new function for handling updates to timestep ui update in temporal c…

…ontroller widget

src/gui/qgstemporalcontrollerwidget.cpp

@@ -59,7 +59,7 @@ QgsTemporalControllerWidget::QgsTemporalControllerWidget( QWidget *parent )
       return;
 
     mBlockFrameDurationUpdates++;
-    setTimeStep( timeStep );
+    updateTimeStepInputs( timeStep );
     mBlockFrameDurationUpdates--;
   } );
   connect( mNavigationOff, &QPushButton::clicked, this, &QgsTemporalControllerWidget::mNavigationOff_clicked );
@@ -534,6 +534,53 @@ void QgsTemporalControllerWidget::mRangeSetToAllLayersAction_triggered()
 }
 
 void QgsTemporalControllerWidget::setTimeStep( const QgsInterval &timeStep )
+{
+  if ( ! timeStep.isValid() || timeStep.seconds() <= 0 )
+    return;
+
+  // Search the time unit the most appropriate :
+  // the one that gives the smallest time step value for double spin box with round value (if possible) and/or the less signifiant digits
+
+  int selectedUnit = -1;
+  int stringSize = std::numeric_limits<int>::max();
+  int precision = mStepSpinBox->decimals();
+  double selectedValue = std::numeric_limits<double>::max();
+  for ( int i = 0; i < mTimeStepsComboBox->count(); ++i )
+  {
+    QgsUnitTypes::TemporalUnit unit = static_cast<QgsUnitTypes::TemporalUnit>( mTimeStepsComboBox->itemData( i ).toInt() );
+    double value = timeStep.seconds() * QgsUnitTypes::fromUnitToUnitFactor( QgsUnitTypes::TemporalSeconds, unit );
+    QString string = QString::number( value, 'f', precision );
+    string.remove( QRegExp( "0+$" ) ); //remove trailing zero
+    string.remove( QRegExp( "[.]+$" ) ); //remove last point if present
+
+    if ( value >= 1
+         && string.size() <= stringSize // less significant digit than currently selected
+         && value < selectedValue ) // less than currently selected
+    {
+      selectedUnit = i;
+      selectedValue = value;
+      stringSize = string.size();
+    }
+    else if ( string != '0'
+              && string.size() < precision + 2 //round value (ex: 0.xx with precision=3)
+              && string.size() < stringSize ) //less significant digit than currently selected
+    {
+      selectedUnit = i ;
+      selectedValue = value ;
+      stringSize = string.size();
+    }
+  }
+
+  if ( selectedUnit >= 0 )
+  {
+    mStepSpinBox->setValue( selectedValue );
+    mTimeStepsComboBox->setCurrentIndex( selectedUnit );
+  }
+
+  updateFrameDuration();
+}
+
+void QgsTemporalControllerWidget::updateTimeStepInputs( const QgsInterval &timeStep )
 {
   if ( ! timeStep.isValid() || timeStep.seconds() <= 0 )
     return;

src/gui/qgstemporalcontrollerwidget.h

@@ -93,6 +93,23 @@ class GUI_EXPORT QgsTemporalControllerWidget : public QgsPanelWidget, private Ui
     void firstTemporalLayerLoaded( QgsMapLayer *layer );
     void setTimeStep( const QgsInterval &timeStep );
 
+    /**
+     * Updates the widget timestep and timestep unit inputs using the passed
+     * interval \a timeStep original duration and original unit.
+     *
+     * If the passed interval \a timeStep has different values of original duration
+     * and original unit compared to the widget input values for timestep and
+     * timestep unit then the corresponding widget input values will be updated
+     * to match the \a timeStep original duration and unit.
+     *
+     * After updating the widget inputs, an update to the frame duration is executed.
+     *
+     * \note Updates will only be made if the \a timeStep is valid.
+     *
+     * \since 3.18
+     */
+    void updateTimeStepInputs( const QgsInterval &timeStep );
+
   private slots:
 
     /**