[feature][layouts] Expose control over layer legend splitting behavio…

…r on a layer-by-layer basis This allows users to manually override the legend's default setting for "split layers" on a layer-by-layer basis, by double clicking a layer in the layout legend panel and choosing whether that layer: - follows the default legend setting for splitting - can ALWAYS be split over multiple columns (regardless of the legend's setting) or - can NEVER be split over multiple columns (regardless of the legend's setting) Sponsored by SLYR
qgis · May 6, 2020 · 1e0b890 · 1e0b890
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diff --git a/python/core/auto_generated/layertree/qgslayertreelayer.sip.in b/python/core/auto_generated/layertree/qgslayertreelayer.sip.in
@@ -177,6 +177,35 @@ symbol width or height from :py:class:`QgsLegendSettings`.
 
 .. seealso:: :py:func:`patchSize`
 
+.. versionadded:: 3.14
+%End
+
+    enum LegendNodesSplitBehavior
+    {
+      UseDefaultLegendSetting,
+      AllowSplittingLegendNodesOverMultipleColumns,
+      PreventSplittingLegendNodesOverMultipleColumns,
+    };
+
+    LegendNodesSplitBehavior legendSplitBehavior() const;
+%Docstring
+Returns the column split behavior for the node.
+
+This value controls how legend nodes belonging the to layer may be split over multiple columns in legends.
+
+.. seealso:: :py:func:`setLegendSplitBehavior`
+
+.. versionadded:: 3.14
+%End
+
+    void setLegendSplitBehavior( LegendNodesSplitBehavior behavior );
+%Docstring
+Sets the column split ``behavior`` for the node.
+
+This value controls how legend nodes belonging the to layer may be split over multiple columns in legends.
+
+.. seealso:: :py:func:`legendSplitBehavior`
+
 .. versionadded:: 3.14
 %End
 

diff --git a/src/core/layertree/qgslayertreelayer.cpp b/src/core/layertree/qgslayertreelayer.cpp
@@ -42,6 +42,7 @@ QgsLayerTreeLayer::QgsLayerTreeLayer( const QgsLayerTreeLayer &other )
   , mLayerName( other.mLayerName )
   , mPatchShape( other.mPatchShape )
   , mPatchSize( other.mPatchSize )
+  , mSplitBehavior( other.mSplitBehavior )
 {
   attachToLayer();
 }
@@ -134,6 +135,8 @@ QgsLayerTreeLayer *QgsLayerTreeLayer::readXml( QDomElement &element, const QgsRe
 
   nodeLayer->setPatchSize( QgsSymbolLayerUtils::decodeSize( element.attribute( QStringLiteral( "patch_size" ) ) ) );
 
+  nodeLayer->setLegendSplitBehavior( static_cast< LegendNodesSplitBehavior >( element.attribute( QStringLiteral( "legend_split_behavior" ), QStringLiteral( "0" ) ).toInt() ) );
+
   return nodeLayer;
 }
 
@@ -170,6 +173,8 @@ void QgsLayerTreeLayer::writeXml( QDomElement &parentElement, const QgsReadWrite
   }
   elem.setAttribute( QStringLiteral( "patch_size" ), QgsSymbolLayerUtils::encodeSize( mPatchSize ) );
 
+  elem.setAttribute( QStringLiteral( "legend_split_behavior" ), mSplitBehavior );
+
   writeCommonXml( elem );
 
   parentElement.appendChild( elem );

diff --git a/src/core/layertree/qgslayertreelayer.h b/src/core/layertree/qgslayertreelayer.h
@@ -181,6 +181,38 @@ class CORE_EXPORT QgsLayerTreeLayer : public QgsLayerTreeNode
      */
     void setPatchSize( QSizeF size ) { mPatchSize = size; }
 
+    /**
+     * Legend node column split behavior.
+     *
+     * \since QGIS 3.14
+     */
+    enum LegendNodesSplitBehavior
+    {
+      UseDefaultLegendSetting, //!< Inherit default legend column splitting setting
+      AllowSplittingLegendNodesOverMultipleColumns, //!< Allow splitting node's legend nodes across multiple columns
+      PreventSplittingLegendNodesOverMultipleColumns, //!< Prevent splitting node's legend nodes across multiple columns
+    };
+
+    /**
+     * Returns the column split behavior for the node.
+     *
+     * This value controls how legend nodes belonging the to layer may be split over multiple columns in legends.
+     *
+     * \see setLegendSplitBehavior()
+     * \since QGIS 3.14
+     */
+    LegendNodesSplitBehavior legendSplitBehavior() const { return mSplitBehavior; }
+
+    /**
+     * Sets the column split \a behavior for the node.
+     *
+     * This value controls how legend nodes belonging the to layer may be split over multiple columns in legends.
+     *
+     * \see legendSplitBehavior()
+     * \since QGIS 3.14
+     */
+    void setLegendSplitBehavior( LegendNodesSplitBehavior behavior ) { mSplitBehavior = behavior; }
+
   signals:
 
