiguration/main.cpp b/examples/charts/pointconfiguration/main.cpp
new file mode 100644
index 00000000..0279d636
--- /dev/null
+++ b/examples/charts/pointconfiguration/main.cpp
@@ -0,0 +1,17 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+
+#include "chartwindow.h"
+
+#include <QApplication>
+
+//![1]
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    ChartWindow mainWindow;
+    mainWindow.resize(640, 480);
+    mainWindow.show();
+    return a.exec();
+}
+//![1]
diff --git a/examples/charts/pointconfiguration/pointconfiguration.pro b/examples/charts/pointconfiguration/pointconfiguration.pro
new file mode 100644
index 00000000..b10359d1
--- /dev/null
+++ b/examples/charts/pointconfiguration/pointconfiguration.pro
@@ -0,0 +1,12 @@
+QT += charts \
+      widgets
+
+SOURCES += \
+    chartwindow.cpp
+    main.cpp
+
+HEADERS += \
+    chartwindow.h
+
+target.path = $$[QT_INSTALL_EXAMPLES]/charts/pointconfiguration
+INSTALLS += target
diff --git a/src/charts/doc/images/examples_pointconfiguration.png b/src/charts/doc/images/examples_pointconfiguration.png
new file mode 100644
index 00000000..6ee8fca5
--- /dev/null
+++ b/src/charts/doc/images/examples_pointconfiguration.png
diff --git a/src/charts/doc/images/xyseries_point_configuration.png b/src/charts/doc/images/xyseries_point_configuration.png
index 362b898a..abf203a8 100644
--- a/src/charts/doc/images/xyseries_point_configuration.png
+++ b/src/charts/doc/images/xyseries_point_configuration.png
diff --git a/src/charts/doc/src/examples-pointconfiguration.qdoc b/src/charts/doc/src/examples-pointconfiguration.qdoc
new file mode 100644
index 00000000..a061b948
--- /dev/null
+++ b/src/charts/doc/src/examples-pointconfiguration.qdoc
@@ -0,0 +1,103 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
+
+/*!
+    \example pointconfiguration
+    \title Selected Point Configuration Example
+    \ingroup qtcharts_examples
+
+    \brief This example shows how to modify the configuration of individual points.
+
+    \image examples_pointconfiguration.png
+
+    \section1 Features Demonstrated
+    In this application you will learn how to:
+    \list
+    \li Provide click-selection of points in a series.
+    \li Override the individual configuration of specific points, configuring:
+        \list
+        \li Color
+        \li Size
+        \li Visibility of the label
+        \li Text format of the label
+        \endlist
+    \endlist
+
+    \include examples-run.qdocinc
+
+    \section1 Subclass QMainWindow
+
+    We start by creating a subclass of QMainWindow that will contain the chart and controls.
+    \snippet pointconfiguration/chartwindow.h 1
+    And we provide the boilerplate for the constructor implementation:
+    \snippet pointconfiguration/chartwindow.cpp 1
+    \snippet pointconfiguration/chartwindow.cpp 7
+
+    \section1 Create a Line Series
+
+    Then we create a QLineSeries, giving it a name, making the points visible, and giving it some
+    points to plot.
+    \snippet pointconfiguration/chartwindow.cpp 2
+
+    \section1 Create the Point Configuration Controls
+
+    Now we create some controls to configure the color, size, label visibility, and the label
+    itself. We create an associated label for each control so the user knows what the control does.
+
+    For the color and size, we use a QComboBox, populating it with a variety of color and size
+    choices.
+
+    Next we create the final two controls. A Checkbox controls the visibility of the selected
+    point. The other control is a QLineEdit allowing the user to provide a custom label for the
+    point.
+
+    Note that we do not set initial values for any of the controls, as a point will always be
+    selected showing its current settings.
+    \snippet pointconfiguration/chartwindow.cpp 3
+
+    \section1 Populate the Controls upon Selecting a Point
+
+    Now that we have the controls, we need to provide the logic that sets the current control values
+    for the selected point. Note that the whole series value is used if there is no customization
+    for a selected point. In this case, if the series is set to show blue points, a blue color value
+    will be shown in the color combobox.
+
+    Upon clicking on the lineseries, we look up the point clicked on, remove the prior point
+    selection, and then select the point that was clicked on. This visually indicates the selected
+    point on the chart - making the point larger to indicate its selection. The index of the
+    current selected point and its \c PointConfigurations are saved to a member variable for later
+    use.
+
+    The \c PointConfigurations are queried and matching values in the comboboxes are looked up.
+    Then the current indices of the comboboxes are set accordingly. Similarly for the checkbox and
+    line edit, the values are looked up from the \c PointConfigurations, and the controls are set
+    to match them.
+    \snippet pointconfiguration/chartwindow.cpp 4
+
+    \section1 Provide the Logic to Configure the Selected Point
+
+    Now that the controls are populated with the current configuration, we need to make them do
+    something. We connect up their signals to logic that will do the work of configuring the
+    selected point with the setting chosen. It is a simple matter of setting the
+    QXYSeries::PointConfiguration value associated with the control to the \c m_selectedPointConfig
+    \c PointConfigurations member variable, and calling QXYSeries::setPointConfiguration.
+    \snippet pointconfiguration/chartwindow.cpp 5
+
+    \section1 Create the Chart and Lay out the Controls
+
+    Finally we create the chart and its view, add the series to the chart, and create the layout
+    of the window.
+    As part of this, we connect to the \c geometryChanged signal to catch a signal when the
+    chart is
+    first painted. This is so that we can get correct values for the initially selected point. If
+    we do this earlier, the point values are incorrect. This connection is disconnected after the
+    first time that it is fired.
+    \snippet pointconfiguration/chartwindow.cpp 6
+
+    In \c main.cpp we simply instantiate the \c ChartWindow, resize it, show it, and start the event
+    loop.
+    \snippet pointconfiguration/main.cpp 1
+
+    Now we have a fully functioning application that demonstrates how to customize individual chart
+    points.
+*/
diff --git a/src/charts/xychart/qxyseries.cpp b/src/charts/xychart/qxyseries.cpp
index c3b51636..07963e18 100644
--- a/src/charts/xychart/qxyseries.cpp
+++ b/src/charts/xychart/qxyseries.cpp
@@ -1,4 +1,4 @@
-// Copyright (C) 2021 The Qt Company Ltd.
+// Copyright (C) 2022 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
 #include <QtCharts/QXYSeries>
@@ -58,8 +58,15 @@ QT_BEGIN_NAMESPACE
            This enum value can be used to hide or show the label of the point. If used
            together with QXYSeries::setPointConfiguration, the configuration's value
            should be boolean.
+    \value [since 6.5] LabelFormat
+           This enum value can be used to set custom label text per-point. If used together with
+           QXYSeries::setPointConfiguration, the configuration's value should be a string.
+           \note If an empty string is set as the LabelFormat, it will be ignored, and the series
+           pointLabelsFormat will be used.
+           \sa pointLabelsFormat
 
