1 /*
   2  * Copyright (c) 2010, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javafx.scene.chart;
  27 
  28 import java.util.ArrayList;
  29 import java.util.HashMap;
  30 import java.util.List;
  31 import java.util.Map;
  32 
  33 import javafx.animation.FadeTransition;
  34 import javafx.animation.Interpolator;
  35 import javafx.animation.KeyFrame;
  36 import javafx.animation.KeyValue;
  37 import javafx.animation.Timeline;
  38 import javafx.animation.Animation;
  39 import javafx.application.Platform;
  40 import javafx.beans.NamedArg;
  41 import javafx.beans.property.BooleanProperty;
  42 import javafx.beans.property.DoubleProperty;
  43 import javafx.beans.property.ObjectProperty;
  44 import javafx.beans.property.ObjectPropertyBase;
  45 import javafx.beans.property.SimpleDoubleProperty;
  46 import javafx.beans.value.WritableValue;
  47 import javafx.collections.FXCollections;
  48 import javafx.collections.ListChangeListener;
  49 import javafx.collections.ObservableList;
  50 import javafx.scene.AccessibleRole;
  51 import javafx.scene.Node;
  52 import javafx.scene.layout.StackPane;
  53 import javafx.scene.shape.LineTo;
  54 import javafx.scene.shape.MoveTo;
  55 import javafx.scene.shape.Path;
  56 import javafx.scene.shape.PathElement;
  57 import javafx.scene.shape.StrokeLineJoin;
  58 import javafx.util.Duration;
  59 
  60 import com.sun.javafx.charts.Legend.LegendItem;
  61 
  62 import javafx.css.StyleableBooleanProperty;
  63 import javafx.css.CssMetaData;
  64 
  65 import javafx.css.converter.BooleanConverter;
  66 
  67 import java.util.*;
  68 
  69 import javafx.css.Styleable;
  70 import javafx.css.StyleableProperty;
  71 
  72 /**
  73  * Line Chart plots a line connecting the data points in a series. The data points
  74  * themselves can be represented by symbols optionally. Line charts are usually used
  75  * to view data trends over time or category.
  76  * @since JavaFX 2.0
  77  */
  78 public class LineChart<X,Y> extends XYChart<X,Y> {
  79 
  80     // -------------- PRIVATE FIELDS ------------------------------------------
  81 
  82     /** A multiplier for the Y values that we store for each series, it is used to animate in a new series */
  83     private Map<Series<X,Y>, DoubleProperty> seriesYMultiplierMap = new HashMap<>();
  84     private Timeline dataRemoveTimeline;
  85     private Series<X,Y> seriesOfDataRemoved = null;
  86     private Data<X,Y> dataItemBeingRemoved = null;
  87     private FadeTransition fadeSymbolTransition = null;
  88     private Map<Data<X,Y>, Double> XYValueMap =
  89                                 new HashMap<Data<X,Y>, Double>();
  90     private Timeline seriesRemoveTimeline = null;
  91     // -------------- PUBLIC PROPERTIES ----------------------------------------
  92 
  93     /** When true, CSS styleable symbols are created for any data items that don't have a symbol node specified. */
  94     private BooleanProperty createSymbols = new StyleableBooleanProperty(true) {
  95         @Override protected void invalidated() {
  96             for (int seriesIndex=0; seriesIndex < getData().size(); seriesIndex ++) {
  97                 Series<X,Y> series = getData().get(seriesIndex);
  98                 for (int itemIndex=0; itemIndex < series.getData().size(); itemIndex ++) {
  99                     Data<X,Y> item = series.getData().get(itemIndex);
 100                     Node symbol = item.getNode();
 101                     if(get() && symbol == null) { // create any symbols
 102                         symbol = createSymbol(series, getData().indexOf(series), item, itemIndex);
 103                         getPlotChildren().add(symbol);
 104                     } else if (!get() && symbol != null) { // remove symbols
 105                         getPlotChildren().remove(symbol);
 106                         symbol = null;
 107                         item.setNode(null);
 108                     }
 109                 }
 110             }
 111             requestChartLayout();
 112         }
 113 
 114         public Object getBean() {
 115             return LineChart.this;
 116         }
 117 
 118         public String getName() {
 119             return "createSymbols";
 120         }
 121 
 122         public CssMetaData<LineChart<?,?>,Boolean> getCssMetaData() {
 123             return StyleableProperties.CREATE_SYMBOLS;
 124         }
 125     };
 126 
 127     /**
 128      * Indicates whether symbols for data points will be created or not.
