Making a symbol model persistent means providing a way
to embed SDM model information inside a map file.
You should not use this feature if you intend to use
JViews Diagrammer Designer with your map, as it stores
and sets up symbol model differently, in separated xml files. You
should use an
IlvMapStyleSheetRenderer if you want to take advantage
of this feature. If you do not, the manager layers that will be used
to place your symbols may not be instances of the
IlvMapStyleSheetRenderer.IlvMapSymbolManagerLayer class, which means that the
graphical representation of the symbols will be saved separately in
the ivl file, causing its duplication when you read the map back.
The persistent SDM model property
This class is a named property that will be attached
to a manager, and trigger the saving and reading of an engine model
inside an IVL file.
Example of use:
IlvPersistentSDMModelProperty property =
IlvPersistentSDMModelProperty.GetPersistentSDMModel(engine,factory,listenToChanges);
This call will register the property on the engine’s
manager. It will be saved (like every named property) when the manager
gets saved, and will invoke an internal
IlvXMLConnector that will save the XML content
of the engine model as a string.
At read time, this property requires the use a node factory
to create SDM nodes in the engine model, detailed below.
If you use this call with listenToChanges set
to true, you can register this property for an engine before reading
the map IVL file. The listener attached will ensure that the factory
and engine used when reading the property get replaced by the ones
you specify before the data is read.
If you do not do this, internal XML data will be read,
and you will have to attach the engine manually later.
The persistent SDM Node factory
The principal
purpose of the
IlvPersistentSDMNodeFactory interface is to provide
a way for model nodes to be created when you read the model data back
in. Usually creating a symbol is dependent on some application so
this interface also includes methods to manage that persistent context.
The following provides a simple code example which can
help you to write your own factory.
public class SampleFactory implements IlvPersistentSDMNodeFactory {
static public class SampleContext extends IlvPersistentObject {
// some implementation of a persistent object ...
}
IlvPersistentObject _factoryPersistentContext;
public IlvPersistentObject getPersistentContext() {
// the persistent context should be created or updated at this point.
_factoryPersistentContext=new SampleContext();
_factoryPersistentContext.setSomeData(this.getSomeData());
return _factoryPersistentContext;
}
public boolean isPropertyIgnored(IlvSDMModel model, Object node, String name) {
// ignore the “data” property
if(“data”.equals(name)) return true;
return false;
}
public Object newSymbol(String tag) {
// we will create default SDM nodes
IlvDefaultSDMNode node=new IlvDefaultSDMNode(tag);
// configure the node, for example
node.setProperty("data", this.getSomeData());
return node;
}
public void setPersistentContext(IlvPersistentObject context) {
// the local information should be updated with what was stored in the context
this.setSomeData(context.getSomeData());
}