001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ---------------------
028 * XYSplineRenderer.java
029 * ---------------------
030 * (C) Copyright 2007-2011, by Klaus Rheinwald and Contributors.
031 *
032 * Original Author:  Klaus Rheinwald;
033 * Contributor(s):   Tobias von Petersdorff (tvp@math.umd.edu,
034 *                       http://www.wam.umd.edu/~petersd/);
035 *                   David Gilbert (for Object Refinery Limited);
036 *
037 * Changes:
038 * --------
039 * 25-Jul-2007 : Version 1, contributed by Klaus Rheinwald (DG);
040 * 03-Aug-2007 : Added new constructor (KR);
041 * 25-Oct-2007 : Prevent duplicate control points (KR);
042 * 19-May-2009 : Fixed FindBugs warnings, patch by Michal Wozniak (DG);
043 *
044 */
045
046package org.jfree.chart.renderer.xy;
047
048import java.awt.Graphics2D;
049import java.awt.geom.Rectangle2D;
050import java.util.Vector;
051
052import org.jfree.chart.axis.ValueAxis;
053import org.jfree.chart.event.RendererChangeEvent;
054import org.jfree.chart.plot.PlotOrientation;
055import org.jfree.chart.plot.PlotRenderingInfo;
056import org.jfree.chart.plot.XYPlot;
057import org.jfree.data.xy.XYDataset;
058import org.jfree.ui.RectangleEdge;
059
060/**
061 * A renderer that connects data points with natural cubic splines and/or
062 * draws shapes at each data point.  This renderer is designed for use with
063 * the {@link XYPlot} class. The example shown here is generated by the
064 * <code>XYSplineRendererDemo1.java</code> program included in the JFreeChart
065 * demo collection:
066 * <br><br>
067 * <img src="../../../../../images/XYSplineRendererSample.png"
068 * alt="XYSplineRendererSample.png" />
069 *
070 * @since 1.0.7
071 */
072public class XYSplineRenderer extends XYLineAndShapeRenderer {
073
074    /**
075     * To collect data points for later splining.
076     */
077    private Vector points;
078
079    /**
080     * Resolution of splines (number of line segments between points)
081     */
082    private int precision;
083
084    /**
085     * Creates a new instance with the 'precision' attribute defaulting to
086     * 5.
087     */
088    public XYSplineRenderer() {
089        this(5);
090    }
091
092    /**
093     * Creates a new renderer with the specified precision.
094     *
095     * @param precision  the number of points between data items.
096     */
097    public XYSplineRenderer(int precision) {
098        super();
099        if (precision <= 0) {
100            throw new IllegalArgumentException("Requires precision > 0.");
101        }
102        this.precision = precision;
103    }
104
105    /**
106     * Get the resolution of splines.
107     *
108     * @return Number of line segments between points.
109     *
110     * @see #setPrecision(int)
111     */
112    public int getPrecision() {
113        return this.precision;
114    }
115
116    /**
117     * Set the resolution of splines and sends a {@link RendererChangeEvent}
118     * to all registered listeners.
119     *
120     * @param p  number of line segments between points (must be > 0).
121     *
122     * @see #getPrecision()
123     */
124    public void setPrecision(int p) {
125        if (p <= 0) {
126            throw new IllegalArgumentException("Requires p > 0.");
127        }
128        this.precision = p;
129        fireChangeEvent();
130    }
131
132    /**
133     * Initialises the renderer.
134     * <P>
135     * This method will be called before the first item is rendered, giving the
136     * renderer an opportunity to initialise any state information it wants to
137     * maintain.  The renderer can do nothing if it chooses.
138     *
139     * @param g2  the graphics device.
140     * @param dataArea  the area inside the axes.
141     * @param plot  the plot.
142     * @param data  the data.
143     * @param info  an optional info collection object to return data back to
144     *              the caller.
145     *
146     * @return The renderer state.
