[gui] Move Diagrams properties to a panel widget, showing tabs instead of a list when docked; harmonize stacked diagram configuration with rule-based labeling; allow QgsDiagramProperties to sync to renderers and diagram layer settings, in addition to syncing to layers; when editing a subdiagram of a stacked diagram, only show widgets for diagram layer settings if the subdiagram is the first one, for the rest, hide those widgets and show a note informing users; make sure stacked diagrams handle enabled and disabled subdiagrams (i.e., don't take into account disabled subdiagrams) and add a test for it; switching from single to stacked diagram: take the single diagram definition as the first stacked diagram; fix #58782 (calling twice the apply method for label rendering)

python/PyQt6/core/auto_generated/qgsdiagramrenderer.sip.in

@@ -1017,30 +1017,24 @@ Writes stacked renderers state to a DOM element.
     virtual QList< QgsLayerTreeModelLegendNode * > legendItems( QgsLayerTreeLayer *nodeLayer ) const /Factory/;
 
 
-    QList< QgsDiagramRenderer * > renderers() const;
+    QList< QgsDiagramRenderer * > renderers( bool sortByDiagramMode = false ) const;
 %Docstring
 Returns an ordered list with the renderers of the stacked renderer object.
-If the stacked diagram orientation is vertical, the list is returned backwards.
+@param sortByDiagramMode If true, the list is returned backwards for vertical orientation.
 %End
 
     void addRenderer( QgsDiagramRenderer *renderer );
 %Docstring
 Adds a renderer to the stacked renderer object.
-
+@param renderer diagram renderer to be added to the stacked renderer
-:param renderer: diagram renderer to be added to the stacked renderer
+Renderers added first will render their diagrams first, i.e., more to
-                 Renderers added first will render their diagrams first, i.e., more to
+the left (horizontal mode) or more to the top (vertical mode).
-                 the left (horizontal mode) or more to the top (vertical mode).
 %End
 
     const QgsDiagramRenderer *renderer( const int index ) const;
 %Docstring
 Returns the renderer at the given ``index``.
 @param index index of the disired renderer in the stacked renderer
-%End
-
-    int rendererCount() const;
-%Docstring
-Returns the number of renderers that this stacked renderer is composed of.
 %End
 
   protected:

python/core/auto_generated/qgsdiagramrenderer.sip.in

@@ -1017,30 +1017,24 @@ Writes stacked renderers state to a DOM element.
     virtual QList< QgsLayerTreeModelLegendNode * > legendItems( QgsLayerTreeLayer *nodeLayer ) const /Factory/;
 
 
-    QList< QgsDiagramRenderer * > renderers() const;
+    QList< QgsDiagramRenderer * > renderers( bool sortByDiagramMode = false ) const;
 %Docstring
 Returns an ordered list with the renderers of the stacked renderer object.
-If the stacked diagram orientation is vertical, the list is returned backwards.
+@param sortByDiagramMode If true, the list is returned backwards for vertical orientation.
 %End
 
     void addRenderer( QgsDiagramRenderer *renderer );
 %Docstring
 Adds a renderer to the stacked renderer object.
-
+@param renderer diagram renderer to be added to the stacked renderer
-:param renderer: diagram renderer to be added to the stacked renderer
+Renderers added first will render their diagrams first, i.e., more to
-                 Renderers added first will render their diagrams first, i.e., more to
+the left (horizontal mode) or more to the top (vertical mode).
-                 the left (horizontal mode) or more to the top (vertical mode).
 %End
 
     const QgsDiagramRenderer *renderer( const int index ) const;
 %Docstring
 Returns the renderer at the given ``index``.
 @param index index of the disired renderer in the stacked renderer
-%End
-
-    int rendererCount() const;
-%Docstring
-Returns the number of renderers that this stacked renderer is composed of.
 %End
 
   protected:

src/app/qgisapp.cpp

@@ -8049,35 +8049,8 @@ void QgisApp::diagramProperties()
     return;
   }
 
-  QDialog dlg;
+  mapStyleDock( true );
-  dlg.setWindowTitle( tr( "Layer Diagram Properties" ) );
+  mMapStyleWidget->setCurrentPage( QgsLayerStylingWidget::VectorDiagram );
-  QgsStackedDiagramProperties *gui = new QgsStackedDiagramProperties( vlayer, &dlg, mMapCanvas );
-  gui->layout()->setContentsMargins( 0, 0, 0, 0 );
-  QVBoxLayout *layout = new QVBoxLayout( &dlg );
-  layout->addWidget( gui );
-
-  QDialogButtonBox *buttonBox = new QDialogButtonBox(
-    QDialogButtonBox::Help | QDialogButtonBox::Ok | QDialogButtonBox::Cancel | QDialogButtonBox::Apply,
-    Qt::Horizontal, &dlg );
-  layout->addWidget( buttonBox );
-
-  dlg.setLayout( layout );
-
-  connect( buttonBox->button( QDialogButtonBox::Ok ), &QAbstractButton::clicked,
-           &dlg, &QDialog::accept );
-  connect( buttonBox->button( QDialogButtonBox::Cancel ), &QAbstractButton::clicked,
-           &dlg, &QDialog::reject );
-  connect( buttonBox->button( QDialogButtonBox::Apply ), &QAbstractButton::clicked,
-           gui, &QgsStackedDiagramProperties::apply );
-  connect( buttonBox->button( QDialogButtonBox::Help ), &QAbstractButton::clicked, gui, [ = ]
-  {
-    QgsHelp::openHelp( QStringLiteral( "working_with_vector/vector_properties.html#diagrams-properties" ) );
-  } );
-
-  if ( dlg.exec() )
-    gui->apply();
-
-  activateDeactivateLayerRelatedActions( vlayer );
 }
 
 void QgisApp::createAnnotationLayer()

src/app/qgslayerstylingwidget.cpp

@@ -23,6 +23,7 @@
 #include "qgsapplication.h"
 #include "qgslabelingwidget.h"
 #include "qgsmaskingwidget.h"
+#include "qgsdiagramwidget.h"
 #include "qgslayerstylingwidget.h"
 #include "qgsrastertransparencywidget.h"
 #include "qgsrendererpropertiesdialog.h"
@@ -217,6 +218,11 @@ void QgsLayerStylingWidget::setLayer( QgsMapLayer *layer )
       symbol3DItem->setToolTip( tr( "3D View" ) );
       mOptionsListWidget->addItem( symbol3DItem );
 #endif
+
+      QListWidgetItem *diagramItem = new QListWidgetItem( QgsApplication::getThemeIcon( QStringLiteral( "/propertyicons/diagram.svg" ) ), QString() );
+      diagramItem->setData( Qt::UserRole, VectorDiagram );
+      diagramItem->setToolTip( tr( "Diagrams" ) );
+      mOptionsListWidget->addItem( diagramItem );
       break;
     }
     case Qgis::LayerType::Raster:
@@ -334,12 +340,6 @@ void QgsLayerStylingWidget::apply()
 
   bool styleWasChanged = false;
   bool triggerRepaint = false;  // whether the change needs the layer to be repainted
-  if ( QgsLabelingWidget *widget = qobject_cast<QgsLabelingWidget *>( current ) )
-  {
-    widget->apply();
-    styleWasChanged = true;
-    undoName = QStringLiteral( "Label Change" );
-  }
   if ( QgsMaskingWidget *widget = qobject_cast<QgsMaskingWidget *>( current ) )
   {
     widget->apply();
@@ -373,8 +373,23 @@ void QgsLayerStylingWidget::apply()
     styleWasChanged = true;
     triggerRepaint = true;
   }
+  else if ( QgsLabelingWidget *widget = qobject_cast<QgsLabelingWidget *>( current ) )
+  {
+    widget->apply();
+    styleWasChanged = true;
+    undoName = QStringLiteral( "Label Change" );
+  }
+  else if ( QgsDiagramWidget *widget = qobject_cast<QgsDiagramWidget *>( current ) )
+  {
+    widget->apply();
+    styleWasChanged = true;
+    undoName = QStringLiteral( "Diagram Change" );
+  }
   else if ( QgsMapLayerConfigWidget *widget = qobject_cast<QgsMapLayerConfigWidget *>( current ) )
   {
+    // Warning: All classes inheriting from QgsMapLayerConfigWidget
+    // should come in the current if block, before this else-if
+    // clause, to avoid duplicate calls to apply()!
     widget->apply();
     styleWasChanged = true;
     triggerRepaint = widget->shouldTriggerLayerRepaint();
@@ -463,6 +478,10 @@ void QgsLayerStylingWidget::updateCurrentWidgetLayer()
       mMesh3DWidget = widget;
     }
 #endif
+    else if ( QgsDiagramWidget *widget = qobject_cast<QgsDiagramWidget *>( current ) )
+    {
+      mDiagramWidget = widget;
+    }
   }
 
   mWidgetStack->clear();
@@ -495,6 +514,11 @@ void QgsLayerStylingWidget::updateCurrentWidgetLayer()
       {
         QgsVectorLayer *vlayer = qobject_cast<QgsVectorLayer *>( mCurrentLayer );
 
+#ifdef HAVE_3D
+        const int tabShift = 1;  // To move subsequent tabs
+#else
+        const int tabShift = 0;
+#endif
         switch ( row )
         {
           case 0: // Style
@@ -550,6 +574,15 @@ void QgsLayerStylingWidget::updateCurrentWidgetLayer()
             break;
           }
 #endif
+          case 3 + tabShift: // Diagrams
+          {
+            mDiagramWidget = new QgsDiagramWidget( vlayer, mMapCanvas, mWidgetStack );
+            mDiagramWidget->setDockMode( true );
+            connect( mDiagramWidget, &QgsDiagramWidget::widgetChanged, this, &QgsLayerStylingWidget::autoApply );
+            mDiagramWidget->syncToOwnLayer();
+            mWidgetStack->setMainPanel( mDiagramWidget );
+            break;
+          }
           default:
             break;
         }

src/app/qgslayerstylingwidget.h

@@ -34,6 +34,7 @@
 
 class QgsLabelingWidget;
 class QgsMaskingWidget;
+class QgsDiagramWidget;
 class QgsMapLayer;
 class QgsMapCanvas;
 class QgsRendererPropertiesDialog;
@@ -101,6 +102,7 @@ class APP_EXPORT QgsLayerStylingWidget : public QWidget, private Ui::QgsLayerSty
       History,
       Symbology3D,
       RasterAttributeTables, //!< Raster attribute tables, since QGIS 3.30
+      VectorDiagram, //!< Vector diagram, since QGIS 3.40
     };
 
     QgsLayerStylingWidget( QgsMapCanvas *canvas, QgsMessageBar *messageBar, const QList<const QgsMapLayerConfigWidgetFactory *> &pages, QWidget *parent = nullptr );
@@ -175,6 +177,7 @@ class APP_EXPORT QgsLayerStylingWidget : public QWidget, private Ui::QgsLayerSty
     QgsVectorLayer3DRendererWidget *mVector3DWidget = nullptr;
     QgsMeshLayer3DRendererWidget *mMesh3DWidget = nullptr;
 #endif
+    QgsDiagramWidget *mDiagramWidget = nullptr;
     QgsRendererRasterPropertiesWidget *mRasterStyleWidget = nullptr;
     QgsRasterAttributeTableWidget *mRasterAttributeTableWidget = nullptr;
     QgsPanelWidget *mRasterAttributeTableDisabledWidget = nullptr;

src/core/qgsdiagramrenderer.cpp

@@ -528,7 +528,7 @@ void QgsDiagramRenderer::renderDiagram( const QgsFeature &feature, QgsRenderCont
 QSizeF QgsDiagramRenderer::sizeMapUnits( const QgsFeature &feature, const QgsRenderContext &c ) const
 {
   QgsDiagramSettings s;
-  if ( !diagramSettings( feature, c, s ) )
+  if ( !diagramSettings( feature, c, s ) || !s.enabled )
   {
     return QSizeF();
   }
@@ -845,16 +845,18 @@ QgsStackedDiagramRenderer *QgsStackedDiagramRenderer::clone() const
 QSizeF QgsStackedDiagramRenderer::sizeMapUnits( const QgsFeature &feature, const QgsRenderContext &c ) const
 {
   QSizeF stackedSize( 0, 0 );
+  int enabledDiagramCount = 0;  // We'll add spacing only for enabled subDiagrams
 
   // Iterate renderers. For each renderer, get the diagram
   // size for the feature and add it to the total size
   // accounting for stacked diagram defined spacing
-  for ( int i = 0; i < mDiagramRenderers.count(); i++ )
+  for ( const auto &subRenderer : std::as_const( mDiagramRenderers ) )
   {
-    QSizeF size = mDiagramRenderers.at( i )->sizeMapUnits( feature, c );
+    QSizeF size = subRenderer->sizeMapUnits( feature, c );
 
     if ( size.isValid() )
     {
+      enabledDiagramCount++;
       switch ( mSettings.stackedDiagramMode )
       {
         case QgsDiagramSettings::Horizontal:
@@ -875,11 +877,11 @@ QSizeF QgsStackedDiagramRenderer::sizeMapUnits( const QgsFeature &feature, const
   switch ( mSettings.stackedDiagramMode )
   {
     case QgsDiagramSettings::Horizontal:
-      stackedSize.scale( stackedSize.width() + spacing * ( mDiagramRenderers.count() - 1 ), stackedSize.height(), Qt::IgnoreAspectRatio );
+      stackedSize.scale( stackedSize.width() + spacing * ( enabledDiagramCount - 1 ), stackedSize.height(), Qt::IgnoreAspectRatio );
       break;
 
     case QgsDiagramSettings::Vertical:
-      stackedSize.scale( stackedSize.width(), stackedSize.height() + spacing * ( mDiagramRenderers.count() - 1 ), Qt::IgnoreAspectRatio );
+      stackedSize.scale( stackedSize.width(), stackedSize.height() + spacing * ( enabledDiagramCount - 1 ), Qt::IgnoreAspectRatio );
       break;
   }
   return stackedSize;
@@ -893,11 +895,15 @@ void QgsStackedDiagramRenderer::renderDiagram( const QgsFeature &feature, QgsRen
   }
 
   QPointF newPos = pos; // Each subdiagram will have its own newPos
-  QList< QgsDiagramRenderer * > stackedRenderers = renderers();
+
-  for ( const auto &stackedRenderer : std::as_const( stackedRenderers ) )
+  // Get subrenderers sorted by mode (vertical diagrams are returned backwards)
+  const QList< QgsDiagramRenderer * > stackedRenderers = renderers( true );
+
+  for ( const auto &stackedRenderer : stackedRenderers )
   {
     if ( stackedRenderer->rendererName() == QStringLiteral( "Stacked" ) )
     {
+      // Nested stacked diagrams will use this recursion
       stackedRenderer->renderDiagram( feature, c, newPos, properties );
       continue;
     }
@@ -905,7 +911,12 @@ void QgsStackedDiagramRenderer::renderDiagram( const QgsFeature &feature, QgsRen
     QgsDiagramSettings s;
     if ( !stackedRenderer->diagramSettings( feature, c, s ) )
     {
-      return;
+      continue;
+    }
+
+    if ( !s.enabled )
+    {
+      continue;
     }
 
     if ( properties.hasActiveProperties() )
@@ -963,26 +974,19 @@ QList<QString> QgsStackedDiagramRenderer::diagramAttributes() const
 QList< QgsLayerTreeModelLegendNode * > QgsStackedDiagramRenderer::legendItems( QgsLayerTreeLayer *nodeLayer ) const
 {
   QList< QgsLayerTreeModelLegendNode * > nodes;
-  for ( int i = 0; i < rendererCount(); i++ )
+  for ( const auto &renderer : std::as_const( mDiagramRenderers ) )
   {
-    nodes << mDiagramRenderers.at( i )->legendItems( nodeLayer );
+    nodes << renderer->legendItems( nodeLayer );
   }
 
   return nodes;
 }
 
-QList< QgsDiagramRenderer * > QgsStackedDiagramRenderer::renderers() const
+QList< QgsDiagramRenderer * > QgsStackedDiagramRenderer::renderers( bool sortByDiagramMode ) const
 {
   QList< QgsDiagramRenderer * > renderers;
 
