reduce SessionItem usage for particle layout, improve title of particle layout

GUI/View/SampleDesigner/ParticleLayoutForm.cpp

@@ -15,6 +15,7 @@
 #include "GUI/View/SampleDesigner/ParticleLayoutForm.h"
 #include "GUI/Model/Sample/InterferenceItems.h"
 #include "GUI/Model/Sample/ItemWithParticles.h"
+#include "GUI/Model/Sample/LayerItem.h"
 #include "GUI/Model/Sample/ParticleLayoutItem.h"
 #include "GUI/Util/ActionFactory.h"
 #include "GUI/View/Edit/DoubleSpinBox.h"
@@ -31,8 +32,6 @@ ParticleLayoutForm::ParticleLayoutForm(LayerForm* parent, ParticleLayoutItem* la
                                        SampleEditorController* ec)
     : QGroupBox(parent), m_layoutItem(layoutItem), m_ec(ec)
 {
-    setTitle(m_layoutItem->itemName());
-
     FormLayouter layouter(this, ec);
     layouter.setContentsMargins(30, 6, 0, 0);
     int rowOfTotalDensity = layouter.addValue(m_layoutItem->totalDensity());
@@ -57,12 +56,13 @@ ParticleLayoutForm::ParticleLayoutForm(LayerForm* parent, ParticleLayoutItem* la
     auto* showInRealSpaceAction = ActionFactory::createShowInRealSpaceAction(
         this, "particle layout", [=] { ec->requestViewInRealSpace(layoutItem); });
 
-    auto* collapser = GroupBoxCollapser::installIntoGroupBox(this);
-    collapser->addAction(showInRealSpaceAction);
-    collapser->addAction(m_removeAction);
+    m_collapser = GroupBoxCollapser::installIntoGroupBox(this);
+    m_collapser->addAction(showInRealSpaceAction);
+    m_collapser->addAction(m_removeAction);
     m_layout = layouter.layout();
 
     updateDensityEnabling();
+    updateTitle(parent->layerItem());
 }
 
 void ParticleLayoutForm::enableStructureEditing(bool b)
@@ -115,3 +115,13 @@ void ParticleLayoutForm::updateDensityValue()
 {
     m_totalDensitySpinBox->updateValue();
 }
+
+void ParticleLayoutForm::updateTitle(const LayerItem* layerItem)
+{
+    const auto layouts = layerItem->layouts();
+    if (layouts.size() > 1)
+        m_collapser->setTitle("Particle layout "
+                              + QString::number(layouts.indexOf(m_layoutItem) + 1));
+    else
+        m_collapser->setTitle("Particle layout");
+}

GUI/View/SampleDesigner/ParticleLayoutForm.h

@@ -26,6 +26,8 @@ class LayerForm;
 class SessionItem;
 class ItemWithParticles;
 class DoubleSpinBox;
+class LayerItem;
+class GroupBoxCollapser;
 
 //! Form for editing a particle layout
 class ParticleLayoutForm : public QGroupBox {
@@ -50,6 +52,8 @@ public:
     //! This does not update any internal values, it only refreshes the shown value.
     void updateDensityValue();
 
+    void updateTitle(const LayerItem* layerItem);
+
 private:
     QFormLayout* m_layout;
     ParticleLayoutItem* m_layoutItem;
@@ -57,6 +61,7 @@ private:
     SampleEditorController* m_ec;
     QList<QWidget*> m_structureEditingWidgets;
     DoubleSpinBox* m_totalDensitySpinBox;
+    GroupBoxCollapser* m_collapser;
 };
 
 #endif // BORNAGAIN_GUI_VIEW_SAMPLEDESIGNER_PARTICLELAYOUTFORM_H

GUI/View/SampleDesigner/SampleEditorController.cpp

@@ -111,6 +111,9 @@ void SampleEditorController::addLayout(LayerForm* layerItemWidget)
     auto* newLayoutItem = layerItemWidget->layerItem()->addLayout();
     layerItemWidget->onLayoutAdded(newLayoutItem);
     m_multiLayerForm->updateUnits();
+
+    for (auto* layoutForms : layerItemWidget->findChildren<ParticleLayoutForm*>())
+        layoutForms->updateTitle(layerItemWidget->layerItem());
 }
 
 void SampleEditorController::removeLayer(LayerItem* layerItem)
@@ -122,6 +125,9 @@ void SampleEditorController::removeLayout(LayerForm* layerItemWidget, ParticleLa
 {
     layerItemWidget->onAboutToRemoveLayout(layout);
     layerItemWidget->layerItem()->removeLayout(layout);
+
+    for (auto* layoutForms : layerItemWidget->findChildren<ParticleLayoutForm*>())
+        layoutForms->updateTitle(layerItemWidget->layerItem());
 }
 
 void SampleEditorController::addParticle(ParticleLayoutItem* layoutItem, const QString& classname)