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## com.bbn.openmap.layer.policy
Class StandardPCPolicy

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

All Implemented Interfaces:
  ProjectionChangePolicy

public class StandardPCPolicy
extends java.lang.Object
implements ProjectionChangePolicy

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.
`protected OMGraphicHandlerLayer` | `layer` The OMGraphicHandlerLayer using this policy.

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()`
`OMGraphicHandlerLayer` | `getLayer()` Get the OMGraphicHandlerLayer to work with.
`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)` Set the number of OMGraphics that have to be on the list before a thread gets spawned to call generate() on them.
`void` | `setLayer(OMGraphicHandlerLayer l)` Set the OMGraphicHandlerLayer to work with.
`protected boolean` | `shouldSpawnThreadForPrepare()` We're assuming that the list is somewhat constant for the layer.
`void` | `workerComplete(OMGraphicList aList)` This is a subtle call, that dictates what should happen when the LayerWorker has completed working in it's thread.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### layer

    protected OMGraphicHandlerLayer layer

  The OMGraphicHandlerLayer using this policy. Don't let this be null.

### 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

### setLayer

    public void setLayer(OMGraphicHandlerLayer l)

  Description copied from interface: `ProjectionChangePolicy`
  Set the OMGraphicHandlerLayer to work with.

  Specified by:
    `setLayer` in interface `ProjectionChangePolicy`

### getLayer

    public OMGraphicHandlerLayer getLayer()

  Description copied from interface: `ProjectionChangePolicy`
  Get the OMGraphicHandlerLayer to work with.

  Specified by:
    `getLayer` in interface `ProjectionChangePolicy`

### setAlwaysSpawnThread

    public void setAlwaysSpawnThread(boolean val)

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

### 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().

  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.

  Specified by:
    `projectionChanged` in interface `ProjectionChangePolicy`

### workerComplete

    public void workerComplete(OMGraphicList aList)

  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.

  Specified by:
    `workerComplete` in interface `ProjectionChangePolicy`

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

### setGraphicCutoff

    public void setGraphicCutoff(int 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()

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