从javaFX折线图中的CategoryAxis中检索String值 - .getValueForDisplay(double displayPosition)中的类别Ajis JavaFx 2.2.3错误 -

时间:2012-11-30 15:19:07

标签: javafx-2 linechart

我有一个包含月份与值的JavaFXline图表。我每次点击图表时都试图在控制台中打印月份和线图中的值。问题是当我在getValueForDisplay对象中调用方法CategoryAxis时,它返回null
当我点击(x,y):jan,3
我想打印:
X value = jan Y value: 3
但程序正在打印:
X value = **null** Y value: 2.7796610169491527

另一个问题;
2)为什么在尝试打印坐标时似乎没有校准(如果我点击3程序打印2.779661016949152?你可以注意到这个问题,检查控制台上打印的值。

以下是我正在使用的代码:

public class LineChartTest extends Application {
String xValue;
Number yValue;
private void init(Stage primaryStage) {
    Group root = new Group();
    primaryStage.setScene(new Scene(root));
    final CategoryAxis xAxis = new CategoryAxis();

    final NumberAxis yAxis = new NumberAxis("Values for Y-Axis", 0, 3, 1);

    yAxis.setUpperBound(5);

    ObservableList<XYChart.Series<String,Double>> lineChartData = FXCollections.observableArrayList(
        new LineChart.Series<String,Double>("en", FXCollections.observableArrayList(
            new XYChart.Data<String,Double>("jan", 1.0),
            new XYChart.Data<String,Double>("feb", 2.0),
            new XYChart.Data<String,Double>("mar", 3.0),
            new XYChart.Data<String,Double>("apr", 4.0),
            new XYChart.Data<String,Double>("may", 0.5)
        )),
        new LineChart.Series<String,Double>("to", FXCollections.observableArrayList(
            new XYChart.Data<String,Double>("jan", 1.6),
            new XYChart.Data<String,Double>("feb", 0.4),
            new XYChart.Data<String,Double>("mar", 2.9),
            new XYChart.Data<String,Double>("apr", 1.3),
            new XYChart.Data<String,Double>("may", 0.9)
        ))
    );


    //define a new line
    final Series<String,Double> otherSeries = new Series<String,Double>();
    //set points
    otherSeries.getData().add(new XYChart.Data("jan",3));
    otherSeries.getData().add(new XYChart.Data("feb",2));
    otherSeries.getData().add(new XYChart.Data("mar",4));
    //set name to the line
    otherSeries.setName("tre");
    //add the new line to the graph
    lineChartData.add(otherSeries);
    final LineChart chart = new LineChart(xAxis, yAxis, lineChartData);

    //set title to the figure
    chart.setTitle("Line Chart Test");

    root.getChildren().add(chart);

    chart.setOnMouseClicked(new EventHandler<MouseEvent>() {

          @Override
        public void handle(MouseEvent t) {

            //Why this seems to be not working properly?
            double sceneX = t.getSceneX();
            double sceneY = t.getSceneY();

            //gives the point of the graph
            xValue = xAxis.getValueForDisplay(sceneX);
            yValue = yAxis.getValueForDisplay(sceneY);


            System.out.println("sceneX-25: "+ sceneX);
            System.out.println("getDisplayPosition: " + xAxis.getValueForDisplay(sceneX));

            //Test
            System.out.println(" X value = " +  
            xValue + " Y value: " + yValue );  

            }
    });

}

@Override public void start(Stage primaryStage) throws Exception {
    init(primaryStage);
    primaryStage.show();


}


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

答案:

感谢Sergey Grinev和Uluk Biy

在上一段代码中你必须修改:

折线图代码:

    chart.setOnMouseClicked(new EventHandler<MouseEvent>() {


          @Override
          public void handle(MouseEvent e) {
            Node chartPlotBackground = chart.lookup(".chart-plot-background");
            final double shiftX = xSceneShift(chartPlotBackground);
            final double shiftY = ySceneShift(chartPlotBackground);    

            double x = e.getSceneX() - shiftX;
            double y = e.getSceneY() - shiftY;

            xValue = xAxis.getValueForDisplay(x);
            yValue = yAxis.getValueForDisplay(y );
            System.out.println("shiftX = " + shiftX + " shiftY: " + shiftY);
            System.out.println("X value = "
                + xValue + " \nY value: " + yValue);
          }
    });


}
//recursive calls    
private double xSceneShift(Node node) {
return node.getParent() == null ? 0 : node.getBoundsInParent().getMinX() +    xSceneShift(node.getParent());
}

private double ySceneShift(Node node) {
return node.getParent() == null ? 0 : node.getBoundsInParent().getMinY() + ySceneShift(node.getParent());
}

    @Override 
    public void start(Stage primaryStage) throws Exception {
    init(primaryStage);
    primaryStage.show();


}


public static void main(String[] args) {
    launch(args);
    }
}
你需要修改的CategoryAxis源代码中的

(查看评论!):

 @Override public String getValueForDisplay(double displayPosition) {
    if (getSide().equals(Side.TOP) || getSide().equals(Side.BOTTOM)) { // HORIZONTAL
        if (displayPosition < 0 || displayPosition > getHeight()) return null; //   <-------------- WRONG SHOULD BE displayPosition > getWidth()
        double d = (displayPosition - firstCategoryPos.get()) / categorySpacing.get();
        return toRealValue(d);
    } else { // VERTICAL
        if (displayPosition < 0 || displayPosition > getWidth()) return null; // <-------------- WRONG SHOULD BE displayPosition > getHeight()
        double d = (displayPosition - firstCategoryPos.get()) / (categorySpacing.get() * -1);
        return toRealValue(d);
    }
} 

