bundles/org.eclipse.rap.draw2d/src/org/eclipse/draw2d/DefaultRangeModel.java

/*******************************************************************************
 * Copyright (c) 2000, 2010 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.draw2d;

import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

/**
 * Generic implementation for a RangeModel.
 * 
 * 
 * <pre>
 *                    |<----extent--->|                     
 *    ----|-----------|---------------|---------------|----
 *       min          |                              max
 *                  value
 * </pre>
 */
public class DefaultRangeModel implements RangeModel {

	/**
	 * Listeners interested in the range model's property changes.
	 */
	protected PropertyChangeSupport propertyListeners = new PropertyChangeSupport(
			this);
	private int minimum = 0;
	private int maximum = 100;
	private int extent = 20;
	private int value = 0;

	/**
	 * Registers the given listener as a PropertyChangeListener.
	 * 
	 * @param listener
	 *            the listener to be added
	 * @since 2.0
	 */
	public void addPropertyChangeListener(PropertyChangeListener listener) {
		propertyListeners.addPropertyChangeListener(listener);
	}

	/**
	 * Notifies any listening PropertyChangeListeners that the property with the
	 * given id has changed.
	 * 
	 * @param string
	 *            the property name
	 * @param oldValue
	 *            the old value
	 * @param newValue
	 *            the new value
	 * @since 2.0
	 */
	protected void firePropertyChange(String string, int oldValue, int newValue) {
		propertyListeners.firePropertyChange(string, oldValue, newValue);
	}

	/**
	 * @return the extent
	 */
	public int getExtent() {
		return extent;
	}

	/**
	 * @return the maximum value
	 */
	public int getMaximum() {
		return maximum;
	}

	/**
	 * @return the minimum value
	 */
	public int getMinimum() {
		return minimum;
	}

	/**
	 * @return the current value
	 */
	public int getValue() {
		return value;
	}

	/**
	 * @return whether the extent is between the minimum and maximum values
	 */
	public boolean isEnabled() {
		return (getMaximum() - getMinimum()) > getExtent();
	}

	/**
	 * Removes the given PropertyChangeListener from the list of listeners.
	 * 
	 * @param listener
	 *            the listener to be removed
	 */
	public void removePropertyChangeListener(PropertyChangeListener listener) {
		propertyListeners.removePropertyChangeListener(listener);
	}

	/**
	 * @see org.eclipse.draw2d.RangeModel#setAll(int, int, int)
	 */
	public void setAll(int min, int ext, int max) {
		int oldMin = minimum;
		int oldExtent = extent;
		int oldMax = maximum;
		maximum = max;
		minimum = min;
		extent = ext;
		if (oldMax != max)
			firePropertyChange(PROPERTY_MAXIMUM, oldMax, max);
		if (oldExtent != ext)
			firePropertyChange(PROPERTY_EXTENT, oldExtent, ext);
		if (oldMin != min)
			firePropertyChange(PROPERTY_MINIMUM, oldMin, min);
		setValue(getValue());
	}

	/**
	 * Sets this RangeModel's extent and fires a property change if the given
	 * value is different from the current extent.
	 * 
	 * @param extent
	 *            the new extent value
	 */
	public void setExtent(int extent) {
		if (this.extent == extent)
			return;
		int oldValue = this.extent;
		this.extent = extent;
		firePropertyChange(PROPERTY_EXTENT, oldValue, extent);
		setValue(getValue());
	}

	/**
	 * Sets this RangeModel's maximum value and fires a property change if the
	 * given value is different from the current maximum value.
	 * 
	 * @param maximum
	 *            the new maximum value
	 */
	public void setMaximum(int maximum) {
		if (this.maximum == maximum)
			return;
		int oldValue = this.maximum;
		this.maximum = maximum;
		firePropertyChange(PROPERTY_MAXIMUM, oldValue, maximum);
		setValue(getValue());
	}

	/**
	 * Sets this RangeModel's minimum value and fires a property change if the
	 * given value is different from the current minimum value.
	 * 
	 * @param minimum
	 *            the new minumum value
	 */
	public void setMinimum(int minimum) {
		if (this.minimum == minimum)
			return;
		int oldValue = this.minimum;
		this.minimum = minimum;
		firePropertyChange(PROPERTY_MINIMUM, oldValue, minimum);
		setValue(getValue());
	}

	/**
	 * Sets this RangeModel's current value. If the given value is greater than
	 * the maximum, the maximum value is used. If the given value is less than
	 * the minimum, the minimum value is used. If the adjusted value is
	 * different from the current value, a property change is fired.
	 * 
	 * @param value
	 *            the new value
	 */
	public void setValue(int value) {
		value = Math.max(getMinimum(),
				Math.min(getMaximum() - getExtent(), value));
		if (this.value == value)
			return;
		int oldValue = this.value;
		this.value = value;
		firePropertyChange(PROPERTY_VALUE, oldValue, value);
	}

	/**
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		return super.toString() + " (" + minimum + ", " + maximum //$NON-NLS-2$ //$NON-NLS-1$
				+ ", " + extent + ", " + value + ")"; //$NON-NLS-3$ //$NON-NLS-2$ //$NON-NLS-1$
	}

}