Add more options for filtering legend elements

This introduces two new options to filter legend elements:
- filter by expression: a boolean expression can be set. Only symbols of
features that make the expression evaluated to true will be kept in the legend
- filter by polygon: only symbols of features that are inside the given
polygon will be part of the legend.

The polygon filtering is used in particular for a new option in the
composer legend that allows to filter out anything that is not included
in the current atlas polygon.

python/core/composer/qgsatlascomposition.sip

@@ -260,6 +260,9 @@ public:
     /** Returns the current atlas feature. Must be called after prepareForFeature(). */
     QgsFeature* currentFeature() /Deprecated/;
 
+    /** Returns the current atlas geometry in the given projection system (default to the coverage layer's CRS) */
+    QgsGeometry currentGeometry( const QgsCoordinateReferenceSystem& projectedTo = QgsCoordinateReferenceSystem() ) const;
+
   public slots:
 
     /** Refreshes the current atlas feature, by refetching its attributes from the vector layer provider

python/core/composer/qgscomposerlegend.sip

@@ -65,6 +65,16 @@ class QgsComposerLegend : QgsComposerItem
     //! @note added in 2.6
     bool legendFilterByMapEnabled() const;
 
+    //! When set to true, during an atlas rendering, it will filter out legend elements
+    //! where features are outside the current atlas feature.
+    //! @note added in 2.14
+    void setLegendFilterOutAtlas( bool doFilter );
+
+    //! Whether to filter out legend elements outside of the current atlas feature
+    //! @see setLegendFilterOutAtlas()
+    //! @note added in 2.14
+    bool legendFilterOutAtlas() const;
+
     //setters and getters
     void setTitle( const QString& t );
     QString title() const;

python/core/layertree/qgslayertreemodel.sip

@@ -133,8 +133,23 @@ class QgsLayerTreeModel : QAbstractItemModel
     //! Ownership of map settings pointer does not change.
     //! @note added in 2.6
     void setLegendFilterByMap( const QgsMapSettings* settings );
+
+    //! Filter display of legend nodes for given map settings
+    //! @param settings Map settings. Setting a null pointer or invalid settings will disable any filter. Ownership is not changed, a copy is made
+    //! @param useExtent Whether to use the extent of the map settings as a first spatial filter on legend nodes
+    //! @param polygon If not empty, this polygon will be used instead of the map extent to filter legend nodes
+    //! @param useExpressions Whether to use legend node filter expressions
+    //! @note added in 2.14
+    void setLegendFilter( const QgsMapSettings* settings, bool useExtent = true, const QgsGeometry& polygon = QgsGeometry(), bool useExpressions = true );
+
+    //! Returns the current map settings used for legend filtering
+    //! @deprecated It has been renamed to legendFilterMapSettings()
     const QgsMapSettings* legendFilterByMap() const;
 
+    //! Returns the current map settings used for the current legend filter (or null if none is enabled)
+    //! @note added in 2.14
+    const QgsMapSettings* legendFilterMapSettings() const;
+
     //! Give the layer tree model hints about the currently associated map view
     //! so that legend nodes that use map units can be scaled currectly
     //! @note added in 2.6

python/core/layertree/qgslayertreeutils.sip

@@ -37,4 +37,11 @@ class QgsLayerTreeUtils
 
     //! get invisible layers
     static QStringList invisibleLayerList( QgsLayerTreeNode *node );
+
+    //! Set the expression filter of a legend layer
+    static void setLegendFilterByExpression( QgsLayerTreeLayer& layer, const QString& expr, bool enabled = true );
+    //! Return the expression filter of a legend layer
+    static QString legendFilterByExpression( const QgsLayerTreeLayer& layer, bool* enabled = 0 );
+    //! Test if one of the layers in a group has an expression filter
+    static bool hasLegendFilterExpression( const QgsLayerTreeGroup& group );
 };

python/gui/gui.sip

@@ -70,6 +70,7 @@
 %Include qgshtmlannotationitem.sip
 %Include qgsidentifymenu.sip
 %Include qgslegendinterface.sip
+%Include qgslegendfilterbutton.sip
 %Include qgslonglongvalidator.sip
 %Include qgsludialog.sip
 %Include qgsmanageconnectionsdialog.sip