你可以在这里找到源代码:

http://hg.openjdk.java.net/openjfx/2.1/master/rt/file/5c3b3d524f07/javafx-ui-controls/src/javafx/scene/chart/CategoryAxis.java

2 个答案:

答案 0 :(得分:2)

如果您的目标是显示用户在图表上单击的数据点,则可以直接访问下划线数据。在此示例中,将鼠标悬停在数据X-Y交叉点上:

import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Cursor;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Label;
import javafx.scene.control.LabelBuilder;
import javafx.scene.effect.DropShadow;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.stage.Stage;

public class ChartDemo extends Application {

    private DropShadow ds = new DropShadow();

    @Override
    public void start(Stage stage) {
        stage.setTitle("Linear plot");

        final CategoryAxis xAxis = new CategoryAxis();
        final NumberAxis yAxis = new NumberAxis(0, 22, 0.5);

        yAxis.setTickLabelFormatter(new NumberAxis.DefaultFormatter(yAxis) {
            @Override
            public String toString(Number object) {
                return String.format("%7.2f", object);
            }
        });
        final LineChart<String, Number> lineChart = new LineChart<String, Number>(xAxis, yAxis);

        lineChart.setCreateSymbols(true);
        lineChart.setAlternativeRowFillVisible(false);
        lineChart.setLegendVisible(false);

        final XYChart.Series series1 = new XYChart.Series();

        series1.getData().add(new XYChart.Data("Jan", 1));
        series1.getData().add(new XYChart.Data("Feb", 1.5));
        series1.getData().add(new XYChart.Data("Mar", 2));
        series1.getData().add(new XYChart.Data("Apr", 2.5));
        series1.getData().add(new XYChart.Data("May", 3));
        series1.getData().add(new XYChart.Data("Jun", 4));
        series1.getData().add(new XYChart.Data("Jul", 6));
        series1.getData().add(new XYChart.Data("Aug", 9));
        series1.getData().add(new XYChart.Data("Sep", 12));
        series1.getData().add(new XYChart.Data("Oct", 15));
        series1.getData().add(new XYChart.Data("Nov", 20));
        series1.getData().add(new XYChart.Data("Dec", 22));

        final Label lbl = LabelBuilder.create().font(Font.font("Arial", FontWeight.BOLD, 25))
                .textFill(Color.BLUEVIOLET).translateY(-200).build();
        StackPane pane = new StackPane();
        pane.getChildren().addAll(lineChart, lbl);
        Scene scene = new Scene(pane, 800, 600);
        lineChart.getData().addAll(series1);

        for (Object obj : series1.getData()) {
            final XYChart.Data data = (XYChart.Data) obj;
            final Node node = data.getNode();

            node.setOnMouseEntered(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent arg0) {
                    node.setEffect(ds);
                    node.setCursor(Cursor.HAND);
                    lbl.setText("X-value=" + data.getXValue().toString() + "\nY-value=" + data.getYValue().toString());
                    System.out.println("X-value=" + data.getXValue().toString() + ", Y-value=" + data.getYValue().toString());
                }
            });

            node.setOnMouseExited(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent arg0) {
                    node.setEffect(null);
                    node.setCursor(Cursor.DEFAULT);
                    lbl.setText("");
                }
            });
        }
        stage.setScene(scene);
        stage.show();
    }

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

答案 1 :(得分:1)

有两个问题。

1)您使用了错误的坐标。 getValueForDisplay需要相对于图表绘制区域的坐标,而不是场景。

要解决这个问题,你可以使用下一个技巧。

引入下一个递归调用来计算场景转换:

private double xSceneShift(Node node) {
    return node.getParent() == null ? 0 : node.getBoundsInParent().getMinX() + xSceneShift(node.getParent());
}

private double ySceneShift(Node node) {
    return node.getParent() == null ? 0 : node.getBoundsInParent().getMinY() + ySceneShift(node.getParent());
}

查找图表绘图区域的移位:

Node chartPlotBackground = chart.lookup(".chart-plot-background");
final double shiftX = xSceneShift(chartPlotBackground);
final double shiftY = ySceneShift(chartPlotBackground);

并在鼠标处理程序中使用它们:

public void handle(MouseEvent e) {
    double x = e.getSceneX() - shiftX;
    double y = e.getSceneY() - shiftY;

    xValue = xAxis.getValueForDisplay(x );
    yValue = yAxis.getValueForDisplay(y);

    System.out.println(" X value = "
                    + xValue + " \nY value: " + yValue);
}

2)您在CategoryAxis遇到了一个问题,该问题已修复但在下一版本(8.0)中已解决:http://javafx-jira.kenai.com/browse/RT-25899

作为一种变通方法,您可以下载CategoryAxis来源,将其重命名为MyCategoryAxis并修复方法getValueForDisplay()中的错误 - 只需切换getWidth()和{{1}的位置调用。

http://hg.openjdk.java.net/openjfx/2.1/master/rt/file/5c3b3d524f07/javafx-ui-controls/src/javafx/scene/chart/CategoryAxis.java