     /**
@@ -233,6 +265,7 @@ class CORE_EXPORT QgsLayerTreeLayer : public QgsLayerTreeNode
 
     QgsLegendPatchShape mPatchShape;
     QSizeF mPatchSize;
+    LegendNodesSplitBehavior mSplitBehavior = UseDefaultLegendSetting;
 };
 
 

diff --git a/src/core/qgslegendrenderer.cpp b/src/core/qgslegendrenderer.cpp
@@ -151,7 +151,7 @@ QSizeF QgsLegendRenderer::paintAndDetermineSize( QgsRenderContext &context )
   // to send the full render context so that an expression context is available during the size calculation
   QgsScopedRenderContextPainterSwap noPainter( context, nullptr );
 
-  QList<LegendComponentGroup> componentGroups = createComponentGroupList( rootGroup, mSettings.splitLayer(), context );
+  QList<LegendComponentGroup> componentGroups = createComponentGroupList( rootGroup, context );
 
   const int columnCount = setColumns( componentGroups );
 
@@ -265,7 +265,7 @@ void QgsLegendRenderer::widthAndOffsetForTitleText( const Qt::AlignmentFlag hali
   }
 }
 
-QList<QgsLegendRenderer::LegendComponentGroup> QgsLegendRenderer::createComponentGroupList( QgsLayerTreeGroup *parentGroup, bool splitLayer, QgsRenderContext &context )
+QList<QgsLegendRenderer::LegendComponentGroup> QgsLegendRenderer::createComponentGroupList( QgsLayerTreeGroup *parentGroup, QgsRenderContext &context )
 {
   QList<LegendComponentGroup> componentGroups;
 
@@ -280,7 +280,7 @@ QList<QgsLegendRenderer::LegendComponentGroup> QgsLegendRenderer::createComponen
       QgsLayerTreeGroup *nodeGroup = QgsLayerTree::toGroup( node );
 
       // Group subitems
-      QList<LegendComponentGroup> subgroups = createComponentGroupList( nodeGroup, splitLayer, context );
+      QList<LegendComponentGroup> subgroups = createComponentGroupList( nodeGroup, context );
       bool hasSubItems = !subgroups.empty();
 
       if ( nodeLegendStyle( nodeGroup ) != QgsLegendStyle::Hidden )
@@ -323,6 +323,20 @@ QList<QgsLegendRenderer::LegendComponentGroup> QgsLegendRenderer::createComponen
     {
       QgsLayerTreeLayer *nodeLayer = QgsLayerTree::toLayer( node );
 
+      bool allowColumnSplit = false;
+      switch ( nodeLayer->legendSplitBehavior() )
+      {
+        case QgsLayerTreeLayer::UseDefaultLegendSetting:
+          allowColumnSplit = mSettings.splitLayer();
+          break;
+        case QgsLayerTreeLayer::AllowSplittingLegendNodesOverMultipleColumns:
+          allowColumnSplit = true;
+          break;
+        case QgsLayerTreeLayer::PreventSplittingLegendNodesOverMultipleColumns:
+          allowColumnSplit = false;
+          break;
+      }
+
       LegendComponentGroup group;
       group.placeColumnBreakBeforeGroup = nodeLayer->customProperty( QStringLiteral( "legend/column-break" ) ).toInt();
 
@@ -357,7 +371,7 @@ QList<QgsLegendRenderer::LegendComponentGroup> QgsLegendRenderer::createComponen
 
         const bool forceBreak = legendNode->columnBreak();
 
-        if ( !mSettings.splitLayer() || j == 0 )
+        if ( !allowColumnSplit || j == 0 )
         {
           if ( forceBreak )
           {

diff --git a/src/core/qgslegendrenderer.h b/src/core/qgslegendrenderer.h
@@ -215,7 +215,7 @@ class CORE_EXPORT QgsLegendRenderer
      * Returns a list of component groups for the specified \a parentGroup, respecting the current layer's
      * splitting settings.
      */
-    QList<LegendComponentGroup> createComponentGroupList( QgsLayerTreeGroup *parentGroup, bool splitLayer, QgsRenderContext &context );
+    QList<LegendComponentGroup> createComponentGroupList( QgsLayerTreeGroup *parentGroup, QgsRenderContext &context );
 
     /**
      * Divides a list of component groups into columns, and sets the column index for each group in the list.

