Add label editing feature to the QValueAxis

Add a new property (labelsEditable) to the QAbstractAxis. If this
property set to true the user will be able to manipulate the axis
labels by double clicking on it and entering a new value. After
finishing the edit the axis range will adjusted according to the
entered value. At the moment only the QValueAxis is supported,
but I am planning to add support for QLogValueAxis, and QDateTimeAxis
after the basic implementation details got reviewed.

Change-Id: Id87ebfbfb37ed00f09cf7b651395cf3caead1dbb
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

13 files changed, 383 insertions, 1 deletions

diff --git a/src/charts/axis/axis.pri b/src/charts/axis/axis.pri
index 340f5b35..4909e77c 100644
--- a/src/charts/axis/axis.pri
+++ b/src/charts/axis/axis.pri
@@ -15,6 +15,7 @@ SOURCES += \
     $$PWD/valueaxis/chartvalueaxisx.cpp \
     $$PWD/valueaxis/chartvalueaxisy.cpp \
     $$PWD/valueaxis/qvalueaxis.cpp \
+    $$PWD/valueaxis/valueaxislabel.cpp \
     $$PWD/barcategoryaxis/chartbarcategoryaxisx.cpp \
     $$PWD/barcategoryaxis/chartbarcategoryaxisy.cpp \
     $$PWD/barcategoryaxis/qbarcategoryaxis.cpp \
@@ -35,6 +36,7 @@ PRIVATE_HEADERS += \
     $$PWD/valueaxis/chartvalueaxisx_p.h \
     $$PWD/valueaxis/chartvalueaxisy_p.h \
     $$PWD/valueaxis/qvalueaxis_p.h \
+    $$PWD/valueaxis/valueaxislabel_p.h \
     $$PWD/barcategoryaxis/chartbarcategoryaxisx_p.h \
     $$PWD/barcategoryaxis/chartbarcategoryaxisy_p.h \
     $$PWD/barcategoryaxis/qbarcategoryaxis_p.h \
diff --git a/src/charts/axis/cartesianchartaxis.cpp b/src/charts/axis/cartesianchartaxis.cpp
index 571af7a9..34e618c2 100644
--- a/src/charts/axis/cartesianchartaxis.cpp
+++ b/src/charts/axis/cartesianchartaxis.cpp
@@ -81,7 +81,17 @@ void CartesianChartAxis::createItems(int count)
     for (int i = 0; i < count; ++i) {
         QGraphicsLineItem *arrow = new QGraphicsLineItem(this);
         QGraphicsLineItem *grid = new QGraphicsLineItem(this);
-        QGraphicsTextItem *label = new QGraphicsTextItem(this);
+        QGraphicsTextItem *label = axis()->type() == QAbstractAxis::AxisTypeValue
+                ? new ValueAxisLabel(this)
+                : new QGraphicsTextItem(this);
+        if (axis()->type() == QAbstractAxis::AxisTypeValue) {
+            ValueAxisLabel *valueLabel = static_cast<ValueAxisLabel *>(label);
+            connect(valueLabel, &ValueAxisLabel::valueChanged,
+                    this, &ChartAxisElement::labelEdited);
+            // only QValueAxis labels editable for now
+            if (labelsEditable())
+                valueLabel->setEditable(true);
+        }
         label->document()->setDocumentMargin(ChartPresenter::textMargin());
         arrow->setPen(axis()->linePen());
         grid->setPen(axis()->gridLinePen());
@@ -327,6 +337,35 @@ void CartesianChartAxis::handleShadesPenChanged(const QPen &pen)
         static_cast<QGraphicsRectItem *>(item)->setPen(pen);
 }
 
