Robustify atlas generation

src/app/composer/qgscomposer.cpp

@@ -608,7 +608,7 @@ void QgsComposer::on_mActionExportAsPDF_triggered()
       {
 	return;
       }
-      atlasMap->setAtlasFilenamePattern( "'output_'||$id" );
+      atlasMap->setAtlasFilenamePattern( "'output_'||$feature" );
     }
 
     QSettings myQSettings;
@@ -858,7 +858,7 @@ void QgsComposer::on_mActionExportAsImage_triggered()
       {
 	return;
       }
-      atlasMap->setAtlasFilenamePattern( "'output_'||$id" );
+      atlasMap->setAtlasFilenamePattern( "'output_'||$feature" );
     }
 
     QSettings myQSettings;
@@ -1054,7 +1054,7 @@ void QgsComposer::on_mActionExportAsSVG_triggered()
       {
 	return;
       }
-      atlasMap->setAtlasFilenamePattern( "'output_'||$id||'_'||$page" );
+      atlasMap->setAtlasFilenamePattern( "'output_'||$feature" );
     }
 
     QSettings myQSettings;

src/core/composer/qgscomposerlabel.cpp

@@ -89,7 +89,9 @@ QString QgsComposerLabel::displayText() const
 {
   QString displayText = mText;
   replaceDateText( displayText );
-  return QgsExpression::replaceExpressionText( displayText, mExpressionFeature, mExpressionLayer, &mSubstitutions );
+  QMap<QString, QVariant> subs = mSubstitutions;
+  subs[ "$page" ] = QVariant((int)mComposition->itemPageNumber( this ) + 1);
+  return QgsExpression::replaceExpressionText( displayText, mExpressionFeature, mExpressionLayer, &subs );
 }
 
 void QgsComposerLabel::replaceDateText( QString& text ) const

src/core/composer/qgscomposermap.cpp

@@ -45,7 +45,7 @@ QgsComposerMap::QgsComposerMap( QgsComposition *composition, int x, int y, int w
     mBottomGridAnnotationPosition( OutsideMapFrame ), mAnnotationFrameDistance( 1.0 ), mLeftGridAnnotationDirection( Horizontal ), mRightGridAnnotationDirection( Horizontal ),
     mTopGridAnnotationDirection( Horizontal ), mBottomGridAnnotationDirection( Horizontal ), mGridFrameStyle( NoGridFrame ), mGridFrameWidth( 2.0 ),
       mCrossLength( 3 ), mMapCanvas( 0 ), mDrawCanvasItems( true ),
-      mAtlasMargin( 0.10 ), mAtlasFilenamePattern("'output_'||$id"), mAtlasCoverageLayer(0)
+      mAtlasMargin( 0.10 ), mAtlasFilenamePattern("'output_'||$feature"), mAtlasCoverageLayer(0)
 {
   mComposition = composition;
   mOverviewFrameMapSymbol = 0;
@@ -87,7 +87,7 @@ QgsComposerMap::QgsComposerMap( QgsComposition *composition )
     mBottomGridAnnotationPosition( OutsideMapFrame ), mAnnotationFrameDistance( 1.0 ), mLeftGridAnnotationDirection( Horizontal ), mRightGridAnnotationDirection( Horizontal ),
     mTopGridAnnotationDirection( Horizontal ), mBottomGridAnnotationDirection( Horizontal ), mGridFrameStyle( NoGridFrame ), mGridFrameWidth( 2.0 ), mCrossLength( 3 ),
       mMapCanvas( 0 ), mDrawCanvasItems( true ),
-      mAtlasMargin( 0.10 ), mAtlasFilenamePattern("'output_'||$id"), mAtlasCoverageLayer(0)
+      mAtlasMargin( 0.10 ), mAtlasFilenamePattern("'output_'||$feature"), mAtlasCoverageLayer(0)
 {
   mOverviewFrameMapSymbol = 0;
   createDefaultOverviewFrameSymbol();
@@ -633,6 +633,13 @@ void QgsComposerMap::syncAtlasCoverageLayer( QString lname )
   }
 }
 
+void QgsComposerMap::setAtlasCoverageLayer( QgsVectorLayer* map )
+{
+  mAtlasCoverageLayer = map;
+
+  emit atlasCoverageLayerChanged( map );
+}
+
 bool QgsComposerMap::writeXML( QDomElement& elem, QDomDocument & doc ) const
 {
   if ( elem.isNull() )

src/core/composer/qgscomposermap.h

@@ -330,7 +330,7 @@ class CORE_EXPORT QgsComposerMap : public QgsComposerItem
     void setAtlasFilenamePattern( const QString& pattern ) { mAtlasFilenamePattern = pattern; }
 