147     */
148    public XYItemRendererState initialise(Graphics2D g2, Rectangle2D dataArea,
149            XYPlot plot, XYDataset data, PlotRenderingInfo info) {
150
151        State state = (State) super.initialise(g2, dataArea, plot, data, info);
152        state.setProcessVisibleItemsOnly(false);
153        this.points = new Vector();
154        setDrawSeriesLineAsPath(true);
155        return state;
156    }
157
158    /**
159     * Draws the item (first pass). This method draws the lines
160     * connecting the items. Instead of drawing separate lines,
161     * a GeneralPath is constructed and drawn at the end of
162     * the series painting.
163     *
164     * @param g2  the graphics device.
165     * @param state  the renderer state.
166     * @param plot  the plot (can be used to obtain standard color information
167     *              etc).
168     * @param dataset  the dataset.
169     * @param pass  the pass.
170     * @param series  the series index (zero-based).
171     * @param item  the item index (zero-based).
172     * @param domainAxis  the domain axis.
173     * @param rangeAxis  the range axis.
174     * @param dataArea  the area within which the data is being drawn.
175     */
176    protected void drawPrimaryLineAsPath(XYItemRendererState state,
177            Graphics2D g2, XYPlot plot, XYDataset dataset, int pass,
178            int series, int item, ValueAxis domainAxis, ValueAxis rangeAxis,
179            Rectangle2D dataArea) {
180
181        RectangleEdge xAxisLocation = plot.getDomainAxisEdge();
182        RectangleEdge yAxisLocation = plot.getRangeAxisEdge();
183
184        // get the data points
185        double x1 = dataset.getXValue(series, item);
186        double y1 = dataset.getYValue(series, item);
187        double transX1 = domainAxis.valueToJava2D(x1, dataArea, xAxisLocation);
188        double transY1 = rangeAxis.valueToJava2D(y1, dataArea, yAxisLocation);
189
190        // collect points
191        if (!Double.isNaN(transX1) && !Double.isNaN(transY1)) {
192            ControlPoint p = new ControlPoint(plot.getOrientation()
193                                == PlotOrientation.HORIZONTAL ? (float) transY1
194                                : (float) transX1, plot.getOrientation()
195                                == PlotOrientation.HORIZONTAL ? (float) transX1
196                                        : (float) transY1);
197            if (!this.points.contains(p)) {
198                this.points.add(p);
199            }
200        }
201        if (item == dataset.getItemCount(series) - 1) {
202            State s = (State) state;
203            // construct path
204            if (this.points.size() > 1) {
205                // we need at least two points to draw something
206                ControlPoint cp0 = (ControlPoint) this.points.get(0);
207                s.seriesPath.moveTo(cp0.x, cp0.y);
208                if (this.points.size() == 2) {
209                    // we need at least 3 points to spline. Draw simple line
210                    // for two points
211                    ControlPoint cp1 = (ControlPoint) this.points.get(1);
212                    s.seriesPath.lineTo(cp1.x, cp1.y);
213                }
214                else {
215                    // construct spline
216                    int np = this.points.size(); // number of points
217                    float[] d = new float[np]; // Newton form coefficients
218                    float[] x = new float[np]; // x-coordinates of nodes
219                    float y;
220                    float t;
221                    float oldy = 0;
222                    float oldt = 0;
223
224                    float[] a = new float[np];
225                    float t1;
226                    float t2;
227                    float[] h = new float[np];
228
229                    for (int i = 0; i < np; i++) {
230                        ControlPoint cpi = (ControlPoint) this.points.get(i);
231                        x[i] = cpi.x;
232                        d[i] = cpi.y;
233                    }
234
235                    for (int i = 1; i <= np - 1; i++) {
236                        h[i] = x[i] - x[i - 1];
237                    }
238                    float[] sub = new float[np - 1];
239                    float[] diag = new float[np - 1];
240                    float[] sup = new float[np - 1];
241