+void CartesianChartAxis::updateLabelsValues(QValueAxis *axis)
+{
+    const QVector<qreal> &layout = ChartAxisElement::layout();
+    if (layout.isEmpty())
+        return;
+
+    if (axis->tickType() == QValueAxis::TicksFixed) {
+        for (int i = 0; i < layout.size(); ++i) {
+            qreal value = axis->isReverse()
+                    ? min() + ((layout.size() - 1 - i) * (max() - min()) / (layout.size() - 1))
+                    : min() + (i * (max() - min()) / (layout.size() - 1));
+            static_cast<ValueAxisLabel *>(labelItems().at(i))->setValue(value);
+        }
+    } else {
+        qreal value = axis->tickAnchor();
+        if (value > min())
+            value = value - int((value - min()) / axis->tickInterval()) * axis->tickInterval();
+        else
+            value = value + qCeil((min() - value) / axis->tickInterval()) * axis->tickInterval();
+
+        int i = axis->isReverse() ? labelItems().count()-1 : 0;
+        while (value <= max() || qFuzzyCompare(value, max())) {
+            static_cast<ValueAxisLabel *>(labelItems().at(i))->setValue(value);
+            value += axis->tickInterval();
+            i += axis->isReverse() ? -1 : 1;
+        }
+    }
+}
+
 QT_CHARTS_END_NAMESPACE
 
 #include "moc_cartesianchartaxis_p.cpp"
diff --git a/src/charts/axis/cartesianchartaxis_p.h b/src/charts/axis/cartesianchartaxis_p.h
index 60cabd19..dc274522 100644
--- a/src/charts/axis/cartesianchartaxis_p.h
+++ b/src/charts/axis/cartesianchartaxis_p.h
@@ -77,6 +77,9 @@ public Q_SLOTS:
     virtual void handleGridLineColorChanged(const QColor &color);
     virtual void handleMinorGridLineColorChanged(const QColor &color);
 
+protected:
+    void updateLabelsValues(QValueAxis *axis);
+
 private:
     void createItems(int count);
     void deleteItems(int count);
diff --git a/src/charts/axis/chartaxiselement.cpp b/src/charts/axis/chartaxiselement.cpp
index fc2b3e27..bf33d330 100644
--- a/src/charts/axis/chartaxiselement.cpp
+++ b/src/charts/axis/chartaxiselement.cpp
@@ -157,6 +157,30 @@ void ChartAxisElement::handleLabelsPositionChanged()
     presenter()->layout()->invalidate();
 }
 
+void ChartAxisElement::labelEdited(qreal oldValue, qreal newValue)
+{
+    qreal range = max() - min();
+    qreal center = ((max() - min()) / 2) + min();
+    qreal newRange = 0.0;
+    auto label = static_cast<ValueAxisLabel *>(this->sender());
+    if ((oldValue >= center && newValue >=  min())
+     || (oldValue <  center && newValue >= max() && oldValue != min())) {
+        newRange = range * ((newValue - min()) / (oldValue - min()));
+        if (newRange > 0) {
+            m_axis->setRange(min(), min() + newRange);
+            return;
+        }
+    } else if ((oldValue >= center && newValue <= min() && max() != oldValue)
+            || (oldValue <  center && newValue < max())) {
+        newRange = range * ((max() - newValue) / (max() - oldValue));
+        if (newRange > 0) {
+            m_axis->setRange(max() - newRange, max());
+            return;
+        }
+    }
+    label->reloadBeforeEditContent();
+}
+
 void ChartAxisElement::handleLabelsVisibleChanged(bool visible)
 {
     QGraphicsLayoutItem::updateGeometry();
@@ -502,6 +526,23 @@ QStringList ChartAxisElement::createDateTimeLabels(qreal min, qreal max,int tick
     return labels;
 }
 
+
+bool ChartAxisElement::labelsEditable() const
+{
+    return m_labelsEditable;
+}
+
+void ChartAxisElement::setLabelsEditable(bool labelsEditable)
+{
+    if (axis()->type() == QAbstractAxis::AxisTypeValue) {
+        labelGroup()->setHandlesChildEvents(!labelsEditable);
+        const QList<QGraphicsItem *> childItems = labelGroup()->childItems();
+        for (auto item : childItems)
+            static_cast<ValueAxisLabel *>(item)->setEditable(labelsEditable);
+        m_labelsEditable = labelsEditable;
+    }
+}
+
 void ChartAxisElement::axisSelected()
 {
     emit clicked();
diff --git a/src/charts/axis/chartaxiselement_p.h b/src/charts/axis/chartaxiselement_p.h
index 7aced068..4bc1475e 100644
--- a/src/charts/axis/chartaxiselement_p.h
+++ b/src/charts/axis/chartaxiselement_p.h
@@ -43,6 +43,7 @@
 #include <QtCharts/private/qchartglobal_p.h>
 #include <private/chartelement_p.h>
 #include <private/axisanimation_p.h>
+#include <private/valueaxislabel_p.h>
 #include <QtWidgets/QGraphicsItem>
 #include <QtWidgets/QGraphicsLayoutItem>
 #include <QtCharts/QValueAxis>
@@ -111,6 +112,9 @@ public:
     {
     }
 