 129      *
 130      * @return true if symbols for data points will be created and false otherwise.
 131      */
 132     public final boolean getCreateSymbols() { return createSymbols.getValue(); }
 133     public final void setCreateSymbols(boolean value) { createSymbols.setValue(value); }
 134     public final BooleanProperty createSymbolsProperty() { return createSymbols; }
 135 
 136 
 137     /**
 138      * Indicates whether the data passed to LineChart should be sorted by natural order of one of the axes.
 139      * If this is set to {@link SortingPolicy#NONE}, the order in {@link #dataProperty()} will be used.
 140      *
 141      * @since JavaFX 8u40
 142      * @see SortingPolicy
 143      * @defaultValue SortingPolicy#X_AXIS
 144      */
 145     private ObjectProperty<SortingPolicy> axisSortingPolicy = new ObjectPropertyBase<SortingPolicy>(SortingPolicy.X_AXIS) {
 146         @Override protected void invalidated() {
 147             requestChartLayout();
 148         }
 149 
 150         public Object getBean() {
 151             return LineChart.this;
 152         }
 153 
 154         public String getName() {
 155             return "axisSortingPolicy";
 156         }
 157 
 158     };
 159 
 160     public final SortingPolicy getAxisSortingPolicy() { return axisSortingPolicy.getValue(); }
 161     public final void setAxisSortingPolicy(SortingPolicy value) { axisSortingPolicy.setValue(value); }
 162     public final ObjectProperty<SortingPolicy> axisSortingPolicyProperty() { return axisSortingPolicy; }
 163 
 164     // -------------- CONSTRUCTORS ----------------------------------------------
 165 
 166     /**
 167      * Construct a new LineChart with the given axis.
 168      *
 169      * @param xAxis The x axis to use
 170      * @param yAxis The y axis to use
 171      */
 172     public LineChart(@NamedArg("xAxis") Axis<X> xAxis, @NamedArg("yAxis") Axis<Y> yAxis) {
 173         this(xAxis, yAxis, FXCollections.<Series<X, Y>>observableArrayList());
 174     }
 175 
 176     /**
 177      * Construct a new LineChart with the given axis and data.
 178      *
 179      * @param xAxis The x axis to use
 180      * @param yAxis The y axis to use
 181      * @param data The data to use, this is the actual list used so any changes to it will be reflected in the chart
 182      */
 183     public LineChart(@NamedArg("xAxis") Axis<X> xAxis, @NamedArg("yAxis") Axis<Y> yAxis, @NamedArg("data") ObservableList<Series<X,Y>> data) {
 184         super(xAxis,yAxis);
 185         setData(data);
 186     }
 187 
 188     // -------------- METHODS ------------------------------------------------------------------------------------------
 189 
 190     /** {@inheritDoc} */
 191     @Override protected void updateAxisRange() {
 192         final Axis<X> xa = getXAxis();
 193         final Axis<Y> ya = getYAxis();
 194         List<X> xData = null;
 195         List<Y> yData = null;
 196         if(xa.isAutoRanging()) xData = new ArrayList<X>();
 197         if(ya.isAutoRanging()) yData = new ArrayList<Y>();
 198         if(xData != null || yData != null) {
 199             for(Series<X,Y> series : getData()) {
 200                 for(Data<X,Y> data: series.getData()) {
 201                     if(xData != null) xData.add(data.getXValue());
 202                     if(yData != null) yData.add(data.getYValue());
 203                 }
 204             }
 205             // RT-32838 No need to invalidate range if there is one data item - whose value is zero.
