// **********************************************************************
//
// <copyright>
//
// BBN Technologies
// 10 Moulton Street
// Cambridge, MA 02138
// (617) 873-8000
//
// Copyright (C) BBNT Solutions LLC. All rights reserved.
//
// </copyright>
// **********************************************************************
//
// $Source: /cvs/distapps/openmap/src/openmap/com/bbn/openmap/layer/policy/StandardPCPolicy.java,v $
// $RCSfile: StandardPCPolicy.java,v $
// $Revision: 1.5.2.4 $
// $Date: 2006/05/19 16:44:35 $
// $Author: dietrick $
//
// **********************************************************************
package com.bbn.openmap.layer.policy;
import com.bbn.openmap.layer.OMGraphicHandlerLayer;
import com.bbn.openmap.event.LayerStatusEvent;
import com.bbn.openmap.event.ProjectionEvent;
import com.bbn.openmap.omGraphics.OMGraphicList;
import com.bbn.openmap.proj.Projection;
import com.bbn.openmap.util.Debug;
/**
* ProjectionChangePolicy that uses a Layer SwingWorker to kick off a
* thread to call layer.prepare() and doesn't delete the OMGraphicList
* between projection changes. The standard behavior for simple layers
* that maintain a constant list of OMGraphics.
*/
public class StandardPCPolicy implements ProjectionChangePolicy {
/**
* The OMGraphicHandlerLayer using this policy. Don't let this be
* null.
*/
protected OMGraphicHandlerLayer layer;
/**
* The number of OMGraphics that have to be on the layer's
* OMGraphicList before a thread is spawned. The default is 50;
*/
protected int graphicCutoff = 50;
/**
* A flag to tell the policy to always spawn a thread.
*/
protected boolean alwaysSpawnThread = false;
/**
* You must set a layer at some point before using this class.
*/
public StandardPCPolicy() {}
/**
* Don't pass in a null layer.
*/
public StandardPCPolicy(OMGraphicHandlerLayer layer) {
this(layer, true);
}
/**
* Don't pass in a null layer.
*
* @param layer layer to work for
* @param alwaysSpawnThreadForPrepare should be true if the
* layer's prepare method takes a while. Normally, the
* policy looks at the number of OMGraphics on the list to
* determine if a thread should be spawned. True by
* default.
*/
public StandardPCPolicy(OMGraphicHandlerLayer layer,
boolean alwaysSpawnThreadForPrepare) {
setLayer(layer);
setAlwaysSpawnThread(alwaysSpawnThreadForPrepare);
}
public void setLayer(OMGraphicHandlerLayer l) {
layer = l;
}
public OMGraphicHandlerLayer getLayer() {
return layer;
}
/**
* Tell the policy whether to spawn a thread when
* projectionChanged() is called with a new projection.
*/
public void setAlwaysSpawnThread(boolean val) {
alwaysSpawnThread = val;
}
public boolean getAlwaysSpawnThread() {
return alwaysSpawnThread;
}
/**
* When the projection changes, the StandardPCPolicy sets the
* current projection on the layer, and calls prepare() on the
* layer. repaint() will be automatically called. This method does
* not generate the OMGraphics in the list. The layer is still
* expected to do that in prepare().
* <P>
* If a Layer is using this PC policy, then it's kind of assumed
* that the layer is setting the list and generating the same list
* over and over again with the new projection. So, when we look
* at the min and max scales set on the layer, we don't want to
* clear out that list if the projection scale is outside of the
* acceptable range of good projection scales. Instead, we want to
* skip the prepare() method call as to not waste CPU cycles
* generating things we won't see, and let the RenderPolicy check
* to see if the list should be painted.
*/
public void projectionChanged(ProjectionEvent pe) {
if (layer != null) {
Projection proj = layer.setProjection(pe);
// proj will be null if the projection hasn't changed, a
// signal that work does not need to be done.
if (proj != null) {
// Some criteria can decide whether
// starting another thread is worth it...
if (shouldSpawnThreadForPrepare()) {
if (Debug.debugging("layer")) {
Debug.output(getLayer().getName()
+ ": StandardPCPolicy projectionChanged with NEW projection, spawning thread to handle it.");
}
if (layer.isProjectionOK(proj)) {
layer.doPrepare();
}
return;
} else {
if (Debug.debugging("layer")) {
Debug.output(getLayer().getName()
+ ": StandardPCPolicy projectionChanged with NEW projection, handling it within current thread.");
}
layer.fireStatusUpdate(LayerStatusEvent.START_WORKING);
if (layer.isProjectionOK(proj)) {
layer.prepare();
}
layer.repaint();
}
} else {
layer.repaint();
}
layer.fireStatusUpdate(LayerStatusEvent.FINISH_WORKING);
} else {
Debug.error("StandardPCPolicy.projectionChanged(): NULL layer, can't do anything.");
}
}
/**
* This is a subtle call, that dictates what should happen when
* the LayerWorker has completed working in it's thread. The
* LayerWorker.get() method returns whatever was returned in the
* OMGraphicHandler.prepare() method, an OMGraphicList. In most
* cases, this object should be set as the Layer's list at this
* time. Some Layers, working asynchronously with their data
* sources, might want nothing to happen.
*/
public void workerComplete(OMGraphicList aList) {
if (layer != null) {
layer.setList(aList);
}
}
/**
* We're assuming that the list is somewhat constant for the
* layer. If the number of OMGraphics on the layer's list is more
* than the cutoff number, thena thread should be launched to
* generate them with the new projection. You can extend this
* method so that different criteria may be considered.
*/
protected boolean shouldSpawnThreadForPrepare() {
if (layer != null && !alwaysSpawnThread) {
com.bbn.openmap.omGraphics.OMGraphicList list = layer.getList();
if (list != null) {
return layer.getList().size() > graphicCutoff;
}
}
// If we have to create a list, might as well assume that
// is should be done in a new thread.
return true;
}
/**
* Set the number of OMGraphics that have to be on the list before
* a thread gets spawned to call generate() on them.
*/
public void setGraphicCutoff(int number) {
graphicCutoff = number;
}
public int getGraphicCutoff() {
return graphicCutoff;
}
}