python/gui/qgslegendfilterbutton.sip

@@ -0,0 +1,50 @@
+/** \ingroup gui
+ * \class QgsFilterLegendButton
+ * A tool button that allows to enable or disable legend filter by contents of the map.
+ * An additional pop down menu allows to define a boolean expression to refine the filtering.
+ * @note added in 2.14
+ */
+
+class QgsLegendFilterButton: public QToolButton
+{
+%TypeHeaderCode
+#include <qgslegendfilterbutton.h>
+%End
+
+  public:
+    /**
+     * Construct a new filter legend button
+     *
+     * @param parent The parent QWidget
+     */
+    QgsLegendFilterButton( QWidget* parent = 0 );
+    ~QgsLegendFilterButton();
+
+    /**
+     * Returns the current text used as filter expression
+     */
+    QString expressionText() const;
+
+    /**
+     * Sets the current text used as filter expression.
+     * This will update the menu
+     */
+    void setExpressionText( const QString& expression );
+
+    /**
+     * Returns the current associated vectorLayer
+     * May be null
+     */
+    QgsVectorLayer* vectorLayer() const;
+    /**
+     * Sets the associated vectorLayer
+     * May be null
+     */
+    void setVectorLayer( QgsVectorLayer* layer );
+
+  signals:
+    /**
+     * Emitted when the expression text changes
+     */
+    void expressionTextChanged();
+};

src/app/composer/qgscomposerlegendwidget.cpp

@@ -28,6 +28,7 @@
 #include "qgisapp.h"
 #include "qgsapplication.h"
 #include "qgslayertree.h"
+#include "qgslayertreeutils.h"
 #include "qgslayertreemodel.h"
 #include "qgslayertreemodellegendnode.h"
 #include "qgslegendrenderer.h"
@@ -119,6 +120,10 @@ QgsComposerLegendWidget::QgsComposerLegendWidget( QgsComposerLegend* legend )
     mItemTreeView->setMenuProvider( new QgsComposerLegendMenuProvider( mItemTreeView, this ) );
     connect( legend, SIGNAL( itemChanged() ), this, SLOT( setGuiElements() ) );
     mWrapCharLineEdit->setText( legend->wrapChar() );
+
+    // connect atlas state to the filter legend by atlas checkbox
+    connect( &legend->composition()->atlasComposition(), SIGNAL( toggled( bool ) ), this, SLOT( updateFilterLegendByAtlasButton() ) );
+    connect( &legend->composition()->atlasComposition(), SIGNAL( coverageLayerChanged( QgsVectorLayer* ) ), this, SLOT( updateFilterLegendByAtlasButton() ) );
   }
 
   setGuiElements();
@@ -574,15 +579,22 @@ void QgsComposerLegendWidget::on_mCheckBoxAutoUpdate_stateChanged( int state )
 
   mLegend->setAutoUpdateModel( state == Qt::Checked );
 
-  mLegend->update();
+  mLegend->updateItem();
   mLegend->endCommand();
 
   // do not allow editing of model if auto update is on - we would modify project's layer tree
   QList<QWidget*> widgets;
   widgets << mMoveDownToolButton << mMoveUpToolButton << mRemoveToolButton << mAddToolButton
-  << mEditPushButton << mCountToolButton << mUpdateAllPushButton << mAddGroupToolButton;
+  << mEditPushButton << mCountToolButton << mUpdateAllPushButton << mAddGroupToolButton
+  << mExpressionFilterButton;
   Q_FOREACH ( QWidget* w, widgets )
     w->setEnabled( state != Qt::Checked );
+
+  if ( state == Qt::Unchecked )
+  {
+    // update widgets state based on current selection
+    selectedChanged( QModelIndex(), QModelIndex() );
+  }
 }
 
 void QgsComposerLegendWidget::on_mMapComboBox_currentIndexChanged( int index )
@@ -616,7 +628,7 @@ void QgsComposerLegendWidget::on_mMapComboBox_currentIndexChanged( int index )
     {
       mLegend->beginCommand( tr( "Legend map changed" ) );
       mLegend->setComposerMap( map );
-      mLegend->update();
+      mLegend->updateItem();
       mLegend->endCommand();
     }
   }
@@ -748,7 +760,7 @@ void QgsComposerLegendWidget::on_mRemoveToolButton_clicked()
   }
 
   mLegend->adjustBoxSize();
-  mLegend->update();
+  mLegend->updateItem();
   mLegend->endCommand();
 }
 
