[FEATURE][composer] Data defined legend titles and column count

(fix #11913)

Author: nyalldawson

python/core/composer/qgscomposerlegend.sip

@@ -242,9 +242,13 @@ class QgsComposerLegend : QgsComposerItem
     //Overridden to show legend title
     virtual QString displayName() const;
 
+    const QgsLegendSettings& legendSettings() const;
+
   public slots:
     /** Data changed*/
     void synchronizeWithModel();
     /** Sets mCompositionMap to 0 if the map is deleted*/
     void invalidateCurrentMap();
+    virtual void refreshDataDefinedProperty( const QgsComposerObject::DataDefinedProperty property = QgsComposerObject::AllProperties, const QgsExpressionContext* context = nullptr );
+
 };

python/core/composer/qgscomposerobject.sip

@@ -51,6 +51,9 @@ class QgsComposerObject : QObject, QgsExpressionContextGenerator
       PictureSvgOutlineWidth, //!< SVG outline width
       //html item
       SourceUrl /*!< html source url */
+      //legend item
+      LegendTitle, //!< Legend title
+      LegendColumnCount, //!< Legend column count
     };
 
     /** Specifies whether the value returned by a function should be the original, user

src/app/composer/qgscomposerlegendwidget.cpp

@@ -100,6 +100,11 @@ QgsComposerLegendWidget::QgsComposerLegendWidget( QgsComposerLegend* legend )
     connect( &legend->composition()->atlasComposition(), SIGNAL( coverageLayerChanged( QgsVectorLayer* ) ), this, SLOT( updateFilterLegendByAtlasButton() ) );
   }
 
+  registerDataDefinedButton( mLegendTitleDDBtn, QgsComposerObject::LegendTitle,
+                             QgsDataDefinedButtonV2::AnyType, QgsDataDefinedButtonV2::anyStringDesc() );
+  registerDataDefinedButton( mColumnsDDBtn, QgsComposerObject::LegendColumnCount,
+                             QgsDataDefinedButtonV2::AnyType, QgsDataDefinedButtonV2::intPosOneDesc() );
+
   setGuiElements();
 
   connect( mItemTreeView->selectionModel(), SIGNAL( currentChanged( const QModelIndex &, const QModelIndex & ) ),
@@ -160,6 +165,8 @@ void QgsComposerLegendWidget::setGuiElements()
   blockAllSignals( false );
 
   on_mCheckBoxAutoUpdate_stateChanged( mLegend->autoUpdateModel() ? Qt::Checked : Qt::Unchecked );
+  updateDataDefinedButton( mLegendTitleDDBtn );
+  updateDataDefinedButton( mColumnsDDBtn );
 }
 
 void QgsComposerLegendWidget::on_mWrapCharLineEdit_textChanged( const QString &text )

src/core/composer/qgscomposerlegend.cpp

@@ -265,6 +265,7 @@ void QgsComposerLegend::setLegendFilterByMapEnabled( bool enabled )
 
 void QgsComposerLegend::setTitle( const QString& t )
 {
+  mTitle = t;
   mSettings.setTitle( t );
 
   if ( mComposition && id().isEmpty() )
@@ -273,7 +274,7 @@ void QgsComposerLegend::setTitle( const QString& t )
     mComposition->itemsModel()->updateItemDisplayName( this );
   }
 }
-QString QgsComposerLegend::title() const { return mSettings.title(); }
+QString QgsComposerLegend::title() const { return mTitle; }
 
 Qt::AlignmentFlag QgsComposerLegend::titleAlignment() const { return mSettings.titleAlignment(); }
 void QgsComposerLegend::setTitleAlignment( Qt::AlignmentFlag alignment ) { mSettings.setTitleAlignment( alignment ); }
@@ -315,8 +316,8 @@ void QgsComposerLegend::setWmsLegendHeight( double h ) { mSettings.setWmsLegendS
 void QgsComposerLegend::setWrapChar( const QString& t ) { mSettings.setWrapChar( t ); }
 QString QgsComposerLegend::wrapChar() const {return mSettings.wrapChar(); }
 
-int QgsComposerLegend::columnCount() const { return mSettings.columnCount(); }
-void QgsComposerLegend::setColumnCount( int c ) { mSettings.setColumnCount( c ); }
+int QgsComposerLegend::columnCount() const { return mColumnCount; }
+void QgsComposerLegend::setColumnCount( int c ) { mColumnCount = c; mSettings.setColumnCount( c ); }
 
 bool QgsComposerLegend::splitLayer() const { return mSettings.splitLayer(); }
 void QgsComposerLegend::setSplitLayer( bool s ) { mSettings.setSplitLayer( s ); }
@@ -362,9 +363,9 @@ bool QgsComposerLegend::writeXml( QDomElement& elem, QDomDocument & doc ) const
   elem.appendChild( composerLegendElem );
 
   //write general properties
-  composerLegendElem.setAttribute( QStringLiteral( "title" ), mSettings.title() );
+  composerLegendElem.setAttribute( QStringLiteral( "title" ), mTitle );
   composerLegendElem.setAttribute( QStringLiteral( "titleAlignment" ), QString::number( static_cast< int >( mSettings.titleAlignment() ) ) );
-  composerLegendElem.setAttribute( QStringLiteral( "columnCount" ), QString::number( mSettings.columnCount() ) );
+  composerLegendElem.setAttribute( QStringLiteral( "columnCount" ), QString::number( mColumnCount ) );
   composerLegendElem.setAttribute( QStringLiteral( "splitLayer" ), QString::number( mSettings.splitLayer() ) );
   composerLegendElem.setAttribute( QStringLiteral( "equalColumnWidth" ), QString::number( mSettings.equalColumnWidth() ) );
 