-  if ( mSettings.stackedDiagramMode == QgsDiagramSettings::Horizontal )
+  if ( sortByDiagramMode && mSettings.stackedDiagramMode == QgsDiagramSettings::Vertical )
-  {
-    for ( const auto &item : std::as_const( mDiagramRenderers ) )
-    {
-      renderers.append( item );
-    }
-  }
-  else
   {
     // We draw vertical diagrams backwards, so
     // we return the subrenderers in reverse order
@@ -992,6 +996,10 @@ QList< QgsDiagramRenderer * > QgsStackedDiagramRenderer::renderers() const
       renderers.append( *iter );
     }
   }
+  else
+  {
+    renderers = mDiagramRenderers;
+  }
   return renderers;
 }
 
@@ -1013,11 +1021,6 @@ const QgsDiagramRenderer *QgsStackedDiagramRenderer::renderer( const int index )
   return nullptr;
 }
 
-int QgsStackedDiagramRenderer::rendererCount() const
-{
-  return mDiagramRenderers.count();
-}
-
 void QgsStackedDiagramRenderer::readXml( const QDomElement &elem, const QgsReadWriteContext &context )
 {
   const QDomElement categoryElem = elem.firstChildElement( QStringLiteral( "DiagramCategory" ) );
@@ -1234,7 +1237,7 @@ QList< QgsLayerTreeModelLegendNode * > QgsDiagramRenderer::legendItems( QgsLayer
 QList< QgsLayerTreeModelLegendNode * > QgsSingleCategoryDiagramRenderer::legendItems( QgsLayerTreeLayer *nodeLayer ) const
 {
   QList< QgsLayerTreeModelLegendNode * > nodes;
-  if ( mShowAttributeLegend )
+  if ( mShowAttributeLegend && mSettings.enabled )
     nodes = mSettings.legendItems( nodeLayer );
 
   return nodes;
@@ -1243,6 +1246,11 @@ QList< QgsLayerTreeModelLegendNode * > QgsSingleCategoryDiagramRenderer::legendI
 QList< QgsLayerTreeModelLegendNode * > QgsLinearlyInterpolatedDiagramRenderer::legendItems( QgsLayerTreeLayer *nodeLayer ) const
 {
   QList< QgsLayerTreeModelLegendNode * > nodes;
+  if ( !mSettings.enabled )
+  {
+    return nodes;
+  }
+
   if ( mShowAttributeLegend )
     nodes = mSettings.legendItems( nodeLayer );
 

src/core/qgsdiagramrenderer.h

@@ -1039,13 +1039,13 @@ class CORE_EXPORT QgsStackedDiagramRenderer : public QgsDiagramRenderer
 
     /**
      * Returns an ordered list with the renderers of the stacked renderer object.
-     * If the stacked diagram orientation is vertical, the list is returned backwards.
+     * @param sortByDiagramMode If true, the list is returned backwards for vertical orientation.
      */
-    QList< QgsDiagramRenderer * > renderers() const;
+    QList< QgsDiagramRenderer * > renderers( bool sortByDiagramMode = false ) const;
 
     /**
      * Adds a renderer to the stacked renderer object.
-     * \param renderer diagram renderer to be added to the stacked renderer
+     * @param renderer diagram renderer to be added to the stacked renderer
      * Renderers added first will render their diagrams first, i.e., more to
      * the left (horizontal mode) or more to the top (vertical mode).
      */
@@ -1057,11 +1057,6 @@ class CORE_EXPORT QgsStackedDiagramRenderer : public QgsDiagramRenderer
      */
     const QgsDiagramRenderer *renderer( const int index ) const;
 
-    /**
-     * Returns the number of renderers that this stacked renderer is composed of.
-     */
-    int rendererCount() const;
-
   protected:
     bool diagramSettings( const QgsFeature &feature, const QgsRenderContext &c, QgsDiagramSettings &s ) const override;
     QSizeF diagramSize( const QgsFeature &, const QgsRenderContext &c ) const override;

src/gui/CMakeLists.txt

@@ -35,6 +35,7 @@ set(QGIS_GUI_SRCS
   vector/qgsattributesforminitcode.cpp
   vector/qgsattributesformproperties.cpp
   vector/qgsdiagramproperties.cpp
+  vector/qgsdiagramwidget.cpp
   vector/qgsfieldcalculator.cpp
   vector/qgsjoindialog.cpp
   vector/qgssourcefieldsproperties.cpp
@@ -1497,6 +1498,7 @@ set(QGIS_GUI_HDRS
   vector/qgsattributesforminitcode.h
   vector/qgsattributesformproperties.h
   vector/qgsdiagramproperties.h
+  vector/qgsdiagramwidget.h
   vector/qgsfieldcalculator.h
   vector/qgsjoindialog.h
   vector/qgssourcefieldsproperties.h

src/gui/vector/qgsdiagramproperties.cpp

@@ -59,10 +59,10 @@ QgsExpressionContext QgsDiagramProperties::createExpressionContext() const
 }
 
 QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas )
-  : QWidget( parent )
+  : QgsPanelWidget( parent )
+  , mLayer( layer )
   , mMapCanvas( canvas )
 {
-  mLayer = layer;
   if ( !layer )
   {
     return;
@@ -80,6 +80,10 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *pare
   // get rid of annoying outer focus rect on Mac
   mDiagramOptionsListWidget->setAttribute( Qt::WA_MacShowFocusRect, false );
 
+  const int iconSize = QgsGuiUtils::scaleIconSize( 20 );
+  mOptionsTab->setIconSize( QSize( iconSize, iconSize ) );
+  mDiagramOptionsListWidget->setIconSize( QSize( iconSize, iconSize ) ) ;
+
   mBarSpacingSpinBox->setClearValue( 0 );
   mBarSpacingUnitComboBox->setUnits( { Qgis::RenderUnit::Millimeters,
                                        Qgis::RenderUnit::MetersInMapUnits,
@@ -144,6 +148,7 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *pare
   if ( layerType == Qgis::GeometryType::Unknown || layerType == Qgis::GeometryType::Null )
   {
     mDiagramTypeComboBox->setEnabled( false );
+    mOptionsTab->setEnabled( false );
     mDiagramFrame->setEnabled( false );
   }
 
@@ -224,6 +229,10 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *pare
   mDiagramOptionsSplitter->restoreState( settings.value( QStringLiteral( "Windows/Diagrams/OptionsSplitState" ) ).toByteArray() );
   mDiagramOptionsListWidget->setCurrentRow( settings.value( QStringLiteral( "Windows/Diagrams/Tab" ), 0 ).toInt() );
 
+  // set correct initial tab to match displayed setting page
+  whileBlocking( mOptionsTab )->setCurrentIndex( mDiagramStackedWidget->currentIndex() );
+  mOptionsTab->tabBar()->setUsesScrollButtons( true );
+
   // field combo and expression button
   mSizeFieldExpressionWidget->setLayer( mLayer );
   QgsDistanceArea myDa;
@@ -250,6 +259,11 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *pare
   mOrientationUpButton->setProperty( "direction", QgsDiagramSettings::Up );
   mOrientationDownButton->setProperty( "direction", QgsDiagramSettings::Down );
 
+  // Labels to let users know some widgets are not present
+  // when editing sub diagrams in a stacked diagram.
+  mDlsLabel_1->hide();
+  mDlsLabel_2->hide();
+
   //force a refresh of widget status to match diagram type
   mDiagramTypeComboBox_currentIndexChanged( mDiagramTypeComboBox->currentIndex() );
 
@@ -268,15 +282,99 @@ QgsDiagramProperties::QgsDiagramProperties( QgsVectorLayer *layer, QWidget *pare
   registerDataDefinedButton( mStartAngleDDBtn, QgsDiagramLayerSettings::Property::StartAngle );
 
   connect( mButtonSizeLegendSettings, &QPushButton::clicked, this, &QgsDiagramProperties::showSizeLegendDialog );
+
+  QList<QWidget *> widgets;
+  widgets << chkLineAbove;
+  widgets << chkLineBelow;
+  widgets << chkLineOn;
+  widgets << chkLineOrientationDependent;
+  widgets << mAngleDirectionComboBox;
+  widgets << mAngleOffsetComboBox;
+  widgets << mAttributeBasedScalingRadio;
+  widgets << mAxisLineStyleButton;
+  widgets << mBackgroundColorButton;
+  widgets << mBarSpacingSpinBox;
+  widgets << mBarSpacingUnitComboBox;
+  widgets << mBarWidthSpinBox;
+  widgets << mCheckBoxAttributeLegend;
+  widgets << mDiagramAttributesTreeWidget;
+  widgets << mDiagramDistanceSpinBox;
+  //widgets << mDiagramFontButton;
+  widgets << mDiagramPenColorButton;
+  widgets << mDiagramSizeSpinBox;
+  widgets << mDiagramLineUnitComboBox;
+  widgets << mDiagramTypeComboBox;
+  widgets << mDiagramUnitComboBox;
+  widgets << mFixedSizeRadio;
+  widgets << mIncreaseMinimumSizeSpinBox;
+  widgets << mIncreaseSmallDiagramsCheck;
+  widgets << mLabelPlacementComboBox;
+  widgets << mMaxValueSpinBox;
+  widgets << mPenWidthSpinBox;
+  widgets << mPrioritySlider;
+  widgets << mOpacityWidget;
+  widgets << mOrientationDownButton;
+  widgets << mOrientationLeftButton;
+  widgets << mOrientationRightButton;
+  widgets << mOrientationUpButton;
+  widgets << mScaleDependencyComboBox;
+  widgets << mScaleRangeWidget;
+  widgets << mScaleVisibilityGroupBox;
+  widgets << mShowAllCheckBox;
+  widgets << mShowAxisGroupBox;
+  widgets << mSizeFieldExpressionWidget;
+  widgets << mSizeSpinBox;
+  widgets << mZIndexSpinBox;
+  widgets << radAroundCentroid;
+  widgets << radAroundLine;
+  widgets << radAroundPoint;
+  widgets << radInsidePolygon;
+  widgets << radOverCentroid;
+  widgets << radOverLine;
+  widgets << radOverPoint;
+  widgets << radPolygonPerimeter;
+
+  connectValueChanged( widgets, SIGNAL( widgetChanged() ) );
 }
 
-void QgsDiagramProperties::syncToLayer( const QgsDiagramRenderer *dr )
+void QgsDiagramProperties::setDockMode( bool dockMode )
+{
+  QgsPanelWidget::setDockMode( dockMode );
+  mOptionsTab->setVisible( dockMode );
+  mOptionsTab->setTabToolTip( 0, tr( "Attributes" ) );
+  mOptionsTab->setTabToolTip( 1, tr( "Rendering" ) );
+  mOptionsTab->setTabToolTip( 2, tr( "Size" ) );
+  mOptionsTab->setTabToolTip( 3, tr( "Placement" ) );
+  mOptionsTab->setTabToolTip( 4, tr( "Options" ) );
+  mOptionsTab->setTabToolTip( 5, tr( "Legend" ) );
+  mDiagramOptionsListFrame->setVisible( !dockMode );
+}
+
+void QgsDiagramProperties::setDiagramType( const QString diagramType )
+{
+  mDiagramType = diagramType;
+
+  mDiagramTypeComboBox->setVisible( false );
+  mDiagramTypeComboBox->blockSignals( true );
+  mDiagramTypeComboBox->setCurrentIndex( mDiagramTypeComboBox->findData( mDiagramType ) );
+  mDiagramTypeComboBox->blockSignals( false );
+
+  //force a refresh of widget status to match diagram type
+  mDiagramTypeComboBox_currentIndexChanged( mDiagramTypeComboBox->currentIndex() );
+}
+
+void QgsDiagramProperties::syncToLayer()
+{
+  const QgsDiagramRenderer *renderer = mLayer->diagramRenderer();
+  syncToRenderer( renderer );
+
+  const QgsDiagramLayerSettings *layerDls = mLayer->diagramLayerSettings();
+  syncToSettings( layerDls );
+}
+
+void QgsDiagramProperties::syncToRenderer( const QgsDiagramRenderer *dr )
 {
   mDiagramAttributesTreeWidget->clear();
-  if ( !dr )
-  {
-    dr = mLayer->diagramRenderer();
-  }
 
   if ( !dr ) //no diagram renderer yet, insert reasonable default
   {
@@ -344,6 +442,7 @@ void QgsDiagramProperties::syncToLayer( const QgsDiagramRenderer *dr )
     const QList<QgsDiagramSettings> settingList = dr->diagramSettings();
     if ( !settingList.isEmpty() )
     {
+      mOptionsTab->setEnabled( settingList.at( 0 ).enabled );
       mDiagramFrame->setEnabled( settingList.at( 0 ).enabled );
       mDiagramFontButton->setCurrentFont( settingList.at( 0 ).font );
       const QSizeF size = settingList.at( 0 ).size;
@@ -458,51 +557,6 @@ void QgsDiagramProperties::syncToLayer( const QgsDiagramRenderer *dr )
       }
     }
 
-    const QgsDiagramLayerSettings *dls = mLayer->diagramLayerSettings();
-    if ( dls )
-    {
-      mDiagramDistanceSpinBox->setValue( dls->distance() );
-      mPrioritySlider->setValue( dls->priority() );
-      mZIndexSpinBox->setValue( dls->zIndex() );
-
-      switch ( dls->placement() )
-      {
-        case QgsDiagramLayerSettings::AroundPoint:
-          radAroundPoint->setChecked( true );
-          radAroundCentroid->setChecked( true );
-          break;
-
-        case QgsDiagramLayerSettings::OverPoint:
-          radOverPoint->setChecked( true );
-          radOverCentroid->setChecked( true );
-          break;
-
-        case QgsDiagramLayerSettings::Line:
-          radAroundLine->setChecked( true );
-          radPolygonPerimeter->setChecked( true );
-          break;
-
-        case QgsDiagramLayerSettings::Horizontal:
-          radOverLine->setChecked( true );
-          radInsidePolygon->setChecked( true );
-          break;
-
-        default:
-          break;
-      }
-
-      chkLineAbove->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::AboveLine );
-      chkLineBelow->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::BelowLine );
-      chkLineOn->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::OnLine );
-      if ( !( dls->linePlacementFlags() & QgsDiagramLayerSettings::MapOrientation ) )
-        chkLineOrientationDependent->setChecked( true );
-      updatePlacementWidgets();
-
-      mShowAllCheckBox->setChecked( dls->showAllDiagrams() );
-
-      mDataDefinedProperties = dls->dataDefinedProperties();
-    }
-
     if ( dr->diagram() )
     {
       mDiagramType = dr->diagram()->diagramName();
@@ -523,6 +577,53 @@ void QgsDiagramProperties::syncToLayer( const QgsDiagramRenderer *dr )
   mPaintEffectWidget->setPaintEffect( mPaintEffect.get() );
 }
 