     QgsVectorLayer* atlasCoverageLayer() const { return mAtlasCoverageLayer; }
-    void setAtlasCoverageLayer( QgsVectorLayer* lmap ) { mAtlasCoverageLayer = lmap; }
+    void setAtlasCoverageLayer( QgsVectorLayer* lmap );
 
     bool atlasSingleFile() const { return mAtlasSingleFile; }
     void setAtlasSingleFile( bool single ) { mAtlasSingleFile = single; }
@@ -338,6 +338,8 @@ class CORE_EXPORT QgsComposerMap : public QgsComposerItem
   signals:
     void extentChanged();
 
+    void atlasCoverageLayerChanged( QgsVectorLayer* );
+
   public slots:
 
     /**Called if map canvas has changed*/

src/core/composer/qgscomposition.cpp

@@ -74,6 +74,9 @@ QgsAtlasRendering::QgsAtlasRendering( QgsComposition* composition )
 
 void QgsAtlasRendering::begin( const QString& filenamePattern )
 {
+  if ( !impl->composition || !impl->composition->atlasMap() || !impl->composition->atlasMap()->atlasCoverageLayer() )
+    return;
+
   impl->filenamePattern = filenamePattern;
 
   QgsVectorLayer* coverage = impl->composition->atlasMap()->atlasCoverageLayer();
@@ -103,12 +106,7 @@ void QgsAtlasRendering::begin( const QString& filenamePattern )
   }
 
   // select all features with all attributes
-  QgsAttributeList selectedAttributes;
+  provider->select( provider->attributeIndexes() );
-  for ( QgsFieldMap::const_iterator fit = fieldmap.begin(); fit != fieldmap.end(); ++fit )
-  {
-    selectedAttributes.push_back( fit.key() );
-  }
-  provider->select( selectedAttributes );
 
   // features must be stored in a list, since modifying the layer's extent rewinds nextFeature()
   QgsFeature feature;
@@ -134,11 +132,13 @@ void QgsAtlasRendering::begin( const QString& filenamePattern )
 
   // special columns for expressions
   QgsExpression::setSpecialColumn( "$numfeatures", QVariant( (int)impl->nFeatures ) );
-  QgsExpression::setSpecialColumn( "$numpages", QVariant( (int)impl->composition->numPages() ) );
 }
 
 void QgsAtlasRendering::prepareForFeature( size_t featureI )
 {
+  if ( !impl->composition || !impl->composition->atlasMap() || !impl->composition->atlasMap()->atlasCoverageLayer() )
+    return;
+
   QgsFeature* fit = &impl->features[featureI];
   
   if ( impl->filenamePattern.size() > 0 )
@@ -159,8 +159,13 @@ void QgsAtlasRendering::prepareForFeature( size_t featureI )
   // and apply a margin
   
   // QgsGeometry::boundingBox is expressed in the geometry"s native CRS
-    // They have to be transformed to the MapRenderer's one
+  // We have to transform the grometry to the destination CRS and ask for the bounding box
-    QgsRectangle geom_rect = impl->transform.transform( fit->geometry()->boundingBox() );
+  // Note: we cannot directly take the transformation of the bounding box, since transformations are not linear
+
+  QgsGeometry tgeom( *fit->geometry() );
+  tgeom.transform( impl->transform );
+  QgsRectangle geom_rect = tgeom.boundingBox();
+
   double xa1 = geom_rect.xMinimum();
   double xa2 = geom_rect.xMaximum();
   double ya1 = geom_rect.yMinimum();
@@ -220,13 +225,9 @@ void QgsAtlasRendering::prepareForFeature( size_t featureI )
   
   for ( QList<QgsComposerLabel*>::iterator lit = labels.begin(); lit != labels.end(); ++lit )
   {
-      // build a local substitution map
+    (*lit)->setExpressionContext( fit, impl->composition->atlasMap()->atlasCoverageLayer() );
-      QMap<QString, QVariant> pageMap;
-      pageMap.insert( "$page", QVariant( (int)impl->composition->itemPageNumber( *lit ) + 1 ) ); 
-      (*lit)->setExpressionContext( fit, impl->composition->atlasMap()->atlasCoverageLayer(), pageMap );
   }
   
-
   // set the new extent (and render)
   impl->composition->atlasMap()->setNewExtent( new_extent );
 }
@@ -243,6 +244,9 @@ const QString& QgsAtlasRendering::currentFilename() const
 
 void QgsAtlasRendering::end()
 {
+  if ( !impl->composition || !impl->composition->atlasMap() || !impl->composition->atlasMap()->atlasCoverageLayer() )
+    return;
+
   // reset label expression contexts
   QList<QgsComposerLabel*> labels;
   impl->composition->composerItems( labels );
@@ -350,6 +354,10 @@ void QgsComposition::setNumPages( int pages )
       mPages.removeLast();
     }
   }
+
+  // update the corresponding variable
+  QgsExpression::setSpecialColumn( "$numpages", QVariant((int)numPages()) );
+
   emit nPagesChanged();
 }
 