@@ -811,7 +823,7 @@ void QgsComposerLegendWidget::on_mEditPushButton_clicked()
   }
 
   mLegend->adjustBoxSize();
-  mLegend->update();
+  mLegend->updateItem();
   mLegend->endCommand();
 }
 
@@ -853,7 +865,7 @@ void QgsComposerLegendWidget::resetLayerNodeToDefaults()
 
   mItemTreeView->layerTreeModel()->refreshLayerLegend( nodeLayer );
 
-  mLegend->update();
+  mLegend->updateItem();
   mLegend->adjustBoxSize();
   mLegend->endCommand();
 }
@@ -879,16 +891,43 @@ void QgsComposerLegendWidget::on_mCountToolButton_clicked( bool checked )
 
   mLegend->beginCommand( tr( "Legend updated" ) );
   currentNode->setCustomProperty( "showFeatureCount", checked ? 1 : 0 );
-  mLegend->update();
+  mLegend->updateItem();
   mLegend->adjustBoxSize();
   mLegend->endCommand();
 }
 
-void QgsComposerLegendWidget::on_mFilterByMapToolButton_clicked( bool checked )
+void QgsComposerLegendWidget::on_mFilterByMapToolButton_toggled( bool checked )
 {
   mLegend->beginCommand( tr( "Legend updated" ) );
   mLegend->setLegendFilterByMapEnabled( checked );
-  mLegend->update();
+  mLegend->adjustBoxSize();
+  mLegend->endCommand();
+}
+
+void QgsComposerLegendWidget::on_mExpressionFilterButton_toggled( bool checked )
+{
+  if ( !mLegend )
+  {
+    return;
+  }
+
+  //get current item
+  QModelIndex currentIndex = mItemTreeView->currentIndex();
+  if ( !currentIndex.isValid() )
+  {
+    return;
+  }
+
+  QgsLayerTreeNode* currentNode = mItemTreeView->currentNode();
+  if ( !QgsLayerTree::isLayer( currentNode ) )
+    return;
+
+  QgsLayerTreeUtils::setLegendFilterByExpression( *qobject_cast<QgsLayerTreeLayer*>( currentNode ),
+      mExpressionFilterButton->expressionText(),
+      checked );
+
+  mLegend->beginCommand( tr( "Legend updated" ) );
+  mLegend->updateItem();
   mLegend->adjustBoxSize();
   mLegend->endCommand();
 }
@@ -904,11 +943,24 @@ void QgsComposerLegendWidget::on_mAddGroupToolButton_clicked()
   {
     mLegend->beginCommand( tr( "Legend group added" ) );
     mLegend->modelV2()->rootGroup()->addGroup( tr( "Group" ) );
-    mLegend->update();
+    mLegend->updateItem();
     mLegend->endCommand();
   }
 }
 
+void QgsComposerLegendWidget::on_mFilterLegendByAtlasCheckBox_toggled( bool toggled )
+{
+  if ( mLegend )
+  {
+    mLegend->setLegendFilterOutAtlas( toggled );
+    // force update of legend when in preview mode
+    if ( mLegend->composition()->atlasMode() == QgsComposition::PreviewAtlas )
+    {
+      mLegend->composition()->atlasComposition().refreshFeature();
+    }
+  }
+}
+
 void QgsComposerLegendWidget::updateLegend()
 {
   if ( mLegend )
@@ -918,8 +970,7 @@ void QgsComposerLegendWidget::updateLegend()
     // this will reset the model completely, loosing any changes
     mLegend->setAutoUpdateModel( true );
     mLegend->setAutoUpdateModel( false );
-
-    mLegend->update();
+    mLegend->updateItem();
     mLegend->endCommand();
   }
 }
@@ -997,11 +1048,16 @@ void QgsComposerLegendWidget::selectedChanged( const QModelIndex & current, cons
   Q_UNUSED( previous );
   QgsDebugMsg( "Entered" );
 