     \sa setPointConfiguration()
+    \since 6.2
 */
 
 /*!
@@ -147,6 +154,8 @@ QT_BEGIN_NAMESPACE
     QXYSeries supports the following format tags:
     \table
       \row
+        \li @index       \li The index in the series of the data point. [since 6.5]
+      \row
         \li @xPoint      \li The x-coordinate of the data point.
       \row
         \li @yPoint      \li The y-coordinate of the data point.
@@ -157,7 +166,7 @@ QT_BEGIN_NAMESPACE
     (x, y):
 
     \code
-    series->setPointLabelsFormat("(@xPoint, @yPoint)");
+    series->setPointLabelsFormat("@index: (@xPoint, @yPoint)");
     \endcode
 
     By default, the labels' format is set to \c {@xPoint, @yPoint}. The labels
@@ -509,6 +518,11 @@ QT_BEGIN_NAMESPACE
 */
 
 /*!
+    \fn void QXYSeries::selectedPointsChanged()
+    This signal is emitted when the points selection changes.
+*/
+
+/*!
     \fn void QXYSeries::lightMarkerChanged(const QImage &lightMarker)
     This signal is emitted when the light marker image changes to \a lightMarker.
     \sa QXYSeries::setLightMarker()
@@ -775,7 +789,7 @@ void QXYSeries::clearPointsConfiguration(const QXYSeries::PointConfiguration key
     keys and QVariant values. For example:
     \code
     QLineSeries *series = new QLineSeries();
-    series->setName("Customized serie");
+    series->setName("Customized series");
     series->setPointsVisible(true);
 
     *series << QPointF(0, 6) << QPointF(2, 4) << QPointF(3, 6) << QPointF(7, 4) << QPointF(10, 5)
@@ -793,16 +807,19 @@ void QXYSeries::clearPointsConfiguration(const QXYSeries::PointConfiguration key
 
     series->setPointConfiguration(4, conf);
 
-    conf.remove(QXYSeries::PointConfiguration::LabelVisibility);
+    conf.remove(QXYSeries::PointConfiguration::Color);
+    conf[QXYSeries::PointConfiguration::LabelFormat] = "This Point";
     series->setPointConfiguration(6, conf);
     \endcode
 
-    In this example, you can see a default QLineSeries with 10 points
-    and with changed configuration of two points. Both changed points are
-    red and visibly bigger than the others with a look derived from series.
-    By default, points don't have labels, but the point at index 4 has
-    the label thanks to the QXYSeries::PointConfiguration::LabelVisibility
-    configuration value.
+    In this example, you can see a default QLineSeries with 10 points and with changed configuration
+    of two points. Both changed points are visibly bigger than the others with a look derived from
+    the series configuration.
+    By default, points don't have labels, but the point at index 4 has a label thanks to the
+    QXYSeries::PointConfiguration::LabelVisibility and QXYSeries::PointConfiguration::LabelFormat
+    configuration values.
+    The point at index 6 has a custom label \e {This Point} thanks to the
+    QXYSeries::PointConfiguration::LabelFormat configuration value.
     Below is an example of a chart created in this way:
     \image xyseries_point_configuration.png
 