+    bool labelsEditable() const;
+    void setLabelsEditable(bool labelsEditable);
+
 protected:
     virtual QVector<qreal> calculateLayout() const = 0;
     virtual void updateLayout(QVector<qreal> &layout) = 0;
@@ -155,6 +159,7 @@ public Q_SLOTS:
     void handleMinorArrowVisibleChanged(bool visible);
     void handleMinorGridVisibleChanged(bool visible);
     void handleLabelsPositionChanged();
+    void labelEdited(qreal oldValue, qreal newValue);
 
 Q_SIGNALS:
     void clicked();
@@ -179,6 +184,7 @@ private:
     QScopedPointer<QGraphicsItemGroup> m_labels;
     QScopedPointer<QGraphicsTextItem> m_title;
     bool m_intervalAxis;
+    bool m_labelsEditable = false;
 };
 
 QT_CHARTS_END_NAMESPACE
diff --git a/src/charts/axis/qabstractaxis.cpp b/src/charts/axis/qabstractaxis.cpp
index 73fa5920..ed246536 100644
--- a/src/charts/axis/qabstractaxis.cpp
+++ b/src/charts/axis/qabstractaxis.cpp
@@ -102,6 +102,17 @@ QT_CHARTS_BEGIN_NAMESPACE
 */
 
 /*!
+  \property QAbstractAxis::labelsEditable
+  \since 5.13
+  \brief This property holds whether the labels of the axis are editable or not.
+  When the labels set to editable the user will be able to change the range of the
+  axis conveniently by editing any of the labels. This feature is only implemented
+  for the QValueAxis.
+
+  By default, the value is \c false.
+*/
+
+/*!
   \property QAbstractAxis::labelsBrush
   \brief The brush used to draw the labels.
 
@@ -368,6 +379,12 @@ QT_CHARTS_BEGIN_NAMESPACE
 */
 
 /*!
+  \fn void QAbstractAxis::labelsEditableChanged(bool editable)
+  \since 5.13
+  This signal is emitted when the labels editability changes.
+*/
+
+/*!
   \fn void QAbstractAxis::gridVisibleChanged(bool visible)
   This signal is emitted when the visibility of the grid lines of the axis changes to \a visible.
 */
@@ -948,6 +965,25 @@ bool QAbstractAxis::isReverse() const
     return d_ptr->m_reverse;
 }
 
