How to add two vertical lines with JavaFX LineChart

Question

My desktop application has a timer for starting and stopping a test. On the graph, I want to create two vertical lines to indicate the start and stop time. \"Adding vertical

Answer 1

I was able to create a drag and zoom in feature using the Line Chart Example mentioned here. The code listens to the mouse events and adds to the vertical ranges, which makes it appear to be dragging. JavaFX Drag and Zoom Line Chart Example

/**
 * The ChartView.
 */
public class ChartController {

  private ChartViewModel chartViewModel;
  private CustomLineChart lineChart;
  private NumberAxis xAxis;
  private NumberAxis yAxis;
  private XYChart.Series series;
  private List data;
  private boolean mouseDragged;
  private double initialNumberStart;
  private double initialNumberEnd;

  @FXML
  private VBox mainContainer;

  @FXML
  private HBox chartContainer;

  /**
   * The constructor.
   */
  public ChartController() {
    chartViewModel = new ChartViewModel();
    mouseDragged = false;
  }

  /**
   * The initialize method.
   */
  public void initialize() {
    createChart();
    handleEvents();
  }

  /**
   * Handles the events.
   */
  private void handleEvents() {
    lineChart.setOnMousePressed(pressed -> {
      int minSize = 1;
      // Get coordinate from the scene and transform to coordinates from the chart axis
      Point2D firstSceneCoordinate = new Point2D(pressed.getSceneX(), pressed.getSceneY());
      double firstX = xAxis.sceneToLocal(firstSceneCoordinate).getX();

      lineChart.setOnMouseDragged(dragged -> {
        mouseDragged = true;

        Point2D draggedSceneCoordinate = new Point2D(dragged.getSceneX(), dragged.getSceneY());
        double draggedX = xAxis.sceneToLocal(draggedSceneCoordinate).getX();

        List numbers = filterSeries(firstX, draggedX);
        int size = numbers.size();
        double numberStart = size > minSize ? numbers.get(0) : initialNumberStart;
        double numberEnd = numbers.size() > minSize ? numbers.get(size - 1) : initialNumberEnd;

        if (size > minSize) {
          lineChart.addVerticalRangeLines(new Data<>(numberStart, numberEnd));
        }

        lineChart.setOnMouseReleased(released -> {
          if (mouseDragged) {
            initialNumberStart = numberStart;
            initialNumberEnd = numberEnd;
            mouseDragged = false;

            redrawChart();
          }
        });
      });
    });
  }

  /**
   * Creates the charts.
   */
  private void createChart() {
    xAxis = new NumberAxis();
    yAxis = new NumberAxis();

    lineChart = new CustomLineChart<>(xAxis, yAxis);

    data = chartViewModel.getData();

    createSeries(data);
    lineChart.getData().add(series);

    initialNumberStart = 1;
    initialNumberEnd = data.size() - 1;

    chartContainer.getChildren().add(lineChart);

    HBox.setHgrow(lineChart, Priority.ALWAYS);
  }

  /**
   * Creates the series for the line chart.
   * 
   * @param numbers The list of numbers for the series
   */
  private void createSeries(List numbers) {
    int size = numbers.size();
    series = new XYChart.Series<>();
    series.setName("Example");

    for (int i = 0; i < size; i++) {
      series.getData().add(new XYChart.Data(i, numbers.get(i)));
    }
  }

  /**
   * Filters the nodes and returns the node x positions within the firstX and lastX positions.
   * 
   * @param firstX The first x position
   * @param lastX The last x position
   * @return The x positions for the nodes within the firstX and lastX
   */
  private List filterSeries(double firstX, double lastX) {
    List nodeXPositions = new ArrayList<>();

    lineChart.getData().get(0).getData().forEach(node -> {

      double nodeXPosition = lineChart.getXAxis().getDisplayPosition(node.getXValue());

      if (nodeXPosition >= firstX && nodeXPosition <= lastX) {
        nodeXPositions.add(Double.parseDouble(node.getXValue().toString()));
      }
    });

    return nodeXPositions;
  }

  /**
   * Updates the series for the chart.
   */
  private void updateSeries() {
    lineChart.getData().remove(0);
    lineChart.getData().add(series);
  }

  /**
   * Redraws the chart.
   */
  private void redrawChart() {
    List filteredSeries = new ArrayList<>();

    data.forEach(number -> {
      if (number >= initialNumberStart && number <= initialNumberEnd) {
        filteredSeries.add(number);
      }
    });

    if (!filteredSeries.isEmpty()) {
      createSeries(filteredSeries);
      updateSeries();
      lineChart.removeVerticalRangeLines();
    }
  }

  /**
   * Resets the series for the chart.
   * 
   * @param event The event
   */
  @FXML
  void resetChart(ActionEvent event) {
    createSeries(data);
    updateSeries();
  }

}