+  if ( mLegend && mLegend->autoUpdateModel() )
+    return;
+
   mCountToolButton->setChecked( false );
   mCountToolButton->setEnabled( false );
 
-  if ( mLegend && mLegend->autoUpdateModel() )
-    return;
+  mExpressionFilterButton->blockSignals( true );
+  mExpressionFilterButton->setChecked( false );
+  mExpressionFilterButton->setEnabled( false );
+  mExpressionFilterButton->blockSignals( false );
 
   QgsLayerTreeNode* currentNode = mItemTreeView->currentNode();
   if ( !QgsLayerTree::isLayer( currentNode ) )
@@ -1014,6 +1070,15 @@ void QgsComposerLegendWidget::selectedChanged( const QModelIndex & current, cons
 
   mCountToolButton->setChecked( currentNode->customProperty( "showFeatureCount", 0 ).toInt() );
   mCountToolButton->setEnabled( true );
+
+  bool exprEnabled;
+  QString expr = QgsLayerTreeUtils::legendFilterByExpression( *qobject_cast<QgsLayerTreeLayer*>( currentNode ), &exprEnabled );
+  mExpressionFilterButton->blockSignals( true );
+  mExpressionFilterButton->setExpressionText( expr );
+  mExpressionFilterButton->setVectorLayer( vl );
+  mExpressionFilterButton->setEnabled( true );
+  mExpressionFilterButton->setChecked( exprEnabled );
+  mExpressionFilterButton->blockSignals( false );
 }
 
 void QgsComposerLegendWidget::setCurrentNodeStyleFromAction()
@@ -1023,5 +1088,11 @@ void QgsComposerLegendWidget::setCurrentNodeStyleFromAction()
     return;
 
   QgsLegendRenderer::setNodeLegendStyle( mItemTreeView->currentNode(), ( QgsComposerLegendStyle::Style ) a->data().toInt() );
-  mLegend->update();
+  mLegend->updateItem();
+}
+
+void QgsComposerLegendWidget::updateFilterLegendByAtlasButton()
+{
+  const QgsAtlasComposition& atlas = mLegend->composition()->atlasComposition();
+  mFilterLegendByAtlasCheckBox->setEnabled( atlas.enabled() && atlas.coverageLayer() && atlas.coverageLayer()->geometryType() == QGis::Polygon );
 }

src/app/composer/qgscomposerlegendwidget.h

@@ -80,11 +80,14 @@ class QgsComposerLegendWidget: public QgsComposerItemBaseWidget, private Ui::Qgs
     void on_mAddToolButton_clicked();
     void on_mEditPushButton_clicked();
     void on_mCountToolButton_clicked( bool checked );
-    void on_mFilterByMapToolButton_clicked( bool checked );
+    void on_mExpressionFilterButton_toggled( bool checked );
+    void on_mFilterByMapToolButton_toggled( bool checked );
     void resetLayerNodeToDefaults();
     void on_mUpdateAllPushButton_clicked();
     void on_mAddGroupToolButton_clicked();
 
+    void on_mFilterLegendByAtlasCheckBox_toggled( bool checked );
+
     void selectedChanged( const QModelIndex & current, const QModelIndex & previous );
 
     void setCurrentNodeStyleFromAction();
@@ -96,6 +99,9 @@ class QgsComposerLegendWidget: public QgsComposerItemBaseWidget, private Ui::Qgs
     /** Sets GUI according to state of mLegend*/
     void setGuiElements();
 
+    /** update the enabling state of the filter by atlas button */
+    void updateFilterLegendByAtlasButton();
+
   private:
     QgsComposerLegendWidget();
     void blockAllSignals( bool b );