path: root/libjava/javax/swing/DefaultListSelectionModel.java

/* DefaultListSelectionModel.java --
   Copyright (C) 2002, 2004 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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package javax.swing;

import java.io.Serializable;
import java.util.BitSet;
import java.util.EventListener;

import javax.swing.event.EventListenerList;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

/**
 * <p>This class provides a default implementation of {@link
 * ListSelectioModel}, which is used by {@link javax.swing.JList} and
 * similar classes to manage the selection status of a number of data
 * elements. </p>
 *
 * <p>The class is organized <em>abstractly</em> as a set of intervals of
 * integers. Each interval indicates an inclusive range of indices in a
 * list -- held by some other object and unknown to this class -- which is
 * considered "selected". There are various accessors for querying and
 * modifying the set of intervals, with simplified forms accepting a single
 * index, representing an interval with only one element. </p>
 */
public class DefaultListSelectionModel implements Cloneable,
                                                  ListSelectionModel,
                                                  Serializable
{
  private static final long serialVersionUID = -5718799865110415860L;

  /** The list of ListSelectionListeners subscribed to this selection model. */
  protected EventListenerList listenerList = new EventListenerList();


  /** 
   * The current list selection mode. Must be one of the numeric constants
   * <code>SINGLE_SELECTION</code>, <code>SINGLE_INTERVAL_SELECTION</code>
   * or <code>MULTIPLE_INTERVAL_SELECTION</code> from {@link
   * ListSelectionModel}. The default value is
   * <code>MULTIPLE_INTERVAL_SELECTION</code>.
   */
  int selectionMode = MULTIPLE_INTERVAL_SELECTION;


  /**
   * The index of the "lead" of the most recent selection. The lead is the
   * second argument in any call to {@link #setSelectionInterval}, {@link
   * #addSelectionInterval} or {@link #removeSelectionInterval}. Generally
   * the lead refers to the most recent position a user dragged their mouse
   * over.
   */
  int leadSelectionIndex = -1;


  /**
   * The index of the "anchor" of the most recent selection. The anchor is
   * the first argument in any call to {@link #setSelectionInterval},
   * {@link #addSelectionInterval} or {@link
   * #removeSelectionInterval}. Generally the anchor refers to the first
   * recent position a user clicks when they begin to drag their mouse over
   * a list.
   *
   * @see #getAnchorSelectionIndex
   * @see #setAnchorSelectionIndex
   */
  int anchorSelectionIndex = -1;


  /**
   * controls the range of indices provided in any {@link
   * ListSelectionEvent} fired by the selectionModel. Let
   * <code>[A,L]</code> be the range of indices between {@link
   * anchorSelectionIndex} and {@link leadSelectionIndex} inclusive, and
   * let <code>[i0,i1]</code> be the range of indices changed in a given
   * call which generates a {@link ListSelectionEvent}. Then when this
   * property is <code>true</code>, the {@link ListSelectionEvent} contains
   * the range <code>[A,L] union [i0,i1]</code>; when <code>false</code> it
   * will contain only <code>[i0,i1]</code>. The default is
   * <code>true</code>.
   *
   * @see #isLeadAnchorNotificationEnabled
   * @see #setLeadAnchorNotificationEnabled
   */
  boolean leadAnchorNotificationEnabled = true;


  /**
   * Whether the selection is currently "adjusting". Any {@link
   * ListSelectionEvent} events constructed in response to changes in this
   * list selection model will have their {@link
   * ListSelectionEvent#isAdjusting} field set to this value.
   *
   * @see #getValueIsAdjusting
   * @see #setValueIsAdjusting
   */
  boolean valueIsAdjusting = false;


  /** 
   * The current set of "intervals", represented simply by a {@link
   * java.util.BitSet}. A set bit indicates a selected index, whereas a
   * cleared bit indicates a non-selected index.
   */
  BitSet sel = new BitSet();


  /**
   * Gets the value of the {@link #selectionMode} property.
   *
   * @return The current value of the property
   */
  public int getSelectionMode()
  {
    return selectionMode;
  }

  /**
   * Sets the value of the {@link #selectionMode} property.
   *
   * @param a The new value of the property
   */
  public void setSelectionMode(int a)
  {
    selectionMode = a;
  }

  /**
   * Gets the value of the {@link #anchorSelectionIndex} property.
   * 
   * @return The current property value
   *
   * @see #setAnchorSelectionIndex
   */
  public int getAnchorSelectionIndex()
  {
    return anchorSelectionIndex;
  }

  /**
   * Sets the value of the {@link #anchorSelectionIndex} property.
   * 
   * @param anchorIndex The new property value
   *
   * @see #getAnchorSelectionIndex
   */
  public void setAnchorSelectionIndex(int anchorIndex)
  {
    anchorSelectionIndex = anchorIndex;
  }
  
  /**
   * Gets the value of the {@link #leadSelectionIndex} property.
   * 
   * @return The current property value
   *
   * @see #setLeadSelectionIndex
   */
  public int getLeadSelectionIndex()
  {
    return leadSelectionIndex;
  }

  /**
   * <p>Sets the value of the {@link #anchorSelectionIndex} property. As a
   * side effect, alters the selection status of two ranges of indices. Let
   * <code>OL</code> be the old lead selection index, <code>NL</code> be
   * the new lead selection index, and <code>A</code> be the anchor
   * selection index. Then if <code>A</code> is a valid selection index,
   * one of two things happens depending on the seleciton status of
   * <code>A</code>:</p>
   *
   * <ul>
   *
   * <li><code>isSelectedIndex(A) == true</code>: set <code>[A,OL]</code>
   * to <em>deselected</em>, then set <code>[A,NL]</code> to
   * <em>selected</em>.</li>
   *
   * <li><code>isSelectedIndex(A) == false</code>: set <code>[A,OL]</code>
   * to <em>selected</em>, then set <code>[A,NL]</code> to
   * <em>deselected</em>.</li>
   *
   * </ul>
   *
   * <p>This method generates at most a single {@link ListSelectionEvent}
   * despite changing multiple ranges. The range of values provided to the
   * {@link ListSelectionEvent} includes only the minimum range of values
   * which changed selection status between the beginning and end of the
   * method.</p>
   * 
   * @param anchorIndex The new property value
   *
   * @see #getAnchorSelectionIndex
   */
  public void setLeadSelectionIndex(int leadIndex)
  {
    int oldLeadIndex = leadSelectionIndex;
    leadSelectionIndex = leadIndex;

    if (anchorSelectionIndex == -1)
      return;

    int R1 = Math.min(anchorSelectionIndex, oldLeadIndex);
    int R2 = Math.max(anchorSelectionIndex, oldLeadIndex);
    int S1 = Math.min(anchorSelectionIndex, leadIndex);
    int S2 = Math.max(anchorSelectionIndex, leadIndex);
    
    int lo = Math.min(R1, S1);
    int hi = Math.max(R2, S2);

    BitSet oldRange = sel.get(lo, hi+1);

    if (isSelectedIndex(anchorSelectionIndex))
      {
        sel.clear(R1, R2+1);
        sel.set(S1, S2+1);
      }
    else
      {
        sel.set(R1, R2+1);
        sel.clear(S1, S2+1);
      }
    
    BitSet newRange = sel.get(lo, hi+1);
    newRange.xor(oldRange);

    int beg = sel.nextSetBit(0), end = -1;
    for(int i=beg; i >= 0; i=sel.nextSetBit(i+1)) 
      { 
        end = i;
      }
    fireValueChanged(beg, end, valueIsAdjusting);    
  }

  /**
   * Gets the value of the {@link #leadAnchorNotificationEnabled} property.
   * 
   * @return The current property value
   *
   * @see #setLeadAnchorNotificationEnabled
   */
  public boolean isLeadAnchorNotificationEnabled()
  {
    return leadAnchorNotificationEnabled;
  }

  /**
   * Sets the value of the {@link #leadAnchorNotificationEnabled} property.
   * 
   * @param flag The new property value
   *
   * @see #getLeadAnchorNotificationEnabled
   */
  public void setLeadAnchorNotificationEnabled(boolean l)
  {
    leadAnchorNotificationEnabled = l;
  }


