add label line javafx

Question

I am looking to add a text of my scale and add arrows in the corner of my line in javafx.
thank you.

Answer 1

I recommend extending Region to keep the elements together and layout the children.

ScaleView

This is simpler to implement. I recommend using Path instead of individual lines, since this makes setting the size simpler.

public class ScaleView extends Region {

    private final Label text;
    private final Path path;
    private final VLineTo down;
    private final HLineTo right;
    private final VLineTo up;

    public ScaleView(String text) {
        this();
        setText(text);
    }

    public ScaleView() {
        setMaxHeight(USE_PREF_SIZE); // don't resize beyond text size by default
        setMinHeight(USE_PREF_SIZE);

        text = new Label();

        // assemble path for line
        down = new VLineTo();
        up = new VLineTo();
        right = new HLineTo();

        down.setAbsolute(false);
        up.setAbsolute(false);
        right.setAbsolute(false);

        path = new Path(new MoveTo(), down, right, up);
        path.setStrokeWidth(2);
        path.setManaged(false);
        getChildren().addAll(text, path);
    }

    public final StringProperty textProperty() {
        return text.textProperty();
    }

    public final void setText(String value) {
        text.setText(value);
    }

    public final String getText() {
        return text.getText();
    }

    @Override
    protected void layoutChildren() {
        Insets insets = getInsets();

        double left = insets.getLeft();
        double top = insets.getTop();

        double h = getHeight() - top - insets.getBottom();
        double w = getWidth() - left - insets.getRight();

        // fix path
        down.setY(h);
        up.setY(-h);
        right.setX(w);
        path.relocate(left, top);

        layoutInArea(text,
                left, top,
                w, h,
                0,
                HPos.CENTER, VPos.CENTER);
    }

}

QuoteView

This is a bit more complex, since the arrow line is centered and different strokes are used. In this case I'd use Polygons for the arrow heads and Lines for the vertical lines at both sides and the arrow line.

public class QuoteView extends Region {

    private final Line leftBound;
    private final Line rightBound;
    private final Line line;
    private final Label text;
    private final Polygon arrowLeft;
    private final Polygon arrowRight;
    private final Node[] hOrder;

    public QuoteView(String text) {
        this();
        setText(text);
    }

    public QuoteView() {
        text = new Label();

        line = new Line();

        // vertical lines
        leftBound = new Line();
        rightBound = new Line();
        leftBound.getStrokeDashArray().setAll(5d);
        rightBound.getStrokeDashArray().setAll(5d);

        // arrow heads
        final double arrowHeight = 15;
        final double arrowWidth = 10;
        arrowLeft = new Polygon(0, arrowHeight / 2, arrowWidth, 0, arrowWidth, arrowHeight);
        arrowRight = new Polygon(0, 0, arrowWidth, arrowHeight / 2, 0, arrowHeight);

        arrowLeft.setFill(null);
        arrowLeft.setStroke(Color.BLACK);
        arrowRight.setFill(null);
        arrowRight.setStroke(Color.BLACK);

        // nodes that contribute to horizontal size
        hOrder = new Node[]{ leftBound, arrowLeft, text, arrowRight, rightBound};

        getChildren().addAll(leftBound, arrowLeft, line, arrowRight, rightBound, text);
    }

    @Override
    protected double computePrefHeight(double width) {
        Insets insets = getInsets();

        double arrowHeight = arrowLeft.getLayoutBounds().getHeight();
        double textHeight = text.prefHeight(width);

        // preferred height is the height of the arrows
        // or 2*textHeight + arrow line height (higher value)
        return Math.max(arrowHeight,
                2 * textHeight + line.getLayoutBounds().getHeight()) + insets.getBottom() + insets.getTop();
    }

    @Override
    protected double computePrefWidth(double height) {
        Insets insets = getInsets();

        // the width is computed by putting the vertical lines, arrows and text next to each other
        double w = 0;
        for (Node n : hOrder) {
            w += n.prefWidth(height);
        }

        return w + insets.getLeft() + insets.getRight();
    }

    @Override
    protected double computeMinHeight(double width) {
        Insets insets = getInsets();

        double arrowHeight = arrowLeft.getLayoutBounds().getHeight();
        double textHeight = text.minHeight(width);

        // min height is the height of the arrows
        // or 2*textHeight + arrow line height (higher value)
        return Math.max(arrowHeight,
                2 * textHeight + line.getLayoutBounds().getHeight()) + insets.getBottom() + insets.getTop();
    }

    @Override
    protected double computeMinWidth(double height) {
        Insets insets = getInsets();

        // the width is computed by putting the vertical lines, arrows and text next to each other
        double w = 0;
        for (Node n : hOrder) {
            w += n.minWidth(height);
        }

        return w + insets.getLeft() + insets.getRight();
    }

    public final StringProperty textProperty() {
        return text.textProperty();
    }

    public final void setText(String value) {
        text.setText(value);
    }

    public final String getText() {
        return text.getText();
    }

    @Override
    protected void layoutChildren() {
        Insets insets = getInsets();

        double left = insets.getLeft();
        double top = insets.getTop();

        double h = getHeight();
        double w = getWidth();

        // set vertical line size
        double contentHeight = h - top - insets.getBottom();
        leftBound.setEndY(contentHeight);
        rightBound.setEndY(contentHeight);

        // layout left arrow & move left vertical line
        double x = left;
        leftBound.relocate(x, top);
        x += leftBound.getLayoutBounds().getWidth();
        Bounds bounds = arrowLeft.getLayoutBounds();
        arrowLeft.relocate(x, top + (contentHeight - bounds.getHeight()) / 2);
        x += bounds.getWidth();

        // layout right arrow & move right vertical line
        double xEnd = w - insets.getRight() - rightBound.getLayoutBounds().getWidth();
        rightBound.relocate(xEnd, top);
        bounds = arrowRight.getLayoutBounds();
        xEnd -= bounds.getWidth();
        arrowRight.relocate(xEnd, top + (contentHeight - bounds.getHeight()) / 2);

        // layout line
        double lineY = top + (contentHeight - line.getLayoutBounds().getHeight()) / 2;
        line.setStartX(x);
        line.setStartY(lineY);
        line.setEndX(xEnd);
        line.setEndY(lineY);

        // position text on top of the line
        layoutInArea(text,
                x, top,
                xEnd - x, lineY,
                0,
                HPos.CENTER, VPos.BOTTOM);
    }

}