 206             if(xData != null && !(xData.size() == 1 && getXAxis().toNumericValue(xData.get(0)) == 0)) {
 207                 xa.invalidateRange(xData);
 208             }
 209             if(yData != null && !(yData.size() == 1 && getYAxis().toNumericValue(yData.get(0)) == 0)) {
 210                 ya.invalidateRange(yData);
 211             }
 212 
 213         }
 214     }
 215 
 216     @Override protected void dataItemAdded(final Series<X,Y> series, int itemIndex, final Data<X,Y> item) {
 217         final Node symbol = createSymbol(series, getData().indexOf(series), item, itemIndex);
 218         if (shouldAnimate()) {
 219             if (dataRemoveTimeline != null && dataRemoveTimeline.getStatus().equals(Animation.Status.RUNNING)) {
 220                 if (seriesOfDataRemoved == series) {
 221                     dataRemoveTimeline.stop();
 222                     dataRemoveTimeline = null;
 223                     getPlotChildren().remove(dataItemBeingRemoved.getNode());
 224                     removeDataItemFromDisplay(seriesOfDataRemoved, dataItemBeingRemoved);
 225                     seriesOfDataRemoved = null;
 226                     dataItemBeingRemoved = null;
 227                 }
 228             }
 229             boolean animate = false;
 230             if (itemIndex > 0 && itemIndex < (series.getData().size()-1)) {
 231                 animate = true;
 232                 Data<X,Y> p1 = series.getData().get(itemIndex - 1);
 233                 Data<X,Y> p2 = series.getData().get(itemIndex + 1);
 234                 if (p1 != null && p2 != null) {
 235                     double x1 = getXAxis().toNumericValue(p1.getXValue());
 236                     double y1 = getYAxis().toNumericValue(p1.getYValue());
 237                     double x3 = getXAxis().toNumericValue(p2.getXValue());
 238                     double y3 = getYAxis().toNumericValue(p2.getYValue());
 239 
 240                     double x2 = getXAxis().toNumericValue(item.getXValue());
 241                     //double y2 = getYAxis().toNumericValue(item.getYValue());
 242                     if (x2 > x1 && x2 < x3) {
 243                          //1. y intercept of the line : y = ((y3-y1)/(x3-x1)) * x2 + (x3y1 - y3x1)/(x3 -x1)
 244                         double y = ((y3-y1)/(x3-x1)) * x2 + (x3*y1 - y3*x1)/(x3-x1);
 245                         item.setCurrentY(getYAxis().toRealValue(y));
 246                         item.setCurrentX(getXAxis().toRealValue(x2));
 247                     } else {
 248                         //2. we can simply use the midpoint on the line as well..
 249                         double x = (x3 + x1)/2;
 250                         double y = (y3 + y1)/2;
 251                         item.setCurrentX(getXAxis().toRealValue(x));
 252                         item.setCurrentY(getYAxis().toRealValue(y));
 253                     }
 254                 }
 255             } else if (itemIndex == 0 && series.getData().size() > 1) {
 256                 animate = true;
 257                 item.setCurrentX(series.getData().get(1).getXValue());
 258                 item.setCurrentY(series.getData().get(1).getYValue());
 259             } else if (itemIndex == (series.getData().size() - 1) && series.getData().size() > 1) {
 260                 animate = true;
 261                 int last = series.getData().size() - 2;
 262                 item.setCurrentX(series.getData().get(last).getXValue());
 263                 item.setCurrentY(series.getData().get(last).getYValue());
 264             } else if(symbol != null) {
 265                 // fade in new symbol