+void QgsDiagramProperties::syncToSettings( const QgsDiagramLayerSettings *dls )
+{
+  if ( dls )
+  {
+    mDiagramDistanceSpinBox->setValue( dls->distance() );
+    mPrioritySlider->setValue( dls->priority() );
+    mZIndexSpinBox->setValue( dls->zIndex() );
+
+    switch ( dls->placement() )
+    {
+      case QgsDiagramLayerSettings::AroundPoint:
+        radAroundPoint->setChecked( true );
+        radAroundCentroid->setChecked( true );
+        break;
+
+      case QgsDiagramLayerSettings::OverPoint:
+        radOverPoint->setChecked( true );
+        radOverCentroid->setChecked( true );
+        break;
+
+      case QgsDiagramLayerSettings::Line:
+        radAroundLine->setChecked( true );
+        radPolygonPerimeter->setChecked( true );
+        break;
+
+      case QgsDiagramLayerSettings::Horizontal:
+        radOverLine->setChecked( true );
+        radInsidePolygon->setChecked( true );
+        break;
+
+      default:
+        break;
+    }
+
+    chkLineAbove->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::AboveLine );
+    chkLineBelow->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::BelowLine );
+    chkLineOn->setChecked( dls->linePlacementFlags() & QgsDiagramLayerSettings::OnLine );
+    if ( !( dls->linePlacementFlags() & QgsDiagramLayerSettings::MapOrientation ) )
+      chkLineOrientationDependent->setChecked( true );
+    updatePlacementWidgets();
+
+    mShowAllCheckBox->setChecked( dls->showAllDiagrams() );
+
+    mDataDefinedProperties = dls->dataDefinedProperties();
+  }
+}
+
 QgsDiagramProperties::~QgsDiagramProperties()
 {
   QgsSettings settings;
@@ -543,6 +644,7 @@ void QgsDiagramProperties::updateProperty()
   QgsPropertyOverrideButton *button = qobject_cast<QgsPropertyOverrideButton *>( sender() );
   const QgsDiagramLayerSettings::Property key = static_cast<  QgsDiagramLayerSettings::Property >( button->propertyKey() );
   mDataDefinedProperties.setProperty( key, button->toProperty() );
+  emit widgetChanged();
 }
 
 void QgsDiagramProperties::mDiagramTypeComboBox_currentIndexChanged( int index )
@@ -750,6 +852,29 @@ void QgsDiagramProperties::mDiagramAttributesTreeWidget_itemDoubleClicked( QTree
   }
 }
 
+std::unique_ptr< QgsDiagram > QgsDiagramProperties::createDiagramObject()
+{
+  std::unique_ptr< QgsDiagram > diagram;
+
+  if ( mDiagramType == DIAGRAM_NAME_TEXT )
+  {
+    diagram = std::make_unique< QgsTextDiagram >();
+  }
+  else if ( mDiagramType == DIAGRAM_NAME_PIE )
+  {
+    diagram = std::make_unique< QgsPieDiagram >();
+  }
+  else if ( mDiagramType == DIAGRAM_NAME_STACKED_BAR )
+  {
+    diagram = std::make_unique< QgsStackedBarDiagram >();
+  }
+  else // if ( diagramType == DIAGRAM_NAME_HISTOGRAM )
+  {
+    diagram = std::make_unique< QgsHistogramDiagram >();
+  }
+  return diagram;
+}
+
 std::unique_ptr<QgsDiagramSettings> QgsDiagramProperties::createDiagramSettings()
 {
   std::unique_ptr< QgsDiagramSettings > ds = std::make_unique< QgsDiagramSettings>();
@@ -821,13 +946,15 @@ std::unique_ptr<QgsDiagramSettings> QgsDiagramProperties::createDiagramSettings(
   return ds;
 }
 
-std::unique_ptr<QgsDiagramRenderer> QgsDiagramProperties::createRendererBaseInfo( const QgsDiagramSettings &ds )
+std::unique_ptr<QgsDiagramRenderer> QgsDiagramProperties::createRenderer()
 {
+  std::unique_ptr< QgsDiagramSettings > ds = createDiagramSettings();
+
   std::unique_ptr< QgsDiagramRenderer > renderer;
   if ( mFixedSizeRadio->isChecked() )
   {
     std::unique_ptr< QgsSingleCategoryDiagramRenderer > dr = std::make_unique< QgsSingleCategoryDiagramRenderer >();
-    dr->setDiagramSettings( ds );
+    dr->setDiagramSettings( *ds );
     renderer = std::move( dr );
   }
   else
@@ -849,7 +976,7 @@ std::unique_ptr<QgsDiagramRenderer> QgsDiagramProperties::createRendererBaseInfo
     {
       dr->setClassificationField( sizeFieldNameOrExp );
     }
-    dr->setDiagramSettings( ds );
+    dr->setDiagramSettings( *ds );
 
     dr->setDataDefinedSizeLegend( mSizeLegend ? new QgsDataDefinedSizeLegend( *mSizeLegend ) : nullptr );
 
@@ -857,6 +984,10 @@ std::unique_ptr<QgsDiagramRenderer> QgsDiagramProperties::createRendererBaseInfo
   }
 
   renderer->setAttributeLegend( mCheckBoxAttributeLegend->isChecked() );
+
+  std::unique_ptr< QgsDiagram > diagram = createDiagramObject();
+  renderer->setDiagram( diagram.release() );
+
   return renderer;
 }
 
@@ -914,34 +1045,18 @@ void QgsDiagramProperties::apply()
   const int index = mDiagramTypeComboBox->currentIndex();
   const bool diagramsEnabled = ( index != -1 );
 
-  std::unique_ptr< QgsDiagram > diagram;
+  // Avoid this messageBox when in both dock and liveUpdate mode
-
+  QgsSettings settings;
-  if ( diagramsEnabled && 0 == mDiagramAttributesTreeWidget->topLevelItemCount() )
+  if ( !dockMode() || !settings.value( QStringLiteral( "UI/autoApplyStyling" ), true ).toBool() )
   {
-    QMessageBox::warning( this, tr( "Diagrams: No attributes added." ),
+    if ( diagramsEnabled && 0 == mDiagramAttributesTreeWidget->topLevelItemCount() )
-                          tr( "You did not add any attributes to this diagram layer. Please specify the attributes to visualize on the diagrams or disable diagrams." ) );
+    {
+      QMessageBox::warning( this, tr( "Diagrams: No attributes added." ),
+                            tr( "You did not add any attributes to this diagram layer. Please specify the attributes to visualize on the diagrams or disable diagrams." ) );
+    }
   }
 
-  if ( mDiagramType == DIAGRAM_NAME_TEXT )
+  std::unique_ptr< QgsDiagramRenderer > renderer = createRenderer();
-  {
-    diagram = std::make_unique< QgsTextDiagram >();
-  }
-  else if ( mDiagramType == DIAGRAM_NAME_PIE )
-  {
-    diagram = std::make_unique< QgsPieDiagram >();
-  }
-  else if ( mDiagramType == DIAGRAM_NAME_STACKED_BAR )
-  {
-    diagram = std::make_unique< QgsStackedBarDiagram >();
-  }
-  else // if ( diagramType == DIAGRAM_NAME_HISTOGRAM )
-  {
-    diagram = std::make_unique< QgsHistogramDiagram >();
-  }
-
-  std::unique_ptr< QgsDiagramSettings > ds = createDiagramSettings();
-  std::unique_ptr< QgsDiagramRenderer > renderer = createRendererBaseInfo( *ds );
-  renderer->setDiagram( diagram.release() );
   mLayer->setDiagramRenderer( renderer.release() );
 
   QgsDiagramLayerSettings dls = createDiagramLayerSettings();
@@ -1051,6 +1166,30 @@ void QgsDiagramProperties::scalingTypeChanged()
   mButtonSizeLegendSettings->setEnabled( mAttributeBasedScalingRadio->isChecked() );
 }
 
+void QgsDiagramProperties::setAllowedToEditDiagramLayerSettings( bool allowed )
+{
+  mAllowedToEditDls = allowed;
+
+  label_16->setVisible( allowed );
+  mZIndexSpinBox->setVisible( allowed );
+  mZOrderDDBtn->setVisible( allowed );
+  mShowAllCheckBox->setVisible( allowed );
+  mDlsLabel_1->setVisible( !allowed );
+
+  mCoordinatesGrpBox->setVisible( allowed );
+  mLinePlacementFrame->setVisible( allowed );
+  mObstaclesGrpBox->setVisible( allowed );
+  mPlacementFrame->setVisible( allowed );
+  mPriorityGrpBox->setVisible( allowed );
+  stackedPlacement->setVisible( allowed );
+  mDlsLabel_2->setVisible( !allowed );
+}
+
+bool QgsDiagramProperties::isAllowedToEditDiagramLayerSettings() const
+{
+  return mAllowedToEditDls;
+}
+
 void QgsDiagramProperties::showSizeLegendDialog()
 {
   // prepare size transformer
@@ -1112,3 +1251,71 @@ void QgsDiagramProperties::createAuxiliaryField()
 
   emit auxiliaryFieldCreated();
 }
+
+void QgsDiagramProperties::connectValueChanged( const QList<QWidget *> &widgets, const char *signal )
+{
+  const auto constWidgets = widgets;
+  for ( QWidget *widget : constWidgets )
+  {
+    if ( QgsSymbolButton *w = qobject_cast<QgsSymbolButton *>( widget ) )
+    {
+      connect( w, SIGNAL( changed() ), this, signal );
+    }
+    else if ( QgsFieldExpressionWidget *w = qobject_cast< QgsFieldExpressionWidget *>( widget ) )
+    {
+      connect( w, SIGNAL( fieldChanged( QString ) ), this, signal );
+    }
+    else if ( QgsOpacityWidget *w = qobject_cast< QgsOpacityWidget *>( widget ) )
+    {
+      connect( w, SIGNAL( opacityChanged( double ) ), this, signal );
+    }
+    else if ( QgsUnitSelectionWidget *w = qobject_cast<QgsUnitSelectionWidget *>( widget ) )
+    {
+      connect( w, SIGNAL( changed() ), this, signal );
+    }
+    else if ( QComboBox *w = qobject_cast<QComboBox *>( widget ) )
+    {
+      connect( w, SIGNAL( currentIndexChanged( int ) ), this, signal );
+    }
+    else if ( QSpinBox *w = qobject_cast<QSpinBox *>( widget ) )
+    {
+      connect( w, SIGNAL( valueChanged( int ) ), this, signal );
+    }
+    else if ( QDoubleSpinBox *w = qobject_cast<QDoubleSpinBox *>( widget ) )
+    {
+      connect( w, SIGNAL( valueChanged( double ) ), this, signal );
+    }
+    else if ( QgsColorButton *w = qobject_cast<QgsColorButton *>( widget ) )
+    {
+      connect( w, SIGNAL( colorChanged( QColor ) ), this, signal );
+    }
+    else if ( QCheckBox *w = qobject_cast<QCheckBox *>( widget ) )
+    {
+      connect( w, SIGNAL( toggled( bool ) ), this, signal );
+    }
+    else if ( QRadioButton *w = qobject_cast<QRadioButton *>( widget ) )
+    {
+      connect( w, SIGNAL( toggled( bool ) ), this, signal );
+    }
+    else if ( QSlider *w = qobject_cast<QSlider *>( widget ) )
+    {
+      connect( w, SIGNAL( valueChanged( int ) ), this, signal );
+    }
+    else if ( QGroupBox *w = qobject_cast<QGroupBox *>( widget ) )
+    {
+      connect( w, SIGNAL( toggled( bool ) ), this, signal );
+    }
+    else if ( QTreeWidget *w = qobject_cast<QTreeWidget *>( widget ) )
+    {
+      connect( w, SIGNAL( itemChanged( QTreeWidgetItem *, int ) ), this, signal );
+    }
+    else if ( QgsScaleRangeWidget *w = qobject_cast<QgsScaleRangeWidget *>( widget ) )
+    {
+      connect( w, SIGNAL( rangeChanged( double, double ) ), this, signal );
+    }
+    else
+    {
+      QgsLogger::warning( QStringLiteral( "Could not create connection for widget %1" ).arg( widget->objectName() ) );
+    }
+  }
+}

src/gui/vector/qgsdiagramproperties.h

@@ -36,26 +36,68 @@ class QgsMapCanvas;
 /**
  * \ingroup gui
  * \class QgsDiagramProperties
+ *
+ * \note This class is not a part of public API
  */
-class GUI_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPropertiesBase, private QgsExpressionContextGenerator
+class GUI_EXPORT QgsDiagramProperties : public QgsPanelWidget, private Ui::QgsDiagramPropertiesBase, private QgsExpressionContextGenerator
 {
     Q_OBJECT
 
   public:
     QgsDiagramProperties( QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas );
+    ~QgsDiagramProperties() override;
 
     /**
      * Updates the widget to reflect the layer's current diagram settings.
      *
      * \since QGIS 3.16
      */
-    void syncToLayer( const QgsDiagramRenderer *dr = nullptr );
+    void syncToLayer();
 
-    ~QgsDiagramProperties() override;
+    /**
+     * Updates the widget to reflect the diagram renderer.
+     * \param dr Diagram renderer where settings are taken from.
+     *
+     * \since QGIS 3.40
+     */
+    void syncToRenderer( const QgsDiagramRenderer *dr );
+
+    /**
+     * Updates the widget to reflect the diagram layer settings.
+     * \param dls Diagram Layer Settings to update the widget.
+     *
+     * \since QGIS 3.40
+     */
+    void syncToSettings( const QgsDiagramLayerSettings *dls );
 
     //! Adds an attribute from the list of available attributes to the assigned attributes with a random color.
     void addAttribute( QTreeWidgetItem *item );
 
+    /**
+     * Sets the widget in dock mode.
+     * \param dockMode TRUE for dock mode.
+     */
+    void setDockMode( bool dockMode ) override;
+
+    /**
+     * Defines the widget's diagram type and lets it know it should hide the type comboBox.
+     * @param diagramType Type of diagram to be set
+     */
+    void setDiagramType( const QString diagramType );
+
+    /**
+     * Sets whether the widget should show diagram layer settings.
+     * Used by stacked diagrams, which disable editing of DLS for sub diagrams
+     * other than the first one.
+     * @param allowed Whether this widget should be allowed to edit diagram layer settings.
+    */
+    void setAllowedToEditDiagramLayerSettings( bool allowed );
+
+    /**
+     * Returns whether this widget is allowed to edit diagram layer settings.
+     */
+    bool isAllowedToEditDiagramLayerSettings() const;
+
   signals:
 
     void auxiliaryFieldCreated();
@@ -118,8 +160,24 @@ class GUI_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPr
 
