QXYSeries: Support for selection in a plot

In order to support selection of points in a chart there is a support
for this in scatterchartitem and linechartitem.
The interface for that is available on QXYSeries level.
Selected points can have changed color and they are a bit bigger than
other points.
Selected points are visible regardless of other points visibility.

Task-number: QTBUG-89445
Change-Id: I6d11afa84288f4f949e53b005410659b0ecf3c55
Reviewed-by: Keith Kyzivat <keith.kyzivat@qt.io>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>

6 files changed, 297 insertions, 9 deletions

diff --git a/src/charts/linechart/linechartitem.cpp b/src/charts/linechart/linechartitem.cpp
index ef35a4f2..f2b30df2 100644
--- a/src/charts/linechart/linechartitem.cpp
+++ b/src/charts/linechart/linechartitem.cpp
@@ -64,6 +64,8 @@ LineChartItem::LineChartItem(QLineSeries *series, QGraphicsItem *item)
     QObject::connect(series, SIGNAL(pointLabelsFontChanged(QFont)), this, SLOT(handleUpdated()));
     QObject::connect(series, SIGNAL(pointLabelsColorChanged(QColor)), this, SLOT(handleUpdated()));
     QObject::connect(series, SIGNAL(pointLabelsClippingChanged(bool)), this, SLOT(handleUpdated()));
+    connect(series, &QLineSeries::selectedColorChanged, this, &LineChartItem::handleUpdated);
+    connect(series, &QLineSeries::selectedPointsChanged, this, &LineChartItem::handleUpdated);
     handleUpdated();
 }
 
@@ -329,11 +331,12 @@ void LineChartItem::updateGeometry()
 
 void LineChartItem::handleUpdated()
 {
-    // If points visibility has changed, a geometry update is needed.
-    // Also, if pen changes when points are visible, geometry update is needed.
     bool doGeometryUpdate =
         (m_pointsVisible != m_series->pointsVisible())
-        || (m_series->pointsVisible() && (m_linePen != m_series->pen()));
+        || (m_series->pointsVisible()
+            && (m_linePen != m_series->pen()
+            || m_selectedColor != m_series->selectedColor()
+            || m_selectedPoints != m_series->selectedPoints()));
     bool visibleChanged = m_series->isVisible() != isVisible();
     setVisible(m_series->isVisible());
     setOpacity(m_series->opacity());
@@ -343,6 +346,8 @@ void LineChartItem::handleUpdated()
     m_pointLabelsVisible = m_series->pointLabelsVisible();
     m_pointLabelsFont = m_series->pointLabelsFont();
     m_pointLabelsColor = m_series->pointLabelsColor();
+    m_selectedColor = m_series->selectedColor();
+    m_selectedPoints = m_series->selectedPoints();
     bool labelClippingChanged = m_pointLabelsClipping != m_series->pointLabelsClipping();
     m_pointLabelsClipping = m_series->pointLabelsClipping();
     if (doGeometryUpdate)
@@ -414,14 +419,24 @@ void LineChartItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *opt
 
     painter->restore();
 
-    if (m_pointsVisible) {
+    if (m_pointsVisible || !m_selectedPoints.isEmpty()) {
         // draw points that lie inside clipRect only
         qreal ptSize = m_linePen.width() * 1.5;
         painter->setPen(Qt::NoPen);
         painter->setBrush(m_linePen.color());
         for (int i = 0; i < m_linePoints.size(); ++i) {
-            if (clipRect.contains(m_linePoints.at(i)))
-                painter->drawEllipse(m_linePoints.at(i), ptSize, ptSize);
+            if (clipRect.contains(m_linePoints.at(i))) {
+                if (m_series->isPointSelected(i)) {
+                    painter->save();
+                    if (m_selectedColor.isValid())
+                        painter->setBrush(m_selectedColor);
+
+                    painter->drawEllipse(m_linePoints.at(i), ptSize * 1.5, ptSize * 1.5);
+                    painter->restore();
+                } else if (m_pointsVisible) {
+                    painter->drawEllipse(m_linePoints.at(i), ptSize, ptSize);
+                }
+            }
         }
     }
 }
diff --git a/src/charts/scatterchart/scatterchartitem.cpp b/src/charts/scatterchart/scatterchartitem.cpp
index 515f3678..0f81ee54 100644
--- a/src/charts/scatterchart/scatterchartitem.cpp
+++ b/src/charts/scatterchart/scatterchartitem.cpp
@@ -68,6 +68,8 @@ ScatterChartItem::ScatterChartItem(QScatterSeries *series, QGraphicsItem *item)
     QObject::connect(series, SIGNAL(pointLabelsFontChanged(QFont)), this, SLOT(handleUpdated()));
     QObject::connect(series, SIGNAL(pointLabelsColorChanged(QColor)), this, SLOT(handleUpdated()));
     QObject::connect(series, SIGNAL(pointLabelsClippingChanged(bool)), this, SLOT(handleUpdated()));
+    connect(series, &QXYSeries::selectedColorChanged, this, &ScatterChartItem::handleUpdated);
+    connect(series, &QXYSeries::selectedPointsChanged, this, &ScatterChartItem::handleUpdated);
 
