chess/src/main/java/dev/kske/chess/ui/GameTabComponent.java

package dev.kske.chess.ui;

import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.*;
import javax.swing.plaf.basic.BasicButtonUI;

/**
 * Renders the title and the closing button of a {@link JTabbedPane}.<br>
 * <br>
 * Project: <strong>Chess</strong><br>
 * File: <strong>GameTabComponent.java</strong><br>
 * Created: <strong>11 Dec 2019</strong><br>
 *
 * @author Kai S. K. Engelbart
 */
public class GameTabComponent extends JPanel {

	private final JTabbedPane tabbedPane;

	private static final long serialVersionUID = 9022979950018125935L;

	/**
	 * Creates an instance of {@link GameTabComponent}.
	 *
	 * @param tabbedPane the tabbed pane which contains this
	 *                   {@link GameTabComponent}
	 */
	public GameTabComponent(JTabbedPane tabbedPane) {
		super(new FlowLayout(FlowLayout.LEFT, 0, 0));
		if (tabbedPane == null)
			throw new NullPointerException("TabbedPane is null");
		this.tabbedPane = tabbedPane;

		// Create title JLabel
		JLabel label = new JLabel() {

			private static final long serialVersionUID = 7902391411509551586L;

			@Override
			public String getText() {
				int i = tabbedPane.indexOfTabComponent(GameTabComponent.this);
				return i != -1 ? tabbedPane.getTitleAt(i) : "";
			}
		};
		label.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 5));
		add(label);

		// Create close JButton
		add(new TabButton());
		setBorder(BorderFactory.createEmptyBorder(2, 0, 0, 0));
	}

	private class TabButton extends JButton {

		private static final long serialVersionUID = -2757857832337636731L;

		public TabButton() {
			final int size = 17;
			setPreferredSize(new Dimension(size, size));
			setToolTipText("Close this tab");
			setUI(new BasicButtonUI());
			setContentAreaFilled(false);
			setFocusable(false);
			setBorder(BorderFactory.createEtchedBorder());
			setBorderPainted(false);
			addMouseListener(new MouseAdapter() {

				@Override
				public void mouseEntered(MouseEvent evt) {
					setBorderPainted(true);
				}

				@Override
				public void mouseExited(MouseEvent evt) {
					setBorderPainted(false);
				}
			});
			setRolloverEnabled(true);
			addActionListener(evt -> {
				int i = tabbedPane.indexOfTabComponent(GameTabComponent.this);
				if (i != -1)
					tabbedPane.remove(i);
			});
		}

		@Override
		public void updateUI() {}

		@Override
		public void paintComponent(Graphics g) {
			super.paintComponent(g);
			Graphics2D g2 = (Graphics2D) g.create();
			// shift the image for pressed buttons
			if (getModel().isPressed())
				g2.translate(1, 1);
			g2.setStroke(new BasicStroke(2));
			g2.setColor(Color.BLACK);
			if (getModel().isRollover())
				g2.setColor(Color.MAGENTA);
			final int delta = 6;
			g2.drawLine(
				delta,
				delta,
				getWidth() - delta - 1,
				getHeight() - delta - 1
			);
			g2.drawLine(
				getWidth() - delta - 1,
				delta,
				delta,
				getHeight() - delta - 1
			);
			g2.dispose();
		}
	}
}