  /**
   * Gets the value of the {@link #valueIsAdjusting} property.
   *
   * @return The current property value
   *
   * @see #setValueIsAdjusting
   */
  public boolean getValueIsAdjusting()
  {
    return valueIsAdjusting;
  }

  /**
   * Sets the value of the {@link #valueIsAdjusting} property.
   *
   * @param v The new property value
   *
   * @see #getValueIsAdjusting
   */
  public void setValueIsAdjusting(boolean v)
  {
    valueIsAdjusting = v;
  }

  /**
   * Determines whether the selection is empty.
   *
   * @return <code>true</code> if the selection is empty, otherwise
   * <code>false</code>
   */
  public boolean isSelectionEmpty()
  {
    return sel.isEmpty();
  }


  /**
   * Gets the smallest index which is currently a member of a selection
   * interval.
   *
   * @return The least integer <code>i</code> such that <code>i >=
   * 0</code> and <code>i</code> is a member of a selected interval, or
   * <code>-1</code> if there are no selected intervals
   *
   * @see #getMaxSelectionIndex
   */
  public int getMinSelectionIndex()
  {
    if (isSelectionEmpty())
      return -1;
    
    return sel.nextSetBit(0);
  }

  /**
   * Gets the largest index which is currently a member of a selection
   * interval.
   *
   * @return The greatest integer <code>i</code> such that <code>i >=
   * 0</code> and <code>i</code> is a member of a selected interval, or
   * <code>-1</code> if there are no selected intervals
   *
   * @see #getMinSelectionIndex
   */
  public int getMaxSelectionIndex()
  {
    if (isSelectionEmpty())
      return -1;

    int mx = -1;
    for(int i=sel.nextSetBit(0); i >= 0; i=sel.nextSetBit(i+1)) 
      { 
        mx = i;
      }
    return mx;
  }

  /**
   * Determines whether a particular index is a member of a selection
   * interval.
   *
   * @param a The index to search for
   *
   * @return <code>true</code> if the index is a member of a selection interval,
   * otherwise <code>false</code>
   */
  public boolean isSelectedIndex(int a)
  {
    return sel.get(a);
  }

  /**
   * If the {@link #selectionMode} property is equal to
   * <code>SINGLE_SELECTION</code> or
   * <code>SINGLE_INTERVAL_SELECTION</code>, equivalent to calling
   * <code>setSelectionInterval(index1, index2)</code>; otherwise adds the
   * range <code>[index0, index1]</code> to the selection interval set.
   *
   * @param index0 The beginning of the range of indices to select
   * @param index1 The end of the range of indices to select
   *
   * @see #setSelectionInterval
   * @see #removeSelectionInterval
   */
  public void addSelectionInterval(int index0, int index1) 
  {
    if (selectionMode == SINGLE_SELECTION
        || selectionMode == SINGLE_INTERVAL_SELECTION)
      sel.clear();
    
    if (selectionMode == SINGLE_SELECTION)
      index0 = index1;

    int lo = Math.min(index0, index1);
    int hi = Math.max(index0, index1);

    sel.set(lo, hi+1);
    fireValueChanged(lo, hi, valueIsAdjusting);
  }


  /**
   * Deselects all indices in the inclusive range
   * <code>[index0,index1]</code>.
   *
   * @param index0 The beginning of the range of indices to deselect
   * @param index1 The end of the range of indices to deselect
   *
   * @see #addSelectionInterval
   * @see #setSelectionInterval
   */
  public void removeSelectionInterval(int index0,
                                      int index1)
  {
    int lo = Math.min(index0, index1);
    int hi = Math.max(index0, index1);
    sel.clear(lo, hi+1); 
    fireValueChanged(lo, hi, valueIsAdjusting);
  }

  /**
   * Removes all intervals in the selection set.
   */
  public void clearSelection()
  {
    int sz = sel.size();
    sel.clear();
    fireValueChanged(0, sz, valueIsAdjusting);
  }
  
