DictionaryRenderer Class

Detailed Description

The dictionary renderer applies symbols to features or graphics according to a set of input attribute values. The symbol primitives and logic (rule engine) for applying symbols is provided by an associated DictionarySymbolStyle.

The DictionarySymbolStyle depends on attribute names to define the symbology of each feature. The attributes reference different symbol components in the style, which are assembled to create a complex symbol. In order to display geoelements using the dictionary renderer, attributes in your data must either use the expected attribute names or be mapped to the proper style attributes.

The DictionarySymbolStyle is created using a given specification such as "mil2525d". Each specification depends on attribute names that define the symbology and text of each feature. For example, the mil2525d specification looks for attributes named "identity", "symbolset", "symbolentity", and "modifier1", among many others. These attributes reference different symbols in the style file that are assembled to create a unique symbol. In order to display features using the DictionaryRenderer, you must make sure the DictionaryRenderer and associated DictionarySymbolStyle know which attributes in your data to use. This can be achieved in multiple ways:

• Pre-author your data so that the attribute names match the attributes needed by the specification. In the case of the mil2525d specification, author a feature service (or other data source) with a field named "identity", another named "symbolset", and so on. In this scenario, you create a FeatureTable from the source data, create a FeatureLayer from the FeatureTable, apply the DictionaryRenderer to the FeatureLayer, and the symbols are generated automatically and applied to the layer in the map. The same workflow applies for Graphics in a GraphicsOverlay. Ideally when creating graphics on the fly, you can give the attributes names that match the specification. When fields in the FeatureTable and attributes in Graphics have expected names, the DictionaryRenderer automatically finds them.
• Manually map your attribute names to those expected by the specification. You can map as many attribute names as necessary for the specification, but only need to map attribute names that do not match the specification (all matching attribute names will be automatically matched by the renderer). For example, an expected attribute "symbolset" might appear as the "symbol_set" field in your FeatureTable. In this scenario, you can create a ServiceFeatureTable from a feature service, create a FeatureLayer from that feature table, create a DictionaryRenderer by manually mapping the "symbol_set" name to the "symbolset" name expected by the specification, and finally apply the renderer to the FeatureLayer.

A DictionaryRenderer can be applied to pre-authored data, such as feature services, mobile geodatabases (generated from ArcMap or a sync-enabled feature service), and feature layers in a mobile map package. You can also apply it to a GraphicsOverlay, which allow for on-the-fly graphic generation.

Example:

Apply a DictionaryRenderer to a FeatureLayer:

// Create a layer and set the feature table
FeatureLayer* layer = new FeatureLayer(table, this);

// Create a dictionary renderer and apply to the layer
DictionaryRenderer* renderer = new DictionaryRenderer(dictionarySymbolStyle, this);
layer->setRenderer(renderer);

Relevant samples:

• Custom dictionary style: Use a custom dictionary style created from a web style or local style file (.stylx) to symbolize features using a variety of attribute values.
• Feature layer (dictionary renderer): Convert features into graphics to show them with mil2525d symbols.
• Graphics overlay (dictionary renderer): This sample demonstrates applying a dictionary renderer to graphics, in order to display military symbology without the need for a feature table.
• Graphics overlay (dictionary renderer) 3D: This sample demonstrates applying a dictionary renderer to a graphics overlay in a 3D scene to display military symbology.