Fix #10473 (raster preview icons in layer tree view)

Author: wonder-sk

src/app/qgisapp.cpp

@@ -2305,6 +2305,8 @@ void QgisApp::initLayerTreeView()
   mLayerTreeView->setModel( model );
   mLayerTreeView->setMenuProvider( new QgsAppLayerTreeViewMenuProvider( mLayerTreeView, mMapCanvas ) );
 
+  setupLayerTreeViewFromSettings();
+
   connect( mLayerTreeView, SIGNAL( doubleClicked( QModelIndex ) ), this, SLOT( layerTreeViewDoubleClicked( QModelIndex ) ) );
   connect( mLayerTreeView, SIGNAL( currentLayerChanged( QgsMapLayer* ) ), this, SLOT( activeLayerChanged( QgsMapLayer* ) ) );
   connect( mLayerTreeView->selectionModel(), SIGNAL( currentChanged( QModelIndex, QModelIndex ) ), this, SLOT( updateNewLayerInsertionPoint() ) );
@@ -2329,6 +2331,13 @@ void QgisApp::initLayerTreeView()
   mLayerOrderDock->hide();
 }
 
+void QgisApp::setupLayerTreeViewFromSettings()
+{
+  QSettings s;
+
+  mLayerTreeView->layerTreeModel()->setFlag( QgsLayerTreeModel::ShowRasterPreviewIcon, s.value( "/qgis/createRasterLegendIcons", false ).toBool() );
+}
+
 
 void QgisApp::updateNewLayerInsertionPoint()
 {
@@ -7239,6 +7248,8 @@ void QgisApp::showOptionsDialog( QWidget *parent, QString currentPage )
 
     QgsProject::instance()->layerTreeRegistryBridge()->setNewLayersVisible( mySettings.value( "/qgis/new_layers_visible", true ).toBool() );
 
+    setupLayerTreeViewFromSettings();
+
     mMapCanvas->enableAntiAliasing( mySettings.value( "/qgis/enable_anti_aliasing" ).toBool() );
 
     int action = mySettings.value( "/qgis/wheel_action", 2 ).toInt();

src/app/qgisapp.h

@@ -1338,6 +1338,9 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     /**Removes annotation items in the canvas*/
     void removeAnnotationItems();
 
+    //! Configure layer tree view according to the user options from QSettings
+    void setupLayerTreeViewFromSettings();
+
     /// QgisApp aren't copyable
     QgisApp( QgisApp const & );
     /// QgisApp aren't copyable

src/gui/layertree/qgslayertreemodel.cpp

@@ -189,7 +189,15 @@ QVariant QgsLayerTreeModel::data( const QModelIndex &index, int role ) const
       if ( !layer )
         return QVariant();
       if ( layer->type() == QgsMapLayer::RasterLayer )
-        return QgsLayerItem::iconRaster();
+      {
+        if ( testFlag( ShowRasterPreviewIcon ) )
+        {
+          QgsRasterLayer* rlayer = qobject_cast<QgsRasterLayer *>( layer );
+          return QIcon( rlayer->previewAsPixmap( QSize( 32, 32 ) ) );
+        }
+        else
+          return QgsLayerItem::iconRaster();
+      }
       else if ( layer->type() == QgsMapLayer::VectorLayer )
       {
         QgsVectorLayer* vlayer = static_cast<QgsVectorLayer*>( layer );

src/gui/layertree/qgslayertreemodel.h

@@ -89,6 +89,7 @@ class GUI_EXPORT QgsLayerTreeModel : public QAbstractItemModel
     {
       // display flags
       ShowSymbology             = 0x0001,  //!< Add symbology items for layer nodes
+      ShowRasterPreviewIcon     = 0x0002,  //!< Will use real preview of raster layer as icon (may be slow)
 
       // behavioral flags
       AllowNodeReorder          = 0x1000,  //!< Allow reordering with drag'n'drop