java - 如何在 JavaFX 折线图上添加形状

Question

我要在 LineChart 上添加一些形状。我将 LineChart 和 AnchorPane 放入 StackPane 中。我通过从图表系列中获取 x 和 y 坐标向 AnchorPane 添加了形状。这是示例。

LineChartApp.java

package shapes;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class LineChartApp extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(new Scene(new ChartContent()));
        primaryStage.setMaximized(true);
        primaryStage.show();
    }

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

}

ChartContent.java

package shapes;

import java.util.ArrayList;
import java.util.List;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Side;
import javafx.scene.Node;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart.Data;
import javafx.scene.chart.XYChart.Series;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Shape;
import javafx.util.Duration;

public class ChartContent extends StackPane {

    private AnchorPane objectsLayer;
    private LineChart<Number, Number> chart;
    private NumberAxis xAxis;
    private NumberAxis yAxis;
    private Series<Number, Number> series = new Series<Number, Number>();
    private int level = 0;
    private int datas[][] = { { 15, 8, 12, 11, 16, 21, 13 },
            { 10, 24, 20, 16, 31, 25, 44 }, { 88, 60, 105, 75, 151, 121, 137 },
            { 1000, 1341, 1211, 1562, 1400, 1600, 1550 }

    };
    private List<Shape> shapes = new ArrayList<Shape>();

    public ChartContent() {

        xAxis = new NumberAxis();
        yAxis = new NumberAxis();

        yAxis.setSide(Side.RIGHT);
        yAxis.setForceZeroInRange(false);

        xAxis.setForceZeroInRange(false);

        chart = new LineChart<Number, Number>(xAxis, yAxis);
        chart.setCreateSymbols(false);
        chart.setLegendVisible(false);
        chart.setAnimated(false);
        chart.setVerticalZeroLineVisible(false);

        Timeline timer = new Timeline(new KeyFrame(Duration.seconds(5),
                new EventHandler<ActionEvent>() {

                    @Override
                    public void handle(ActionEvent event) {

                        chartRefresh();
                    }
                }));
        timer.setCycleCount(datas.length - 1);
        timer.play();

        objectsLayer = new AnchorPane();
        objectsLayer.prefHeightProperty().bind(heightProperty());
        objectsLayer.prefWidthProperty().bind(widthProperty());

        getChildren().addAll(chart, objectsLayer);
        chartRefresh();
    }

    private void chartRefresh() {

        series.getData().clear();
        if (level < datas.length) {

            for (int i = 0; i < datas[level].length; i++) {
                series.getData().add(
                        new Data<Number, Number>(i, datas[level][i]));
            }
        }
        level++;

        chart.getData().clear();
        chart.getData().add(series);
        series.getNode().setStyle("-fx-stroke:blue;-fx-stroke-width:1");

        reDrawShapes(series);
    }

    private void reDrawShapes(Series<Number, Number> series) {

        Node chartPlotBackground = chart.lookup(".chart-plot-background");
        chartPlotBackground.setStyle("-fx-background-color:white");

        Circle circle;
        objectsLayer.getChildren().removeAll(shapes);

        shapes.clear();
        double top = chart.getPadding().getTop(), left = chart.getPadding()
                .getLeft();
        double minX = chartPlotBackground.getBoundsInParent().getMinX();
        double minY = chartPlotBackground.getBoundsInParent().getMinY();

        for (Data<Number, Number> data : series.getData()) {

            circle = new Circle(minX
                    + chart.getXAxis().getDisplayPosition(data.getXValue())
                    + left, minY
                    + chart.getYAxis().getDisplayPosition(data.getYValue())
                    + top, 3, Color.RED);

            shapes.add(circle);
        }

        objectsLayer.getChildren().addAll(shapes);
    }
}

我每五秒刷新一次图表系列，并重新绘制其形状。但是在将形状添加到 AnchorPane 之后，它们不在我期望的位置。

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预期结果

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实际结果

Answer 1

首先，请注意，对于您要实现的确切功能，只需在数据上设置一个节点即可完成。

(旁白:可以争论，我会争论，让节点成为图表中显示的数据的属性几乎违反了 UI 开发中 View 与数据分离的所有良好实践。Chart API 具有许多糟糕的设计缺陷，恕我直言，这就是其中之一。图表本身可能应该有类似 Function<Data<X,Y>, Node> nodeFactory 的属性。但是，它就是这样。)

private void chartRefresh() {

    series.getData().clear();
    if (level < datas.length) {

        for (int i = 0; i < datas[level].length; i++) {
            Data<Number, Number> data = new Data<Number, Number>(i, datas[level][i]);
            data.setNode(new Circle(3, Color.RED));
            series.getData().add(data);
        }
    }
    level++;

    chart.getData().clear();
    chart.getData().add(series);
    series.getNode().setStyle("-fx-stroke:blue;-fx-stroke-width:1");

