added wms getLegendGraphic management in case of rasterLayerSymbology - Developed with funding from Regione Toscana-SITA

This commit add the getLegendGraphic pixmap as legend in the QgsLegend.
Due to architectural QgsLegend limitation pixmap is shown of the same dimension of every single legend element (too little)

managing of getLegendGraphic popup and refresh - Developed with funding from Regione Toscana-SITA
Due the fact that WMS pixmap is too little, has been added a popup to show WMS legend in the original size
Has been added feature to refresh getLegendGraphics to every scale change due to extend modification. In this way
getLagendGraphic can be updated basing on scale and in the future also basing on viewport.

Modified QPixmap to QImage to be device independent

set absolute position due to popup is not referred to legendInterface (avoid hiding of the legend)

Author: luipir

src/app/legend/qgslegend.cpp

@@ -113,6 +113,8 @@ QgsLegend::QgsLegend( QgsMapCanvas *canvas, QWidget * parent, const char *name )
 
   connect( mMapCanvas, SIGNAL( layersChanged() ),
            this, SLOT( refreshCheckStates() ) );
+  connect( mMapCanvas, SIGNAL( extentsChanged() ),
+           this, SLOT( updateLegendItemSymbologies() ) );
 
   // Initialise the line indicator widget.
   mInsertionLine = new QWidget( viewport() );
@@ -141,6 +143,7 @@ QgsLegend::QgsLegend( QgsMapCanvas *canvas, QWidget * parent, const char *name )
 QgsLegend::~QgsLegend()
 {
   delete mInsertionLine;
+  delete mGetLegendGraphicPopup;
 }
 
 #ifdef QGISDEBUG
@@ -395,6 +398,24 @@ void QgsLegend::mousePressEvent( QMouseEvent * e )
 {
   if ( e->button() == Qt::LeftButton )
   {
+    // show WMS legend in case itemAt( e->pos() ) is a wms legend
+    // if it's not a legend later it return a null pixmap
+    QImage legend = getWmsLegendPixmap( itemAt( e->pos() ) );
+    if ( !legend.isNull() )
+    {
+      mGetLegendGraphicPopup = new QFrame();
+      mGetLegendGraphicPopup->setFrameStyle(QFrame::Box | QFrame::Raised);
+      mGetLegendGraphicPopup->setLineWidth(2);
+      mGetLegendGraphicPopup->setAutoFillBackground(true);
+      QVBoxLayout *layout = new QVBoxLayout;
+      QLabel *label = new QLabel(mGetLegendGraphicPopup);
+      label->setPixmap( QPixmap::fromImage(legend) );
+      layout->addWidget(label);
+      mGetLegendGraphicPopup->setLayout(layout);
+      mGetLegendGraphicPopup->move(e->globalX(), e->globalY());
+      mGetLegendGraphicPopup->show();
+    }
+
     mMousePressedFlag = true;
     mDropTarget = itemAt( e->pos() );
     if ( !mDropTarget )
@@ -624,6 +645,11 @@ void QgsLegend::updateGroupCheckStates( QTreeWidgetItem *item )
 
 void QgsLegend::mouseReleaseEvent( QMouseEvent * e )
 {
+  if (mGetLegendGraphicPopup) {
+    delete mGetLegendGraphicPopup;
+    mGetLegendGraphicPopup = 0;
+  }
+  
   QStringList layersPriorToEvent = layerIDs();
   QTreeWidget::mouseReleaseEvent( e );
   mMousePressedFlag = false;
@@ -3208,3 +3234,43 @@ void QgsLegend::updateLegendItemSymbologies()
     ll->refreshSymbology( ll->layer()->id() );
   }
 }
+
+QImage QgsLegend::getWmsLegendPixmap( QTreeWidgetItem *item )
+{
+  if ( !item )
+  {
+    return QImage();
+  }
+
+  QTreeWidgetItem *parent = item->parent();
+  if ( !parent ) 
+  {
+    return QImage();
+  }
+
+  QgsLegendItem* li = dynamic_cast<QgsLegendItem *>( parent );
+  if ( !li )
+  {
+    return QImage();
+  }
+
+  if ( li->type() != QgsLegendItem::LEGEND_LAYER )
+  {
+    return QImage();
+  }
+
+  QgsLegendLayer *lyr = qobject_cast<QgsLegendLayer*>( li );
+  QgsRasterLayer *rasterLayer = dynamic_cast<QgsRasterLayer*>( lyr->layer() );
+  if ( !rasterLayer )
+  {
+    return QImage();
+  }
+
+  if ( rasterLayer->providerType() != "wms" )
+  {
+    return QImage();
+  }
+  
+  return rasterLayer->dataProvider()->getLegendGraphic( canvas()->scale() );
+}
+

src/app/legend/qgslegend.h

@@ -590,6 +590,16 @@ class QgsLegend : public QTreeWidget
 
     bool verifyDrawingOrder();
 
+    /*!
+     * Check if current LegendItem belogs to a WMS layer 
+     * @param item LegendItem to check if belongs to a WMS layer
+     * @return QImage A valid Legend image if belogs to WMS otherwise QImage()
+     */
+    QImage getWmsLegendPixmap( QTreeWidgetItem *item );
+
+    //! popup QFrame containing WMS getLegendGraphic pixmap
+    QFrame *mGetLegendGraphicPopup;
+
   signals:
     void itemAdded( QModelIndex index );
     void itemMoved( QModelIndex oldIndex, QModelIndex newIndex );

src/app/legend/qgslegendlayer.cpp

@@ -208,6 +208,26 @@ void QgsLegendLayer::rasterLayerSymbology( QgsRasterLayer* layer )
 #if QT_VERSION >= 0x40700
   itemList.reserve( rasterItemList.size() );
 #endif
+
+  // GetLegendGraphics in case of WMS service... pixmap can return null if GetLegendGraphics 
+  // is not supported by server
+  QgsDebugMsg( QString( "layer providertype:: %1" ).arg( layer->providerType() ) );
+  if ( layer->providerType() == "wms" )
+  {
+    double currentScale = legend()->canvas()->scale();
+
+    QImage legendGraphic = layer->dataProvider()->getLegendGraphic( currentScale );
+    if ( !legendGraphic.isNull() )
+    {
+      QgsDebugMsg( QString( "downloaded legend with dimension Width:" )+QString::number(legendGraphic.width())+QString(" and Height:")+QString::number(legendGraphic.height()) );
+      
+#if QT_VERSION >= 0x40700
+      if ( rasterItemList.size() == 0) itemList.reserve( 1 );
+#endif
+      itemList.append( qMakePair( QString(""), legendGraphic ) );
+    }
+  }
+
   // Paletted raster may have many colors, for example UInt16 may have 65536 colors
   // and it is very slow, so we limit max count
   QSize iconSize = treeWidget()->iconSize();