AbstractComponent.java

package org.newdawn.slick.gui;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import org.newdawn.slick.Graphics;
import org.newdawn.slick.Input;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.geom.Rectangle;
import org.newdawn.slick.util.InputAdapter;

/**
 * The utility class to handle all the input related gubbins for basic GUI
 * components
 * 
 * @author kevin
 */
public abstract class AbstractComponent extends InputAdapter {
	/** The component that currently has focus */
	private static AbstractComponent currentFocus = null;
	
	/** The game container */
	protected GUIContext container;

	/** Listeners for the component to notify */
	protected Set listeners;

	/** True if this component currently has focus */
	private boolean focus = false;

	/** The input we're responding to */
	protected Input input;
	
	/**
	 * Create a new component
	 * 
	 * @param container
	 *            The container displaying this component
	 */
	public AbstractComponent(GUIContext container) {
		this.container = container;

		listeners = new HashSet();

		input = container.getInput();
		input.addPrimaryListener(this);

		setLocation(0, 0);
	}
	
	/**
	 * Add a component listener to be informed when the component sees fit.
	 * 
	 * It will ignore listeners already added.
	 * 
	 * @param listener
	 *            listener
	 */
	public void addListener(ComponentListener listener) {
		listeners.add(listener);
	}

	/**
	 * Remove a component listener.
	 * 
	 * It will ignore if the listener wasn't added.
	 * 
	 * @param listener
	 *            listener
	 */
	public void removeListener(ComponentListener listener) {
		listeners.remove(listener);
	}

	/**
	 * Notify all the listeners.
	 */
	protected void notifyListeners() {
		Iterator it = listeners.iterator();
		while (it.hasNext()) {
			((ComponentListener) it.next()).componentActivated(this);
		}
	}

	/**
	 * Render this component to the screen
	 * 
	 * @param container
	 *            The container displaying this component
	 * @param g
	 *            The graphics context used to render to the display
	 * @throws SlickException
	 *             If there has been an error rendering the component
	 */
	public abstract void render(GUIContext container, Graphics g)
			throws SlickException;

	/**
	 * Moves the component.
	 * 
	 * @param x
	 *            X coordinate
	 * @param y
	 *            Y coordinate
	 */
	public abstract void setLocation(int x, int y);

	/**
	 * Returns the position in the X coordinate
	 * 
	 * @return x
	 */
	public abstract int getX();

	/**
	 * Returns the position in the Y coordinate
	 * 
	 * @return y
	 */
	public abstract int getY();

	/**
	 * Get the width of the component
	 * 
	 * @return The width of the component
	 */
	public abstract int getWidth();

	/**
	 * Get the height of the component
	 * 
	 * @return The height of the component
	 */
	public abstract int getHeight();

	/**
	 * Indicate whether this component should be focused or not
	 * 
	 * @param focus
	 *            if the component should be focused
	 */
	public void setFocus(boolean focus) {
		if (focus) {
			if (currentFocus != null) {
				currentFocus.setFocus(false);
			}
			currentFocus = this;
		} else {
			if (currentFocus == this) {
				currentFocus = null;
			}
		}
		this.focus = focus;
	}

	/**
	 * Check if this component currently has focus
	 * 
	 * @return if this field currently has focus
	 */
	public boolean hasFocus() {
		return focus;
	}

	/**
	 * Consume the event currently being processed
	 */
	protected void consumeEvent() {
		input.consumeEvent();
	}
	
	/**
	 * Gives the focus to this component with a click of the mouse.
	 * 
	 * @see org.newdawn.slick.gui.AbstractComponent#mouseReleased(int, int, int)
	 */
	public void mouseReleased(int button, int x, int y) {
		setFocus(Rectangle.contains(x, y, getX(), getY(), getWidth(),
				getHeight()));
	}
}