Avoid assert when vtkControlPoints current point is changed

In setCurrentPoint(), calling updateCurrentPoint() before updating the point
lead to an assert in updateCurrentPoint().

Libs/Visualization/VTK/Widgets/ctkVTKScalarsToColorsWidget.cpp

@@ -281,7 +281,7 @@ void ctkVTKScalarsToColorsWidget::setCurrentPoint(vtkObject* caller, void* callD
     // When a new point is added, the modified event is fired later.
     // however we need to update the max of the current spin box before
     // setting the new value.
-    this->updateCurrentPoint();
+    this->updateNumberOfPoints();
     }
   this->setCurrentPoint(newPoint);
 }
@@ -363,13 +363,21 @@ void ctkVTKScalarsToColorsWidget::onCurrentPointChanged(int currentPoint)
 }
 
 // ----------------------------------------------------------------------------
+void ctkVTKScalarsToColorsWidget::updateNumberOfPoints()
+{
+  Q_D(ctkVTKScalarsToColorsWidget);
+  const int numberOfPoints = d->CurrentControlPointsItem ?
+    d->CurrentControlPointsItem->GetNumberOfPoints() : 0;
+  d->PointIdSpinBox->setMaximum( numberOfPoints - 1 );
+}
+
+// ----------------------------------------------------------------------------
 void ctkVTKScalarsToColorsWidget::updateCurrentPoint()
 {
   Q_D(ctkVTKScalarsToColorsWidget);
   Q_ASSERT(d->CurrentControlPointsItem);
   Q_ASSERT(d->PointIdSpinBox->value() == d->CurrentControlPointsItem->GetCurrentPoint());
-  d->PointIdSpinBox->setMaximum((d->CurrentControlPointsItem ?
-                                 d->CurrentControlPointsItem->GetNumberOfPoints() : 0) - 1);
+  this->updateNumberOfPoints();
 
   int pointId = d->PointIdSpinBox->value();
   if (pointId == -1)

Libs/Visualization/VTK/Widgets/ctkVTKScalarsToColorsWidget.h

@@ -85,6 +85,7 @@ protected Q_SLOTS:
   void onPlotAdded(vtkPlot*);
   void onBoundsChanged();
   void setCurrentPoint(vtkObject* controlPointsItem, void* pointId);
+  void updateNumberOfPoints();
   void updateCurrentPoint();
   void onCurrentPointChanged(int pointId);
   void onColorChanged(const QColor& color);