@@ -1805,6 +1822,7 @@ void QXYSeriesPrivate::drawPointLabels(QPainter *painter, const QList<QPointF> &
             painter->setClipping(false);
 
         QList<int> pointsToSkip;
+        QHash<int, QString> labelFormats;
         QHash<int, int> offsets;
 
         if (!m_pointsConfiguration.isEmpty()) {
@@ -1812,14 +1830,16 @@ void QXYSeriesPrivate::drawPointLabels(QPainter *painter, const QList<QPointF> &
                 bool drawLabel = m_pointLabelsVisible;
                 if (m_pointsConfiguration.contains(i)) {
                     const auto &conf = m_pointsConfiguration[i];
-                    if (conf.contains(QXYSeries::PointConfiguration::LabelVisibility)) {
-                        drawLabel = m_pointsConfiguration
-                                            [i][QXYSeries::PointConfiguration::LabelVisibility]
-                                                    .toBool();
-
-                        if (drawLabel && conf.contains(QXYSeries::PointConfiguration::Size))
-                            offsets[i] = conf[QXYSeries::PointConfiguration::Size].toReal();
+                    auto key = QXYSeries::PointConfiguration::LabelVisibility;
+                    if (conf.contains(key)) {
+                        drawLabel = m_pointsConfiguration[i][key].toBool();
+                        key = QXYSeries::PointConfiguration::Size;
+                        if (drawLabel && conf.contains(key))
+                            offsets[i] = conf[key].toReal();
                     }
+                    key = QXYSeries::PointConfiguration::LabelFormat;
+                    if (conf.contains(key) && !conf[key].toString().isEmpty())
+                        labelFormats[i] = conf[key].toString();
                 }
 
                 if (!drawLabel)
@@ -1827,19 +1847,21 @@ void QXYSeriesPrivate::drawPointLabels(QPainter *painter, const QList<QPointF> &
             }
         }
 
-        drawSeriesPointLabels(painter, allPoints, offset, offsets, pointsToSkip);
+        drawSeriesPointLabels(painter, allPoints, offset, offsets, pointsToSkip, labelFormats);
     }
 }
 
 void QXYSeriesPrivate::drawSeriesPointLabels(QPainter *painter, const QList<QPointF> &points,
                                              const int offset, const QHash<int, int> &offsets,
-                                             const QList<int> &indexesToSkip)
+                                             const QList<int> &indexesToSkip,
+                                             const QHash<int, QString> &labelFormats)
 {
     if (points.size() == 0)
         return;
 
     static const QString xPointTag(QLatin1String("@xPoint"));
     static const QString yPointTag(QLatin1String("@yPoint"));
+    static const QString indexTag(QLatin1String("@index"));
 
     QFont f(m_pointLabelsFont);
     f.setPixelSize(QFontInfo(m_pointLabelsFont).pixelSize());
@@ -1853,9 +1875,10 @@ void QXYSeriesPrivate::drawSeriesPointLabels(QPainter *painter, const QList<QPoi
         if (indexesToSkip.contains(i))
             continue;
 
-        QString pointLabel = m_pointLabelsFormat;
+        QString pointLabel = labelFormats.contains(i) ? labelFormats[i] : m_pointLabelsFormat;
         pointLabel.replace(xPointTag, presenter()->numberToString(m_points.at(i).x()));
         pointLabel.replace(yPointTag, presenter()->numberToString(m_points.at(i).y()));
+        pointLabel.replace(indexTag, presenter()->numberToString(i));
 
         int currOffset = offset;
         if (offsets.contains(i))
diff --git a/src/charts/xychart/qxyseries.h b/src/charts/xychart/qxyseries.h
index fac75698..23f6bfd7 100644
--- a/src/charts/xychart/qxyseries.h
+++ b/src/charts/xychart/qxyseries.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2021 The Qt Company Ltd.
+// Copyright (C) 2022 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
 #ifndef QXYSERIES_H
@@ -41,7 +41,8 @@ public:
         Color = 0,
         Size,
         Visibility,
-        LabelVisibility
+        LabelVisibility,
+        LabelFormat
     };
     Q_ENUM(PointConfiguration)
 
diff --git a/src/charts/xychart/qxyseries_p.h b/src/charts/xychart/qxyseries_p.h
index cbb5aa4e..21408610 100644
--- a/src/charts/xychart/qxyseries_p.h
+++ b/src/charts/xychart/qxyseries_p.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2021 The Qt Company Ltd.
+// Copyright (C) 2022 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
 
 //  W A R N I N G
@@ -47,7 +47,8 @@ public:
     void drawPointLabels(QPainter *painter, const QList<QPointF> &allPoints, const int offset = 0);
     void drawSeriesPointLabels(QPainter *painter, const QList<QPointF> &points,
                                const int offset = 0, const QHash<int, int> &offsets = {},
-                               const QList<int> &indexesToSkip = {});
+                               const QList<int> &indexesToSkip = {},
+                               const QHash<int, QString> &customLabels = {});
 
     void drawBestFitLine(QPainter *painter, const QRectF &clipRect);
     QPair<qreal, qreal> bestFitLineEquation(bool &ok) const;