org.apache.log4j.lf5.viewer: public class: TrackingAdjustmentListener

org.apache.log4j.lf5.viewer
public class: TrackingAdjustmentListener [javadoc | source]

java.lang.Object
   org.apache.log4j.lf5.viewer.TrackingAdjustmentListener

All Implemented Interfaces:
AdjustmentListener

An AdjustmentListener which ensures that an Adjustable (e.g. a Scrollbar) will "track" when the Adjustable expands. For example, when a vertical scroll bar is at its bottom anchor, the scrollbar will remain at the bottom. When the vertical scroll bar is at any other location, then no tracking will happen. An instance of this class should only listen to one Adjustable as it retains state information about the Adjustable it listens to.

author: Richard - Wan

Field Summary
protected int	_lastMaximum

Method from org.apache.log4j.lf5.viewer.TrackingAdjustmentListener Summary:
adjustmentValueChanged

Methods from java.lang.Object:
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from org.apache.log4j.lf5.viewer.TrackingAdjustmentListener Detail:
public void adjustmentValueChanged(AdjustmentEvent e) { //-------------------------------------------------------------------------- // Private Variables: //-------------------------------------------------------------------------- //-------------------------------------------------------------------------- // Constructors: //-------------------------------------------------------------------------- //-------------------------------------------------------------------------- // Public Methods: //-------------------------------------------------------------------------- Adjustable bar = e.getAdjustable(); int currentMaximum = bar.getMaximum(); if (bar.getMaximum() == _lastMaximum) { return; // nothing to do, the adjustable has not expanded } int bottom = bar.getValue() + bar.getVisibleAmount(); if (bottom + bar.getUnitIncrement() >= _lastMaximum) { bar.setValue(bar.getMaximum()); // use the most recent maximum } _lastMaximum = currentMaximum; }

Method from org.apache.log4j.lf5.viewer.TrackingAdjustmentListener Detail:

 public  void adjustmentValueChanged(AdjustmentEvent e) {
  //--------------------------------------------------------------------------
  //   Private Variables:
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  //   Constructors:
  //--------------------------------------------------------------------------
  //--------------------------------------------------------------------------
  //   Public Methods:
  //--------------------------------------------------------------------------
    Adjustable bar = e.getAdjustable();
    int currentMaximum = bar.getMaximum();
    if (bar.getMaximum() == _lastMaximum) {
      return; // nothing to do, the adjustable has not expanded
    }
    int bottom = bar.getValue() + bar.getVisibleAmount();
    if (bottom + bar.getUnitIncrement()  >= _lastMaximum) {
      bar.setValue(bar.getMaximum()); // use the most recent maximum
    }
    _lastMaximum = currentMaximum;
}