     setZValue(ChartPresenter::ScatterSeriesZValue);
     setFlags(QGraphicsItem::ItemClipsChildrenToShape);
@@ -262,8 +264,18 @@ void ScatterChartItem::setPen(const QPen &pen)
 
 void ScatterChartItem::setBrush(const QBrush &brush)
 {
-    foreach (QGraphicsItem *item , m_items.childItems())
-        static_cast<QAbstractGraphicsShapeItem*>(item)->setBrush(brush);
+    const auto &items = m_items.childItems();
+    for (auto item : items) {
+        if (m_markerMap.contains(item)) {
+            auto index = m_series->points().indexOf(m_markerMap[item]);
+            if (m_selectedPoints.contains(index))
+                static_cast<QAbstractGraphicsShapeItem *>(item)->setBrush(m_selectedColor);
+            else
+                static_cast<QAbstractGraphicsShapeItem *>(item)->setBrush(brush);
+        } else {
+            static_cast<QAbstractGraphicsShapeItem *>(item)->setBrush(brush);
+        }
+    }
 }
 
 void ScatterChartItem::handleUpdated()
@@ -282,7 +294,9 @@ void ScatterChartItem::handleUpdated()
 
     bool recreate = m_visible != m_series->isVisible()
                     || m_size != m_series->markerSize()
-                    || m_shape != m_series->markerShape();
+                    || m_shape != m_series->markerShape()
+                    || m_selectedColor != m_series->selectedColor()
+                    || m_selectedPoints != m_series->selectedPoints();
     m_visible = m_series->isVisible();
     m_size = m_series->markerSize();
     m_shape = m_series->markerShape();
@@ -292,6 +306,8 @@ void ScatterChartItem::handleUpdated()
     m_pointLabelsVisible = m_series->pointLabelsVisible();
     m_pointLabelsFont = m_series->pointLabelsFont();
     m_pointLabelsColor = m_series->pointLabelsColor();
+    m_selectedColor = m_series->selectedColor();
+    m_selectedPoints = m_series->selectedPoints();
     bool labelClippingChanged = m_pointLabelsClipping != m_series->pointLabelsClipping();
     m_pointLabelsClipping = m_series->pointLabelsClipping();
 
diff --git a/src/charts/xychart/qxyseries.cpp b/src/charts/xychart/qxyseries.cpp
index e991755a..ca93f07a 100644
--- a/src/charts/xychart/qxyseries.cpp
+++ b/src/charts/xychart/qxyseries.cpp
@@ -246,6 +246,22 @@ QT_BEGIN_NAMESPACE
     \sa pointLabelsVisible
 */
 /*!
+    \property QXYSeries::selectedColor
+    \brief The color of the selected points.
+
+    This is the fill (brush) color of points marked as selected. If not specified,
+    value of QXYSeries::color is used as default.
+    \sa color
+    \since 6.2
+*/
+/*!
+    \qmlproperty color XYSeries::selectedColor
+    The color of the selected points. This is the fill (brush) color of points marked
+    as selected.
+    If not specified, value of QXYSeries::color is used as default.
+    \sa color
+*/
+/*!
     \fn void QXYSeries::pointLabelsClippingChanged(bool clipping)
     This signal is emitted when the clipping of the data point labels changes to
     \a clipping.
@@ -607,6 +623,159 @@ void QXYSeries::replace(const QList<QPointF> &points)
 }
 