     QgsExpressionContext createExpressionContext() const override;
 
+    bool mAllowedToEditDls = true;
+
     void registerDataDefinedButton( QgsPropertyOverrideButton *button, QgsDiagramLayerSettings::Property key );
 
+    /**
+     * Convenience function to chain widgets' change value signal to another signal.
+     * @param widgets List of widgets.
+     * @param signal Signal to be triggered by each widget's change value signal.
+     */
+    void connectValueChanged( const QList<QWidget *> &widgets, const char *signal );
+
+    /**
+     * Creates a QgsDiagram object from the GUI settings.
+     *
+     * \since QGIS 3.40
+     */
+    std::unique_ptr< QgsDiagram > createDiagramObject();
+
     /**
      * Creates a QgsDiagramSettings object from the GUI settings.
      *
@@ -132,7 +190,7 @@ class GUI_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPr
      *
      * \since QGIS 3.40
      */
-    std::unique_ptr<QgsDiagramRenderer> createRendererBaseInfo( const QgsDiagramSettings &ds );
+    std::unique_ptr<QgsDiagramRenderer> createRenderer();
 
     /**
      * Creates a QgsDiagramLayerSettings object from the GUI settings.
@@ -142,6 +200,7 @@ class GUI_EXPORT QgsDiagramProperties : public QWidget, private Ui::QgsDiagramPr
     QgsDiagramLayerSettings createDiagramLayerSettings();
 
     friend class QgsStackedDiagramProperties;
+    friend class QgsStackedDiagramPropertiesDialog;
 };
 
 

src/gui/vector/qgsdiagramwidget.cpp

@@ -0,0 +1,220 @@
+/***************************************************************************
+  qgsdiagramwidget.h
+  Container widget for diagram layers
+  -------------------
+         begin                : September 2024
+         copyright            : (C) Germán Carrillo
+         email                : german at opengis dot ch
+
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "diagram/qgshistogramdiagram.h"
+#include "diagram/qgspiediagram.h"
+#include "diagram/qgstextdiagram.h"
+#include "diagram/qgsstackedbardiagram.h"
+
+#include "qgsdiagramwidget.h"
+#include "qgsvectorlayer.h"
+#include "qgsapplication.h"
+#include "qgsguiutils.h"
+#include "qgslabelengineconfigdialog.h"
+#include "qgsdiagramproperties.h"
+#include "qgsstackeddiagramproperties.h"
+
+
+QgsDiagramWidget::QgsDiagramWidget( QgsVectorLayer *layer, QgsMapCanvas *canvas, QWidget *parent )
+  : QgsMapLayerConfigWidget( layer, canvas, parent )
+  , mLayer( layer )
+  , mCanvas( canvas )
+{
+  if ( !layer )
+  {
+    return;
+  }
+
+  setupUi( this );
+
+  // Initialize stacked diagram controls
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "diagramNone.svg" ) ), tr( "No Diagrams" ), ModeNone );
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "pie-chart.svg" ) ), tr( "Pie Chart" ), ModePie );
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "text.svg" ) ), tr( "Text Diagram" ), ModeText );
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "histogram.svg" ) ), tr( "Histogram" ), ModeHistogram );
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "stacked-bar.svg" ) ), tr( "Stacked Bars" ), ModeStackedBar );
+  mDiagramTypeComboBox->addItem( QgsApplication::getThemeIcon( QStringLiteral( "diagramNone.svg" ) ), tr( "Stacked Diagram" ), ModeStacked );
+
+  connect( mEngineSettingsButton, &QAbstractButton::clicked, this, &QgsDiagramWidget::showEngineConfigDialog );
+
+  connect( mDiagramTypeComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsDiagramWidget::mDiagramTypeComboBox_currentIndexChanged );
+
+  const int iconSize16 = QgsGuiUtils::scaleIconSize( 16 );
+  mEngineSettingsButton->setIconSize( QSize( iconSize16, iconSize16 ) );
+}
+
+void QgsDiagramWidget::apply()
+{
+  const Mode mode = static_cast< Mode >( mDiagramTypeComboBox->currentData().toInt() );
+
+  switch ( mode )
+  {
+    case ModeStacked:
+    {
+      // Delegate to stacked diagram's apply
+      static_cast<QgsStackedDiagramProperties *>( mWidget )->apply();
+      break;
+    }
+    case ModePie:
+    case ModeText:
+    case ModeHistogram:
+    case ModeStackedBar:
+    {
+      // Delegate to single diagram's apply
+      static_cast<QgsDiagramProperties *>( mWidget )->apply();
+      break;
+    }
+    case ModeNone:
+    {
+      mLayer->setDiagramRenderer( nullptr );
+
+      QgsDiagramLayerSettings dls;
+      mLayer->setDiagramLayerSettings( dls );
+
+      // refresh
+      QgsProject::instance()->setDirty( true );
+      mLayer->triggerRepaint();
+    }
+  }
+}
+
+void QgsDiagramWidget::syncToOwnLayer()
+{
+  if ( !mLayer )
+  {
+    return;
+  }
+
+  whileBlocking( mDiagramTypeComboBox )->setCurrentIndex( -1 );
+
+  const QgsDiagramRenderer *dr = mLayer->diagramRenderer();
+
+  // pick the right mode from the layer
+  if ( dr && dr->diagram() )
+  {
+    if ( dr->rendererName() == QStringLiteral( "Stacked" ) )
+    {
+      mDiagramTypeComboBox->setCurrentIndex( ModeStacked );
+    }
+    else // Single diagram
+    {
+      const QString diagramName = dr->diagram()->diagramName();
+      if ( diagramName == DIAGRAM_NAME_PIE )
+      {
+        mDiagramTypeComboBox->setCurrentIndex( ModePie ) ;
+      }
+      else if ( diagramName == DIAGRAM_NAME_TEXT )
+      {
+        mDiagramTypeComboBox->setCurrentIndex( ModeText ) ;
+      }
+      else if ( diagramName == DIAGRAM_NAME_STACKED_BAR )
+      {
+        mDiagramTypeComboBox->setCurrentIndex( ModeStackedBar ) ;
+      }
+      else // diagramName == DIAGRAM_NAME_HISTOGRAM
+      {
+        // Play safe and set to histogram by default if the diagram name is unknown
+        mDiagramTypeComboBox->setCurrentIndex( ModeHistogram );
+      }
+      // TODO: if we get a stacked diagram, take the first subdiagram,
+      // Set its diagram type and sync to its settings
+
+      // Delegate to single diagram's syncToLayer
+      static_cast<QgsDiagramProperties *>( mWidget )->syncToLayer();
+    }
+  }
+  else // No Diagram
+  {
+    mDiagramTypeComboBox->setCurrentIndex( ModeNone );
+  }
+}
+
+void QgsDiagramWidget::mDiagramTypeComboBox_currentIndexChanged( int index )
+{
+  if ( mWidget )
+    mStackedWidget->removeWidget( mWidget );
+
+  delete mWidget;
+  mWidget = nullptr;
+
+  if ( index < 0 )
+    return;
+
+  const Mode mode = static_cast< Mode >( mDiagramTypeComboBox->currentData().toInt() );
+
+  switch ( mode )
+  {
+    case ModePie:
+    case ModeText:
+    case ModeHistogram:
+    case ModeStackedBar:
+    {
+      QgsDiagramProperties *singleWidget = new QgsDiagramProperties( mLayer, this, mMapCanvas );
+      singleWidget->layout()->setContentsMargins( 0, 0, 0, 0 );
+      singleWidget->setDockMode( dockMode() );
+
+      if ( mode == ModePie )
+        singleWidget->setDiagramType( DIAGRAM_NAME_PIE );
+      else if ( mode == ModeText )
+        singleWidget->setDiagramType( DIAGRAM_NAME_TEXT );
+      else if ( mode == ModeHistogram )
+        singleWidget->setDiagramType( DIAGRAM_NAME_HISTOGRAM );
+      else if ( mode == ModeStackedBar )
+        singleWidget->setDiagramType( DIAGRAM_NAME_STACKED_BAR );
+
+      connect( singleWidget, &QgsDiagramProperties::widgetChanged, this, &QgsDiagramWidget::widgetChanged );
+      connect( singleWidget, &QgsDiagramProperties::auxiliaryFieldCreated, this, &QgsDiagramWidget::auxiliaryFieldCreated );
+
+      mWidget = singleWidget;
+      mStackedWidget->addWidget( mWidget );
+      mStackedWidget->setCurrentWidget( mWidget );
+      break;
+    }
+    case ModeStacked:
+    {
+      QgsStackedDiagramProperties *stackedWidget = new QgsStackedDiagramProperties( mLayer, this, mCanvas );
+      stackedWidget->setDockMode( dockMode() );
+      connect( stackedWidget, &QgsPanelWidget::showPanel, this, &QgsPanelWidget::openPanel );
+      connect( stackedWidget, &QgsStackedDiagramProperties::widgetChanged, this, &QgsDiagramWidget::widgetChanged );
+      mWidget = stackedWidget;
+      mStackedWidget->addWidget( mWidget );
+      mStackedWidget->setCurrentWidget( mWidget );
+      break;
+    }
+    case ModeNone:
+      break;
+  }
+  emit widgetChanged();
+}
+
+void QgsDiagramWidget::showEngineConfigDialog()
+{
+  QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
+  if ( panel && panel->dockMode() )
+  {
+    QgsLabelEngineConfigWidget *widget = new QgsLabelEngineConfigWidget( mCanvas );
+    connect( widget, &QgsLabelEngineConfigWidget::widgetChanged, widget, &QgsLabelEngineConfigWidget::apply );
+    panel->openPanel( widget );
+  }
+  else
+  {
+    QgsLabelEngineConfigDialog dialog( mCanvas, this );
+    dialog.exec();
+    // reactivate button's window
+    activateWindow();
+  }
+}

src/gui/vector/qgsdiagramwidget.h

@@ -0,0 +1,78 @@
+/***************************************************************************
+  qgsdiagramwidget.h
+  Container widget for diagram layers
+  -------------------
+         begin                : September 2024
+         copyright            : (C) Germán Carrillo
+         email                : german at opengis dot ch
+
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSDIAGRAMWIDGET_H
+#define QGSDIAGRAMWIDGET_H
+
+// We don't want to expose this in the public API
+#define SIP_NO_FILE
+
+#include <qgsmaplayerconfigwidget.h>
+#include "ui_qgsdiagramwidget.h"
+
+#include <QWidget>
+
+/**
+ * \ingroup gui
+ * \class QgsDiagramWidget
+ *
+ * \since QGIS 3.40
+ */
+class GUI_EXPORT QgsDiagramWidget : public QgsMapLayerConfigWidget, private Ui::QgsDiagramWidget
+{
+    Q_OBJECT
+
+  public:
+    //! constructor
+    QgsDiagramWidget( QgsVectorLayer *layer, QgsMapCanvas *canvas, QWidget *parent = nullptr );
+
+    /**
+     * Updates the widget to reflect the layer's current diagram settings.
+     */
+    void syncToOwnLayer();
+
+  public slots:
+    //! Saves the labeling configuration and immediately updates the map canvas to reflect the changes
+    void apply() override;
+
+  signals:
+    //! Emitted when an auxiliary field is created
+    void auxiliaryFieldCreated();
+
+  private slots:
+    void mDiagramTypeComboBox_currentIndexChanged( int index );
+    void showEngineConfigDialog();
+
+  private:
+
+    enum Mode
+    {
+      ModeNone,
+      ModePie,
+      ModeText,
+      ModeHistogram,
+      ModeStackedBar,
+      ModeStacked
+    };
+
+    QgsVectorLayer *mLayer = nullptr;
+    QgsMapCanvas *mCanvas = nullptr;
+
+    QWidget *mWidget = nullptr;
+};
+
+#endif // QGSDIAGRAMWIDGET_H

src/gui/vector/qgsstackeddiagramproperties.cpp

@@ -19,40 +19,37 @@
 #include "diagram/qgspiediagram.h"
 #include "diagram/qgstextdiagram.h"
 #include "diagram/qgsstackedbardiagram.h"
+#include "diagram/qgsstackeddiagram.h"
 
-#include "qgsapplication.h"
+#include "qgsgui.h"
 #include "qgsdiagramproperties.h"
 #include "qgslabelengineconfigdialog.h"
 #include "qgsproject.h"
-#include "qgsstackeddiagram.h"
 #include "qgsstackeddiagramproperties.h"
 #include "qgsvectorlayer.h"
+#include "qgshelp.h"
 
 QgsStackedDiagramProperties::QgsStackedDiagramProperties( QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas )
-  : QWidget{parent}
+  : QgsPanelWidget( parent )
+  , mLayer( layer )
   , mMapCanvas( canvas )
 {
-  mLayer = layer;
   if ( !layer )
   {
     return;
   }
 
   setupUi( this );
-  connect( mDiagramTypeComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsStackedDiagramProperties::mDiagramTypeComboBox_currentIndexChanged );
+
-  connect( mEngineSettingsButton, &QPushButton::clicked, this, &QgsStackedDiagramProperties::mEngineSettingsButton_clicked );
+  connect( mSubDiagramsView, &QAbstractItemView::doubleClicked, this, static_cast<void ( QgsStackedDiagramProperties::* )( const QModelIndex & )>( &QgsStackedDiagramProperties::editSubDiagram ) );
+
   connect( mAddSubDiagramButton, &QPushButton::clicked, this, &QgsStackedDiagramProperties::addSubDiagram );
+  connect( mEditSubDiagramButton, &QAbstractButton::clicked, this, static_cast<void ( QgsStackedDiagramProperties::* )()>( &QgsStackedDiagramProperties::editSubDiagram ) );
   connect( mRemoveSubDiagramButton, &QPushButton::clicked, this, &QgsStackedDiagramProperties::removeSubDiagram );
-  connect( mSubDiagramsTabWidget->tabBar(), &QTabBar::tabMoved, this, &QgsStackedDiagramProperties::mSubDiagramsTabWidget_tabMoved );
 
   // Initialize stacked diagram controls
-  QIcon icon = QgsApplication::getThemeIcon( QStringLiteral( "diagramNone.svg" ) );
-  mDiagramTypeComboBox->addItem( icon, tr( "No Diagrams" ), "None" );
-  mDiagramTypeComboBox->addItem( tr( "Single diagram" ), QgsDiagramLayerSettings::Single );
-  mDiagramTypeComboBox->addItem( tr( "Stacked diagrams" ), QgsDiagramLayerSettings::Stacked );
   mStackedDiagramModeComboBox->addItem( tr( "Horizontal" ), QgsDiagramSettings::Horizontal );
   mStackedDiagramModeComboBox->addItem( tr( "Vertical" ), QgsDiagramSettings::Vertical );
-  mRemoveSubDiagramButton->setEnabled( false );
 
   mStackedDiagramSpacingSpinBox->setClearValue( 0 );
   mStackedDiagramSpacingUnitComboBox->setUnits( { Qgis::RenderUnit::Millimeters,
@@ -62,37 +59,117 @@ QgsStackedDiagramProperties::QgsStackedDiagramProperties( QgsVectorLayer *layer,
       Qgis::RenderUnit::Points,
       Qgis::RenderUnit::Inches } );
 
-  // Add default subdiagram tab
+  connect( mStackedDiagramModeComboBox, qOverload< int >( &QComboBox::currentIndexChanged ), this, &QgsStackedDiagramProperties::widgetChanged );
-  addSubDiagram();
+  connect( mStackedDiagramSpacingSpinBox, qOverload< double >( &QgsDoubleSpinBox::valueChanged ), this, &QgsStackedDiagramProperties::widgetChanged );
+  connect( mStackedDiagramSpacingUnitComboBox, &QgsUnitSelectionWidget::changed, this, &QgsStackedDiagramProperties::widgetChanged );
+
+  mModel = new QgsStackedDiagramPropertiesModel();
+  mSubDiagramsView->setModel( mModel );
+
+  connect( mModel, &QAbstractItemModel::dataChanged, this, &QgsStackedDiagramProperties::widgetChanged );
+  connect( mModel, &QAbstractItemModel::rowsInserted, this, &QgsStackedDiagramProperties::widgetChanged );
+  connect( mModel, &QAbstractItemModel::rowsRemoved, this, &QgsStackedDiagramProperties::widgetChanged );
 
   syncToLayer();
 }
 
 void QgsStackedDiagramProperties::addSubDiagram()
 {
-  QgsDiagramProperties *gui = new QgsDiagramProperties( mLayer, this, mMapCanvas );
+  // Create a single category renderer by default
-  gui->layout()->setContentsMargins( 6, 6, 6, 6 );
+  std::unique_ptr< QgsDiagramRenderer > renderer;
-  connect( gui, &QgsDiagramProperties::auxiliaryFieldCreated, this, &QgsStackedDiagramProperties::auxiliaryFieldCreated );
+  std::unique_ptr< QgsSingleCategoryDiagramRenderer > dr = std::make_unique< QgsSingleCategoryDiagramRenderer >();
+  renderer = std::move( dr );
 
-  mSubDiagramsTabWidget->addTab( gui, tr( "Diagram %1" ).arg( mSubDiagramsTabWidget->count() + 1 ) );
+  QItemSelectionModel *sel = mSubDiagramsView->selectionModel();
+  const QModelIndex index = sel->currentIndex();
 
-  mRemoveSubDiagramButton->setEnabled( mSubDiagramsTabWidget->count() > 2 );
+  if ( index.isValid() )
+  {
+    // add after this subDiagram
+    const QModelIndex currentIndex = mSubDiagramsView->selectionModel()->currentIndex();
+    mModel->insertSubDiagram( currentIndex.row() + 1, renderer.release() );
+    const QModelIndex newIndex = mModel->index( currentIndex.row() + 1, 0 );
+    mSubDiagramsView->selectionModel()->setCurrentIndex( newIndex, QItemSelectionModel::ClearAndSelect );
+  }
+  else
+  {
+    // append to root
+    appendSubDiagram( renderer.release() );
+  }
+  editSubDiagram();
+}
+
+void QgsStackedDiagramProperties::appendSubDiagram( QgsDiagramRenderer *dr )
+{
+  const int rows = mModel->rowCount();
+  mModel->insertSubDiagram( rows, dr );
+  const QModelIndex newIndex = mModel->index( rows, 0 );
+  mSubDiagramsView->selectionModel()->setCurrentIndex( newIndex, QItemSelectionModel::ClearAndSelect );
+}
+
+void QgsStackedDiagramProperties::editSubDiagram()
+{
+  editSubDiagram( mSubDiagramsView->selectionModel()->currentIndex() );
+}
+
+void QgsStackedDiagramProperties::editSubDiagram( const QModelIndex &index )
+{
+  if ( !index.isValid() )
+    return;
+
+  QgsDiagramRenderer *renderer = mModel->subDiagramForIndex( index );
+  QgsDiagramLayerSettings dls = mModel->diagramLayerSettings();
+  QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
+
+  if ( panel && panel->dockMode() )
+  {
+    QgsDiagramProperties *widget = new QgsDiagramProperties( mLayer, this, mMapCanvas );
+    widget->setPanelTitle( tr( "Edit Sub Diagram" ) );
+    widget->layout()->setContentsMargins( 0, 0, 0, 0 );
+    widget->syncToRenderer( renderer );
+    widget->syncToSettings( &dls );
+    if ( !couldBeFirstSubDiagram( index ) )
+    {
+      widget->setAllowedToEditDiagramLayerSettings( false );
+    }
+
+    connect( widget, &QgsDiagramProperties::auxiliaryFieldCreated, this, &QgsStackedDiagramProperties::auxiliaryFieldCreated );
+    connect( widget, &QgsPanelWidget::panelAccepted, this, &QgsStackedDiagramProperties::subDiagramWidgetPanelAccepted );
+    connect( widget, &QgsDiagramProperties::widgetChanged, this, &QgsStackedDiagramProperties::liveUpdateSubDiagramFromPanel );
+    openPanel( widget );
+    return;
+  }
+
+  QgsStackedDiagramPropertiesDialog dlg( mLayer, this, mMapCanvas );
+  dlg.syncToRenderer( renderer );
+  dlg.syncToSettings( &dls );
+  if ( !couldBeFirstSubDiagram( index ) )
+  {
+    dlg.setAllowedToEditDiagramLayerSettings( false );
+  }
+
+  if ( dlg.exec() )
+  {
+    const QModelIndex index = mSubDiagramsView->selectionModel()->currentIndex();
+    if ( dlg.isAllowedToEditDiagramLayerSettings() )
+      mModel->updateDiagramLayerSettings( dlg.diagramLayerSettings() );
+
+    // This call will emit dataChanged, which in turns triggers widgetChanged()
+    mModel->updateSubDiagram( index, dlg.renderer() );
+  }
 }
 
 void QgsStackedDiagramProperties::removeSubDiagram()
 {
-  if ( mSubDiagramsTabWidget->count() > 2 )
+  const QItemSelection sel = mSubDiagramsView->selectionModel()->selection();
+  const auto constSel = sel;
+  for ( const QItemSelectionRange &range : constSel )
   {
-    const int index = mSubDiagramsTabWidget->currentIndex();
+    if ( range.isValid() )
-    delete mSubDiagramsTabWidget->widget( index );
+      mModel->removeRows( range.top(), range.bottom() - range.top() + 1, range.parent() );
-
-    mRemoveSubDiagramButton->setEnabled( mSubDiagramsTabWidget->count() > 2 );
-
-    for ( int i = index; i < mSubDiagramsTabWidget->count(); i++ )
-    {
-      mSubDiagramsTabWidget->setTabText( i, tr( "Diagram %1" ).arg( i + 1 ) );
-    }
   }
+  // make sure that the selection is gone
+  mSubDiagramsView->selectionModel()->clear();
 }
 
 void QgsStackedDiagramProperties::syncToLayer()
@@ -101,222 +178,372 @@ void QgsStackedDiagramProperties::syncToLayer()
 
   if ( dr && dr->diagram() )
   {
-    if ( dr->rendererName() == QStringLiteral( "Stacked" ) )
+    const QList<QgsDiagramSettings> settingList = dr->diagramSettings();
+    mStackedDiagramModeComboBox->setCurrentIndex( settingList.at( 0 ).stackedDiagramMode );
+    mStackedDiagramSpacingSpinBox->setValue( settingList.at( 0 ).stackedDiagramSpacing() );
+    mStackedDiagramSpacingUnitComboBox->setUnit( settingList.at( 0 ).stackedDiagramSpacingUnit() );
+
+    if ( dr->rendererName() == QLatin1String( "Stacked" ) )
     {
-      mDiagramTypeComboBox->blockSignals( true );
-      mDiagramTypeComboBox->setCurrentIndex( mDiagramTypeComboBox->findData( QgsDiagramLayerSettings::Stacked ) );
-      mDiagramTypeComboBox->blockSignals( false );
-      //force a refresh of widget status to match diagram type
-      mDiagramTypeComboBox_currentIndexChanged( mDiagramTypeComboBox->currentIndex() );
-
-      const QList<QgsDiagramSettings> settingList = dr->diagramSettings();
-      mStackedDiagramModeComboBox->setCurrentIndex( settingList.at( 0 ).stackedDiagramMode );
-      mStackedDiagramSpacingSpinBox->setValue( settingList.at( 0 ).stackedDiagramSpacing() );
-      mStackedDiagramSpacingUnitComboBox->setUnit( settingList.at( 0 ).stackedDiagramSpacingUnit() );
-
-      // Create/remove as many tabs as necessary
       const QgsStackedDiagramRenderer *stackedDiagramRenderer = static_cast< const QgsStackedDiagramRenderer * >( dr );
-      const int rendererCount = stackedDiagramRenderer->rendererCount();
+      const auto renderers = stackedDiagramRenderer->renderers();
-      while ( mSubDiagramsTabWidget->count() < rendererCount )
+      for ( const auto &renderer : renderers )
       {
-        addSubDiagram();
+        appendSubDiagram( renderer );
-      }
-      while ( mSubDiagramsTabWidget->count() > rendererCount )
-      {
-        mSubDiagramsTabWidget->setCurrentIndex( mSubDiagramsTabWidget->count() - 1 );
-        removeSubDiagram();
-      }
-
-      // Call subdiagrams' syncToLayer with the corresponding rendering object
-      for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
-      {
-        QgsDiagramProperties *diagramProperties = static_cast<QgsDiagramProperties *>( mSubDiagramsTabWidget->widget( i ) );
-        diagramProperties->syncToLayer( stackedDiagramRenderer->renderer( i ) );
       }
     }
-    else // Single diagram
+    else
     {
-      mDiagramTypeComboBox->blockSignals( true );
+      // Take this single renderer as the first stacked renderer
-      mDiagramTypeComboBox->setCurrentIndex( mDiagramTypeComboBox->findData( QgsDiagramLayerSettings::Single ) );
+      appendSubDiagram( dr->clone() );
-      mDiagramTypeComboBox->blockSignals( false );
-      //force a refresh of widget status to match diagram type
-      mDiagramTypeComboBox_currentIndexChanged( mDiagramTypeComboBox->currentIndex() );
-
-      // Delegate to single diagram's syncToLayer
-      // If the diagram name is unknown, the single diagram will choose a default one (pie)
-      static_cast<QgsDiagramProperties *>( mSubDiagramsTabWidget->widget( 0 ) )->syncToLayer();
     }
-  }
-  else // No Diagram
-  {
-    mDiagramTypeComboBox->blockSignals( true );
-    mDiagramTypeComboBox->setCurrentIndex( 0 );
-    mDiagramTypeComboBox->blockSignals( false );
-    //force a refresh of widget status to match diagram type
-    mDiagramTypeComboBox_currentIndexChanged( mDiagramTypeComboBox->currentIndex() );
 
-    // Delegate to first diagram's syncToLayer
+    const QgsDiagramLayerSettings *dls = mLayer->diagramLayerSettings();
-    // It will add required reasonable defaults
+    mModel->updateDiagramLayerSettings( *dls );
-    static_cast<QgsDiagramProperties *>( mSubDiagramsTabWidget->widget( 0 ) )->syncToLayer();
-  }
-}
-
-void QgsStackedDiagramProperties::mSubDiagramsTabWidget_tabMoved( int from, int to )
-{
-  Q_UNUSED( from )
-  Q_UNUSED( to )
-  for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
-  {
-    mSubDiagramsTabWidget->setTabText( i, tr( "Diagram %1" ).arg( i + 1 ) );
   }
 }
 
 void QgsStackedDiagramProperties::apply()
 {
-  if ( mDiagramTypeComboBox->currentData( Qt::UserRole ) == "None" )
+  std::unique_ptr< QgsDiagramSettings> ds = std::make_unique< QgsDiagramSettings >();
+  ds->stackedDiagramMode = static_cast<QgsDiagramSettings::StackedDiagramMode>( mStackedDiagramModeComboBox->currentData().toInt() );
+  ds->setStackedDiagramSpacingUnit( mStackedDiagramSpacingUnitComboBox->unit() );
+  ds->setStackedDiagramSpacing( mStackedDiagramSpacingSpinBox->value() );
+
+  // Create diagram renderer for the StackedDiagram
+  QgsStackedDiagramRenderer *dr = new QgsStackedDiagramRenderer();
+  dr->setDiagram( new QgsStackedDiagram() );
+
+  // Get DiagramSettings from each subdiagram
+  const QList< QgsDiagramRenderer *> renderers = mModel->subRenderers();
+  for ( const auto &renderer : renderers )
   {
-    std::unique_ptr< QgsDiagramRenderer > renderer;
+    const QList< QgsDiagramSettings > ds1 = renderer->diagramSettings();
-    mLayer->setDiagramRenderer( renderer.release() );
+    if ( !ds1.isEmpty() )
-
-    QgsDiagramLayerSettings dls;
-    mLayer->setDiagramLayerSettings( dls );
-
-    // refresh
-    QgsProject::instance()->setDirty( true );
-    mLayer->triggerRepaint();
-  }
-  else if ( mDiagramTypeComboBox->currentData( Qt::UserRole ) == QgsDiagramLayerSettings::Single )
-  {
-    static_cast<QgsDiagramProperties *>( mSubDiagramsTabWidget->widget( 0 ) )->apply();
-  }
-  else // Stacked diagram
-  {
-    // Create diagram settings for the StackedDiagram
-    std::unique_ptr< QgsDiagramSettings> ds = std::make_unique< QgsDiagramSettings >();
-    ds->stackedDiagramMode = static_cast<QgsDiagramSettings::StackedDiagramMode>( mStackedDiagramModeComboBox->currentData().toInt() );
-    ds->setStackedDiagramSpacingUnit( mStackedDiagramSpacingUnitComboBox->unit() );
-    ds->setStackedDiagramSpacing( mStackedDiagramSpacingSpinBox->value() );
-
-    // Create diagram renderer for the StackedDiagram
-    QgsStackedDiagramRenderer *dr = new QgsStackedDiagramRenderer();
-    dr->setDiagram( new QgsStackedDiagram() );
-
-    // Get DiagramSettings from each subdiagram
-    for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
     {
-      QgsDiagramProperties *diagramProperties = static_cast<QgsDiagramProperties *>( mSubDiagramsTabWidget->widget( i ) );
+      ds->categoryAttributes += ds1.at( 0 ).categoryAttributes;
-      std::unique_ptr< QgsDiagramSettings > ds1 = diagramProperties->createDiagramSettings();
+      ds->categoryLabels += ds1.at( 0 ).categoryLabels;
-      ds->categoryAttributes += ds1->categoryAttributes;
+      ds->categoryColors += ds1.at( 0 ).categoryColors;
-      ds->categoryLabels += ds1->categoryLabels;
-      ds->categoryColors += ds1->categoryColors;
-
-      std::unique_ptr< QgsDiagramRenderer > dr1 = diagramProperties->createRendererBaseInfo( *ds1 );
-
-      std::unique_ptr< QgsDiagram > diagram;
-
-      if ( diagramProperties->mDiagramType == DIAGRAM_NAME_TEXT )
-      {
-        diagram = std::make_unique< QgsTextDiagram >();
-      }
-      else if ( diagramProperties->mDiagramType == DIAGRAM_NAME_PIE )
-      {
-        diagram = std::make_unique< QgsPieDiagram >();
-      }
-      else if ( diagramProperties->mDiagramType == DIAGRAM_NAME_STACKED_BAR )
-      {
-        diagram = std::make_unique< QgsStackedBarDiagram >();
-      }
-      else // DIAGRAM_NAME_HISTOGRAM
-      {
-        diagram = std::make_unique< QgsHistogramDiagram >();
-      }
-
-      dr1->setDiagram( diagram.release() );
-      dr->addRenderer( dr1.release() );
     }
-
+    dr->addRenderer( renderer );
-    dr->setDiagramSettings( *ds );
-    mLayer->setDiagramRenderer( dr );
-
-    // Create DiagramLayerSettings from first diagram
-    QgsDiagramProperties *firstDiagramProperties = static_cast< QgsDiagramProperties * >( mSubDiagramsTabWidget->widget( 0 ) );
-    QgsDiagramLayerSettings dls = firstDiagramProperties->createDiagramLayerSettings();
-    mLayer->setDiagramLayerSettings( dls );
-
-    // refresh
-    QgsProject::instance()->setDirty( true );
-    mLayer->triggerRepaint();
   }
+
+  dr->setDiagramSettings( *ds );
+  mLayer->setDiagramRenderer( dr );
+
+  // Get DiagramLayerSettings from the model
+  QgsDiagramLayerSettings dls = mModel->diagramLayerSettings();
+  mLayer->setDiagramLayerSettings( dls );
+
+  // refresh
+  QgsProject::instance()->setDirty( true );
+  mLayer->triggerRepaint();
 }
 
