path: root/javax/swing/JScrollBar.java

/* JScrollBar.java --
   Copyright (C) 2002, 2004, 2005, 2006,  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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02110-1301 USA.

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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing;

import java.awt.Adjustable;
import java.awt.Dimension;
import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.beans.PropertyChangeEvent;

import javax.accessibility.Accessible;
import javax.accessibility.AccessibleContext;
import javax.accessibility.AccessibleRole;
import javax.accessibility.AccessibleState;
import javax.accessibility.AccessibleStateSet;
import javax.accessibility.AccessibleValue;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ScrollBarUI;

/**
 * The JScrollBar. Two buttons control how the values that the 
 * scroll bar can take. You can also drag the thumb or click the track
 * to move the scroll bar. Typically, the JScrollBar is used with
 * other components to translate the value of the bar to the viewable
 * contents of the other components.
 */
public class JScrollBar extends JComponent implements Adjustable, Accessible
{
  /**
   * Provides the accessibility features for the <code>JScrollBar</code>
   * component.
   */
  protected class AccessibleJScrollBar extends JComponent.AccessibleJComponent
    implements AccessibleValue
  {
    private static final long serialVersionUID = -7758162392045586663L;
    
    /**
     * Creates a new <code>AccessibleJScrollBar</code> instance.
     */
    protected AccessibleJScrollBar()
    {
      super();
    }

    /**
     * Returns a set containing the current state of the {@link JScrollBar} 
     * component.
     *
     * @return The accessible state set.
     */
    public AccessibleStateSet getAccessibleStateSet()
    {
      AccessibleStateSet result = super.getAccessibleStateSet();
      if (orientation == JScrollBar.HORIZONTAL)
        result.add(AccessibleState.HORIZONTAL);
      else if (orientation == JScrollBar.VERTICAL)
        result.add(AccessibleState.VERTICAL);
      return result;
    }

    /**
     * Returns the accessible role for the <code>JScrollBar</code> component.
     *
     * @return {@link AccessibleRole#SCROLL_BAR}.
     */
    public AccessibleRole getAccessibleRole()
    {
      return AccessibleRole.SCROLL_BAR;
    }

    /**
     * Returns an object that provides access to the current, minimum and 
     * maximum values.
     *
     * @return The accessible value.
     */
    public AccessibleValue getAccessibleValue()
    {
      return this;
    }

    /**
     * Returns the current value of the {@link JScrollBar} component, as an
     * {@link Integer}.
     *
     * @return The current value of the {@link JScrollBar} component.
     */
    public Number getCurrentAccessibleValue()
    {
      return new Integer(getValue());
    }

    /**
     * Sets the current value of the {@link JScrollBar} component and sends a
     * {@link PropertyChangeEvent} (with the property name 
     * {@link AccessibleContext#ACCESSIBLE_VALUE_PROPERTY}) to all registered
     * listeners.  If the supplied value is <code>null</code>, this method 
     * does nothing and returns <code>false</code>.
     *
     * @param value  the new slider value (<code>null</code> permitted).
     *
     * @return <code>true</code> if the slider value is updated, and 
     *     <code>false</code> otherwise.
     */
    public boolean setCurrentAccessibleValue(Number value)
    {
      if (value == null)
        return false;
      Number oldValue = getCurrentAccessibleValue();
      setValue(value.intValue());
      firePropertyChange(AccessibleContext.ACCESSIBLE_VALUE_PROPERTY, oldValue, 
                         new Integer(getValue()));
      return true;
    }

    /**
     * Returns the minimum value of the {@link JScrollBar} component, as an
     * {@link Integer}.
     *
     * @return The minimum value of the {@link JScrollBar} component.
     */
    public Number getMinimumAccessibleValue()
    {
      return new Integer(getMinimum());
    }

    /**
     * Returns the maximum value of the {@link JScrollBar} component, as an
     * {@link Integer}.
     *
     * @return The maximum value of the {@link JScrollBar} component.
     */
    public Number getMaximumAccessibleValue()
    {
      return new Integer(getMaximum() - model.getExtent());
    }
  }

  /**
   * Listens for changes on the model and fires them to interested
   * listeners on the JScrollBar, after re-sourcing them.
   */
  private class ScrollBarChangeListener
    implements ChangeListener
  {

    public void stateChanged(ChangeEvent event)
    {
      Object o = event.getSource();
      if (o instanceof BoundedRangeModel)
        {
          BoundedRangeModel m = (BoundedRangeModel) o;
          fireAdjustmentValueChanged(AdjustmentEvent.ADJUSTMENT_VALUE_CHANGED,
                                     AdjustmentEvent.TRACK, m.getValue(),
                                     m.getValueIsAdjusting());
        }
    }
    
  }

  private static final long serialVersionUID = -8195169869225066566L;
  
  /** How much the thumb moves when moving in a block. */
  protected int blockIncrement = 10;

  /** The model that holds the scroll bar's data. */
  protected BoundedRangeModel model;

  /** The orientation of the scroll bar. */
  protected int orientation = SwingConstants.VERTICAL;

  /** How much the thumb moves when moving in a unit. */
  protected int unitIncrement = 1;

  /**
   * This ChangeListener forwards events fired from the model and re-sources
   * them to originate from this JScrollBar.
   */
  private ChangeListener sbChangeListener;

  /** 
   * Creates a new horizontal JScrollBar object with a minimum
   * of 0, a maxmium of 100, a value of 0 and an extent of 10.
   */
  public JScrollBar()
  {
    this(SwingConstants.VERTICAL, 0, 10, 0, 100);
  }

  /**
   * Creates a new JScrollBar object with a minimum of 0, a 
   * maximum of 100, a value of 0, an extent of 10 and the given
   * orientation.
   *
   * @param orientation The orientation of the JScrollBar.
   */
  public JScrollBar(int orientation)
  {
    this(orientation, 0, 10, 0, 100);
  }

  /**
   * Creates a new JScrollBar object with the given orientation, 
   * value, min, max, and extent.
   *
   * @param orientation The orientation to use.
   * @param value The value to use.
   * @param extent The extent to use.
   * @param min The minimum value of the scrollbar.
   * @param max The maximum value of the scrollbar.
   */
  public JScrollBar(int orientation, int value, int extent, int min, int max)
  {
    model = new DefaultBoundedRangeModel(value, extent, min, max);
    sbChangeListener = new ScrollBarChangeListener();
    model.addChangeListener(sbChangeListener);
    if (orientation != SwingConstants.HORIZONTAL
        && orientation != SwingConstants.VERTICAL)
      throw new IllegalArgumentException(orientation
                                         + " is not a legal orientation");
    this.orientation = orientation;
    updateUI();
  }

  /**
   * This method sets the UI of this scrollbar to
   * the given UI.
   *
   * @param ui The UI to use with this scrollbar.
   */
  public void setUI(ScrollBarUI ui)
  {
    super.setUI(ui);
  }

  /**
   * This method returns the UI that is being used
   * with this scrollbar.
   *
   * @return The scrollbar's current UI.
   */
  public ScrollBarUI getUI()
  {
    return (ScrollBarUI) ui;
  }

  /**
   * This method changes the UI to be the
   * default for the current look and feel.
   */
  public void updateUI()
  {
    setUI((ScrollBarUI) UIManager.getUI(this));
  }

  /**
   * This method returns an identifier to 
   * choose the correct UI delegate for the
   * scrollbar.
   *
   * @return The identifer to choose the UI delegate; "ScrollBarUI"
   */
  public String getUIClassID()
  {
    return "ScrollBarUI";
  }

  /**
   * This method returns the orientation of the scrollbar.
   *
   * @return The orientation of the scrollbar.
   */
  public int getOrientation()
  {
    return orientation;
  }

  /**
   * This method sets the orientation of the scrollbar.
   *
   * @param orientation The orientation of the scrollbar.
   */
  public void setOrientation(int orientation)
  {
    if (orientation != SwingConstants.HORIZONTAL
        && orientation != SwingConstants.VERTICAL)
      throw new IllegalArgumentException("orientation must be one of HORIZONTAL or VERTICAL");
    if (orientation != this.orientation)
      {
	int oldOrientation = this.orientation;
	this.orientation = orientation;
	firePropertyChange("orientation", oldOrientation,
	                   this.orientation);
      }
  }

  /**
   * This method returns the model being used with 
   * the scrollbar.
   *
   * @return The scrollbar's model.
   */
  public BoundedRangeModel getModel()
  {
    return model;
  }

  /**
   * This method sets the model to use with
   * the scrollbar.
   *
   * @param newModel The new model to use with the scrollbar.
   */
  public void setModel(BoundedRangeModel newModel)
  {
    BoundedRangeModel oldModel = model;
    if (oldModel != null)
      oldModel.removeChangeListener(sbChangeListener);
    model = newModel;
    if (model != null)
      model.addChangeListener(sbChangeListener);
    firePropertyChange("model", oldModel, model);
  }

  /**
   * This method returns how much the scrollbar's value
   * should change for a unit increment depending on the 
   * given direction.
   *
   * @param direction The direction to scroll in.
   *
   * @return The amount the scrollbar's value will change given the direction.
   */
  public int getUnitIncrement(int direction)
  {
    return direction * unitIncrement;
  }

  /**
   * This method sets the unitIncrement property.
   *
   * @param unitIncrement The new unitIncrement.
   */
  public void setUnitIncrement(int unitIncrement)
  {
    if (unitIncrement != this.unitIncrement)
      {
	int oldInc = this.unitIncrement;
	this.unitIncrement = unitIncrement;
	firePropertyChange("unitIncrement", oldInc,
	                   this.unitIncrement);
      }
  }

  /**
   * The method returns how much the scrollbar's value
   * should change for a block increment depending on
   * the given direction.
   *
   * @param direction The direction to scroll in.
   *
   * @return The amount the scrollbar's value will change given the direction.
   */
  public int getBlockIncrement(int direction)
  {
    return direction * blockIncrement;
  }

  /**
   * This method sets the blockIncrement property.
   *
   * @param blockIncrement The new blockIncrement.
   */
  public void setBlockIncrement(int blockIncrement)
  {
    if (blockIncrement != this.blockIncrement)
      {
	int oldInc = this.blockIncrement;
	this.blockIncrement = blockIncrement;
	firePropertyChange("blockIncrement", oldInc,
	                   this.blockIncrement);
      }
  }

  /**
   * This method returns the unitIncrement.
   *
   * @return The unitIncrement.
   */
  public int getUnitIncrement()
  {
    return unitIncrement;
  }

  /**
   * This method returns the blockIncrement.
   *
   * @return The blockIncrement.
   */
  public int getBlockIncrement()
  {
    return blockIncrement;
  }

  /**
   * This method returns the value of the scrollbar.
   *
   * @return The value of the scrollbar.
   */
  public int getValue()
  {
    return model.getValue();
  }

  /**
   * This method changes the value of the scrollbar.
   *
   * @param value The new value of the scrollbar.
   */
  public void setValue(int value)
  {
    model.setValue(value);
  }

  /**
   * This method returns the visible amount (AKA extent). 
   * The visible amount can be used by UI delegates to 
   * determine the size of the thumb.
   *
   * @return The visible amount (AKA extent).
   */
  public int getVisibleAmount()
  {
    return model.getExtent();
  }

  /**
   * This method sets the visible amount (AKA extent).
   *
   * @param extent The visible amount (AKA extent).
   */
  public void setVisibleAmount(int extent)
  {
    model.setExtent(extent);
  }

  /**
   * This method returns the minimum value of the scrollbar.
   *
   * @return The minimum value of the scrollbar.
   */
  public int getMinimum()
  {
    return model.getMinimum();
  }

  /**
   * This method sets the minimum value of the scrollbar.
   *
   * @param minimum The minimum value of the scrollbar.
   */
  public void setMinimum(int minimum)
  {
    model.setMinimum(minimum);
  }

  /**
   * This method returns the maximum value of the scrollbar.
   *
   * @return The maximum value of the scrollbar.
   */
  public int getMaximum()
  {
    return model.getMaximum();
  }

  /**
   * This method sets the maximum value of the scrollbar.
   *
   * @param maximum The maximum value of the scrollbar.
   */
  public void setMaximum(int maximum)
  {
    model.setMaximum(maximum);
  }

  /**
   * This method returns the model's isAjusting value.
   *
   * @return The model's isAdjusting value.
   */
  public boolean getValueIsAdjusting()
  {
    return model.getValueIsAdjusting();
  }

  /**
   * This method sets the model's isAdjusting value.
   *
   * @param b The new isAdjusting value.
   */
  public void setValueIsAdjusting(boolean b)
  {
    model.setValueIsAdjusting(b);
  }

  /**
   * This method sets the value, extent, minimum and 
   * maximum.
   *
   * @param newValue The new value.
   * @param newExtent The new extent.
   * @param newMin The new minimum.
   * @param newMax The new maximum.
   */
  public void setValues(int newValue, int newExtent, int newMin, int newMax)
  {
    model.setRangeProperties(newValue, newExtent, newMin, newMax,
                             model.getValueIsAdjusting());
  }