 /*!
+   Returns true if point at given \a index is among selected points and false otherwise.
+   \note Selected points are drawn using the selected color if it was specified.
+   \sa selectedPoints(), setPointSelected(), setSelectedColor()
+   \since 6.2
+ */
+bool QXYSeries::isPointSelected(int index)
+{
+    Q_D(QXYSeries);
+    return d->isPointSelected(index);
+}
+
+/*!
+  Marks point at \a index as selected.
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::selectPoint(int index)
+{
+    setPointSelected(index, true);
+}
+
+/*!
+  Deselects point at given \a index.
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::deselectPoint(int index)
+{
+    setPointSelected(index, false);
+}
+
+/*!
+  Marks point at given \a index as either selected or deselected.
+  \note Selected points are drawn using the selected color if it was specified. Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected(), setSelectedColor()
+  \since 6.2
+ */
+void QXYSeries::setPointSelected(int index, bool selected)
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    d->setPointSelected(index, selected, callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Marks all points in the series as selected,
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::selectAllPoints()
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    for (int i = 0; i < d->m_points.count(); ++i)
+        d->setPointSelected(i, true, callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Deselects all points in the series.
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::deselectAllPoints()
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    for (int i = 0; i < d->m_points.count(); ++i)
+        d->setPointSelected(i, false, callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Marks multiple points passed in a \a indexes list as selected.
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::selectPoints(const QList<int> &indexes)
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    for (const int &index : indexes)
+        d->setPointSelected(index, true, callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Marks multiple points passed in a \a indexes list as deselected.
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::deselectPoints(const QList<int> &indexes)
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    for (const int &index : indexes)
+        d->setPointSelected(index, false, callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Changes selection state of points at given \a indexes to the opposite one. Makes
+  \note Emits QXYSeries::selectedPointsChanged
+  \sa setPointSelected()
+  \since 6.2
+ */
+void QXYSeries::toggleSelection(const QList<int> &indexes)
+{
+    Q_D(QXYSeries);
+
+    bool callSignal = false;
+    for (const int &index : indexes)
+        d->setPointSelected(index, !isPointSelected(index), callSignal);
+
+    if (callSignal)
+        emit selectedPointsChanged();
+}
+
+/*!
+  Returns a list of points indexes marked as selected.
+  Selected points are visible regardless of points visibility.
+  \sa setPointSelected(), pointsVisible()
+  \since 6.2
+ */
+QList<int> QXYSeries::selectedPoints() const
+{
+    Q_D(const QXYSeries);
+    return QList<int>(d->m_selectedPoints.begin(), d->m_selectedPoints.end());
+}
+
+/*!
   Removes the point that has the coordinates \a x and \a y from the series.
   \sa pointRemoved()
 */
@@ -635,6 +804,7 @@ void QXYSeries::remove(const QPointF &point)
 void QXYSeries::remove(int index)
 {
     Q_D(QXYSeries);
+    deselectPoint(index);
     d->m_points.remove(index);
     emit pointRemoved(index);
 }
@@ -650,6 +820,13 @@ void QXYSeries::removePoints(int index, int count)
     // remove(qreal, qreal) overload in some implicit casting cases.
     Q_D(QXYSeries);
     if (count > 0) {
+        if (!d->m_selectedPoints.empty()) {
+            QList<int> indexes;
+            for (int i = index; i < index + count; ++i)
+                indexes << i;
+            deselectPoints(indexes);
+        }
+
         d->m_points.remove(index, count);
         emit pointsRemoved(index, count);
     }
@@ -665,6 +842,24 @@ void QXYSeries::insert(int index, const QPointF &point)
     Q_D(QXYSeries);
     if (isValidValue(point)) {
         index = qMax(0, qMin(index, d->m_points.size()));
+
+        if (!d->m_selectedPoints.isEmpty()) {
+            // if point was inserted we need to move already selected points by 1
+            QSet<int> selectedAfterInsert;
+            bool callSignal = false;
+            for (const auto &value : d->m_selectedPoints) {
+                if (value >= index) {
+                    selectedAfterInsert << value + 1;
+                    callSignal = true;
+                } else {
+                    selectedAfterInsert << value;
+                }
+            }
+            d->m_selectedPoints = selectedAfterInsert;
+            if (callSignal)
+                emit selectedPointsChanged();
+        }
+
         d->m_points.insert(index, point);
         emit pointAdded(index);
     }
@@ -788,6 +983,21 @@ QColor QXYSeries::color() const
     return pen().color();
 }
 
+void QXYSeries::setSelectedColor(const QColor &color)
+{
+    Q_D(QXYSeries);
+    if (selectedColor() != color) {
+        d->m_selectedColor = color;
+        emit selectedColorChanged(color);
+    }
+}
+
+QColor QXYSeries::selectedColor() const
+{
+    Q_D(const QXYSeries);
+    return d->m_selectedColor;
+}
+
 void QXYSeries::setPointsVisible(bool visible)
 {
     Q_D(QXYSeries);
@@ -1022,6 +1232,29 @@ void QXYSeriesPrivate::drawSeriesPointLabels(QPainter *painter, const QList<QPoi
     }
 }
 