@@ -462,14 +463,16 @@ bool QgsComposerLegend::readXml( const QDomElement& itemElem, const QDomDocument
   }
 
   //read general properties
-  mSettings.setTitle( itemElem.attribute( QStringLiteral( "title" ) ) );
+  mTitle = itemElem.attribute( QStringLiteral( "title" ) );
+  mSettings.setTitle( mTitle );
   if ( !itemElem.attribute( QStringLiteral( "titleAlignment" ) ).isEmpty() )
   {
     mSettings.setTitleAlignment( static_cast< Qt::AlignmentFlag >( itemElem.attribute( QStringLiteral( "titleAlignment" ) ).toInt() ) );
   }
   int colCount = itemElem.attribute( QStringLiteral( "columnCount" ), QStringLiteral( "1" ) ).toInt();
   if ( colCount < 1 ) colCount = 1;
-  mSettings.setColumnCount( colCount );
+  mColumnCount = colCount;
+  mSettings.setColumnCount( mColumnCount );
   mSettings.setSplitLayer( itemElem.attribute( QStringLiteral( "splitLayer" ), QStringLiteral( "0" ) ).toInt() == 1 );
   mSettings.setEqualColumnWidth( itemElem.attribute( QStringLiteral( "equalColumnWidth" ), QStringLiteral( "0" ) ).toInt() == 1 );
 
@@ -642,6 +645,42 @@ void QgsComposerLegend::invalidateCurrentMap()
   setComposerMap( nullptr );
 }
 
+void QgsComposerLegend::refreshDataDefinedProperty( const QgsComposerObject::DataDefinedProperty property, const QgsExpressionContext* context )
+{
+  QgsExpressionContext scopedContext = createExpressionContext();
+  const QgsExpressionContext* evalContext = context ? context : &scopedContext;
+
+  bool forceUpdate = false;
+  //updates data defined properties and redraws item to match
+  if ( property == QgsComposerObject::LegendTitle || property == QgsComposerObject::AllProperties )
+  {
+    bool ok = false;
+    QString t = mProperties.valueAsString( QgsComposerObject::LegendTitle, *evalContext, mTitle, &ok );
+    if ( ok )
+    {
+      mSettings.setTitle( t );
+      forceUpdate = true;
+    }
+  }
+  if ( property == QgsComposerObject::LegendColumnCount || property == QgsComposerObject::AllProperties )
+  {
+    bool ok = false;
+    int cols = mProperties.valueAsInt( QgsComposerObject::LegendColumnCount, *evalContext, mColumnCount, &ok );
+    if ( ok && cols >= 0 )
+    {
+      mSettings.setColumnCount( cols );
+      forceUpdate = true;
+    }
+  }
+  if ( forceUpdate )
+  {
+    adjustBoxSize();
+    update();
+  }
+
+  QgsComposerObject::refreshDataDefinedProperty( property, context );
+}
+
 void QgsComposerLegend::mapLayerStyleOverridesChanged()
 {
   if ( !mComposerMap )

src/core/composer/qgscomposerlegend.h

@@ -272,12 +272,21 @@ class CORE_EXPORT QgsComposerLegend : public QgsComposerItem
     //Overridden to show legend title
     virtual QString displayName() const override;
 
+    /**
+     * Returns the legend's renderer settings object.
+     * @note added in QGIS 3.0
+     */
+    const QgsLegendSettings& legendSettings() const { return mSettings; }
+
   public slots:
     //! Data changed
     void synchronizeWithModel();
     //! Sets mCompositionMap to 0 if the map is deleted
     void invalidateCurrentMap();
 
+    virtual void refreshDataDefinedProperty( const QgsComposerObject::DataDefinedProperty property = QgsComposerObject::AllProperties, const QgsExpressionContext* context = nullptr ) override;
+
+
   private slots:
     void updateFilterByMap( bool redraw = true );
 
@@ -301,6 +310,9 @@ class CORE_EXPORT QgsComposerLegend : public QgsComposerItem
 
     QgsLegendSettings mSettings;
 
+    QString mTitle;
+    int mColumnCount = 1;
+
     const QgsComposerMap* mComposerMap;
 
     bool mLegendFilterByMap;

src/core/composer/qgscomposerobject.cpp

@@ -61,6 +61,8 @@ const QgsPropertyDefinition QgsComposerObject::sPropertyNameMap
   { QgsComposerObject::PictureSvgBackgroundColor, "dataDefinedSvgBackgroundColor" },
   { QgsComposerObject::PictureSvgOutlineColor, "dataDefinedSvgOutlineColor" },
   { QgsComposerObject::PictureSvgOutlineWidth, "dataDefinedSvgOutlineWidth" },
+  { QgsComposerObject::LegendTitle, "dataDefinedLegendTitle" },
+  { QgsComposerObject::LegendColumnCount, "dataDefinedLegendColumns" },
 };
 
 

src/core/composer/qgscomposerobject.h

@@ -78,6 +78,9 @@ class CORE_EXPORT QgsComposerObject: public QObject, public QgsExpressionContext
       PictureSvgOutlineWidth, //!< SVG outline width
       //html item
       SourceUrl, //!< Html source url
+      //legend item
+      LegendTitle, //!< Legend title
+      LegendColumnCount, //!< Legend column count
     };
 
     static const QgsPropertyDefinition sPropertyNameMap;