-void QgsStackedDiagramProperties::mDiagramTypeComboBox_currentIndexChanged( int index )
+bool QgsStackedDiagramProperties::couldBeFirstSubDiagram( const QModelIndex &index ) const
 {
-  if ( index == 0 ) // No diagram
+  if ( !index.isValid() )
+    return false;
+
+  if ( mModel->rowCount() == 1 )
+    return true;
+
+  // Is there any enabled subdiagram before our index.row()?
+  // If so, ours cannot be the first diagram.
+  const QList< QgsDiagramRenderer * > renderers = mModel->subRenderers();
+
+  for ( int i = 0; i < index.row(); i++ )
   {
-    mDiagramsFrame->setEnabled( false );
+    const auto &renderer = renderers.at( i );
-    mStackedDiagramSettingsFrame->hide();
+    const QList< QgsDiagramSettings > ds = renderer->diagramSettings();
-
+    if ( !ds.isEmpty() && ds.at( 0 ).enabled )
-    // Hide tabs other than the first one
-    for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
     {
-      if ( i < 1 )
+      // First enabled subdiagram found, and we know our row is after.
-        continue;
+      // Therefore, return false to disallow showing DLS settings for it.
-
+      return false;
-      mSubDiagramsTabWidget->setTabVisible( i, false );
-    }
-  }
-  else if ( index == 1 ) // Single
-  {
-    mDiagramsFrame->setEnabled( true );
-    mStackedDiagramSettingsFrame->hide();
-
-    // Hide tabs other than the first one
-    for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
-    {
-      if ( i < 1 )
-        continue;
-
-      mSubDiagramsTabWidget->setTabVisible( i, false );
-    }
-  }
-  else // Stacked
-  {
-    mDiagramsFrame->setEnabled( true );
-    mStackedDiagramSettingsFrame->show();
-
-    // Create the second tab or show all hidden tabs
-    if ( mSubDiagramsTabWidget->count() == 1 )
-    {
-      // Add second subdiagram tab
-      addSubDiagram();
-    }
-    else
-    {
-      for ( int i = 0; i < mSubDiagramsTabWidget->count(); i++ )
-      {
-        if ( i < 1 )
-          continue;
-
-        mSubDiagramsTabWidget->setTabVisible( i, true );
-      }
     }
   }
+  // Either our row is the first subdiagram enabled or it's disabled,
+  // but there are no enabled ones before. So, ours could be the first
+  // enabled one after being edited.
+  // Therefore, we should allow DLS settings on its corresponding widget.
+  return true;
 }
 
-void QgsStackedDiagramProperties::mEngineSettingsButton_clicked()
+void QgsStackedDiagramProperties::subDiagramWidgetPanelAccepted( QgsPanelWidget *panel )
 {
-  QgsPanelWidget *panel = QgsPanelWidget::findParentPanel( this );
+  QgsDiagramProperties *widget = qobject_cast<QgsDiagramProperties *>( panel );
-  if ( panel && panel->dockMode() )
+
+  std::unique_ptr< QgsDiagramRenderer > renderer = widget->createRenderer();
+
+  const QModelIndex index = mSubDiagramsView->selectionModel()->currentIndex();
+  if ( widget->isAllowedToEditDiagramLayerSettings() )
+    mModel->updateDiagramLayerSettings( widget->createDiagramLayerSettings() );
+
+  mModel->updateSubDiagram( index, renderer.release() );
+}
+
+void QgsStackedDiagramProperties::liveUpdateSubDiagramFromPanel()
+{
+  subDiagramWidgetPanelAccepted( qobject_cast<QgsPanelWidget *>( sender() ) );
+}
+
+////
+
+#include "qgsvscrollarea.h"
+
+QgsStackedDiagramPropertiesDialog::QgsStackedDiagramPropertiesDialog( QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *mapCanvas )
+  : QDialog( parent )
+{
+
+#ifdef Q_OS_MAC
+  setWindowModality( Qt::WindowModal );
+#endif
+
+  QVBoxLayout *layout = new QVBoxLayout( this );
+  QgsVScrollArea *scrollArea = new QgsVScrollArea( this );
+  scrollArea->setFrameShape( QFrame::NoFrame );
+  layout->addWidget( scrollArea );
+
+  buttonBox = new QDialogButtonBox( QDialogButtonBox::Cancel | QDialogButtonBox::Help | QDialogButtonBox::Ok );
+  mPropsWidget = new QgsDiagramProperties( layer, this, mapCanvas );
+  mPropsWidget->setDockMode( false );
+
+  scrollArea->setWidget( mPropsWidget );
+  layout->addWidget( buttonBox );
+  this->setWindowTitle( "Edit Sub Diagram" );
+  QgsGui::enableAutoGeometryRestore( this );
+
+  connect( buttonBox, &QDialogButtonBox::accepted, this, &QgsStackedDiagramPropertiesDialog::accept );
+  connect( buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject );
+  connect( buttonBox, &QDialogButtonBox::helpRequested, this, &QgsStackedDiagramPropertiesDialog::showHelp );
+}
+
+void QgsStackedDiagramPropertiesDialog::syncToRenderer( const QgsDiagramRenderer *dr ) const
+{
+  mPropsWidget->syncToRenderer( dr );
+}
+
+void QgsStackedDiagramPropertiesDialog::syncToSettings( const QgsDiagramLayerSettings *dls ) const
+{
+  mPropsWidget->syncToSettings( dls );
+}
+
+void QgsStackedDiagramPropertiesDialog::accept()
+{
+  // Get renderer and diagram layer settings from widget
+  mRenderer = mPropsWidget->createRenderer();
+  mDiagramLayerSettings = mPropsWidget->createDiagramLayerSettings();
+  QDialog::accept();
+}
+
+QgsDiagramRenderer *QgsStackedDiagramPropertiesDialog::renderer()
+{
+  return mRenderer.release();
+}
+
+QgsDiagramLayerSettings QgsStackedDiagramPropertiesDialog::diagramLayerSettings() const
+{
+  return mDiagramLayerSettings;
+}
+
+void QgsStackedDiagramPropertiesDialog::setAllowedToEditDiagramLayerSettings( bool allowed ) const
+{
+  mPropsWidget->setAllowedToEditDiagramLayerSettings( allowed );
+}
+
+bool QgsStackedDiagramPropertiesDialog::isAllowedToEditDiagramLayerSettings() const
+{
+  return mPropsWidget->isAllowedToEditDiagramLayerSettings();
+}
+
+void QgsStackedDiagramPropertiesDialog::showHelp()
+{
+  QgsHelp::openHelp( QStringLiteral( "working_with_vector/vector_properties.html#diagrams-properties" ) );
+}
+
+////
+
+QgsStackedDiagramPropertiesModel::QgsStackedDiagramPropertiesModel( QObject *parent )
+  : QAbstractTableModel( parent )
+{
+}
+
+Qt::ItemFlags QgsStackedDiagramPropertiesModel::flags( const QModelIndex &index ) const
+{
+  const Qt::ItemFlag checkable = ( index.column() == 0 ? Qt::ItemIsUserCheckable : Qt::NoItemFlags );
+
+  return Qt::ItemIsEnabled | Qt::ItemIsSelectable | checkable;
+}
+
+QVariant QgsStackedDiagramPropertiesModel::data( const QModelIndex &index, int role ) const
+{
+  if ( !index.isValid() )
+    return QVariant();
+
+  QgsDiagramRenderer *dr = subDiagramForIndex( index );
+
+  if ( role == Qt::DisplayRole || role == Qt::ToolTipRole )
   {
-    QgsLabelEngineConfigWidget *widget = new QgsLabelEngineConfigWidget( mMapCanvas );
+    switch ( index.column() )
-    connect( widget, &QgsLabelEngineConfigWidget::widgetChanged, widget, &QgsLabelEngineConfigWidget::apply );
+    {
-    panel->openPanel( widget );
+      case 1:
+        return ( !dr || !dr->diagram() ) ? tr( "(no diagram)" ) : dr->diagram()->diagramName();
+      case 2:
+        if ( !dr )
+        {
+          return tr( "(no renderer)" );
+        }
+        else
+        {
+          if ( dr->rendererName() == QLatin1String( "SingleCategory" ) )
+            return tr( "Fixed" );
+          else if ( dr->rendererName() == QLatin1String( "LinearlyInterpolated" ) )
+            return tr( "Scaled" );
+          else
+            return tr( "Unknown" );
+        }
+      case 3:
+        if ( dr && dr->diagram() && !dr->diagramSettings().isEmpty() )
+        {
+          if ( DIAGRAM_NAME_HISTOGRAM == dr->diagram()->diagramName() || DIAGRAM_NAME_STACKED_BAR == dr->diagram()->diagramName() )
+          {
+            switch ( dr->diagramSettings().at( 0 ).diagramOrientation )
+            {
+              case QgsDiagramSettings::Left:
+                return tr( "Left" );
+              case QgsDiagramSettings::Right:
+                return tr( "Right" );
+              case QgsDiagramSettings::Up:
+                return tr( "Up" );
+              case QgsDiagramSettings::Down:
+                return tr( "Down" );
+            }
+          }
+        }
+        return QVariant();
+      case 0:
+      default:
+        return QVariant();
+    }
+  }
+  else if ( role == Qt::TextAlignmentRole )
+  {
+    return index.column() == 0 ? static_cast<Qt::Alignment::Int>( Qt::AlignCenter ) : static_cast<Qt::Alignment::Int>( Qt::AlignLeft );
+  }
+  else if ( role == Qt::CheckStateRole )
+  {
+    if ( index.column() != 0 )
+      return QVariant();
+
+    return ( dr && !dr->diagramSettings().isEmpty() && dr->diagramSettings().at( 0 ).enabled ) ? Qt::Checked : Qt::Unchecked;
   }
   else
   {
-    QgsLabelEngineConfigDialog dialog( mMapCanvas, this );
+    return QVariant();
-    dialog.exec();
-    // reactivate button's window
-    activateWindow();
   }
 }
+
+QVariant QgsStackedDiagramPropertiesModel::headerData( int section, Qt::Orientation orientation, int role ) const
+{
+  if ( orientation == Qt::Horizontal && role == Qt::DisplayRole && section >= 0 && section < 4 )
+  {
+    QStringList lst;
+    lst << tr( "Enabled" ) << tr( "Diagram type" ) << tr( "Size" ) << tr( "Orientation" );
+    return lst[section];
+  }
+
+  return QVariant();
+}
+
+int QgsStackedDiagramPropertiesModel::rowCount( const QModelIndex & ) const
+{
+  return mRenderers.size();
+}
+
+int QgsStackedDiagramPropertiesModel::columnCount( const QModelIndex & ) const
+{
+  return 4;
+}
+
+bool QgsStackedDiagramPropertiesModel::setData( const QModelIndex &index, const QVariant &value, int role )
+{
+  if ( !index.isValid() )
+    return false;
+
+  QgsDiagramRenderer *dr = subDiagramForIndex( index );
+
+  if ( role == Qt::CheckStateRole )
+  {
+    if ( dr && !dr->diagramSettings().isEmpty() )
+    {
+      QgsDiagramSettings ds = dr->diagramSettings().at( 0 );
+      ds.enabled = ( value.toInt() == Qt::Checked );
+
+      if ( dr->rendererName() == QLatin1String( "SingleCategory" ) )
+      {
+        QgsSingleCategoryDiagramRenderer *dsr = static_cast< QgsSingleCategoryDiagramRenderer * >( dr );
+        dsr->setDiagramSettings( ds );
+      }
+      else
+      {
+        QgsLinearlyInterpolatedDiagramRenderer *dlir = static_cast< QgsLinearlyInterpolatedDiagramRenderer * >( dr );
+        dlir->setDiagramSettings( ds );
+      }
+
+      emit dataChanged( index, index );
+      return true;
+    }
+  }
+  return false;
+}
+
+bool QgsStackedDiagramPropertiesModel::removeRows( int row, int count, const QModelIndex &parent )
+{
+  if ( row < 0 || row >= mRenderers.size() )
+    return false;
+
+  beginRemoveRows( parent, row, row + count - 1 );
+  while ( count-- )
+    mRenderers.removeAt( row );
+  endRemoveRows();
+
+  return true;
+}
+
+QgsDiagramRenderer *QgsStackedDiagramPropertiesModel::subDiagramForIndex( const QModelIndex &index ) const
+{
+  if ( index.isValid() )
+    return mRenderers.at( index.row() );
+  return nullptr;
+}
+
+void QgsStackedDiagramPropertiesModel::insertSubDiagram( const int index, QgsDiagramRenderer *newSubDiagram )
+{
+  beginInsertRows( QModelIndex(), index, index );
+  mRenderers.insert( index, newSubDiagram );
+  endInsertRows();
+}
+
+void QgsStackedDiagramPropertiesModel::updateSubDiagram( const QModelIndex &index, QgsDiagramRenderer *dr )
+{
+  mRenderers.replace( index.row(), dr );
+  emit dataChanged( index, index );
+}
+
+QList< QgsDiagramRenderer *> QgsStackedDiagramPropertiesModel::subRenderers() const
+{
+  QList<QgsDiagramRenderer *> subRenderers;
+  subRenderers = mRenderers;
+  return subRenderers;
+}
+
+void QgsStackedDiagramPropertiesModel::updateDiagramLayerSettings( QgsDiagramLayerSettings dls )
+{
+  mDiagramLayerSettings = dls;
+}
+
+QgsDiagramLayerSettings QgsStackedDiagramPropertiesModel::diagramLayerSettings() const
+{
+  return mDiagramLayerSettings;
+}

src/gui/vector/qgsstackeddiagramproperties.h

@@ -22,14 +22,71 @@
 #define SIP_NO_FILE
 
 #include "qgis_gui.h"
+#include "qgsdiagramrenderer.h"
 #include "ui_qgsstackeddiagrampropertiesbase.h"
 