+void QAbstractAxis::setLabelsEditable(bool editable)
+{
+    if (d_ptr->m_labelsEditable != editable) {
+        // In the case if the axis already added to a chart
+        // set the labels editability on the axisItem().
+        // Otherwise the labels editability will be set in the
+        // QValueAxisPrivate::initializeGraphics.
+        if (d_ptr->axisItem() != nullptr)
+            d_ptr->axisItem()->setLabelsEditable(editable);
+        d_ptr->m_labelsEditable = editable;
+        emit labelsEditableChanged(editable);
+    }
+}
+
+bool QAbstractAxis::labelsEditable() const
+{
+    return d_ptr->m_labelsEditable;
+}
+
 void QAbstractAxis::setReverse(bool reverse)
 {
     if (d_ptr->m_reverse != reverse && type() != QAbstractAxis::AxisTypeBarCategory) {
@@ -972,6 +1008,7 @@ QAbstractAxisPrivate::QAbstractAxisPrivate(QAbstractAxis *q)
       m_minorGridLineVisible(true),
       m_minorGridLinePen(QChartPrivate::defaultPen()),
       m_labelsVisible(true),
+      m_labelsEditable(false),
       m_labelsBrush(QChartPrivate::defaultBrush()),
       m_labelsFont(QChartPrivate::defaultFont()),
       m_labelsAngle(0),
diff --git a/src/charts/axis/qabstractaxis.h b/src/charts/axis/qabstractaxis.h
index 4f902679..a1b91a43 100644
--- a/src/charts/axis/qabstractaxis.h
+++ b/src/charts/axis/qabstractaxis.h
@@ -54,6 +54,7 @@ class QT_CHARTS_EXPORT QAbstractAxis : public QObject
     Q_PROPERTY(int labelsAngle READ labelsAngle WRITE setLabelsAngle NOTIFY labelsAngleChanged)
     Q_PROPERTY(QFont labelsFont READ labelsFont WRITE setLabelsFont NOTIFY labelsFontChanged)
     Q_PROPERTY(QColor labelsColor READ labelsColor WRITE setLabelsColor NOTIFY labelsColorChanged)
+    Q_PROPERTY(bool labelsEditable READ labelsEditable WRITE setLabelsEditable NOTIFY labelsEditableChanged)
     //grid
     Q_PROPERTY(bool gridVisible READ isGridLineVisible WRITE setGridLineVisible NOTIFY gridVisibleChanged)
     Q_PROPERTY(QPen gridLinePen READ gridLinePen WRITE setGridLinePen NOTIFY gridLinePenChanged)
@@ -173,6 +174,10 @@ public:
     void setReverse(bool reverse = true);
     bool isReverse() const;
 
+    //label editable handling
+    void setLabelsEditable(bool editable = true);
+    bool labelsEditable() const;
+
 Q_SIGNALS:
     void visibleChanged(bool visible);
     void linePenChanged(const QPen &pen);
@@ -199,6 +204,7 @@ Q_SIGNALS:
     void shadesPenChanged(const QPen &pen);
     void shadesBrushChanged(const QBrush &brush);
     void reverseChanged(bool reverse);
+    void labelsEditableChanged(bool editable);
 
 protected:
     QScopedPointer<QAbstractAxisPrivate> d_ptr;
diff --git a/src/charts/axis/qabstractaxis_p.h b/src/charts/axis/qabstractaxis_p.h
index 3a635d98..ee3af6a0 100644
--- a/src/charts/axis/qabstractaxis_p.h
+++ b/src/charts/axis/qabstractaxis_p.h
@@ -117,6 +117,7 @@ private:
     QPen m_minorGridLinePen;
 
     bool m_labelsVisible;
+    bool m_labelsEditable;
     QBrush m_labelsBrush;
     QFont m_labelsFont;
     int m_labelsAngle;
diff --git a/src/charts/axis/valueaxis/chartvalueaxisx.cpp b/src/charts/axis/valueaxis/chartvalueaxisx.cpp
index 6eeda781..3eac86e0 100644
--- a/src/charts/axis/valueaxis/chartvalueaxisx.cpp
+++ b/src/charts/axis/valueaxis/chartvalueaxisx.cpp
@@ -32,6 +32,7 @@
 #include <private/chartpresenter_p.h>
 #include <QtCharts/QValueAxis>
 #include <private/abstractchartlayout_p.h>
+#include <private/valueaxislabel_p.h>
 #include <QtWidgets/QGraphicsLayout>
 #include <QtCore/QtMath>
 #include <QtCore/QDebug>
@@ -107,6 +108,7 @@ void ChartValueAxisX::updateGeometry()
     setLabels(createValueLabels(min(), max(), layout.size(), m_axis->tickInterval(),
                                 m_axis->tickAnchor(), m_axis->tickType(), m_axis->labelFormat()));
     HorizontalAxis::updateGeometry();
+    updateLabelsValues(m_axis);
 }
 