 266                 symbol.setOpacity(0);
 267                 getPlotChildren().add(symbol);
 268                 FadeTransition ft = new FadeTransition(Duration.millis(500),symbol);
 269                 ft.setToValue(1);
 270                 ft.play();
 271             }
 272             if (animate) {
 273                 animate(
 274                     new KeyFrame(Duration.ZERO,
 275                             (e) -> { if (symbol != null && !getPlotChildren().contains(symbol)) getPlotChildren().add(symbol); },
 276                                    new KeyValue(item.currentYProperty(),
 277                                         item.getCurrentY()),
 278                                         new KeyValue(item.currentXProperty(),
 279                                         item.getCurrentX())),
 280                     new KeyFrame(Duration.millis(700), new KeyValue(item.currentYProperty(),
 281                                         item.getYValue(), Interpolator.EASE_BOTH),
 282                                         new KeyValue(item.currentXProperty(),
 283                                         item.getXValue(), Interpolator.EASE_BOTH))
 284                 );
 285             }
 286 
 287         } else {
 288             if (symbol != null) getPlotChildren().add(symbol);
 289         }
 290     }
 291 
 292     @Override protected  void dataItemRemoved(final Data<X,Y> item, final Series<X,Y> series) {
 293         final Node symbol = item.getNode();
 294 
 295         if (symbol != null) {
 296             symbol.focusTraversableProperty().unbind();
 297         }
 298 
 299         // remove item from sorted list
 300         int itemIndex = series.getItemIndex(item);
 301         if (shouldAnimate()) {
 302             XYValueMap.clear();
 303             boolean animate = false;
 304             // dataSize represents size of currently visible data. After this operation, the number will decrement by 1
 305             final int dataSize = series.getDataSize();
 306             // This is the size of current data list in Series. Note that it might be totaly different from dataSize as
 307             // some big operation might have happened on the list.
 308             final int dataListSize = series.getData().size();
 309             if (itemIndex > 0 && itemIndex < dataSize - 1) {
 310                 animate = true;
 311                 Data<X,Y> p1 = series.getItem(itemIndex - 1);
 312                 Data<X,Y> p2 = series.getItem(itemIndex + 1);
 313                 double x1 = getXAxis().toNumericValue(p1.getXValue());
 314                 double y1 = getYAxis().toNumericValue(p1.getYValue());
 315                 double x3 = getXAxis().toNumericValue(p2.getXValue());
 316                 double y3 = getYAxis().toNumericValue(p2.getYValue());
 317 
 318                 double x2 = getXAxis().toNumericValue(item.getXValue());
 319                 double y2 = getYAxis().toNumericValue(item.getYValue());
 320                 if (x2 > x1 && x2 < x3) {
 321 //                //1.  y intercept of the line : y = ((y3-y1)/(x3-x1)) * x2 + (x3y1 - y3x1)/(x3 -x1)
 322                     double y = ((y3-y1)/(x3-x1)) * x2 + (x3*y1 - y3*x1)/(x3-x1);
 323                     item.setCurrentX(getXAxis().toRealValue(x2));
 324                     item.setCurrentY(getYAxis().toRealValue(y2));
 325                     item.setXValue(getXAxis().toRealValue(x2));
 326                     item.setYValue(getYAxis().toRealValue(y));
 327                 } else {
 328                 //2.  we can simply use the midpoint on the line as well..
