com.bbn.openmap.layer.policy
Class StandardPCPolicy

java.lang.Object
  com.bbn.openmap.layer.policy.AbstractProjectionChangePolicy
      com.bbn.openmap.layer.policy.StandardPCPolicy

All Implemented Interfaces:

ProjectionChangePolicy

public class StandardPCPolicy
extends AbstractProjectionChangePolicy

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.

Field Summary

protected boolean	alwaysSpawnThread A flag to tell the policy to always spawn a thread.
protected int	graphicCutoff The number of OMGraphics that have to be on the layer's OMGraphicList before a thread is spawned.

Fields inherited from class com.bbn.openmap.layer.policy.AbstractProjectionChangePolicy

layer

Constructor Summary

StandardPCPolicy()
You must set a layer at some point before using this class.

StandardPCPolicy(OMGraphicHandlerLayer layer)
Don't pass in a null layer.

StandardPCPolicy(OMGraphicHandlerLayer layer, boolean alwaysSpawnThreadForPrepare)
Don't pass in a null layer.

Method Summary

boolean	getAlwaysSpawnThread()
int	getGraphicCutoff()
void	projectionChanged(ProjectionEvent pe) When the projection changes, the StandardPCPolicy sets the current projection on the layer, and calls prepare() on the layer.
void	setAlwaysSpawnThread(boolean val) Tell the policy whether to spawn a thread when projectionChanged() is called with a new projection.
void	setGraphicCutoff(int number)
protected boolean	shouldSpawnThreadForPrepare() We're assuming that the list is somewhat constant for the layer.

Methods inherited from class com.bbn.openmap.layer.policy.AbstractProjectionChangePolicy

getLayer, setLayer, workerComplete

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

graphicCutoff

protected int graphicCutoff

The number of OMGraphics that have to be on the layer's OMGraphicList before a thread is spawned. The default is 50;

alwaysSpawnThread

protected boolean alwaysSpawnThread

A flag to tell the policy to always spawn a thread.

Constructor Detail

StandardPCPolicy

public StandardPCPolicy()

You must set a layer at some point before using this class.

StandardPCPolicy

public StandardPCPolicy(OMGraphicHandlerLayer layer)

Don't pass in a null layer.

StandardPCPolicy

public StandardPCPolicy(OMGraphicHandlerLayer layer,
                        boolean alwaysSpawnThreadForPrepare)

Don't pass in a null layer.

Parameters:

layer - layer to work for

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.

Method Detail

setAlwaysSpawnThread

public void setAlwaysSpawnThread(boolean val)

Tell the policy whether to spawn a thread when projectionChanged() is called with a new projection.

Parameters:

val - setting for always spawning thread for every projection change.

getAlwaysSpawnThread

public boolean getAlwaysSpawnThread()

projectionChanged

public void projectionChanged(ProjectionEvent pe)

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(), as well as return that list from prepare.

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.

Parameters:

pe - The ProjectionEvent received from the MapBean.

shouldSpawnThreadForPrepare

protected boolean shouldSpawnThreadForPrepare()

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, a thread should be launched to generate them with the new projection. You can extend this method so that different criteria may be considered.

Returns:

true of thread should always be spawned.

setGraphicCutoff

public void setGraphicCutoff(int number)

Parameters:

number - Set the number of OMGraphics that have to be on the list before a thread gets spawned to call generate() on them.

getGraphicCutoff

public int getGraphicCutoff()