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    
046    package org.jfree.chart.renderer.xy;
047    
048    import java.awt.Graphics2D;
049    import java.awt.geom.Rectangle2D;
050    import java.util.Vector;
051    
052    import org.jfree.chart.axis.ValueAxis;
053    import org.jfree.chart.event.RendererChangeEvent;
054    import org.jfree.chart.plot.PlotOrientation;
055    import org.jfree.chart.plot.PlotRenderingInfo;
056    import org.jfree.chart.plot.XYPlot;
057    import org.jfree.data.xy.XYDataset;
058    import 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     */
072    public 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    }