pageitem.java

J2ME 3D 第一人称射击迷宫类手机游戏源码。

package myGame.gui.menu;

import java.util.Hashtable;

import javax.microedition.lcdui.Image;

/**
 * <p>
 * The <code>PageItem</code> defines a choice in a <code>MenuPage</code>.
 * An item can have a subpage and/or an <code>ItemAction</code>
 * implementation. When an item is selected by user, the <code>ItemAction</code>
 * implementation is invoked, and/or a transition to the subpage is started.
 * </p>
 * <p>
 * <code>PageItem</code>s can also have key/value pairs typed as int/Object.
 * </p>
 * <p>
 * When there is both a subpage and an action; pressing fire on such an item
 * will first start a new thread invokinh the action, then the menu will
 * navigate to the subpage. If the user presses right on such an item, the
 * action is not executed but the subpage is navigated to.
 * </p>
 * 
 * @see Menu
 * @see MenuPage
 * @see ItemAction
 * @author YuBingxing
 */
public class PageItem {
	/** Centered item, image to the left of text (Default layout) */
	public static final int LAYOUT_CENTERED_LEFT = 0;

	/** Centered item, image to the right of text */
	public static final int LAYOUT_CENTERED_RIGHT = 1;

	/** Left aligned image, right aligned text */
	public static final int LAYOUT_ALIGN_LEFT = 2;

	/** Right aligned image, left aligned text */
	public static final int LAYOUT_ALIGN_RIGHT = 3;

	/** The label of the item */
	protected char[] m_label;

	/** The action of the item */
	protected ItemAction m_action;

	/** The next page to goto if this item is selected */
	protected MenuPage m_subPage;

	/** The image of this item */
	protected Image m_image;

	/** Layout of image */
	protected int m_layout = LAYOUT_CENTERED_LEFT;

	/** Enabled / disabled flag */
	protected boolean m_enabled = true;

	/** Properties table */
	protected Hashtable m_props = null;

	/** Item id */
	protected int m_id = Integer.MIN_VALUE;

	/**
	 * Creates an item that is to be inserted into a <code>MenuPage</code>.
	 * Item graphical elements are the label and the image, and logical elements
	 * are action and subpage.
	 * 
	 * @param label
	 *            The text label of this item or null if no text.
	 * @param image
	 *            The image of this item or null if no image.
	 * @param action
	 *            The action that is called when activating this item, or null
	 *            if no action.
	 * @param subPage
	 *            The page that will be navigated to when activating this item,
	 *            or null of no such page.
	 */
	public PageItem(char[] label, Image image, ItemAction action,
			MenuPage subPage) {
		setLabel(label);
		setImage(image);
		setAction(action);
		setSubPage(subPage);
	}

	/**
	 * Creates an item that is to be inserted into a <code>MenuPage</code>.
	 * Item graphical elements are the label and the image, and logical elements
	 * are action and subpage.
	 * 
	 * @param label
	 *            The text label of this item or null if no text.
	 * @param image
	 *            The image of this item or null if no image.
	 * @param action
	 *            The action that is called when activating this item, or null
	 *            if no action.
	 * @param subPage
	 *            The page that will be navigated to when activating this item,
	 *            or null of no such page.
	 * @param id
	 *            The id of this item.
	 */
	public PageItem(char[] label, Image image, ItemAction action,
			MenuPage subPage, int id) {
		this(label, image, action, subPage);
		m_id = id;
	}

	/**
	 * Returns ID of this item, or <code>Integer.MIN_VALUE</code> if not set.
	 * 
	 * @return The item id
	 */
	public int getId() {
		return m_id;
	}

	/**
	 * Called when this item is added to a page. Default implementation does
	 * nothinhg.
	 */
	public void addedToPage() {
	}

	/**
	 * Returns the label of this item.
	 * 
	 * @return The text label of this item.
	 */
	public char[] getLabel() {
		return m_label;
	}

	/**
	 * Sets the text label of this item.
	 * 
	 * @param label
	 *            The text label of this item.
	 */
	public void setLabel(char[] label) {
		m_label = label;
	}

	/**
	 * Returns the subpage that will be displayed when this item is activated,
	 * or null if no such page.
	 * 
	 * @return The sub page or null.
	 */
	public MenuPage getSubPage() {
		return m_subPage;
	}

	/**
	 * Sets the subpage that will be displayed when this item is activated, or
	 * null if no such page.
	 * 
	 * @param page
	 *            The sub page or null.
	 */
	public void setSubPage(MenuPage page) {
		m_subPage = page;
	}

	/**
	 * Returns action which is called upon item activation.
	 * 
	 * @return The action of this item.
	 */
	public ItemAction getAction() {
		return m_action;
	}

	/**
	 * Sets the action which is called upon item activation.
	 * 
	 * @param action
	 *            The action of this item.
	 */
	public void setAction(ItemAction action) {
		m_action = action;
	}

	/**
	 * Returns true if this item is enabled, false otherwise.
	 * 
	 * @return true if enabled, false otherwise
	 */
	public boolean isEnabled() {
		return m_enabled;
	}

	/**
	 * Enables or disables this item.
	 * 
	 * @param enabled
	 *            true to enable, false to disable
	 */
	public void setEnabled(boolean enabled) {
		m_enabled = enabled;
	}

	/**
	 * Returns image of this item, or null if none set.
	 * 
	 * @return The image or null.
	 */
	public Image getImage() {
		return m_image;
	}

	/**
	 * Sets the image of this item.
	 * 
	 * @param image
	 *            The image or null.
	 */
	public void setImage(Image image) {
		m_image = image;
	}

	/**
	 * Sets the layout of the image, any of LAYOUT_CENTERED_LEFT,
	 * LAYOUT_CENTERED_RIGHT, LAYOUT_ALIGN_LEFT, LAYOUT_ALIGN_RIGHT.
	 * 
	 * @param layout
	 *            Image layout.
	 */
	public void setLayout(int layout) {
		m_layout = layout;
	}

	/**
	 * Returns the layout of the image, any of LAYOUT_CENTERED_LEFT,
	 * LAYOUT_CENTERED_RIGHT, LAYOUT_ALIGN_LEFT, LAYOUT_ALIGN_RIGHT.
	 * 
	 * @return Image layout.
	 */
	public int getLayout() {
		return m_layout;
	}

	/**
	 * Returns value of a generic property on this item or null if not set.
	 * 
	 * @param key
	 *            The key of the property.
	 * @return The value of the property or null.
	 */
	public Object getProperty(int key) {
		if (m_props == null)
			return null;
		else
			return m_props.get(new Integer(key));
	}

	/**
	 * Sets a value to a generic property on this item, or resets it by giving
	 * <code>null</code> as a value.
	 * 
	 * @param key
	 *            The key of the property.
	 * @param value
	 *            The value of the property, or null to reset it.
	 */
	public void setProperty(int key, Object value) {
		if (m_props == null) {
			m_props = new Hashtable();
		}
		if (value == null) {
			m_props.remove(new Integer(key));
		} else {
			m_props.put(new Integer(key), value);
		}
	}
}