    // reDrawShapes(series);
}

如果您的节点足够简单，以点为中心就是您所需要的，则此方法可行。

如果你想要更复杂的东西，而这不起作用，支持的机制是子类化图表类并覆盖 layoutPlotChildren()方法。这是使用这种方法的完整类(class):

import java.util.ArrayList;
import java.util.List;

import javafx.animation.KeyFrame;
import javafx.animation.Timeline;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Side;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart.Data;
import javafx.scene.chart.XYChart.Series;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Shape;
import javafx.util.Duration;

public class ChartContent extends StackPane {

    private LineChart<Number, Number> chart;
    private NumberAxis xAxis;
    private NumberAxis yAxis;
    private Series<Number, Number> series = new Series<Number, Number>();
    private int level = 0;
    private int datas[][] = { { 15, 8, 12, 11, 16, 21, 13 },
            { 10, 24, 20, 16, 31, 25, 44 }, { 88, 60, 105, 75, 151, 121, 137 },
            { 1000, 1341, 1211, 1562, 1400, 1600, 1550 }

    };

    public ChartContent() {

        xAxis = new NumberAxis();
        yAxis = new NumberAxis();

        yAxis.setSide(Side.RIGHT);
        yAxis.setForceZeroInRange(false);

        xAxis.setForceZeroInRange(false);

        chart = new LineChart<Number, Number>(xAxis, yAxis) {

            private List<Shape> shapes = new ArrayList<>();

            @Override
            public void layoutPlotChildren() {
                super.layoutPlotChildren();
                getPlotChildren().removeAll(shapes);
                shapes.clear();
                for (Data<Number, Number> d : series.getData()) {
                    double x = xAxis.getDisplayPosition(d.getXValue());
                    double y = yAxis.getDisplayPosition(d.getYValue());
                    shapes.add(new Circle(x, y, 3, Color.RED));
                }
                getPlotChildren().addAll(shapes);
            }
        };
        chart.setCreateSymbols(false);
        chart.setLegendVisible(false);
        chart.setAnimated(false);
        chart.setVerticalZeroLineVisible(false);

        Timeline timer = new Timeline(new KeyFrame(Duration.seconds(5),
                new EventHandler<ActionEvent>() {

                    @Override
                    public void handle(ActionEvent event) {

                        chartRefresh();
                    }
                }));
        timer.setCycleCount(datas.length - 1);
        timer.play();

        getChildren().addAll(chart);
        chartRefresh();
    }

    private void chartRefresh() {

        series.getData().clear();
        if (level < datas.length) {

            for (int i = 0; i < datas[level].length; i++) {
                Data<Number, Number> data = new Data<Number, Number>(i, datas[level][i]);
                data.setNode(new Circle(3, Color.RED));
                series.getData().add(data);
            }
        }
        level++;

        chart.getData().clear();
        chart.getData().add(series);
        series.getNode().setStyle("-fx-stroke:blue;-fx-stroke-width:1");

    }


}

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这导致

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例如，您可以使用此技术将最佳拟合线添加到散点图或将趋势线添加到折线图等。

我不能确切地说出为什么您使用的代码不起作用，但它对如何管理布局(即 chart-plot-background 相对于整个图表本身的位置)以及何时进行了一些假设进行测量是为了做一些事情，比如计算从“图表坐标”到“像素坐标”的映射轴的比例。不难想象，当数据发生变化并且仅在布局过程开始时才重新计算时，它们会变得无效，例如。记录“数据值”( data.getXValue() 和 data.getYValue() )以及您从 Axis.getDisplayValue(...) 获得的值因为这些值表明可能是类似于后一种解释的情况，因为这些值似乎肯定不会产生正确的转换。

连接到 layoutPlotChildren()方法更可靠。