RangeSlider.java

/*
The MIT License

Copyright (c) 2010 Ernest Yu. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package figtree.ui.components;

import javax.swing.JSlider;

/**
 * An extension of JSlider to select a range of values using two thumb controls.
 * The thumb controls are used to select the lower and upper value of a range
 * with predetermined minimum and maximum values.
 * 
 * Note that RangeSlider makes use of the default BoundedRangeModel, which
 * supports an inner range defined by a value and an extent.  The upper value
 * returned by RangeSlider is simply the lower value plus the extent.
 *
 * @version $Id$
 *
 * $HeadURL$
 *
 * $LastChangedBy$
 * $LastChangedDate$
 * $LastChangedRevision$
 */
public class RangeSlider extends JSlider {

    /**
     * Constructs a RangeSlider with default minimum and maximum values of 0
     * and 100.
     */
    public RangeSlider() {
        initSlider();
    }

    /**
     * Constructs a RangeSlider with the specified default minimum and maximum 
     * values.
     */
    public RangeSlider(int min, int max) {
        super(min, max);
        initSlider();
    }

    /**
     * Initializes the slider by setting default properties.
     */
    private void initSlider() {
        setOrientation(HORIZONTAL);
    }

    /**
     * Overrides the superclass method to install the UI delegate to draw two
     * thumbs.
     */
    @Override
    public void updateUI() {
        setUI(new RangeSliderUI(this));
        // Update UI for slider labels.  This must be called after updating the
        // UI of the slider.  Refer to JSlider.updateUI().
        updateLabelUIs();
    }

    /**
     * Returns the lower value in the range.
     */
    @Override
    public int getValue() {
        return super.getValue();
    }

    /**
     * Sets the lower value in the range.
     */
    @Override
    public void setValue(int value) {
        int oldValue = getValue();
        if (oldValue == value) {
            return;
        }

        // Compute new value and extent to maintain upper value.
        int oldExtent = getExtent();
        int newValue = Math.min(Math.max(getMinimum(), value), oldValue + oldExtent);
        int newExtent = oldExtent + oldValue - newValue;

        // Set new value and extent, and fire a single change event.
        getModel().setRangeProperties(newValue, newExtent, getMinimum(), 
            getMaximum(), getValueIsAdjusting());
    }

    /**
     * Returns the upper value in the range.
     */
    public int getUpperValue() {
        return getValue() + getExtent();
    }

    /**
     * Sets the upper value in the range.
     */
    public void setUpperValue(int value) {
        // Compute new extent.
        int lowerValue = getValue();
        int newExtent = Math.min(Math.max(0, value - lowerValue), getMaximum() - lowerValue);
        
        // Set extent to set upper value.
        setExtent(newExtent);
    }
}