JavaFX GridPane resizing of pane children

Question

This may be a duplicate question, but I haven't found a solution that suits my needs.

Inspired from jewelsea's ColorChooserSample, half-way through my implementation I realised that manual size can only be set on Controls, and not on Panes. These panes should be smart enough to resize themselves automatically depending on their parent.

Is there a way for the GridPanes children to grab vertical and horizontal space at the same time? Much like a VBox and HBox combined. I bet the solution involves AnchorPane.

Keep in my the children are panes and not controls.

---

SSCCE with buttons (copy - paste - run - resize window)

import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.geometry.Bounds;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Control;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

/**
 * 
 * @author ggrec
 *
 */
public class DashboardFXGrid extends Application
{

    // ==================== 1. Static Fields ========================

    private final static double GOLDEN_RATIO = 1.618;

    private final static double MIN_TILE_SIZE = 5;
    private final static double MAX_TILE_SIZE = Double.MAX_VALUE;


    // ====================== 2. Instance Fields =============================

    private DoubleProperty prefTileSize = new SimpleDoubleProperty(MIN_TILE_SIZE);

    private double nColumns;
    private double nRows;

    private GridPane gridPane;


    // ==================== 3. Static Methods ====================

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


    // ==================== 4. Constructors ====================

    @Override
    public void start(final Stage primaryStage) throws Exception
    {
        gridPane = new GridPane();

        gridPane.setPadding(new Insets(20));
        gridPane.setHgap(10);
        gridPane.setVgap(10);

        nColumns = Math.floor(Math.sqrt(dummyButtons().length) * 2 / GOLDEN_RATIO);
        nRows    = Math.ceil(dummyButtons().length / nColumns);

        createContents();

        addResizeListeners();

        primaryStage.setScene(new Scene(gridPane));
        primaryStage.show();
    }


    // ==================== 5. Creators ====================

    private void createContents()
    {
        int i = 0;

        for (final Button button : dummyButtons())
        {
            GridPane.setRowIndex(button,       i / (int) nColumns);
            GridPane.setColumnIndex(button, i % (int) nColumns);

            button.setMinSize(MIN_TILE_SIZE, MIN_TILE_SIZE);
            button.setMaxSize(MAX_TILE_SIZE, MAX_TILE_SIZE);

            gridPane.getChildren().add(button);

            i++;
        }
    }

    private void addResizeListeners()
    {
        gridPane.layoutBoundsProperty().addListener(new ChangeListener<Bounds>() {

            @Override public void changed(final ObservableValue<? extends Bounds> observableValue, final Bounds oldBounds, final Bounds newBounds)
            {
                prefTileSize.set(Math.max(MIN_TILE_SIZE, Math.min(newBounds.getWidth() / nColumns, newBounds.getHeight() / nRows)));

                for (final Node child : gridPane.getChildrenUnmodifiable())
                {
                    final Control tile = (Control) child;
                    tile.setPrefSize(prefTileSize.get(), prefTileSize.get());
                }
            }
        });
    }


    // ==================== 15. Other ====================

    private static final Button[] dummyButtons()
    {
        final Button[] buttons = new Button[5];

        for(int i = 0; i < buttons.length; i++)
        {
            buttons[i] = new Button(String.valueOf(i));
        }

        return buttons;
    }

}

Answer 1

Is there a way for the GridPanes children to grab vertical and horizontal space at the same time?

Try to use RowConstraints and ColumnConstraints of GridPane:

for (final Button button : dummyButtons()) {
    GridPane.setRowIndex(button, i / (int) nColumns);
    GridPane.setColumnIndex(button, i % (int) nColumns);

    button.setMinSize(MIN_TILE_SIZE, MIN_TILE_SIZE);
    button.setMaxSize(MAX_TILE_SIZE, MAX_TILE_SIZE);

    gridPane.getChildren().add(button);

    i++;
}

for (int j = 0; j < nColumns; j++) {
    ColumnConstraints cc = new ColumnConstraints();
    cc.setHgrow(Priority.ALWAYS);
    gridPane.getColumnConstraints().add(cc);
}

for (int j = 0; j < nRows; j++) {
    RowConstraints rc = new RowConstraints();
    rc.setVgrow(Priority.ALWAYS);
    gridPane.getRowConstraints().add(rc);
}

and without calling addResizeListeners().