 void ChartValueAxisX::handleTickCountChanged(int tick)
diff --git a/src/charts/axis/valueaxis/chartvalueaxisy.cpp b/src/charts/axis/valueaxis/chartvalueaxisy.cpp
index 961b292e..c4868fc2 100644
--- a/src/charts/axis/valueaxis/chartvalueaxisy.cpp
+++ b/src/charts/axis/valueaxis/chartvalueaxisy.cpp
@@ -32,6 +32,7 @@
 #include <private/chartpresenter_p.h>
 #include <QtCharts/QValueAxis>
 #include <private/abstractchartlayout_p.h>
+#include <private/valueaxislabel_p.h>
 #include <QtWidgets/QGraphicsLayout>
 #include <QtCore/QtMath>
 #include <QtCore/QDebug>
@@ -108,6 +109,7 @@ void ChartValueAxisY::updateGeometry()
     setLabels(createValueLabels(min(), max(), layout.size(), m_axis->tickInterval(),
                                 m_axis->tickAnchor(), m_axis->tickType(), m_axis->labelFormat()));
     VerticalAxis::updateGeometry();
+    updateLabelsValues(m_axis);
 }
 
 void ChartValueAxisY::handleTickCountChanged(int tick)
diff --git a/src/charts/axis/valueaxis/qvalueaxis.cpp b/src/charts/axis/valueaxis/qvalueaxis.cpp
index 1d179e43..905168d7 100644
--- a/src/charts/axis/valueaxis/qvalueaxis.cpp
+++ b/src/charts/axis/valueaxis/qvalueaxis.cpp
@@ -533,6 +533,7 @@ void QValueAxisPrivate::initializeGraphics(QGraphicsItem *parent)
             axis = new ChartValueAxisY(q,parent);
         if (orientation() == Qt::Horizontal)
             axis = new ChartValueAxisX(q,parent);
+        axis->setLabelsEditable(q->labelsEditable());
     }
 
