ComboBox with correct aligned elements

[Eric Jinson]

I need following ComboBox:
1. Arrowbutton needs to be on the left side.
2. Textalignment needs to be left-to-right.
3. Popup alignment needs to be left-to-right, with the left top corner of the popup touching the left bottom corner of the combobox textfield.

As I see it, if I align elements left-to-right, then
1. Text is aligned left-to-right
2. Popup is aligned left-to-right
3. Arrowbutton is on the right side.

If I align elements right-to-left, then
1. Text is aligned right-to-left
2. Popup is aligned right-to-left
3. Arrowbutton is on the left side.

What do I have to do?

[Eric Jinson]

Actually it is not. The solutions available either cover the first or the second variant. But I need everything on the left side!

[John Damien Smith]

You could apply a custom skin to your ComboBox to modify the layout algorithm.

The following will left align the drop-down arrow for the ComboBox, rather than using the default right-aligned drop-down arrow.

import com.sun.javafx.scene.control.skin.ComboBoxListViewSkin;
import javafx.application.Application;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.VPos;
import javafx.scene.Scene;
import javafx.scene.control.ComboBox;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class LeftCombo extends Application {
   public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) {
        ComboBox<String> choices = new ComboBox<>();
        choices.setSkin(new LeftComboBoxSkin<>(choices));
        choices.getItems().addAll(
                "Apples",
                "Oranges",
                "Pears",
                "Lemons"
        );
        choices.getSelectionModel().select(3);

        StackPane stack = new StackPane(choices);
        stack.setPadding(new Insets(50));
        Scene scene = new Scene(stack);

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

    private class LeftComboBoxSkin<T> extends ComboBoxListViewSkin<T> {

        LeftComboBoxSkin(ComboBox<T> comboBox) {
            super(comboBox);
        }

        @Override
        protected void layoutChildren(double x, double y, double w, double h) {
            super.layoutChildren(x, y, w, h);

            final double arrowWidth = snapSize(arrow.prefWidth(-1));
            final double arrowButtonWidth =
                    arrowButton.snappedLeftInset() + arrowWidth +
                            arrowButton.snappedRightInset();

            getChildren().stream()
                    .filter(node -> node.getStyleClass().contains("cell"))
                    .forEach(node -> node.resizeRelocate(x + arrowButtonWidth, y, w - arrowButtonWidth, h));

            positionInArea(arrowButton, x, y,
                    arrowButtonWidth, h, 0, HPos.CENTER, VPos.CENTER);
        }
    }
}