 329                     double x = (x3 + x1)/2;
 330                     double y = (y3 + y1)/2;
 331                     item.setCurrentX(getXAxis().toRealValue(x));
 332                     item.setCurrentY(getYAxis().toRealValue(y));
 333                 }
 334             } else if (itemIndex == 0 && dataListSize > 1) {
 335                 animate = true;
 336                 item.setXValue(series.getData().get(0).getXValue());
 337                 item.setYValue(series.getData().get(0).getYValue());
 338             } else if (itemIndex == (dataSize - 1) && dataListSize > 1) {
 339                 animate = true;
 340                 int last = dataListSize - 1;
 341                 item.setXValue(series.getData().get(last).getXValue());
 342                 item.setYValue(series.getData().get(last).getYValue());
 343             } else if (symbol != null) {
 344                 // fade out symbol
 345                 fadeSymbolTransition = new FadeTransition(Duration.millis(500),symbol);
 346                 fadeSymbolTransition.setToValue(0);
 347                 fadeSymbolTransition.setOnFinished(actionEvent -> {
 348                     item.setSeries(null);
 349                     getPlotChildren().remove(symbol);
 350                     removeDataItemFromDisplay(series, item);
 351                     symbol.setOpacity(1.0);
 352                 });
 353                 fadeSymbolTransition.play();
 354             } else {
 355                 item.setSeries(null);
 356                 removeDataItemFromDisplay(series, item);
 357             }
 358             if (animate) {
 359                 dataRemoveTimeline = createDataRemoveTimeline(item, symbol, series);
 360                 seriesOfDataRemoved = series;
 361                 dataItemBeingRemoved = item;
 362                 dataRemoveTimeline.play();
 363             }
 364         } else {
 365             item.setSeries(null);
 366             if (symbol != null) getPlotChildren().remove(symbol);
 367             removeDataItemFromDisplay(series, item);
 368         }
 369         //Note: better animation here, point should move from old position to new position at center point between prev and next symbols
 370     }
 371 
 372     /** {@inheritDoc} */
 373     @Override protected void dataItemChanged(Data<X, Y> item) {
 374     }
 375 
 376     @Override protected void seriesChanged(ListChangeListener.Change<? extends Series> c) {
 377         // Update style classes for all series lines and symbols
 378         // Note: is there a more efficient way of doing this?
 379         for (int i = 0; i < getDataSize(); i++) {
 380             final Series<X,Y> s = getData().get(i);
 381             Node seriesNode = s.getNode();
 382             if (seriesNode != null) seriesNode.getStyleClass().setAll("chart-series-line", "series" + i, s.defaultColorStyleClass);
 383             for (int j=0; j < s.getData().size(); j++) {
 384                 final Node symbol = s.getData().get(j).getNode();
 385                 if (symbol != null) symbol.getStyleClass().setAll("chart-line-symbol", "series" + i, "data" + j, s.defaultColorStyleClass);
 386             }
 387         }
 388     }
 389 
 390     @Override protected  void seriesAdded(Series<X,Y> series, int seriesIndex) {
 391         // create new path for series
 392         Path seriesLine = new Path();
 393         seriesLine.setStrokeLineJoin(StrokeLineJoin.BEVEL);
 394         series.setNode(seriesLine);
 395         // create series Y multiplier
 396         DoubleProperty seriesYAnimMultiplier = new SimpleDoubleProperty(this, "seriesYMultiplier");
 397         seriesYMultiplierMap.put(series, seriesYAnimMultiplier);
 398         // handle any data already in series
 399         if (shouldAnimate()) {
 400             seriesLine.setOpacity(0);
 401             seriesYAnimMultiplier.setValue(0d);
 402         } else {
 403             seriesYAnimMultiplier.setValue(1d);
 404         }
 405         getPlotChildren().add(seriesLine);
 406 
 407         List<KeyFrame> keyFrames = new ArrayList<KeyFrame>();
 408         if (shouldAnimate()) {
 409             // animate in new series
 410             keyFrames.add(new KeyFrame(Duration.ZERO,
 411                 new KeyValue(seriesLine.opacityProperty(), 0),