diff --git a/src/gui/layout/qgslayoutlegendwidget.cpp b/src/gui/layout/qgslayoutlegendwidget.cpp
@@ -1423,6 +1423,10 @@ QgsLayoutLegendNodeWidget::QgsLayoutLegendNodeWidget( QgsLayoutItemLegend *legen
   // auto close panel if layer removed
   connect( node, &QObject::destroyed, this, &QgsPanelWidget::acceptPanel );
 
+  mColumnSplitBehaviorComboBox->addItem( tr( "Follow Legend Default" ), QgsLayerTreeLayer::UseDefaultLegendSetting );
+  mColumnSplitBehaviorComboBox->addItem( tr( "Allow Splitting Over Columns" ), QgsLayerTreeLayer::AllowSplittingLegendNodesOverMultipleColumns );
+  mColumnSplitBehaviorComboBox->addItem( tr( "Prevent Splitting Over Columns" ), QgsLayerTreeLayer::PreventSplittingLegendNodesOverMultipleColumns );
+
   QString currentLabel;
   if ( mLegendNode )
   {
@@ -1436,6 +1440,8 @@ QgsLayoutLegendNodeWidget::QgsLayoutLegendNodeWidget( QgsLayoutItemLegend *legen
     if ( !v.isNull() )
       currentLabel = v.toString();
     mColumnBreakBeforeCheckBox->setChecked( mLayer->customProperty( QStringLiteral( "legend/column-break" ) ).toInt() );
+
+    mColumnSplitBehaviorComboBox->setCurrentIndex( mColumnSplitBehaviorComboBox->findData( mLayer->legendSplitBehavior() ) );
   }
   else
   {
@@ -1447,9 +1453,12 @@ QgsLayoutLegendNodeWidget::QgsLayoutLegendNodeWidget( QgsLayoutItemLegend *legen
   mHeightSpinBox->setClearValue( 0, tr( "Default" ) );
   mWidthSpinBox->setVisible( mLegendNode || mLayer );
   mHeightSpinBox->setVisible( mLegendNode || mLayer );
+  mPatchGroup->setVisible( mLegendNode || mLayer );
   mPatchWidthLabel->setVisible( mLegendNode || mLayer );
   mPatchHeightLabel->setVisible( mLegendNode || mLayer );
   mCustomSymbolCheckBox->setVisible( mLegendNode || mLegend->model()->legendNodeEmbeddedInParent( mLayer ) );
+  mColumnSplitLabel->setVisible( mLayer && !mLegendNode );
+  mColumnSplitBehaviorComboBox->setVisible( mLayer && !mLegendNode );
   if ( mLegendNode )
   {
     mWidthSpinBox->setValue( mLegendNode->userPatchSize().width() );
@@ -1547,6 +1556,8 @@ QgsLayoutLegendNodeWidget::QgsLayoutLegendNodeWidget( QgsLayoutItemLegend *legen
   connect( mCustomSymbolButton, &QgsSymbolButton::changed, this, &QgsLayoutLegendNodeWidget::customSymbolChanged );
 
   connect( mColumnBreakBeforeCheckBox, &QCheckBox::toggled, this, &QgsLayoutLegendNodeWidget::columnBreakToggled );
+
+  connect( mColumnSplitBehaviorComboBox, qgis::overload<int>::of( &QComboBox::currentIndexChanged ), this, &QgsLayoutLegendNodeWidget::columnSplitChanged );
 }
 
 void QgsLayoutLegendNodeWidget::labelChanged()
@@ -1742,4 +1753,18 @@ void QgsLayoutLegendNodeWidget::columnBreakToggled( bool checked )
   mLegend->endCommand();
 }
 
+void QgsLayoutLegendNodeWidget::columnSplitChanged()
+{
+  mLegend->beginCommand( tr( "Edit Legend Columns" ) );
+
+  if ( mLayer && !mLegendNode )
+  {
+    mLayer->setLegendSplitBehavior( static_cast< QgsLayerTreeLayer::LegendNodesSplitBehavior >( mColumnSplitBehaviorComboBox->currentData().toInt() ) );
+  }
+
+  mLegend->adjustBoxSize();
+  mLegend->updateFilterByMap();
+  mLegend->endCommand();
+}
+
 ///@endcond
diff --git a/src/gui/layout/qgslayoutlegendwidget.h b/src/gui/layout/qgslayoutlegendwidget.h
@@ -196,6 +196,7 @@ class GUI_EXPORT QgsLayoutLegendNodeWidget: public QgsPanelWidget, private Ui::Q
     void sizeChanged( double );
     void customSymbolChanged();
     void columnBreakToggled( bool checked );
+    void columnSplitChanged();
 
   private: