item.java

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 * rows.  (However, a <code>StringItem</code> with an appearance mode of
 * <code>HYPERLINK</code> should be wrapped the same way as if its appearance
 * mode is <code>PLAIN</code>.)</p>
 * 
 * <p>A <code>StringItem</code> or <code>ImageItem</code>
 * in <code>BUTTON</code> mode can be used to create a
 * button-based user interface.  This can easily lead to applications that are
 * inconvenient to use.  For example, in a traversal-based system, users must
 * navigate to a button before they can invoke any commands on it.  If buttons
 * are spread across a long <code>Form</code>, users may be required
 * to perform a
 * considerable amount of navigation in order to discover all the available
 * commands.  Furthermore, invoking a command from a button at the
 * other end of the <code>Form</code> can be quite cumbersome.
 * Traversal-based systems
 * often provide a means of invoking commands from anywhere (such as from a
 * menu), without the need to traverse to a particular item.  Instead of
 * adding a command to a button and placing that button into a
 * <code>Form</code>, it would
 * often be more appropriate and convenient for users if that command were
 * added directly to the <code>Form</code>.  Buttons should be used
 * only in cases where
 * direct user interaction with the item's string or image contents is
 * essential to the user's understanding of the commands that can be invoked
 * from that item.</p>
 * 
 * <h3>Default State</h3>
 * 
 * <p>Unless otherwise specified by a subclass, the default state of newly
 * created <code>Items</code> is as follows:</p>
 * 
 * <ul>
 * <li>the <code>Item</code> is not contained within
 * (&quot;owned by&quot;) any container;</li>
 * <li>there are no <code>Commands</code> present;</li>
 * <li>the default <code>Command</code> is <code>null</code>;</li>
 * <li>the <code>ItemCommandListener</code> is <code>null</code>;</li>
 * <li>the layout directive value is <code>LAYOUT_DEFAULT</code>; and</li>
 * <li>both the preferred width and preferred height are unlocked.</li>
 * </ul>
 * 
 * @since MIDP 1.0
 */
public abstract class Item extends Object
{
	/**
	 * A J2ME Polish constant defining a transparent/invisible color.
	 * TRANSPARENT has the value -1.
	 */
	public static final int TRANSPARENT = -1;
	
	/**
	 * A J2ME Polish constant defining a vertical orientation.
	 * VERTICAL has the value 0.
	 */
	public static final int VERTICAL = 0;
	
	/**
	 * A J2ME Polish constant defining a horizontal orientation.
	 * HORIZONTAL has the value 1.
	 */
	public static final int HORIZONTAL = 1;

	/**
	 * A layout directive indicating that this <code>Item</code>
	 * should follow the default layout policy of its container.
	 * 
	 * <P>Value <code>0</code> is assigned to <code>LAYOUT_DEFAULT</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_DEFAULT = 0;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * left-aligned layout.
	 * 
	 * <P>Value <code>1</code> is assigned to <code>LAYOUT_LEFT</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_LEFT = 1;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * right-aligned layout.
	 * 
	 * <P>Value <code>2</code> is assigned to <code>LAYOUT_RIGHT</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_RIGHT = 2;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * horizontally centered layout.
	 * 
	 * <P>Value <code>3</code> is assigned to <code>LAYOUT_CENTER</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_CENTER = 3;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * top-aligned layout.
	 * 
	 * <P>Value <code>0x10</code> is assigned to <code>LAYOUT_TOP</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_TOP = 0x10;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * bottom-aligned layout.
	 * 
	 * <P>Value <code>0x20</code> is assigned to <code>LAYOUT_BOTTOM</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_BOTTOM = 0x20;

	/**
	 * A layout directive indicating that this <code>Item</code> should have a
	 * vertically centered layout.
	 * 
	 * <P>Value <code>0x30</code> is assigned to
	 * <code>LAYOUT_VCENTER</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_VCENTER = 0x30;

	/**
	 * A layout directive indicating that this <code>Item</code>
	 * should be placed at the beginning of a new line or row.
	 * 
	 * <P>Value <code>0x100</code> is assigned to
	 * <code>LAYOUT_NEWLINE_BEFORE</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_NEWLINE_BEFORE = 0x100;

	/**
	 * A layout directive indicating that this <code>Item</code>
	 * should the last on its line or row, and that the next
	 * <code>Item</code> (if any) in the container
	 * should be placed on a new line or row.
	 * 
	 * <P>Value <code>0x200</code> is assigned to
	 * <code>LAYOUT_NEWLINE_AFTER</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_NEWLINE_AFTER = 0x200;

	/**
	 * A layout directive indicating that this <code>Item's</code>
	 * width may be reduced to its minimum width.
	 * 
	 * <P>Value <code>0x400</code> is assigned to <code>LAYOUT_SHRINK</code></P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_SHRINK = 0x400;

	/**
	 * A layout directive indicating that this <code>Item's</code>
	 * width may be increased to fill available space.
	 * 
	 * <P>Value <code>0x800</code> is assigned to <code>LAYOUT_EXPAND</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_EXPAND = 0x800;

	/**
	 * A layout directive indicating that this <code>Item's</code>
	 * height may be reduced to its minimum height.
	 * 
	 * <P>Value <code>0x1000</code> is assigned to
	 * <code>LAYOUT_VSHRINK</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_VSHRINK = 0x1000;

	/**
	 * A layout directive indicating that this <code>Item's</code>
	 * height may be increased to fill available space.
	 * 
	 * <P>Value <code>0x2000</code> is assigned to
	 * <code>LAYOUT_VEXPAND</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_VEXPAND = 0x2000;

	/**
	 * A layout directive indicating that new MIDP 2.0 layout
	 * rules are in effect for this <code>Item</code>.  If this
	 * bit is clear, indicates that MIDP 1.0 layout behavior
	 * applies to this <code>Item</code>.
	 * 
	 * <P>Value <code>0x4000</code> is assigned to
	 * <code>LAYOUT_2</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int LAYOUT_2 = 0x4000;

	/**
	 * An appearance mode value indicating that the <code>Item</code> is to have
	 * a normal appearance.
	 * 
	 * <P>Value <code>0</code> is assigned to <code>PLAIN</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int PLAIN = 0;

	/**
	 * An appearance mode value indicating that the <code>Item</code>
	 * is to appear as a hyperlink.
	 * <P>Value <code>1</code> is assigned to <code>HYPERLINK</code>.</P>
	 * 
	 * 
	 * @since MIDP 2.0
	 */
	public static final int HYPERLINK = 1;

	/**
	 * An appearance mode value indicating that the <code>Item</code>
	 * is to appear as a button.
	 * <P>Value <code>2</code> is assigned to <code>BUTTON</code>.</P>
	 * 
	 * @since MIDP 2.0
	 */
	public static final int BUTTON = 2;

	/**
	 * A J2ME Polish appearance mode value indicating that the <code>Item</code>
	 * accepts input from the user.
	 * <P>Value <code>3</code> is assigned to <code>INTERACTIVE</code>.</P>
	 */
	public static final int INTERACTIVE = 3;
	
	protected int layout;
	protected ItemCommandListener itemCommandListener;
	protected Command defaultCommand;
	protected int preferredWidth;
	protected int preferredHeight;
	protected int minimumWidth;
	protected int minimumHeight;
	//#ifdef polish.css.max-width
		protected int maximumWidth;
	//#endif
	//#ifdef polish.css.max-height
		//# protected int maximumHeight;
	//#endif
	protected boolean isInitialized;
	public Background background;
	protected Border border;
	protected Style style;
	public int itemWidth;
	public int itemHeight;
	protected int paddingLeft;
	protected int paddingTop;
	protected int paddingRight;
	protected int paddingBottom;
	protected int paddingVertical;
	protected int paddingHorizontal;
	protected int marginLeft;
	protected int marginTop;
	protected int marginRight;
	protected int marginBottom;
	/** The width of this item's content **/
	protected int contentWidth;
	/** The height of this item's content **/
	protected int contentHeight;
	protected int borderWidth;
	protected int backgroundWidth;
	protected int backgroundHeight;
	/** The appearance mode of this item, either PLAIN or one of the interactive modes BUTTON, HYPERLINK or INTERACTIVE. */
	public int appearanceMode;
	/**
	 * The screen to which this item belongs to.
	 */
	protected Screen screen;
	//#ifdef polish.useDynamicStyles
		//# /**
		 //# * The appropriate CSS selector of this item. 
		 //# * This is either the style's name or a selector
		 //# * depending on the state of this item. A StringItem
		 //# * can have the selector "p", "a" or "button", for example.
		 //# * This variable can only be used, when the proprocessing variable
		 //# * "polish.useDynamicStyles" is defined.
		 //# */
		//# protected String cssSelector;
	//#endif
	/**
	 * Determines whether the style has be dynamically assigned already.
	 */
	protected boolean isStyleInitialised;
	/**
	 * The parent of this item.
	 */
	protected Item parent;

	protected ArrayList commands;
	
	protected boolean isLayoutCenter;
	protected boolean isLayoutExpand;
	protected boolean isLayoutRight;
	// the current positions of this item:
	/** the horizontal start position relative to it's parent's item left content edge */
	public int relativeX;
	/** the vertical start position of this item relative to it's parent item top content edge */
	public int relativeY; 
	/** the horizontal position of this item's content relative to it's left edge */
	protected int contentX;
	/** the vertical position of this item's content relative to it's top edge */
	protected int contentY; // absolute top vertical position of the content 
	// the current positions of an internal element relative to the content origin 
	// which should be visible:
	/** 
	 * The internal horizontal position of this item's content relative to it's left edge.