@@ -1700,6 +1708,8 @@ void QgsComposition::addPaperItem()
   addItem( paperItem );
   paperItem->setZValue( 0 );
   mPages.push_back( paperItem );
+
+  QgsExpression::setSpecialColumn( "$numpages", QVariant((int)mPages.size()) );
 }
 
 void QgsComposition::removePaperItems()
@@ -1709,6 +1719,7 @@ void QgsComposition::removePaperItems()
     delete mPages.at( i );
   }
   mPages.clear();
+  QgsExpression::setSpecialColumn( "$numpages", QVariant((int)0) );
 }
 
 void QgsComposition::deleteAndRemoveMultiFrames()
@@ -1836,3 +1847,32 @@ void QgsComposition::renderPage( QPainter* p, int page )
 
   mPlotStyle = savedPlotStyle;
 }
+
+void QgsComposition::setAtlasMap( QgsComposerMap* map )
+{
+  mAtlasMap = map;
+  if ( map != 0 )
+  {
+    QObject::connect( map, SIGNAL( atlasCoverageLayerChanged( QgsVectorLayer* )), this, SLOT( onAtlasCoverageChanged( QgsVectorLayer* ) ) );
+  }
+  else
+  {
+    QObject::disconnect( map, SIGNAL( atlasCoverageLayerChanged( QgsVectorLayer* )), this, SLOT( onAtlasCoverageChanged( QgsVectorLayer* ) ) );
+  }
+}
+
+void QgsComposition::onAtlasCoverageChanged( QgsVectorLayer* )
+{
+  // update variables
+  if ( mAtlasMap != 0 && mAtlasMap->atlasCoverageLayer() != 0 )
+  {
+    QgsVectorDataProvider* provider = mAtlasMap->atlasCoverageLayer()->dataProvider();
+    QgsExpression::setSpecialColumn( "$numfeatures", QVariant( (int)provider->featureCount() ) );
+  }
+  else
+  {
+    QgsExpression::setSpecialColumn( "$numfeatures", QVariant( (int)0 ) );
+  }
+  // 
+  QgsExpression::setSpecialColumn( "$numpages", QVariant( (int)numPages() ) );
+}

src/core/composer/qgscomposition.h

@@ -48,6 +48,7 @@ class QgsComposerShape;
 class QgsComposerAttributeTable;
 class QgsComposerMultiFrame;
 class QgsComposerMultiFrameCommand;
+class QgsVectorLayer;
 
 /** \ingroup MapComposer
  * Class used to render an Atlas, iterating over geometry features.
@@ -59,12 +60,18 @@ class QgsAtlasRendering
  public:
   QgsAtlasRendering( QgsComposition* composition );
 
+  /** Begins the rendering. Sets an optional output filename pattern */
   void begin( const QString& filenamePattern = "" );
+  /** Ends the rendering. Restores original extent*/
   void end();
 
+  /** Returns the number of features in the coverage layer */
   size_t numFeatures() const;
+
+  /** Prepare the atlas map for the given feature. Sets the extent and context variables */
   void prepareForFeature( size_t i );
 
+  /** Returns the current filename. Must be called after prepareForFeature( i ) */
   const QString& currentFilename() const;
 
  private:
@@ -194,7 +201,7 @@ class CORE_EXPORT QgsComposition: public QGraphicsScene
     QgsMapRenderer* mapRenderer() {return mMapRenderer;}
 
     QgsComposerMap* atlasMap() { return mAtlasMap; }
-    void setAtlasMap( QgsComposerMap* map ) { mAtlasMap = map; }
+    void setAtlasMap( QgsComposerMap* map );
 
     QgsComposition::PlotStyle plotStyle() const {return mPlotStyle;}
     void setPlotStyle( QgsComposition::PlotStyle style ) {mPlotStyle = style;}
@@ -333,6 +340,9 @@ class CORE_EXPORT QgsComposition: public QGraphicsScene
     /**Casts object to the proper subclass type and calls corresponding itemAdded signal*/
     void sendItemAddedSignal( QgsComposerItem* item );
 
+  private slots:
+    void onAtlasCoverageChanged( QgsVectorLayer* );
+
   private:
     /**Pointer to map renderer of QGIS main map*/
     QgsMapRenderer* mMapRenderer;