Most of the time, you do not have to create
a totally new renderer. You can use one of the default renderers
that are supplied in the package and tailor it to your needs.
This section shows how to extend an IlvDefaultPointRenderer to add text of the
type IlvLabel next to the point of the feature
being rendered. It also shows the use of IlvMapRenderingStyle which are the classes
used by the renderers in order to customize them. For instance, in
this code example, the color of the labels generated by the
renderer is obtained through the IlvMapPointRenderingStyle of the
IlvDefaultPointRenderer.
The complete source code for the example in
this section can be found in the following file:
The text is stored in an attribute whose name is provided for the
class
MarkerTextRenderer
. When this text exists, it is returned with the marker generated
by the superclass of the renderer; otherwise only the marker is
returned.
public IlvGraphic makeGraphic(IlvMapFeature feature,
IlvCoordinateTransformation tr)
throws IlvMapRenderException, IlvCoordinateTransformationException
{
// Let the super class create the marker.
IlvMarker marker = (IlvMarker)super.makeGraphic(feature, tr);
// Create label if needed.
IlvLabel label = null;
IlvFeatureAttributeProperty attributeList = feature.getAttributes();
if (attributeList != null) {
try {
IlvFeatureAttribute attribute = null;
attribute = attributeList.getAttribute(myAttributeName);
if (attribute != null)
label = new IlvLabel(marker.getPoint(), attribute.toString());
} catch (IllegalArgumentException e) {
label = null;
}
}
// Case no label: return marker.
if (label == null) {
return marker;
}
// Else generate a graphic set containing the marker as the label.
else {
// Make this label of the same color than the marker.
label.setForeground(getPointRenderingStyle().getMarkerColor());
IlvGraphicSet set = new IlvGraphicSet();
set.addObject(marker, false);
set.addObject(label, false);
return set;
}
}