JavaFX图表自动缩放错误,数字较小

Question

我正在使用JavaFX来构建StackedBarChart.随着新数据的出现,图表会发生变化.我正在用一个更新图表的按钮来模拟这个.

它主要工作正常,但我注意到,当值较低(值小于~100)时,Y轴标签在我第一次更新图表时似乎有点偏差:

更奇怪的是,如果我第二次(或第三次,第四次......)更新图表,Y轴的自动缩放是远离的:

如果我使用更大的值(值> ~1000),则自动缩放工作正常.如果我停用图表动画,那么自动缩放工作正常.第一次更新图表时自动缩放工作正常,但之后没有.

这是我正在使用的代码,它与此 JavaFX教程中的代码非常相似.

import java.util.Arrays;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.StackedBarChart;
import javafx.scene.chart.XYChart;
import javafx.scene.control.Button;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!


        Button button = new Button("update");
        button.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                updateChart();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, button);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void updateChart(){

        int m = 1; //change this to 100 and autoscaling works!


        xAxis.setCategories(FXCollections.<String>observableArrayList());
        sbc.getData().clear();

        final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
        final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));


        xAxis.setCategories(FXCollections.<String>observableArrayList(Arrays.asList("one", "two", "three")));
        sbc.getData().addAll(series1, series2);
    }

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

奖励问题:即使动画有效,动画也会显示每个堆叠条形图的2个额外部分,这些部分会在动画完成时消失.有没有办法在动画期间摆脱那些额外的部分？

Answer 1

您正在使用图表,动画和可观察列表的修改,似乎不应该这样做.好吧,我最初也是.我遇到过像这样的问题,其中包括ArrayIndexOutOfBounds Exceptions.简而言之:JavaFX图表的动画非常破碎,或者看起来如此.它似乎不可靠,因此当您直接修改列表时无法使用.

我停止使用动画或修改列表,而是在每次更改时设置列表.这两种方法都解决了这个问题.

使用sbc.setData()而不是sbc.getData().clear()和sbc.getData().addAll()修改示例.这有效,即动画仍在运行:

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    Random rnd = new Random();

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!

        Button button = new Button("update");
        button.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                updateChart();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, button);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void updateChart(){

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
        final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        sbc.setData( FXCollections.observableArrayList(series1, series2));
    }

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

我为你的m添加了随机性,以便看到条形图的变化.

但真正的问题是你使用图表的方式.您不应该修改列表,而是应该修改列表项的数据.然后图表动画按预期工作,条形图随数据上升和下降.

使用"创建"(创建新图表列表)和"修改"(修改列表的数据,但不创建新列表)按钮的示例:

public class StackedBarChartSample extends Application {

    final CategoryAxis xAxis = new CategoryAxis();
    final NumberAxis yAxis = new NumberAxis();
    final StackedBarChart<String, Number> sbc = new StackedBarChart<String, Number>(xAxis, yAxis);

    Random rnd = new Random();

    final XYChart.Series<String, Number> series1 = new XYChart.Series<String, Number>();
    final XYChart.Series<String, Number> series2 = new XYChart.Series<String, Number>();

    @Override
    public void start(Stage stage) {

        stage.setTitle("Bar Chart Sample");

        sbc.setAnimated(true); //change this to false and autoscaling works!

        Button createButton = new Button("Create");
        createButton.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                createChartData();
            }

        });

        Button modifyButton = new Button("Modify");
        modifyButton.setOnAction(new EventHandler<ActionEvent>(){
            @Override
            public void handle(ActionEvent arg0) {
                modifyChartData();
            }

        });

        VBox contentPane = new VBox();
        contentPane.getChildren().addAll(sbc, createButton, modifyButton);

        Scene scene = new Scene(contentPane, 800, 600);

        stage.setScene(scene);
        stage.show();
    }


    private void createChartData(){

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        series1.setName("ABC");
        series1.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series1.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series1.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        series2.setName("XYZ");
        series2.getData().add(new XYChart.Data<String, Number>("one", 25*m));
        series2.getData().add(new XYChart.Data<String, Number>("two", 20*m));
        series2.getData().add(new XYChart.Data<String, Number>("three", 10*m));

        sbc.setData( FXCollections.observableArrayList(series1, series2));
    }

    private void modifyChartData() {

        int m = 1; //change this to 100 and autoscaling works!

        m = rnd.nextInt(100) + 1; // just some random value to see changes in the chart

        System.out.println( "m = " + m);

        for( XYChart.Data<String,Number> data: series1.getData()) {
            data.setYValue(rnd.nextInt(30) * m);
        }

        for( XYChart.Data<String,Number> data: series2.getData()) {
            data.setYValue(rnd.nextInt(30) * m);
        }


    }

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