## com.bbn.openmap.proj
Interface ProjectionStackTrigger

All Known Implementing Classes:
  ProjectionStackTool, ProjMapBeanKeyListener

public interface ProjectionStackTrigger

Provides Projection Stack input by firing BackProkCmd and ForwardProjCmd commands, which cause it to set a projection in the MapBean. The commands used when firing an action event should be the ones listed in the ProjectionStack

Method Summary
`void` `addActionListener(java.awt.event.ActionListener al)` Add an ActionListener for events that trigger events to shift the Projection stack.
`void` `removeActionListener(java.awt.event.ActionListener al)` Remove an ActionListener that receives events that trigger events to shift the Projection stack.
`void` `updateProjectionStackStatus(boolean containsBackProjections, boolean containsForwardProjections)` To receive a status to let the trigger know if any projections in the forward or backward stacks exist, possibly to disable any gui widgets.

Method Detail

### addActionListener

    public void addActionListener(java.awt.event.ActionListener al)

  Add an ActionListener for events that trigger events to shift the Projection stack.

### removeActionListener

    public void removeActionListener(java.awt.event.ActionListener al)

  Remove an ActionListener that receives events that trigger events to shift the Projection stack.

### updateProjectionStackStatus

    public void updateProjectionStackStatus(boolean containsBackProjections,
                                            boolean containsForwardProjections)

  To receive a status to let the trigger know if any projections in the forward or backward stacks exist, possibly to disable any gui widgets.

  Parameters:
    `containsBackProjections` - there is at least one past projection in the back cache.
    `containsForwardProjections` - there is at least one future projection in the forward cache. Used when a past projection is being used.

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