 #include <QWidget>
 #include <QDialog>
+#include <QDialogButtonBox>
 
 class QgsVectorLayer;
 class QgsMapCanvas;
 class QgsDiagramProperties;
+class QgsDiagramRenderer;
+
+
+/**
+ * \ingroup gui
+ * \brief Model for sub diagrams in a stacked diagram view.
+ *
+ * \note This class is not a part of public API
+ * \since QGIS 3.40
+ */
+class GUI_EXPORT QgsStackedDiagramPropertiesModel : public QAbstractTableModel
+{
+    Q_OBJECT
+
+  public:
+    //! constructor
+    QgsStackedDiagramPropertiesModel( QObject *parent = nullptr );
+
+    Qt::ItemFlags flags( const QModelIndex &index ) const override;
+    QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const override;
+    QVariant headerData( int section, Qt::Orientation orientation,
+                         int role = Qt::DisplayRole ) const override;
+    int rowCount( const QModelIndex & = QModelIndex() ) const override;
+    int columnCount( const QModelIndex & = QModelIndex() ) const override;
+
+    // editing support
+    bool setData( const QModelIndex &index, const QVariant &value, int role = Qt::EditRole ) override;
+    bool removeRows( int row, int count, const QModelIndex &parent = QModelIndex() ) override;
+
+    // new methods
+
+    //! Returns the diagram renderer at the specified index
+    QgsDiagramRenderer *subDiagramForIndex( const QModelIndex &index ) const;
+
+    //! Inserts a new diagram at the specified position
+    void insertSubDiagram( const int index, QgsDiagramRenderer *newSubDiagram );
+    //! Replaces the diagram located at \a index by \a dr
+    void updateSubDiagram( const QModelIndex &index, QgsDiagramRenderer *dr );
+
+    //! Returns the list of diagram renderers from the model
+    QList< QgsDiagramRenderer *> subRenderers() const;
+
+    //! Returns the diagram layer settings from the model
+    QgsDiagramLayerSettings diagramLayerSettings() const;
+
+    /**
+     * Sets the diagram layer settings for the model.
+     * @param dls DiagramLayerSettings to be set.
+     */
+    void updateDiagramLayerSettings( QgsDiagramLayerSettings dls );
+
+  protected:
+    QList< QgsDiagramRenderer *> mRenderers;
+    QgsDiagramLayerSettings mDiagramLayerSettings;
+};
 
 
 /**
@@ -38,7 +95,7 @@ class QgsDiagramProperties;
  *
  * \since QGIS 3.40
  */
-class GUI_EXPORT QgsStackedDiagramProperties : public QWidget, private Ui::QgsStackedDiagramPropertiesBase
+class GUI_EXPORT QgsStackedDiagramProperties : public QgsPanelWidget, private Ui::QgsStackedDiagramPropertiesBase
 {
     Q_OBJECT
 
@@ -55,27 +112,127 @@ class GUI_EXPORT QgsStackedDiagramProperties : public QWidget, private Ui::QgsSt
 
   public slots:
     void apply();
-    void mDiagramTypeComboBox_currentIndexChanged( int index );
-    void mSubDiagramsTabWidget_tabMoved( int from, int to );
-    void mEngineSettingsButton_clicked();
 
   private slots:
 
     /**
-     * Adds a diagram tab to the current QgsStackedDiagramProperties.
+     * Adds a diagram to the current QgsStackedDiagramProperties.
      */
     void addSubDiagram();
 
     /**
-     * Removes a diagram tab from the current QgsStackedDiagramProperties.
+     * Appends a diagram to the current QgsStackedDiagramProperties.
-     * Diagram tabs are removed only if the tab count is greater than 2.
+     * @param dr Diagram renderer to be appended.
-     * Tab texts are adjusted after tab removal, to keep sequential order.
+     */
+    void appendSubDiagram( QgsDiagramRenderer *dr );
+
+    /**
+     * Edits the properties of the current diagram.
+     */
+    void editSubDiagram();
+
+    /**
+     * Edits the properties of a diagram located at a given \a index.
+     * @param index Model index where the diagram is located.
+     */
+    void editSubDiagram( const QModelIndex &index );
+
+    /**
+     * Removes a diagram from the current QgsStackedDiagramProperties.
      */
     void removeSubDiagram();
 
   private:
     QgsVectorLayer *mLayer = nullptr;
     QgsMapCanvas *mMapCanvas = nullptr;
+
+    QgsStackedDiagramPropertiesModel *mModel = nullptr;
+
+    /**
+     * Determines whether the subdiagram in the given \a index may be
+     * the first sub diagram in the stacked diagram. This includes the
+     * first enabled sub diagram, as well as disabled sub diagrams that,
+     * after being edited, can become the first enabled one.
+     * @param index Model index where the sub diagram is located.
+     */
+    bool couldBeFirstSubDiagram( const QModelIndex &index ) const;
+
+  private slots:
+    void subDiagramWidgetPanelAccepted( QgsPanelWidget *panel );
+    void liveUpdateSubDiagramFromPanel();
+};
+
+/**
+ * \ingroup gui
+ * \class QgsStackedDiagramPropertiesDialog
+ * \brief Dialog for editing sub diagrams
+ *
+ * \note This class is not a part of public API
+ * \since QGIS 3.40
+ */
+class GUI_EXPORT QgsStackedDiagramPropertiesDialog : public QDialog
+{
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Constructor for QgsStackedDiagramPropertiesDialog
+     * \param layer source vector layer
+     * \param parent parent widget
+     * \param mapCanvas map canvas
+     */
+    QgsStackedDiagramPropertiesDialog( QgsVectorLayer *layer, QWidget *parent = nullptr, QgsMapCanvas *mapCanvas = nullptr );
+
+    /**
+     * Delegates to the diagram properties widget to sync with the given renderer.
+     * @param dr Diagram Renderer to be used for the sync.
+     */
+    void syncToRenderer( const QgsDiagramRenderer *dr ) const;
+
+    /**
+     * Delegates to the diagram properties widget to sync with the given diagram layer settings.
+     * @param dls Diagram Layer Settings to be used for the sync.
+     */
+    void syncToSettings( const QgsDiagramLayerSettings *dls ) const;
+
+    /**
+     * Gets a renderer object built from the diagram properties widget.
+     */
+    QgsDiagramRenderer *renderer();
+
+    /**
+     * Gets diagram layer settings built from the diagram properties widget.
+     */
+    QgsDiagramLayerSettings diagramLayerSettings() const;
+
+    /**
+     * Delegates to the main widget to set whether the widget should show
+     * diagram layer settings to be edited.
+     * @param allowed Whether the main widget should be allowed to edit diagram layer settings.
+    */
+    void setAllowedToEditDiagramLayerSettings( bool allowed ) const;
+
+    /**
+     * Returns whether the main widget is allowed to edit diagram layer settings.
+     */
+    bool isAllowedToEditDiagramLayerSettings() const;
+
+  public slots:
+
+    /**
+     * Applies changes from the widget to the internal renderer and diagram layer settings.
+     */
+    void accept() override;
+
+  private slots:
+    void showHelp();
+
+  private:
+    QgsDiagramProperties *mPropsWidget = nullptr;
+    std::unique_ptr< QgsDiagramRenderer > mRenderer;
+    QgsDiagramLayerSettings mDiagramLayerSettings;
+    QDialogButtonBox *buttonBox = nullptr;
 };
 
 #endif // QGSSTACKEDDIAGRAMPROPERTIES_H

src/gui/vector/qgsvectorlayerproperties.cpp

@@ -26,7 +26,7 @@
 #include "qgsapplication.h"
 #include "qgsattributeactiondialog.h"
 #include "qgsdatumtransformdialog.h"
-#include "qgsstackeddiagramproperties.h"
+#include "qgsdiagramwidget.h"
 #include "qgssourcefieldsproperties.h"
 #include "qgsattributesformproperties.h"
 #include "qgslabelingwidget.h"
@@ -280,6 +280,15 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
   mSelectionSymbolButton->setEnabled( false );
   mRadioDefaultSelectionColor->setChecked( true );
 
+  // Diagram tab, before the syncToLayer
+  QVBoxLayout *diagLayout = new QVBoxLayout( mDiagramFrame );
+  diagLayout->setContentsMargins( 0, 0, 0, 0 );
+  diagramPropertiesDialog = new QgsDiagramWidget( mLayer, mCanvas, mDiagramFrame );
+  diagramPropertiesDialog->layout()->setContentsMargins( 0, 0, 0, 0 );
+  connect( diagramPropertiesDialog, &QgsDiagramWidget::auxiliaryFieldCreated, this, [ = ] { updateAuxiliaryStoragePage(); } );
+  diagLayout->addWidget( diagramPropertiesDialog );
+  mDiagramFrame->setLayout( diagLayout );
+
   syncToLayer();
 
   if ( mLayer->dataProvider() )
@@ -333,14 +342,6 @@ QgsVectorLayerProperties::QgsVectorLayerProperties(
 
   mOldJoins = mLayer->vectorJoins();
 
-  QVBoxLayout *diagLayout = new QVBoxLayout( mDiagramFrame );
-  diagLayout->setContentsMargins( 0, 0, 0, 0 );
-  diagramPropertiesDialog = new QgsStackedDiagramProperties( mLayer, mDiagramFrame, mCanvas );
-  diagramPropertiesDialog->layout()->setContentsMargins( 0, 0, 0, 0 );
-  connect( diagramPropertiesDialog, &QgsStackedDiagramProperties::auxiliaryFieldCreated, this, [ = ] { updateAuxiliaryStoragePage(); } );
-  diagLayout->addWidget( diagramPropertiesDialog );
-  mDiagramFrame->setLayout( diagLayout );
-
   // Legend tab
   mLegendWidget->setMapCanvas( mCanvas );
   mLegendWidget->setLayer( mLayer );
@@ -728,7 +729,7 @@ void QgsVectorLayerProperties::syncToLayer()
   updateVariableEditor();
 
   if ( diagramPropertiesDialog )
-    diagramPropertiesDialog->syncToLayer();
+    diagramPropertiesDialog->syncToOwnLayer();
 
   // sync all plugin dialogs
   for ( QgsMapLayerConfigWidget *page : std::as_const( mConfigWidgets ) )

src/gui/vector/qgsvectorlayerproperties.h

@@ -33,7 +33,7 @@ class QgsMapLayer;
 class QgsAttributeActionDialog;
 class QgsVectorLayer;
 class QgsLabelingWidget;
-class QgsStackedDiagramProperties;
+class QgsDiagramWidget;
 class QgsSourceFieldsProperties;
 class QgsAttributesFormProperties;
 class QgsRendererPropertiesDialog;
@@ -172,7 +172,7 @@ class GUI_EXPORT QgsVectorLayerProperties : public QgsLayerPropertiesDialog, pri
     //! Actions dialog. If apply is pressed, the actions are stored for later use
     QgsAttributeActionDialog *mActionDialog = nullptr;
     //! Diagram dialog. If apply is pressed, options are applied to vector's diagrams
-    QgsStackedDiagramProperties *diagramPropertiesDialog = nullptr;
+    QgsDiagramWidget *diagramPropertiesDialog = nullptr;
     //! SourceFields dialog. If apply is pressed, options are applied to vector's diagrams
     QgsSourceFieldsProperties *mSourceFieldsPropertiesDialog = nullptr;
     //! AttributesForm dialog. If apply is pressed, options are applied to vector's diagrams

src/ui/qgsdiagramwidget.ui

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>QgsDiagramWidget</class>
+ <widget class="QWidget" name="QgsDiagramWidget">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>842</width>
+    <height>472</height>
+   </rect>
+  </property>
+  <layout class="QGridLayout" name="gridLayout">
+   <property name="leftMargin">
+    <number>0</number>
+   </property>
+   <property name="topMargin">
+    <number>0</number>
+   </property>
+   <property name="rightMargin">
+    <number>0</number>
+   </property>
+   <property name="bottomMargin">
+    <number>0</number>
+   </property>
+   <item row="0" column="0">
+    <layout class="QHBoxLayout" name="horizontalLayout_4">
+     <item>
+      <widget class="QComboBox" name="mDiagramTypeComboBox"/>
+     </item>
+     <item>
+      <widget class="QToolButton" name="mEngineSettingsButton">
+       <property name="enabled">
+        <bool>true</bool>
+       </property>
+       <property name="toolTip">
+        <string>Automated placement settings (applies to all layers)</string>
+       </property>
+       <property name="icon">
+        <iconset resource="../../images/images.qrc">
+         <normaloff>:/images/themes/default/mIconAutoPlacementSettings.svg</normaloff>:/images/themes/default/mIconAutoPlacementSettings.svg</iconset>
+       </property>
+      </widget>
+     </item>
+    </layout>
+   </item>
+   <item row="1" column="0">
+    <widget class="QStackedWidget" name="mStackedWidget">
+     <widget class="QWidget" name="page"/>
+     <widget class="QWidget" name="page_2"/>
+    </widget>
+   </item>
+  </layout>
+ </widget>
+ <resources>
+  <include location="../../images/images.qrc"/>
+ </resources>
+ <connections/>
+</ui>