     if (m_chart->chartType() == QChart::ChartTypePolar) {
diff --git a/src/charts/axis/valueaxis/valueaxislabel.cpp b/src/charts/axis/valueaxis/valueaxislabel.cpp
new file mode 100644
index 00000000..cd81a857
--- /dev/null
+++ b/src/charts/axis/valueaxis/valueaxislabel.cpp
@@ -0,0 +1,162 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Charts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+#include "valueaxislabel_p.h"
+
+#include <QtCore/qlocale.h>
+#include <QtGui/qevent.h>
+#include <QtGui/qtextcursor.h>
+#include <QtGui/qtextdocument.h>
+
+QT_CHARTS_BEGIN_NAMESPACE
+
+ValueAxisLabel::ValueAxisLabel(QGraphicsItem *parent) :
+    QGraphicsTextItem(parent)
+{
+
+}
+
+void ValueAxisLabel::focusInEvent(QFocusEvent *event)
+{
+    m_htmlBeforeEdit = toHtml();
+    setTextWidth(-1);
+    m_valueBeforeEdit = m_value;
+    setHtml(QString::number(m_value));
+    m_editing = true;
+    QGraphicsTextItem::focusInEvent(event);
+}
+
+void ValueAxisLabel::focusOutEvent(QFocusEvent *event)
+{
+    // perform the modifications before emitting valueChanged
+    // because slots attached to valueChanged can trigger
+    // a range change which might invalidate the current label
+    QGraphicsTextItem::focusOutEvent(event);
+    setTextInteractionFlags(Qt::NoTextInteraction);
+    m_editing = false;
+
+    bool ok = false;
+    QLocale locale;
+    qreal oldValue = m_value;
+    qreal newValue = locale.toDouble(document()->toPlainText(), &ok);
+    if (ok && newValue != m_value) {
+        m_value = newValue;
+        emit valueChanged(oldValue, newValue);
+    } else {
+        document()->setHtml(m_htmlBeforeEdit);
+    }
+}
+
+qreal ValueAxisLabel::value() const
+{
+    return m_value;
+}
+
+void ValueAxisLabel::setValue(const qreal &value)
+{
+    setTextInteractionFlags(Qt::NoTextInteraction);
+    clearFocus();
+    m_value = value;
+}
+
+void ValueAxisLabel::reloadBeforeEditContent()
+{
+    m_value = m_valueBeforeEdit;
+    setHtml(m_htmlBeforeEdit);
+}
+
+QRectF ValueAxisLabel::boundingRect() const
+{
+    QRectF ret = QGraphicsTextItem::boundingRect();
+
+    // add 2px margin to allow the cursor to
+    // show up properly when editing
+    if (m_editing)
+        ret.setWidth(ret.width() + 2);
+    return ret;
+}
+
+void ValueAxisLabel::setEditable(bool editable)
+{
+    m_editable = editable;
+}
+
+void ValueAxisLabel::keyPressEvent(QKeyEvent *event)
+{
+    if (event->text().length() >= 1) {
+        // finish editing with enter
+        if (event->key() == Qt::Key_Enter ||
+                event->key() == Qt::Key_Return) {
+            clearFocus();
+            // prevent further event processing with a return
+            // because the focusOutEvent could have triggered
+            // a range change which might have invalidated the current label
+            return;
+        } else if (event->key() == Qt::Key_Escape) {
+            document()->setHtml(m_htmlBeforeEdit);
+            clearFocus();
+            // prevent further event processing with a return
+            // because the focusOutEvent could have triggered
+            // a range change which might have invalidated the current label
+            return;
+        }
+
+        QLocale locale;
+        if (!event->text().at(0).isDigit()
+                && event->text().at(0) != locale.decimalPoint()
+                && event->text().at(0) != locale.negativeSign()
+                && event->text().at(0) != locale.exponential()
+                && event->key() != Qt::Key_Backspace
+                && event->key() != Qt::Key_Delete) {
+            event->ignore();
+            return;
+        }
+    }
+    QGraphicsTextItem::keyPressEvent(event);
+}
+
+bool ValueAxisLabel::sceneEvent(QEvent *event)
+{
+    if (m_editable && event->type() == QEvent::GraphicsSceneMouseDoubleClick) {
+        setTextInteractionFlags(Qt::TextEditorInteraction);
+
+        bool ret = QGraphicsTextItem::sceneEvent(event);
+        // QGraphicsTextItem::sceneevent needs to be processed before
+        // the focus and text selection
+        setFocus(Qt::MouseFocusReason);
+        QTextCursor cursor = textCursor();
+        cursor.select(QTextCursor::Document);
+        setTextCursor(cursor);
+        return ret;
+    }
+    return QGraphicsTextItem::sceneEvent(event);
+}
+
+QT_CHARTS_END_NAMESPACE
+
+#include "moc_valueaxislabel_p.cpp"
diff --git a/src/charts/axis/valueaxis/valueaxislabel_p.h b/src/charts/axis/valueaxis/valueaxislabel_p.h
new file mode 100644
index 00000000..14f3eb48
--- /dev/null
+++ b/src/charts/axis/valueaxis/valueaxislabel_p.h
@@ -0,0 +1,80 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Charts module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) any later version
+** approved by the KDE Free Qt Foundation. The licenses are as published by
+** the Free Software Foundation and appearing in the file LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt Chart API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+
+#ifndef VALUEAXISLABEL_H
+#define VALUEAXISLABEL_H
+
+#include <QtWidgets/qgraphicsitem.h>
+#include <QtCharts/private/qchartglobal_p.h>
+
+QT_CHARTS_BEGIN_NAMESPACE
+
+class QT_CHARTS_PRIVATE_EXPORT ValueAxisLabel : public QGraphicsTextItem
+{
+    Q_OBJECT
+public:
+    ValueAxisLabel(QGraphicsItem *parent = nullptr);
+
+    void focusInEvent(QFocusEvent *event);
+    void focusOutEvent(QFocusEvent *event);
+    void keyPressEvent(QKeyEvent *event);
+
+    bool sceneEvent(QEvent *event);
+
+    qreal value() const;
+    void setValue(const qreal &value);
+    void reloadBeforeEditContent();
+
+    QRectF boundingRect() const;
+
+    void setEditable(bool editable);
+
+private:
+    qreal m_value = 0.0;
+    qreal m_valueBeforeEdit = 0.0;
+    QString m_htmlBeforeEdit;
+    bool m_editing = false;
+    bool m_editable = false;
+
+signals:
+    void valueChanged(qreal oldValue, qreal newValue);
+};
+
+QT_CHARTS_END_NAMESPACE
+
+#endif // VALUEAXISLABEL_H