Can PieChart from JavaFX be displayed as a doughnut?

Question

I'm using javafx.scene.chart.PieChart in my Java app which is built using Java7. Is there a way of making the PieChart hollow - turning it into a doughnut?

Answer 1

Yep, you can use a DoughnutChart class.

*DoughnutChart.java**

import javafx.collections.ObservableList;
import javafx.geometry.Bounds;
import javafx.scene.Node;
import javafx.scene.chart.PieChart;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;

public class DoughnutChart extends PieChart {
    private final Circle innerCircle;

    public DoughnutChart(ObservableList<Data> pieData) {
        super(pieData);

        innerCircle = new Circle();

        // just styled in code for demo purposes,
        // use a style class instead to style via css.
        innerCircle.setFill(Color.WHITESMOKE);
        innerCircle.setStroke(Color.WHITE);
        innerCircle.setStrokeWidth(3);
    }

    @Override
    protected void layoutChartChildren(double top, double left, double contentWidth, double contentHeight) {
        super.layoutChartChildren(top, left, contentWidth, contentHeight);

        addInnerCircleIfNotPresent();
        updateInnerCircleLayout();
    }

    private void addInnerCircleIfNotPresent() {
        if (getData().size() > 0) {
            Node pie = getData().get(0).getNode();
            if (pie.getParent() instanceof Pane) {
                Pane parent = (Pane) pie.getParent();

                if (!parent.getChildren().contains(innerCircle)) {
                    parent.getChildren().add(innerCircle);
                }
            }
        }
    }

    private void updateInnerCircleLayout() {
        double minX = Double.MAX_VALUE, minY = Double.MAX_VALUE;
        double maxX = Double.MIN_VALUE, maxY = Double.MIN_VALUE;
        for (PieChart.Data data: getData()) {
            Node node = data.getNode();

            Bounds bounds = node.getBoundsInParent();
            if (bounds.getMinX() < minX) {
                minX = bounds.getMinX();
            }
            if (bounds.getMinY() < minY) {
                minY = bounds.getMinY();
            }
            if (bounds.getMaxX() > maxX) {
                maxX = bounds.getMaxX();
            }
            if (bounds.getMaxY() > maxY) {
                maxY = bounds.getMaxY();
            }
        }

        innerCircle.setCenterX(minX + (maxX - minX) / 2);
        innerCircle.setCenterY(minY + (maxY - minY) / 2);

        innerCircle.setRadius((maxX - minX) / 4);
    }
}

DoughnutChartSample.java

import javafx.application.Application;
import javafx.collections.*;
import javafx.scene.Scene;
import javafx.scene.chart.PieChart;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class DoughnutChartSample extends Application {

    @Override public void start(Stage stage) {
        stage.setTitle("Imported Fruits");
        stage.setWidth(500);
        stage.setHeight(500);

        ObservableList<PieChart.Data> pieChartData = createData();

        final DoughnutChart chart = new DoughnutChart(pieChartData);
        chart.setTitle("Imported Fruits");

        Scene scene = new Scene(new StackPane(chart));
        stage.setScene(scene);
        stage.show();
    }

    private ObservableList<PieChart.Data> createData() {
        return FXCollections.observableArrayList(
                new PieChart.Data("Grapefruit", 13),
                new PieChart.Data("Oranges", 25),
                new PieChart.Data("Plums", 10),
                new PieChart.Data("Pears", 22),
                new PieChart.Data("Apples", 30));
    }

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

}