242                    for (int i = 1; i <= np - 2; i++) {
243                        diag[i] = (h[i] + h[i + 1]) / 3;
244                        sup[i] = h[i + 1] / 6;
245                        sub[i] = h[i] / 6;
246                        a[i] = (d[i + 1] - d[i]) / h[i + 1]
247                                   - (d[i] - d[i - 1]) / h[i];
248                    }
249                    solveTridiag(sub, diag, sup, a, np - 2);
250
251                    // note that a[0]=a[np-1]=0
252                    // draw
253                    oldt = x[0];
254                    oldy = d[0];
255                    s.seriesPath.moveTo(oldt, oldy);
256                    for (int i = 1; i <= np - 1; i++) {
257                        // loop over intervals between nodes
258                        for (int j = 1; j <= this.precision; j++) {
259                            t1 = (h[i] * j) / this.precision;
260                            t2 = h[i] - t1;
261                            y = ((-a[i - 1] / 6 * (t2 + h[i]) * t1 + d[i - 1])
262                                    * t2 + (-a[i] / 6 * (t1 + h[i]) * t2
263                                    + d[i]) * t1) / h[i];
264                            t = x[i - 1] + t1;
265                            s.seriesPath.lineTo(t, y);
266                        }
267                    }
268                }
269                // draw path
270                drawFirstPassShape(g2, pass, series, item, s.seriesPath);
271            }
272
273            // reset points vector
274            this.points = new Vector();
275        }
276    }
277
278    private void solveTridiag(float[] sub, float[] diag, float[] sup,
279            float[] b, int n) {
280/*      solve linear system with tridiagonal n by n matrix a
281        using Gaussian elimination *without* pivoting
282        where   a(i,i-1) = sub[i]  for 2<=i<=n
283        a(i,i)   = diag[i] for 1<=i<=n
284        a(i,i+1) = sup[i]  for 1<=i<=n-1
285        (the values sub[1], sup[n] are ignored)
286        right hand side vector b[1:n] is overwritten with solution
287        NOTE: 1...n is used in all arrays, 0 is unused */
288        int i;
289/*                  factorization and forward substitution */
290        for (i = 2; i <= n; i++) {
291            sub[i] = sub[i] / diag[i - 1];
292            diag[i] = diag[i] - sub[i] * sup[i - 1];
293            b[i] = b[i] - sub[i] * b[i - 1];
294        }
295        b[n] = b[n] / diag[n];
296        for (i = n - 1; i >= 1; i--) {
297            b[i] = (b[i] - sup[i] * b[i + 1]) / diag[i];
298        }
299    }
300
301    /**
302     * Tests this renderer for equality with an arbitrary object.
303     *
304     * @param obj  the object (<code>null</code> permitted).
305     *
306     * @return A boolean.
307     */
308    public boolean equals(Object obj) {
309        if (obj == this) {
310            return true;
311        }
312        if (!(obj instanceof XYSplineRenderer)) {
313            return false;
314        }
315        XYSplineRenderer that = (XYSplineRenderer) obj;
316        if (this.precision != that.precision) {
317            return false;
318        }
319        return super.equals(obj);
320    }
321
322    /**
323     * Represents a control point.
324     */
325    class ControlPoint {
326
327        /** The x-coordinate. */
328        public float x;
329
330        /** The y-coordinate. */
331        public float y;
332
333        /**
334         * Creates a new control point.
335         *
336         * @param x  the x-coordinate.
337         * @param y  the y-coordinate.
338         */
339        public ControlPoint(float x, float y) {
340            this.x = x;
341            this.y = y;
342        }
343
344        /**
345         * Tests this point for equality with an arbitrary object.
346         *
347         * @param obj  the object (<code>null</code> permitted.
348         *
349         * @return A boolean.
350         */
351        public boolean equals(Object obj) {
352            if (obj == this) {
353                return true;
354            }
355            if (!(obj instanceof ControlPoint)) {
356                return false;
357            }
358            ControlPoint that = (ControlPoint) obj;
359            if (this.x != that.x) {
360                return false;
361            }
362            /*&& y == ((ControlPoint) obj).y;*/
363            return true;
364        }
365
366    }
367}