Performance issue with JavaFX LineChart with 65000 data points

Question

It takes JavaFX 15 minutes to build described LineChart which doesn't work for my task.

Similar implementation using good old Swing and jFreeChart takes 1.5 seconds to build chart.

But I would still like to implement a JavaFX one.

Here is my code:

public class FXMLController implements Initializable {

@FXML
private Label statusbar;
@FXML
public LineChart lineChart;
@FXML
public Button connect;
@FXML
public MenuItem options;
@FXML
public NumberAxis xAxis;
@FXML
NumberAxis yAxis;

@FXML
private void connect(ActionEvent event) {

}
public static FileChooser fileChooser = new FileChooser();
public static String path;
public static XYChart.Series<Integer, Integer> dataSeries = new XYChart.Series<Integer, Integer>();
public static int y = 0;
public static XYChart.Data<Integer, Integer> data;


@FXML
private void open(ActionEvent event) {
    fileChooser.setTitle("Open Resource File");
    fileChooser.getExtensionFilters().addAll(
            new ExtensionFilter("Text Files", "*.txt"),
            new ExtensionFilter("Image Files", "*.png", "*.jpg", "*.gif"),
            new ExtensionFilter("Audio Files", "*.wav", "*.mp3", "*.aac"),
            new ExtensionFilter("All Files", "*.*"));
    File selectedFile = fileChooser.showOpenDialog(new Stage());
    if (selectedFile != null) {
        path = selectedFile.getAbsolutePath();
        System.out.println(path);
        try {
            ReadingFromFile.readFile(path);

        } catch (IOException ex) {
            Logger.getLogger(FXMLController.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

}

@FXML
private void close(ActionEvent event) {

}

@FXML
private void getconnect(ActionEvent event) {

}

@Override
public void initialize(URL url, ResourceBundle rb) {
    xAxis.setLabel("Tick");
    xAxis.setTickUnit(100);
    yAxis.setLabel("Signal");
    xAxis.setForceZeroInRange(false);
    lineChart.setLegendVisible(false);
    lineChart.setCreateSymbols(false);
    lineChart.setAnimated(false);
    lineChart.getData().add(dataSeries);
  }
}

and reading from file:

public class ReadingFromFile extends FXMLController {

public static String s = null;
public static String[] str;
public static int parseInt;

public static void readFile(String filename)
        throws IOException {

    BufferedReader br = new BufferedReader(new FileReader(filename));
    try {
        StringBuilder sb = new StringBuilder();
        String line = br.readLine();

        while (line != null) {
            sb.append(line);
            sb.append(System.lineSeparator());
            line = br.readLine();

            System.out.println(line);
            try {
                str = line.split(" ");
                for (int i = 0; i < str.length; i = i + 2) {
                    s = str[i + 1] + str[i];
                    parseInt = Integer.parseInt(s, 16);
                    javafx.application.Platform.runLater(new Runnable() {
                        @Override
                        public void run() {

                            data = new XYChart.Data<Integer, Integer>(y, parseInt);
                            //data.setNode(new HoveredThresholdNode(0, second, ""));
                            dataSeries.getData().add(data);
                            y++;
                        }

                    });
                }
            } catch (java.lang.NullPointerException ex) {
                System.out.println("тут ноль!!!");

            }

        }

    } finally {

        br.close();
    }

}

}

Answer 1

I experienced a similar problem, adding 100,000 points to a LineChart every couple of seconds. We solved it using the Ramer–Douglas–Peucker algorithm, this reduces the number of points in the line without the user noticing. I found an ready-made implementation in the JTS topology suite under LGPL license.

Here's the my test code.

public class ChartUpdate extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {

        NumberAxis xAxis = new NumberAxis(0, 50_000, 5000);
        xAxis.setAutoRanging(false);
        NumberAxis yAxis = new NumberAxis(-1, 1, 25);
        yAxis.setAutoRanging(false);
        LineChart<Number, Number> graph = new LineChart<>(xAxis, yAxis);
        graph.setAnimated(false);
        graph.setCreateSymbols(false);
        graph.setLegendVisible(false);
        Series<Number, Number> series = new Series<>();
        stage.setScene(new Scene(graph));

        GeometryFactory gf = new GeometryFactory();

        long t0 = System.nanoTime();
        Coordinate[] coordinates = new Coordinate[100_000];
        for (int i = 0; i < coordinates.length; i++) {
            coordinates[i] = new Coordinate(i, Math.sin(Math.toRadians(i / 100)));
        }
        Geometry geom = new LineString(new CoordinateArraySequence(coordinates), gf);
        Geometry simplified = DouglasPeuckerSimplifier.simplify(geom, 0.00001);
        List<Data<Number, Number>> update = new ArrayList<Data<Number, Number>>();
        for (Coordinate each : simplified.getCoordinates()) {
            update.add(new Data<>(each.x, each.y));
        }
        long t1 = System.nanoTime();

        System.out.println(String.format("Reduces points from %d to %d in %.1f ms", coordinates.length, update.size(),
                (t1 - t0) / 1e6));
        ObservableList<Data<Number, Number>> list = FXCollections.observableArrayList(update);
        series.setData(list);
        graph.getData().add(series);

        stage.show();

    }
}