// draw the radius grid lines, if any...
        if (isRadiusGridlinesVisible()) {
            Stroke gridStroke = getRadiusGridlineStroke();
            Paint gridPaint = getRadiusGridlinePaint();
            if ((gridStroke != null) && (gridPaint != null)) {
                this.renderer.drawRadialGridLines(
                    g2, this, this.axis, radialTicks, dataArea
                );
            }
        }      
    }
   
    /**
     * Zooms the axis ranges by the specified percentage about the anchor point.
     *
     * @param percent  the amount of the zoom.
     */
    public void zoom(double percent) {
        if (percent > 0.0) {
            double radius = getMaxRadius();
            double scaledRadius = radius * percent;
            this.axis.setUpperBound(scaledRadius);
            getAxis().setAutoRange(false);
        } 
        else {
            getAxis().setAutoRange(true);
        }
    }
   
    /**
     * Returns the range for the specified axis.
     *
     * @param axis  the axis.
     *
     * @return The range.
     */
    public Range getDataRange(ValueAxis axis) {
        Range result = null;
        if (this.dataset != null) {
            result = Range.combine(result, 
                    DatasetUtilities.findRangeBounds(this.dataset));
        }
        return result;
    }
   
    /**
     * Receives notification of a change to the plot's m_Dataset.
     * <P>
     * The axis ranges are updated if necessary.
     *
     * @param event  information about the event (not used here).
     */
    public void datasetChanged(DatasetChangeEvent event) {

        if (this.axis != null) {
            this.axis.configure();
        }
       
        if (getParent() != null) {
            getParent().datasetChanged(event);
        }
        else {
            super.datasetChanged(event);
        }
    }
   
    /**
     * Notifies all registered listeners of a property change.
     * <P>
     * One source of property change events is the plot's m_Renderer.
     *
     * @param event  information about the property change.
     */
    public void rendererChanged(RendererChangeEvent event) {
        notifyListeners(new PlotChangeEvent(this));
    }
   
    /**
     * Returns the number of series in the dataset for this plot.  If the 
     * dataset is <code>null</code>, the method returns 0.
     *
     * @return The series count.
     */
    public int getSeriesCount() {
        int result = 0;
       
        if (this.dataset != null) {
            result = this.dataset.getSeriesCount();
        }
        return result;
    }
   
    /**
     * Returns the legend items for the plot.  Each legend item is generated by
     * the plot's m_Renderer, since the m_Renderer is responsible for the visual
     * representation of the data.
     *
     * @return The legend items.
     */
    public LegendItemCollection getLegendItems() {
        LegendItemCollection result = new LegendItemCollection();
       
        // get the legend items for the main m_Dataset...
        if (this.dataset != null) {
            if (this.renderer != null) {
                int seriesCount = this.dataset.getSeriesCount();
                for (int i = 0; i < seriesCount; i++) {
                    LegendItem item = this.renderer.getLegendItem(i);
                    result.add(item);
                }
            }
        }      
        return result;
    }
   
    /**
     * Tests this plot for equality with another object.
     *
     * @param obj  the object (<code>null</code> permitted).
     *
     * @return <code>true</code> or <code>false</code>.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof PolarPlot)) {
            return false;
        }
        if (!super.equals(obj)) {
            return false;
        }
        PolarPlot that = (PolarPlot) obj;
        if (!ObjectUtilities.equal(this.axis, that.axis)) {
            return false;
        }
        if (!ObjectUtilities.equal(this.renderer, that.renderer)) {
            return false;
        }
        if (this.angleGridlinesVisible != that.angleGridlinesVisible) {
            return false;
        }
        if (this.angleLabelsVisible != that.angleLabelsVisible) {
            return false;   
        }
        if (!this.angleLabelFont.equals(that.angleLabelFont)) {
            return false;   
        }
        if (!PaintUtilities.equal(this.angleLabelPaint, that.angleLabelPaint)) {
            return false;   
        }
        if (!ObjectUtilities.equal(
            this.angleGridlineStroke, that.angleGridlineStroke
        )) {
            return false;
        }
        if (!PaintUtilities.equal(
            this.angleGridlinePaint, that.angleGridlinePaint
        )) {
            return false;
        }
        if (this.radiusGridlinesVisible != that.radiusGridlinesVisible) {
            return false;
        }
        if (!ObjectUtilities.equal(
            this.radiusGridlineStroke, that.radiusGridlineStroke
        )) {
            return false;
        }
        if (!PaintUtilities.equal(
            this.radiusGridlinePaint, that.radiusGridlinePaint
        )) {
            return false;
        }
        return true;
    }
   
    /**
     * Returns a clone of the plot.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException  this can occur if some component of 
     *         the plot cannot be cloned.
     */
    public Object clone() throws CloneNotSupportedException {
      
        PolarPlot clone = (PolarPlot) super.clone();
        if (this.axis != null) {
            clone.axis = (ValueAxis) ObjectUtilities.clone(this.axis);
            clone.axis.setPlot(clone);
            clone.axis.addChangeListener(clone);
        }
      
        if (clone.dataset != null) {
            clone.dataset.addChangeListener(clone);
        }
      
        if (this.renderer != null) {
            clone.renderer 
                = (PolarItemRenderer) ObjectUtilities.clone(this.renderer);
        }
       
        return clone;
    }
   
    /**
     * Provides serialization support.
     *
     * @param stream  the output stream.
     *
     * @throws IOException  if there is an I/O error.
     */
    private void writeObject(ObjectOutputStream stream) throws IOException {
        stream.defaultWriteObject();
        SerialUtilities.writeStroke(this.angleGridlineStroke, stream);
        SerialUtilities.writePaint(this.angleGridlinePaint, stream);
        SerialUtilities.writeStroke(this.radiusGridlineStroke, stream);
        SerialUtilities.writePaint(this.radiusGridlinePaint, stream);
    }
   
    /**
     * Provides serialization support.
     *
     * @param stream  the input stream.
     *
     * @throws IOException  if there is an I/O error.
     * @throws ClassNotFoundException  if there is a classpath problem.
     */
    private void readObject(ObjectInputStream stream) 
        throws IOException, ClassNotFoundException {
      
        stream.defaultReadObject();
        this.angleGridlineStroke = SerialUtilities.readStroke(stream);
        this.angleGridlinePaint = SerialUtilities.readPaint(stream);
        this.radiusGridlineStroke = SerialUtilities.readStroke(stream);
        this.radiusGridlinePaint = SerialUtilities.readPaint(stream);
      
        if (this.axis != null) {
            this.axis.setPlot(this);
            this.axis.addChangeListener(this);
        }
      
        if (this.dataset != null) {
            this.dataset.addChangeListener(this);
        }
    }
   
    /**
     * This method is required by the {@link Zoomable} interface, but since
     * the plot does not have any domain axes, it does nothing.
     *
     * @param factor  the zoom factor.
     * @param state  the plot state.
     * @param source  the source point (in Java2D coordinates).
     */
    public void zoomDomainAxes(double factor, PlotRenderingInfo state, 
                               Point2D source) {
        // do nothing
    }
   
    /**
     * This method is required by the {@link Zoomable} interface, but since
     * the plot does not have any domain axes, it does nothing.
     * 
     * @param lowerPercent  the new lower bound.
     * @param upperPercent  the new upper bound.
     * @param state  the plot state.
     * @param source  the source point (in Java2D coordinates).
     */
    public void zoomDomainAxes(double lowerPercent, double upperPercent, 
                               PlotRenderingInfo state, Point2D source) {
        // do nothing
    }
   
    /**
     * Multiplies the range on the range axis/axes by the specified factor.
     *
     * @param factor  the zoom factor.
     * @param state  the plot state.
     * @param source  the source point (in Java2D coordinates).
     */
    public void zoomRangeAxes(double factor, PlotRenderingInfo state, 
                              Point2D source) {
        zoom(factor);
    }
   
    /**
     * Zooms in on the range axes.
     * 
     * @param lowerPercent  the new lower bound.
     * @param upperPercent  the new upper bound.
     * @param state  the plot state.
     * @param source  the source point (in Java2D coordinates).
     */
    public void zoomRangeAxes(double lowerPercent, double upperPercent, 
                              PlotRenderingInfo state, Point2D source) {
        zoom((upperPercent + lowerPercent) / 2.0);
    }   

    /**
     * Returns <code>true</code>.
     * 
     * @return A boolean.
     */
    public boolean isDomainZoomable() {
        return false;
    }
    
    /**
     * Returns <code>true</code>.
     * 
     * @return A boolean.
     */
    public boolean isRangeZoomable() {
        return true;
    }
    
    /**
     * Returns the orientation of the plot.
     * 
     * @return The orientation.
     */
    public PlotOrientation getOrientation() {
        return PlotOrientation.HORIZONTAL;
    }


    // ----------------------
    // --- Public Methods ---
    // ----------------------

    /**
     * Returns the upper bound of the radius axis.
     * 
     * @return The upper bound.
     */
    public double getMaxRadius() {
        return this.axis.getUpperBound();
    }

    /**
     * Translates a (theta, radius) pair into Java2D coordinates.
     * 
     * @param angleDegrees  the angle in degrees.
     * @param radius  the radius.
     * @param dataArea  the data area.
     * 
     * @return A point in Java2D space.
     */   
    public Point translateValueThetaRadiusToJava2D(double angleDegrees, 
                                                   double radius,
                                                   Rectangle2D dataArea) {
       
        double radians = Math.toRadians(angleDegrees - 90.0);
      
        double minx = dataArea.getMinX() + MARGIN;
        double maxx = dataArea.getMaxX() - MARGIN;
        double miny = dataArea.getMinY() + MARGIN;
        double maxy = dataArea.getMaxY() - MARGIN;
      
        double lengthX = maxx - minx;
        double lengthY = maxy - miny;
        double length = Math.min(lengthX, lengthY);
      
        double midX = minx + lengthX / 2.0;
        double midY = miny + lengthY / 2.0;
      
        double axisMin = this.axis.getLowerBound();
        double axisMax =  getMaxRadius();

        double xv = length / 2.0 * Math.cos(radians);
        double yv = length / 2.0 * Math.sin(radians);

        float x = (float) (midX + (xv * (radius - axisMin) 
                / (axisMax - axisMin)));
        float y = (float) (midY + (yv * (radius - axisMin) 
                / (axisMax - axisMin)));
      
        int ix = Math.round(x);
        int iy = Math.round(y);
      
        Point p = new Point(ix, iy);
        return p;
        
    }
    
}