 412                 new KeyValue(seriesYAnimMultiplier, 0)
 413             ));
 414             keyFrames.add(new KeyFrame(Duration.millis(200),
 415                 new KeyValue(seriesLine.opacityProperty(), 1)
 416             ));
 417             keyFrames.add(new KeyFrame(Duration.millis(500),
 418                 new KeyValue(seriesYAnimMultiplier, 1)
 419             ));
 420         }
 421         for (int j=0; j<series.getData().size(); j++) {
 422             Data<X,Y> item = series.getData().get(j);
 423             final Node symbol = createSymbol(series, seriesIndex, item, j);
 424             if(symbol != null) {
 425                 if (shouldAnimate()) symbol.setOpacity(0);
 426                 getPlotChildren().add(symbol);
 427                 if (shouldAnimate()) {
 428                     // fade in new symbol
 429                     keyFrames.add(new KeyFrame(Duration.ZERO, new KeyValue(symbol.opacityProperty(), 0)));
 430                     keyFrames.add(new KeyFrame(Duration.millis(200), new KeyValue(symbol.opacityProperty(), 1)));
 431                 }
 432             }
 433         }
 434         if (shouldAnimate()) animate(keyFrames.toArray(new KeyFrame[keyFrames.size()]));
 435     }
 436 
 437     @Override protected  void seriesRemoved(final Series<X,Y> series) {
 438         // remove all symbol nodes
 439         seriesYMultiplierMap.remove(series);
 440         if (shouldAnimate()) {
 441             seriesRemoveTimeline = new Timeline(createSeriesRemoveTimeLine(series, 900));
 442             seriesRemoveTimeline.play();
 443         } else {
 444             getPlotChildren().remove(series.getNode());
 445             for (Data<X,Y> d:series.getData()) getPlotChildren().remove(d.getNode());
 446             removeSeriesFromDisplay(series);
 447         }
 448     }
 449 
 450     /** {@inheritDoc} */
 451     @Override protected void layoutPlotChildren() {
 452         List<LineTo> constructedPath = new ArrayList<>(getDataSize());
 453         for (int seriesIndex=0; seriesIndex < getDataSize(); seriesIndex++) {
 454             Series<X,Y> series = getData().get(seriesIndex);
 455             final DoubleProperty seriesYAnimMultiplier = seriesYMultiplierMap.get(series);
 456             final Node seriesNode = series.getNode();
 457             if (seriesNode instanceof Path) {
 458                 AreaChart.makePaths(this, series,
 459                                     constructedPath, null, (Path) seriesNode,
 460                                     seriesYAnimMultiplier.get(), getAxisSortingPolicy());
 461             }
 462         }
 463     }
 464 
 465     /** {@inheritDoc} */
 466     @Override void dataBeingRemovedIsAdded(Data item, Series series) {
 467         if (fadeSymbolTransition != null) {
 468             fadeSymbolTransition.setOnFinished(null);
 469             fadeSymbolTransition.stop();
 470         }
 471         if (dataRemoveTimeline != null) {
 472             dataRemoveTimeline.setOnFinished(null);
 473             dataRemoveTimeline.stop();
 474         }
 475         final Node symbol = item.getNode();
 476         if (symbol != null) getPlotChildren().remove(symbol);
 477 
 478         item.setSeries(null);
 479         removeDataItemFromDisplay(series, item);
 480 
 481         // restore values to item
 482         Double value = XYValueMap.get(item);
 483         if (value != null) {
 484             item.setYValue(value);
 485             item.setCurrentY(value);
 486         }
 487         XYValueMap.clear();
 488     }
 489     /** {@inheritDoc} */
 490     @Override void seriesBeingRemovedIsAdded(Series<X,Y> series) {
 491         if (seriesRemoveTimeline != null) {
 492             seriesRemoveTimeline.setOnFinished(null);
 493             seriesRemoveTimeline.stop();
 494             getPlotChildren().remove(series.getNode());
 495             for (Data<X,Y> d:series.getData()) getPlotChildren().remove(d.getNode());
 496             removeSeriesFromDisplay(series);
 497         }
 498     }
 499 
 500     private Timeline createDataRemoveTimeline(final Data<X,Y> item, final Node symbol, final Series<X,Y> series) {
 501         Timeline t = new Timeline();
 502         // save data values in case the same data item gets added immediately.