src/ui/qgsstackeddiagrampropertiesbase.ui

@@ -11,25 +11,106 @@
    </rect>
   </property>
   <layout class="QVBoxLayout" name="verticalLayout">
+   <property name="leftMargin">
+    <number>0</number>
+   </property>
+   <property name="topMargin">
+    <number>0</number>
+   </property>
+   <property name="rightMargin">
+    <number>0</number>
+   </property>
+   <property name="bottomMargin">
+    <number>0</number>
+   </property>
    <item>
-    <layout class="QHBoxLayout" name="horizontalLayout_4">
+    <widget class="QTreeView" name="mSubDiagramsView">
+     <property name="selectionMode">
+      <enum>QAbstractItemView::SelectionMode::SingleSelection</enum>
+     </property>
+     <property name="itemsExpandable">
+      <bool>false</bool>
+     </property>
+     <property name="expandsOnDoubleClick">
+      <bool>false</bool>
+     </property>
+     <attribute name="headerMinimumSectionSize">
+      <number>57</number>
+     </attribute>
+    </widget>
+   </item>
+   <item>
+    <layout class="QHBoxLayout" name="horizontalLayout">
      <item>
-      <widget class="QComboBox" name="mDiagramTypeComboBox"/>
+      <widget class="QPushButton" name="mAddSubDiagramButton">
-     </item>
+       <property name="sizePolicy">
-     <item>
+        <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
-      <widget class="QToolButton" name="mEngineSettingsButton">
+         <horstretch>0</horstretch>
-       <property name="enabled">
+         <verstretch>0</verstretch>
-        <bool>true</bool>
+        </sizepolicy>
        </property>
        <property name="toolTip">
-        <string>Automated placement settings (apply to all layers)</string>
+        <string>Add subdiagram to the stacked diagram</string>
+       </property>
+       <property name="text">
+        <string/>
        </property>
        <property name="icon">
         <iconset resource="../../images/images.qrc">
-         <normaloff>:/images/themes/default/mIconAutoPlacementSettings.svg</normaloff>:/images/themes/default/mIconAutoPlacementSettings.svg</iconset>
+         <normaloff>:/images/themes/default/symbologyAdd.svg</normaloff>:/images/themes/default/symbologyAdd.svg</iconset>
        </property>
       </widget>
      </item>
+     <item>
+      <widget class="QPushButton" name="mEditSubDiagramButton">
+       <property name="toolTip">
+        <string>Edit subdiagram from the stacked diagram</string>
+       </property>
+       <property name="text">
+        <string/>
+       </property>
+       <property name="icon">
+        <iconset resource="../../images/images.qrc">
+         <normaloff>:/images/themes/default/symbologyEdit.svg</normaloff>:/images/themes/default/symbologyEdit.svg</iconset>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <widget class="QPushButton" name="mRemoveSubDiagramButton">
+       <property name="sizePolicy">
+        <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
+         <horstretch>0</horstretch>
+         <verstretch>0</verstretch>
+        </sizepolicy>
+       </property>
+       <property name="toolTip">
+        <string>Remove subdiagram from the stacked diagram</string>
+       </property>
+       <property name="text">
+        <string/>
+       </property>
+       <property name="icon">
+        <iconset resource="../../images/images.qrc">
+         <normaloff>:/images/themes/default/symbologyRemove.svg</normaloff>:/images/themes/default/symbologyRemove.svg</iconset>
+       </property>
+      </widget>
+     </item>
+     <item>
+      <spacer name="horizontalSpacer_2">
+       <property name="orientation">
+        <enum>Qt::Orientation::Horizontal</enum>
+       </property>
+       <property name="sizeType">
+        <enum>QSizePolicy::Policy::Expanding</enum>
+       </property>
+       <property name="sizeHint" stdset="0">
+        <size>
+         <width>40</width>
+         <height>20</height>
+        </size>
+       </property>
+      </spacer>
+     </item>
     </layout>
    </item>
    <item>
@@ -41,93 +122,6 @@
       <enum>QFrame::Shadow::Raised</enum>
      </property>
      <layout class="QGridLayout" name="gridLayout">
-      <item row="2" column="0">
-       <layout class="QHBoxLayout" name="horizontalLayout">
-        <item>
-         <widget class="QPushButton" name="mAddSubDiagramButton">
-          <property name="sizePolicy">
-           <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-            <horstretch>0</horstretch>
-            <verstretch>0</verstretch>
-           </sizepolicy>
-          </property>
-          <property name="toolTip">
-           <string>Add subdiagram to the stacked diagram</string>
-          </property>
-          <property name="text">
-           <string>Add subdiagram</string>
-          </property>
-          <property name="icon">
-           <iconset resource="../../images/images.qrc">
-            <normaloff>:/images/themes/default/symbologyAdd.svg</normaloff>:/images/themes/default/symbologyAdd.svg</iconset>
-          </property>
-         </widget>
-        </item>
-        <item>
-         <widget class="QPushButton" name="mRemoveSubDiagramButton">
-          <property name="sizePolicy">
-           <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
-            <horstretch>0</horstretch>
-            <verstretch>0</verstretch>
-           </sizepolicy>
-          </property>
-          <property name="toolTip">
-           <string>Remove subdiagram from the stacked diagram</string>
-          </property>
-          <property name="text">
-           <string>Remove subdiagram</string>
-          </property>
-          <property name="icon">
-           <iconset resource="../../images/images.qrc">
-            <normaloff>:/images/themes/default/symbologyRemove.svg</normaloff>:/images/themes/default/symbologyRemove.svg</iconset>
-          </property>
-         </widget>
-        </item>
-        <item>
-         <spacer name="horizontalSpacer_2">
-          <property name="orientation">
-           <enum>Qt::Orientation::Horizontal</enum>
-          </property>
-          <property name="sizeType">
-           <enum>QSizePolicy::Policy::Expanding</enum>
-          </property>
-          <property name="sizeHint" stdset="0">
-           <size>
-            <width>40</width>
-            <height>20</height>
-           </size>
-          </property>
-         </spacer>
-        </item>
-       </layout>
-      </item>
-      <item row="0" column="0">
-       <layout class="QHBoxLayout" name="horizontalLayout_3">
-        <item>
-         <widget class="QLabel" name="stackedDiagramModeLabel">
-          <property name="text">
-           <string>Stacked Diagram Mode</string>
-          </property>
-         </widget>
-        </item>
-        <item>
-         <widget class="QComboBox" name="mStackedDiagramModeComboBox"/>
-        </item>
-        <item>
-         <spacer name="horizontalSpacer">
-          <property name="orientation">
-           <enum>Qt::Orientation::Horizontal</enum>
-          </property>
-          <property name="sizeHint" stdset="0">
-           <size>
-            <width>40</width>
-            <height>20</height>
-           </size>
-          </property>
-         </spacer>
-        </item>
-       </layout>
-      </item>
       <item row="1" column="0">
        <layout class="QHBoxLayout" name="horizontalLayout_2">
         <item>
@@ -175,42 +169,32 @@
         </item>
        </layout>
       </item>
-     </layout>
-    </widget>
-   </item>
-   <item>
-    <widget class="QFrame" name="mDiagramsFrame">
-     <property name="frameShape">
-      <enum>QFrame::Shape::NoFrame</enum>
-     </property>
-     <property name="frameShadow">
-      <enum>QFrame::Shadow::Raised</enum>
-     </property>
-     <layout class="QGridLayout" name="gridLayout_6">
-      <property name="leftMargin">
-       <number>0</number>
-      </property>
-      <property name="topMargin">
-       <number>0</number>
-      </property>
-      <property name="rightMargin">
-       <number>0</number>
-      </property>
-      <property name="bottomMargin">
-       <number>0</number>
-      </property>
-      <property name="horizontalSpacing">
-       <number>0</number>
-      </property>
       <item row="0" column="0">
-       <widget class="QTabWidget" name="mSubDiagramsTabWidget">
+       <layout class="QHBoxLayout" name="horizontalLayout_3">
-        <property name="currentIndex">
+        <item>
-         <number>-1</number>
+         <widget class="QLabel" name="stackedDiagramModeLabel">
-        </property>
+          <property name="text">
-        <property name="movable">
+           <string>Stacked diagram mode</string>
-         <bool>true</bool>
+          </property>
-        </property>
+         </widget>
-       </widget>
+        </item>
+        <item>
+         <widget class="QComboBox" name="mStackedDiagramModeComboBox"/>
+        </item>
+        <item>
+         <spacer name="horizontalSpacer">
+          <property name="orientation">
+           <enum>Qt::Orientation::Horizontal</enum>
+          </property>
+          <property name="sizeHint" stdset="0">
+           <size>
+            <width>40</width>
+            <height>20</height>
+           </size>
+          </property>
+         </spacer>
+        </item>
+       </layout>
       </item>
      </layout>
     </widget>

tests/code_layout/acceptable_missing_doc.py

@@ -286,7 +286,8 @@ ACCEPTABLE_MISSING_DOCS = {
     "QgsEffectStack": ["QgsEffectStack(const QgsEffectStack &other)"],
     "QgsRelationReferenceWidget": ["setRelation(const QgsRelation &relation, bool allowNullValue)", "CanvasExtent", "setOpenFormButtonVisible(bool openFormButtonVisible)", "QgsRelationReferenceWidget(QWidget *parent)", "setReadOnlySelector(bool readOnly)", "setRelationEditable(bool editable)", "init()", "setAllowMapIdentification(bool allowMapIdentification)", "setEmbedForm(bool display)"],
     "QgsDiagramProperties": ["mAttributesTreeWidget_itemDoubleClicked(QTreeWidgetItem *item, int column)", "scalingTypeChanged()", "mAddCategoryPushButton_clicked()", "mEngineSettingsButton_clicked()", "apply()", "mRemoveCategoryPushButton_clicked()", "showSizeLegendDialog()", "QgsDiagramProperties(QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas)", "mDiagramAttributesTreeWidget_itemDoubleClicked(QTreeWidgetItem *item, int column)", "mDiagramStackedWidget_currentChanged(int index)", "mDiagramTypeComboBox_currentIndexChanged(int index)", "mFindMaximumValueButton_clicked()", "showAddAttributeExpressionDialog()", "auxiliaryFieldCreated()", "updatePlacementWidgets()"],
-    "QgsStackedDiagramProperties": ["mDiagramTypeComboBox_currentIndexChanged(int index)", "apply()", "mEngineSettingsButton_clicked()", "mSubDiagramsTabWidget_tabMoved(int from, int to)", "auxiliaryFieldCreated()", "QgsStackedDiagramProperties(QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas)"],
+    "QgsStackedDiagramProperties": ["apply()", "auxiliaryFieldCreated()", "QgsStackedDiagramProperties(QgsVectorLayer *layer, QWidget *parent, QgsMapCanvas *canvas)"],
+    "QgsDiagramWidget": ["mDiagramTypeComboBox_currentIndexChanged(int index)", "showEngineConfigDialog()"],
     "QgsFeatureListView": ["repaintRequested()", "repaintRequested(const QModelIndexList &indexes)"],
     "QgsGradientFillSymbolLayerWidget": ["setGradientSpread(int index)", "setColor(const QColor &color)", "setCoordinateMode(int index)", "setColor2(const QColor &color)", "setGradientType(int index)"],
     "QgsFillSymbol": ["setAngle(double angle) const"],

tests/src/core/testqgsstackeddiagram.cpp

@@ -191,6 +191,96 @@ class TestQgsStackedDiagram : public QgsTest
       QGSVERIFYRENDERMAPSETTINGSCHECK( "stackedhistograms", "stackedhistograms", *mMapSettings, 200, 15 );
     }
 
+    void testDisabledSubDiagram()
+    {
+      // Histogram 1 (disabled)
+      QgsDiagramSettings ds1;
+      QColor col1 = Qt::blue;
+      QColor col2 = Qt::red;
+      QColor col3 = Qt::yellow;
+      QColor col4 = Qt::green;
+      col1.setAlphaF( 0.5 );
+      col2.setAlphaF( 0.5 );
+      col3.setAlphaF( 0.5 );
+      col4.setAlphaF( 0.5 );
+      ds1.categoryColors = QList<QColor>() << col1 << col2 << col3 << col4;
+      ds1.categoryAttributes = QList<QString>() << QStringLiteral( "\"maennlich_ab_65\"" ) << QStringLiteral( "\"maennlich_18_64\"" ) << QStringLiteral( "\"maennlich_6_17\"" ) << QStringLiteral( "\"maennlich_unter_6\"" );  //#spellok
+      ds1.minimumScale = -1;
+      ds1.maximumScale = -1;
+      ds1.minimumSize = 0;
+      ds1.penColor = Qt::black;
+      ds1.penWidth = .5;
+      ds1.scaleByArea = true;
+      ds1.sizeType = Qgis::RenderUnit::Millimeters;
+      ds1.rotationOffset = 0;
+      ds1.diagramOrientation = QgsDiagramSettings::Left;
+      ds1.enabled = false;
+
+      QgsLinearlyInterpolatedDiagramRenderer *dr1 = new QgsLinearlyInterpolatedDiagramRenderer();
+      dr1->setDiagram( new QgsHistogramDiagram() );
+      dr1->setDiagramSettings( ds1 );
+      dr1->setLowerValue( 0.0 );
+      dr1->setLowerSize( QSizeF( 0.0, 0.0 ) );
+      dr1->setUpperValue( 15000 );
+      dr1->setUpperSize( QSizeF( 20, 20 ) );
+      //dr1->setClassificationField( QStringLiteral( "max(\"maennlich_18_64\", \"maennlich_ab_65\", \"maennlich_6_17\", \"maennlich_unter_6\")" ) );  //#spellok
+
+      // Histogram 2
+      QgsDiagramSettings ds2;
+      col1 = Qt::blue;
+      col2 = Qt::red;
+      col3 = Qt::yellow;
+      col4 = Qt::green;
+      col1.setAlphaF( 0.5 );
+      col2.setAlphaF( 0.5 );
+      col3.setAlphaF( 0.5 );
+      col4.setAlphaF( 0.5 );
+      ds2.categoryColors = QList<QColor>() << col1 << col2 << col3 << col4;
+      ds2.categoryAttributes = QList<QString>() << QStringLiteral( "\"weiblich_ab_65\"" ) << QStringLiteral( "\"weiblich_18_64\"" ) << QStringLiteral( "\"weiblich_6_17\"" ) << QStringLiteral( "\"weiblich_unter_6\"" );  //#spellok
+      ds2.minimumScale = -1;
+      ds2.maximumScale = -1;
+      ds2.minimumSize = 0;
+      ds2.penColor = Qt::black;
+      ds2.penWidth = .5;
+      ds2.scaleByArea = true;
+      ds2.sizeType = Qgis::RenderUnit::Millimeters;
+      ds2.rotationOffset = 0;
+      ds2.diagramOrientation = QgsDiagramSettings::Right;
+
+      QgsLinearlyInterpolatedDiagramRenderer *dr2 = new QgsLinearlyInterpolatedDiagramRenderer();
+      dr2->setDiagram( new QgsHistogramDiagram() );
+      dr2->setDiagramSettings( ds2 );
+      dr2->setLowerValue( 0.0 );
+      dr2->setLowerSize( QSizeF( 0.0, 0.0 ) );
+      dr2->setUpperValue( 15000 );
+      dr2->setUpperSize( QSizeF( 20, 20 ) );
+      //dr2->setClassificationField( QStringLiteral( "max(\"weiblich_unter_6\", \"weiblich_6_17\", \"weiblich_18_64\", \"weiblich_ab_65\")" ) );  //#spellok
+
+      QgsDiagramSettings ds;
+      ds.stackedDiagramMode = QgsDiagramSettings::Horizontal;
+      ds.categoryAttributes = ds1.categoryAttributes + ds2.categoryAttributes;
+      ds.setStackedDiagramSpacingUnit( Qgis::RenderUnit::Pixels );
+      ds.setStackedDiagramSpacing( 0 );
+
+      QgsStackedDiagramRenderer *dr = new QgsStackedDiagramRenderer();
+      dr->setDiagram( new QgsStackedDiagram() );
+      dr->setDiagramSettings( ds );
+      dr->addRenderer( dr1 );
+      dr->addRenderer( dr2 );
+      mPointsLayer->setDiagramRenderer( dr );
+
+      QgsDiagramLayerSettings dls = QgsDiagramLayerSettings();
+      dls.setPlacement( QgsDiagramLayerSettings::OverPoint );
+      dls.setShowAllDiagrams( true );
+      mPointsLayer->setDiagramLayerSettings( dls );
+
+      const QgsRectangle extent( 9.7, 53.5, 9.95, 53.6 );
+      mMapSettings->setExtent( extent );
+      mMapSettings->setFlag( Qgis::MapSettingsFlag::ForceVectorOutput );
+      mMapSettings->setOutputDpi( 96 );
+      QGSVERIFYRENDERMAPSETTINGSCHECK( "disabledsubdiagram", "disabledsubdiagram", *mMapSettings, 200, 15 );
+    }
+
     void testVerticallyStackedHistograms()
     {
       // Histogram 1