+void QXYSeriesPrivate::setPointSelected(int index, bool selected, bool &callSignal)
+{
+    if (index < 0 || index > m_points.count() - 1)
+        return;
+
+    if (selected) {
+        if (!isPointSelected(index)) {
+            m_selectedPoints << index;
+            callSignal = true;
+        }
+    } else {
+        if (isPointSelected(index)) {
+            m_selectedPoints.remove(index);
+            callSignal = true;
+        }
+    }
+}
+
+bool QXYSeriesPrivate::isPointSelected(int index)
+{
+    return m_selectedPoints.contains(index);
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qxyseries.cpp"
diff --git a/src/charts/xychart/qxyseries.h b/src/charts/xychart/qxyseries.h
index 43cad845..43d96e9e 100644
--- a/src/charts/xychart/qxyseries.h
+++ b/src/charts/xychart/qxyseries.h
@@ -49,6 +49,7 @@ class Q_CHARTS_EXPORT QXYSeries : public QAbstractSeries
     Q_OBJECT
     Q_PROPERTY(bool pointsVisible READ pointsVisible WRITE setPointsVisible)
     Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY colorChanged)
+    Q_PROPERTY(QColor selectedColor READ color WRITE setSelectedColor NOTIFY selectedColorChanged REVISION 1)
     Q_PROPERTY(QString pointLabelsFormat READ pointLabelsFormat WRITE setPointLabelsFormat NOTIFY pointLabelsFormatChanged)
     Q_PROPERTY(bool pointLabelsVisible READ pointLabelsVisible WRITE setPointLabelsVisible NOTIFY pointLabelsVisibilityChanged)
     Q_PROPERTY(QFont pointLabelsFont READ pointLabelsFont WRITE setPointLabelsFont NOTIFY pointLabelsFontChanged)
@@ -94,6 +95,9 @@ public:
     virtual void setColor(const QColor &color);
     virtual QColor color() const;
 
+    void setSelectedColor(const QColor &color);
+    QColor selectedColor() const;
+
     void setPointsVisible(bool visible = true);
     bool pointsVisible() const;
 
@@ -114,6 +118,17 @@ public:
 
     void replace(const QList<QPointF> &points);
 
+    bool isPointSelected(int index);
+    void selectPoint(int index);
+    void deselectPoint(int index);
+    void setPointSelected(int index, bool selected);
+    void selectAllPoints();
+    void deselectAllPoints();
+    void selectPoints(const QList<int> &indexes);
+    void deselectPoints(const QList<int> &indexes);
+    void toggleSelection(const QList<int> &indexes);
+    QList<int> selectedPoints() const;
+
 Q_SIGNALS:
     void clicked(const QPointF &point);
     void hovered(const QPointF &point, bool state);
@@ -124,6 +139,7 @@ Q_SIGNALS:
     void pointRemoved(int index);
     void pointAdded(int index);
     void colorChanged(QColor color);
+    void selectedColorChanged(const QColor &color);
     void pointsReplaced();
     void pointLabelsFormatChanged(const QString &format);
     void pointLabelsVisibilityChanged(bool visible);
@@ -132,6 +148,7 @@ Q_SIGNALS:
     void pointLabelsClippingChanged(bool clipping);
     void pointsRemoved(int index, int count);
     void penChanged(const QPen &pen);
+    void selectedPointsChanged();
 
 private:
     Q_DECLARE_PRIVATE(QXYSeries)
diff --git a/src/charts/xychart/qxyseries_p.h b/src/charts/xychart/qxyseries_p.h
index 18340201..f9518c07 100644
--- a/src/charts/xychart/qxyseries_p.h
+++ b/src/charts/xychart/qxyseries_p.h
@@ -67,12 +67,17 @@ public:
     void drawSeriesPointLabels(QPainter *painter, const QList<QPointF> &points,
                                const int offset = 0);
 
+    void setPointSelected(int index, bool selected, bool &callSignal);
+    bool isPointSelected(int index);
+
 Q_SIGNALS:
     void updated();
 
 protected:
     QList<QPointF> m_points;
+    QSet<int> m_selectedPoints;
     QPen m_pen;
+    QColor m_selectedColor;
     QBrush m_brush;
     bool m_pointsVisible;
     QString m_pointLabelsFormat;
diff --git a/src/charts/xychart/xychart_p.h b/src/charts/xychart/xychart_p.h
index 63f1115f..66849218 100644
--- a/src/charts/xychart/xychart_p.h
+++ b/src/charts/xychart/xychart_p.h
@@ -98,6 +98,8 @@ private:
 protected:
     QXYSeries *m_series;
     QList<QPointF> m_points;
+    QList<int> m_selectedPoints;
+    QColor m_selectedColor;
     XYAnimation *m_animation;
     bool m_dirty;