package org.wicketstuff.openlayers3.behavior.view;
import com.google.gson.JsonElement;
import com.google.gson.JsonNull;
import com.google.gson.JsonParser;
import org.apache.wicket.Component;
import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.markup.head.IHeaderResponse;
import org.apache.wicket.markup.head.OnDomReadyHeaderItem;
import org.apache.wicket.request.IRequestParameters;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.util.template.PackageTextTemplate;
import java.util.HashMap;
import java.util.Map;
/**
* Provides a behavior that invokes a callback event whenever the map view changes. Specifically, this behavior will
* monitor the map's ol.View for 'center' and 'resolution' events.
*/
public abstract class ViewEventListener extends AbstractDefaultAjaxBehavior {
/**
* Default projection.
*/
public final static String DEFAULT_PROJECTION = "EPSG:4326";
/**
* Counter for generating instance identifiers.
*/
private static Long counter = 0L;
/**
* Map for storing object Ids.
*/
private static java.util.Map<Object, String> objectIds = new HashMap<Object, String>();
/**
* Projection for this map.
*/
private String projection;
/**
* Creates a new instance.
*/
public ViewEventListener() {
this(DEFAULT_PROJECTION);
}
/**
* Creates a new instance and sets the projection used to transform coordinates.
*
* @param projection Projection used to transform coordinates
*/
public ViewEventListener(String projection) {
this.projection = projection;
}
/**
* Callback method that is invoked when the map's view is changed.
*
* @param target Ajax request target
* @param viewEvent The current view
*/
public abstract void handleViewEvent(AjaxRequestTarget target, ViewEvent viewEvent);
/**
* Javascript name of the callback function to invoke when feature data has been loaded into the layer.
*
* @return String with the Javascript callback function name
*/
public String getCallbackFunctionName() {
return "viewEventHandler_" + getId();
}
/**
* Returns a unique ID for this behavior.
*
* @return String with a unique ID
*/
public String getId() {
String objectId = null;
if (objectIds.get(this) != null) {
objectId = objectIds.get(this);
} else {
objectId = getClass().getSimpleName().toLowerCase() + counter++;
objectIds.put(this, objectId);
}
return objectId;
}
@Override
protected void respond(AjaxRequestTarget target) {
IRequestParameters params = RequestCycle.get().getRequest().getRequestParameters();
String viewJson = params.getParameterValue("view").toString();
ViewEvent viewEvent = null;
JsonElement viewParsed = new JsonParser().parse(viewJson);
if(!(viewParsed instanceof JsonNull)) {
viewEvent = new ViewEvent(viewParsed.getAsJsonObject());
}
handleViewEvent(target, viewEvent);
}
@Override
public void renderHead(Component component, IHeaderResponse response) {
super.renderHead(component, response);
final Map<String, CharSequence> params = new HashMap<String, CharSequence>();
params.put("callbackUrl", getCallbackUrl());
params.put("callbackFunctionName", getCallbackFunctionName());
params.put("componentId", component.getMarkupId());
params.put("projection", projection != null ? projection : "NULL");
PackageTextTemplate template = new PackageTextTemplate(ViewEventListener.class,
"ViewEventListener.js");
response.render(OnDomReadyHeaderItem.forScript(template.asString(params)));
}
}