 503         XYValueMap.put(item, ((Number)item.getYValue()).doubleValue());
 504 
 505         t.getKeyFrames().addAll(new KeyFrame(Duration.ZERO, new KeyValue(item.currentYProperty(),
 506                 item.getCurrentY()), new KeyValue(item.currentXProperty(),
 507                 item.getCurrentX())),
 508                 new KeyFrame(Duration.millis(500), actionEvent -> {
 509                     if (symbol != null) getPlotChildren().remove(symbol);
 510                     removeDataItemFromDisplay(series, item);
 511                     XYValueMap.clear();
 512                 },
 513                 new KeyValue(item.currentYProperty(),
 514                 item.getYValue(), Interpolator.EASE_BOTH),
 515                 new KeyValue(item.currentXProperty(),
 516                 item.getXValue(), Interpolator.EASE_BOTH))
 517         );
 518         return t;
 519     }
 520 
 521     private Node createSymbol(Series<X, Y> series, int seriesIndex, final Data<X,Y> item, int itemIndex) {
 522         Node symbol = item.getNode();
 523         // check if symbol has already been created
 524         if (symbol == null && getCreateSymbols()) {
 525             symbol = new StackPane();
 526             symbol.setAccessibleRole(AccessibleRole.TEXT);
 527             symbol.setAccessibleRoleDescription("Point");
 528             symbol.focusTraversableProperty().bind(Platform.accessibilityActiveProperty());
 529             item.setNode(symbol);
 530         }
 531         // set symbol styles
 532         if (symbol != null) symbol.getStyleClass().addAll("chart-line-symbol", "series" + seriesIndex,
 533                 "data" + itemIndex, series.defaultColorStyleClass);
 534         return symbol;
 535     }
 536 
 537     @Override
 538     LegendItem createLegendItemForSeries(Series<X, Y> series, int seriesIndex) {
 539         LegendItem legendItem = new LegendItem(series.getName());
 540         legendItem.getSymbol().getStyleClass().addAll("chart-line-symbol", "series" + seriesIndex,
 541                 series.defaultColorStyleClass);
 542         return legendItem;
 543     }
 544 
 545     // -------------- STYLESHEET HANDLING --------------------------------------
 546 
 547     private static class StyleableProperties {
 548         private static final CssMetaData<LineChart<?,?>,Boolean> CREATE_SYMBOLS =
 549             new CssMetaData<LineChart<?,?>,Boolean>("-fx-create-symbols",
 550                 BooleanConverter.getInstance(), Boolean.TRUE) {
 551 
 552             @Override
 553             public boolean isSettable(LineChart<?,?> node) {
 554                 return node.createSymbols == null || !node.createSymbols.isBound();
 555             }
 556 
 557             @Override
 558             public StyleableProperty<Boolean> getStyleableProperty(LineChart<?,?> node) {
 559                 return (StyleableProperty<Boolean>)(WritableValue<Boolean>)node.createSymbolsProperty();
 560             }
 561         };
 562 
 563         private static final List<CssMetaData<? extends Styleable, ?>> STYLEABLES;
 564         static {
 565             final List<CssMetaData<? extends Styleable, ?>> styleables =
 566                 new ArrayList<CssMetaData<? extends Styleable, ?>>(XYChart.getClassCssMetaData());
 567             styleables.add(CREATE_SYMBOLS);
 568             STYLEABLES = Collections.unmodifiableList(styleables);
 569         }
 570     }
 571 
 572     /**
 573      * @return The CssMetaData associated with this class, which may include the
 574      * CssMetaData of its superclasses.
 575      * @since JavaFX 8.0
 576      */
 577     public static List<CssMetaData<? extends Styleable, ?>> getClassCssMetaData() {
 578         return StyleableProperties.STYLEABLES;
 579     }
 580 
 581     /**
 582      * {@inheritDoc}
 583      * @since JavaFX 8.0
 584      */
 585     @Override
 586     public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() {
 587         return getClassCssMetaData();
 588     }
 589 
 590     /**
 591      * This enum defines a policy for {@link LineChart#axisSortingPolicyProperty()}.
 592      * @since JavaFX 8u40
 593      */
 594     public static enum SortingPolicy {
 595         /**
 596          * The data should be left in the order defined by the list in {@link javafx.scene.chart.LineChart#dataProperty()}.
 597          */
 598         NONE,
 599         /**
 600          * The data is ordered by x axis.
 601          */
 602         X_AXIS,
 603         /**
 604          * The data is ordered by y axis.
 605          */
 606         Y_AXIS
 607     }
 608 }