  /**
   * This method adds an AdjustmentListener to the scroll bar.
   *
   * @param listener The listener to add.
   */
  public void addAdjustmentListener(AdjustmentListener listener)
  {
    listenerList.add(AdjustmentListener.class, listener);
  }

  /**
   * This method removes an AdjustmentListener from the scroll bar. 
   *
   * @param listener The listener to remove.
   */
  public void removeAdjustmentListener(AdjustmentListener listener)
  {
    listenerList.remove(AdjustmentListener.class, listener);
  }

  /**
   * This method returns an arry of all AdjustmentListeners listening to 
   * this scroll bar.
   *
   * @return An array of AdjustmentListeners listening to this scroll bar.
   */
  public AdjustmentListener[] getAdjustmentListeners()
  {
    return (AdjustmentListener[]) listenerList.getListeners(AdjustmentListener.class);
  }

  /**
   * This method is called to fired AdjustmentEvents to the listeners
   * of this scroll bar. All AdjustmentEvents that are fired
   * will have an ID of ADJUSTMENT_VALUE_CHANGED and a type of
   * TRACK. 
   *
   * @param id The ID of the adjustment event.
   * @param type The Type of change.
   * @param value The new value for the property that was changed..
   */
  protected void fireAdjustmentValueChanged(int id, int type, int value)
  {
    fireAdjustmentValueChanged(id, type, value, getValueIsAdjusting());
  }

  /**
   * Helper method for firing adjustment events that can have their
   * isAdjusting field modified.
   *
   * This is package private to avoid an accessor method.
   *
   * @param id the ID of the event
   * @param type the type of the event
   * @param value the value
   * @param isAdjusting if the scrollbar is adjusting or not
   */
  void fireAdjustmentValueChanged(int id, int type, int value,
                                          boolean isAdjusting)
  {
    Object[] adjustmentListeners = listenerList.getListenerList();
    AdjustmentEvent adjustmentEvent = new AdjustmentEvent(this, id, type,
                                                          value, isAdjusting);
    for (int i = adjustmentListeners.length - 2; i >= 0; i -= 2)
      {
        if (adjustmentListeners[i] == AdjustmentListener.class)
          ((AdjustmentListener) adjustmentListeners[i + 1]).adjustmentValueChanged(adjustmentEvent);
      }
  }

  /**
   * This method returns the minimum size for this scroll bar.
   *
   * @return The minimum size.
   */
  public Dimension getMinimumSize()
  {
    return ui.getMinimumSize(this);
  }

  /**
   * This method returns the maximum size for this scroll bar.
   *
   * @return The maximum size.
   */
  public Dimension getMaximumSize()
  {
    return ui.getMaximumSize(this);
  }

  /**
   * This method overrides the setEnabled in JComponent.
   * When the scroll bar is disabled, the knob cannot
   * be moved.
   *
   * @param x Whether the scrollbar is enabled.
   */
  public void setEnabled(boolean x)
  {
    // nothing special needs to be done here since we 
    // just check the enabled setting before changing the value.
    super.setEnabled(x);
  }

  /**
   * Returns a string describing the attributes for the <code>JScrollBar</code>
   * component, for use in debugging.  The return value is guaranteed to be 
   * non-<code>null</code>, but the format of the string may vary between
   * implementations.
   *
   * @return A string describing the attributes of the <code>JScrollBar</code>.
   */
  protected String paramString()
  {
    StringBuffer sb = new StringBuffer(super.paramString());
    sb.append(",blockIncrement=").append(blockIncrement);
    sb.append(",orientation=");
    if (this.orientation == JScrollBar.HORIZONTAL)
      sb.append("HORIZONTAL");
    else 
      sb.append("VERTICAL");
    sb.append(",unitIncrement=").append(unitIncrement);
    return sb.toString();
  }

  /**
   * Returns the object that provides accessibility features for this
   * <code>JScrollBar</code> component.
   *
   * @return The accessible context (an instance of 
   *     {@link AccessibleJScrollBar}).
   */
  public AccessibleContext getAccessibleContext()
  {
    if (accessibleContext == null)
      accessibleContext = new AccessibleJScrollBar();
    return accessibleContext;
  }
}