DirectionCombo.java

package com.kartoflane.superluminal2.ui;

import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;

import com.kartoflane.superluminal2.components.enums.Directions;

/**
 * A Combo widget with some predefined items, plus convenience methods.<br>
 * <br>
 * Subclassing SWT widgets is generally bad practice, however this is a simple
 * wrapper class that automates instantiation to achieve consistent behaviour
 * and reduce the amount of redundant code across the application.<br>
 * <br>
 * Since it doesn't touch any of the internal methods, it should be fine.
 * 
 * @author kartoFlane
 * 
 */
public class DirectionCombo extends Combo {

	private final boolean full;

	/**
	 * Constructs a new instance of the Combo widget and fills it with predefined items,
	 * representing values of the {@link Directions} enum.
	 * 
	 * @param parent
	 *            a composite control which will be the parent of the new instance (cannot be null)
	 * @param style
	 *            the style of control to construct
	 * @param full
	 *            whether to use all values of the {@link Directions} enum; true uses all values, false
	 *            omits {@link Directions#NONE}
	 * 
	 * @see {@link Combo}
	 */
	public DirectionCombo(Composite parent, int style, boolean full) {
		super(parent, style);
		this.full = full;

		add("Up");
		add("Left");
		add("Right");
		add("Down");
		if (full)
			add("None");
	}

	@Override
	protected void checkSubclass() {
		// Need to override this in order to allow subclassing
	}

	public void select(Directions dir) {
		if (dir == Directions.NONE && !full)
			throw new IllegalArgumentException("DirectionCombo wasn't instantiated as full and doesn't have an item for Directions.NONE");
		select(toIndex(dir));
	}

	public Directions getDirection() {
		return toDirection(getSelectionIndex());
	}

	public static int toIndex(Directions dir) {
		switch (dir) {
			case UP:
				return 0;
			case LEFT:
				return 1;
			case RIGHT:
				return 2;
			case DOWN:
				return 3;
			case NONE:
				return 4;
			default:
				throw new IllegalArgumentException("Unknown direction: " + dir);
		}
	}

	public static Directions toDirection(int index) {
		switch (index) {
			case 0:
				return Directions.UP;
			case 1:
				return Directions.LEFT;
			case 2:
				return Directions.RIGHT;
			case 3:
				return Directions.DOWN;
			case 4:
				return Directions.NONE;
			default:
				throw new IllegalArgumentException("Unknown index: " + index);
		}
	}
}