  /**
   * Clears the current selection and marks a given interval as
   * "selected". If the current selection mode is
   * <code>SINGLE_SELECTION</code> only the index <code>index2</code> is
   * selected.
   *
   * @param index0 The low end of the new selection 
   * @param index1 The high end of the new selection
   */
  public void setSelectionInterval(int index0, int index1)
  {
    sel.clear();
    if (selectionMode == SINGLE_SELECTION)
      index0 = index1;

    int lo = Math.min(index0, index1);
    int hi = Math.max(index0, index1);
    sel.set(lo, hi+1);
    fireValueChanged(lo, hi, valueIsAdjusting);
  }

  /**
   * Inserts a number of indices either before or after a particular
   * position in the set of indices. Renumbers all indices after the
   * inserted range. The new indices in the inserted range are not
   * selected. This method is typically called to synchronize the selection
   * model with an inserted range of elements in a {@link ListModel}.
   *
   * @param index The position to insert indices at
   * @param length The number of indices to insert
   * @param before Indicates whether to insert the indices before the index
   * or after it
   */
  public void insertIndexInterval(int index,
                                  int length,
                                  boolean before)
  {
    if (!before)
      {        
        index++;
        length--;
      }
    BitSet tmp = sel.get(index, sel.size());
    sel.clear(index, sel.size());
    int n = tmp.size();
    for (int i = 0; i < n; ++i)
      sel.set(index + length + i, tmp.get(i));
  }

  /**
   * Removes a range from the set of indices. Renumbers all indices after
   * the removed range. This method is typically called to synchronize the
   * selection model with a deleted range of elements in a {@link
   * ListModel}.
   *
   * @param index0 The first index to remove (inclusive)
   * @param index1 The last index to remove (inclusive)
   */
  public void removeIndexInterval(int index0,
                                  int index1)
  {
    int lo = Math.min(index0, index1);
    int hi = Math.max(index0, index1);

    BitSet tmp = sel.get(hi, sel.size());
    sel.clear(lo, sel.size());
    int n = tmp.size();
    for (int i = 0; i < n; ++i)
      sel.set(lo + i, tmp.get(i));
  }

  /**
   * Fires a {@link ListSelectionEvent} to all the listeners of type {@link
   * ListSelectionListener} registered with this selection model.
   *
   * @param firstIndex The low index of the changed range
   * @param lastIndex The high index of the changed range
   * @param isAdjusting Whether this change is part of a seqence of adjustments
   * made to the selection, such as during interactive scrolling
   */
  protected void fireValueChanged(int firstIndex, int lastIndex,
				  boolean isAdjusting)
  {
    ListSelectionEvent evt = new ListSelectionEvent(this, firstIndex,
                                                    lastIndex, isAdjusting);
    ListSelectionListener[] listeners = getListSelectionListeners();
    for (int i = 0; i < listeners.length; ++i)
      listeners[i].valueChanged(evt);
  }

  /**
   * Adds a listener.
   *
   * @param listener The listener to add
   *
   * @see removeListSelectionListener
   * @see getListSelectionListeners
   */
  public void addListSelectionListener(ListSelectionListener listener)
  {
    listenerList.add(ListSelectionListener.class, listener);
  }

  /**
   * Removes a registered listener.
   *
   * @param listener The listener to remove
   *
   * @see addListSelectionListener
   * @see getListSelectionListeners
   */
  public void removeListSelectionListener(ListSelectionListener listener)
  {
    listenerList.remove(ListSelectionListener.class, listener);
  }

  /**
   * Returns an array of all registerers listeners.
   *
   * @param listenerType The type of listener to retrieve
   *
   * @return The array
   *
   * @see getListSelectionListener
   * @since 1.3
   */
  public EventListener[] getListeners(Class listenerType)
  {
    return listenerList.getListeners(listenerType);
  }

  /**
   * Returns an array of all registerd list selection listeners.
   *
   * @return the array
   *
   * @see addListSelectionListener
   * @see removeListSelectionListener
   * @see getListeners
   * @since 1.4
   */
  public ListSelectionListener[] getListSelectionListeners()
  {
    return (ListSelectionListener[]) getListeners(ListSelectionListener.class);
  }
}