RangeSlider.java

/***************************************************
*
* cismet GmbH, Saarbruecken, Germany
*
*              ... and it just works.
*
****************************************************/
package de.cismet.tools.gui;

import javax.swing.JSlider;
import javax.swing.UIManager;
import javax.swing.plaf.metal.MetalLookAndFeel;

/**
 * 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.
 *
 * <p>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.</p>
 *
 * <p>See https://ernienotes.wordpress.com/2010/12/27/creating-a-java-swing-range-slider/ for more details.</p>
 *
 * @version  $Revision$, $Date$
 */
public class RangeSlider extends JSlider {

    //~ Constructors -----------------------------------------------------------

    /**
     * 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.
     *
     * @param  min  The minimum range value.
     * @param  max  The maximum range value.
     */
    public RangeSlider(final int min, final int max) {
        super(min, max);
        initSlider();
    }

    //~ Methods ----------------------------------------------------------------

    /**
     * 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() {
        // Is it a hack or a feature? Metal UI seems to be incompatible with Netbean's Matisse. So let's ask if
        // Metal-LAF is used, if not, use normal LAF.

        if (UIManager.getLookAndFeel() instanceof MetalLookAndFeel) {
            setUI(new MetalRangeSliderUI());
        } else {
            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.
     *
     * @return  The value of the lower knob.
     */
    @Override
    public int getValue() {
        return super.getValue();
    }

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

        // Compute new value and extent to maintain upper value.
        final int oldExtent = getExtent();
        final int newValue = Math.min(Math.max(getMinimum(), value), oldValue + oldExtent);
        final 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.
     *
     * @return  The value of the upper knob.
     */
    public int getUpperValue() {
        return getValue() + getExtent();
    }

    /**
     * Sets the upper value in the range.
     *
     * @param  value  The new value of the upper knob.
     */
    public void setUpperValue(final int value) {
        // Compute new extent.
        final int lowerValue = getValue();
        final int newExtent = Math.min(Math.max(0, value - lowerValue), getMaximum() - lowerValue);

        // Set extent to set upper value.
        setExtent(newExtent);
    }
}