Duplicating feature layer with ArcObjects?

Question

After opening a MxD document and getting the main map then a feature layer, I want to duplicate the layer with ArcObjects in order to inherit its properties (symbology, layer def and labelling). Then, I want to edit the name of the copy and its layer defs query.

I managed to get both IMap and source feature layer.

IMap map = mapDocument.getMap(0);
IFeatureLayer sourceFeatureLayer = map.getLayer(0);
IFeatureLayer destinationFeatureLayer = ...?
destinationFeatureLayer.setName("layer_2");
map.addLayer(destinationFeatureLayer);

How do I duplicate the source layer?

Answer 1

You should take a closer look at all the interfaces that IFeatureLayer implements for a lot of this information. That's .NET documentation, but it will mirror Java pretty closely.

A lot of what you want is on the IGeoFeatureLayer, IDataLayer, and IFeatureLayerDefinition. I have not tested the below code, but it's basically what you want to be doing.

IFeatureLayer old_fLayer = map.Layer[0];
var new_fLayer = new FeatureLayer() as IFeatureLayer;

//copy the data source to the new layer
new_fLayer.FeatureClass = old_fLayer.FeatureClass;
((new_fLayer as IDataLayer).DataSourceName = ((old_fLayer as IDataLayer).DataSourceName;

//copy the symbology (I'm 90% sure that there is no issue in simply assigning the renderer from one layer to another
(new_fLayer as IGeoFeatureLayer).Renderer = (old_fLayer as IGeoFeatureLayer).Renderer;

//move the labeling properties. AnnotationProperties implements IClone so we'll use that instead of direct assignment.
(new_fLayer as IGeoFeatureLayer).AnnotationProperties = 
(IAnnotateLayerPropertiesCollection)((old_fLayer as IGeoFeatureLayer).AnnotationProperties as IClone).Clone();

(new_fLayer as IGeoFeatureLayer).AnnotationPropertiesID = ((old_fLayer as IGeoFeatureLayer).AnnotationPropertiesID;

//update the new properties for this layer
(new_fLayer as IFeatureLayerDefintion).DefinitionExpression = "new expression";
new_fLayer.Name = "New Name";

//add the new layer to the map
map.AddLayer(new_fLayer);
(map as IActiveView).Refresh();