form.java

j2me polish学习的经典代码

	/**
	 * Adds an item consisting of one <code>String</code> to the
	 * <code>Form</code>. The effect of this method is identical to
	 * <p>
	 * <code>
	 * append(new StringItem(null, str))
	 * </code> </p>
	 * 
	 * @param str the String to be added
	 * @param itemStyle the CSS style for this string
	 * @return the assigned index of the Item
	 * @throws NullPointerException if str is null
	 */
	public int append( String str, Style itemStyle )
	{
		return append( new StringItem(null, str, itemStyle), null );
	}

	/**
	 * Adds an item consisting of one <code>String</code> to the
	 * <code>Form</code>. The effect of
	 * this method is identical to
	 * 
	 * <p> <code>
	 * append(new StringItem(null, str))
	 * </code> </p>
	 * 
	 * @param str the String to be added
	 * @return the assigned index of the Item
	 * @throws NullPointerException if str is null
	 */
	public int append( String str)
	{
		return append( new StringItem(null, str), null );
	}

	/**
	 * Adds an item consisting of one <code>Image</code> to the
	 * <code>Form</code>. The effect of
	 * this method is identical to
	 * 
	 * <p> <code>
	 * append(new ImageItem(null, img, ImageItem.LAYOUT_DEFAULT, null))
	 * </code> </p>
	 * 
	 * @param img the image to be added
	 * @param itemStyle the CSS style for this string
	 * @return the assigned index of the Item
	 * @throws NullPointerException if img is null
	 */
	public int append( Image img, Style itemStyle )
	{
		
		return append(new ImageItem(null, img, Item.LAYOUT_DEFAULT, null, itemStyle), null );
	}
	
	/**
	 * Adds an item consisting of one <code>Image</code> to the <code>Form</code>. 
	 * The effect of this method is identical to
	 * <p> <code>
	 * append(new ImageItem(null, img, ImageItem.LAYOUT_DEFAULT, null))
	 * </code> </p>
	 * 
	 * @param img - the image to be added
	 * @return the assigned index of the Item
	 * @throws NullPointerException - if img is null
	 */
	public int append( Image img)
	{
		return append(new ImageItem(null, img, Item.LAYOUT_DEFAULT, null), null);
	}

	/**
	 * Inserts an item into the <code>Form</code> just prior to
	 * the item specified.
	 * The size of the <code>Form</code> grows by one.  The
	 * <code>itemNum</code> parameter must be
	 * within the range <code>[0..size()]</code>, inclusive.
	 * The index of the last item is <code>size()-1</code>, and
	 * so there is actually no item whose index is
	 * <code>size()</code>. If this value
	 * is used for <code>itemNum</code>, the new item is inserted
	 * immediately after
	 * the last item. In this case, the effect is identical to
	 * <A HREF="../../../javax/microedition/lcdui/Form.html#append(javax.microedition.lcdui.Item)"><CODE>append(Item)</CODE></A>.
	 * 
	 * <p> The semantics are otherwise identical to
	 * <A HREF="../../../javax/microedition/lcdui/Form.html#append(javax.microedition.lcdui.Item)"><CODE>append(Item)</CODE></A>. </p>
	 * 
	 * @param itemNum the index where insertion is to occur
	 * @param item the item to be inserted
	 * @throws IndexOutOfBoundsException if itemNum is invalid
	 * @throws IllegalStateException if the item is already owned by a container
	 * @throws NullPointerException if item is null
	 */
	public void insert(int itemNum, Item item)
	{
		if (itemNum == this.container.size()) {
			this.container.add(item);
		} else {
			this.container.add( itemNum, item );
		}
	}

	/**
	 * Deletes the <code>Item</code> referenced by
	 * <code>itemNum</code>. The size of the <code>Form</code>
	 * shrinks by one. It is legal to delete all items from a
	 * <code>Form</code>.
	 * The <code>itemNum</code> parameter must be
	 * within the range <code>[0..size()-1]</code>, inclusive.
	 * 
	 * @param itemNum - the index of the item to be deleted
	 * @throws IndexOutOfBoundsException - if itemNum is invalid
	 */
	public void delete(int itemNum)
	{
		this.container.remove(itemNum);
		if (this.isShown() ) {
			repaint();
		}

	}

	/**
	 * Deletes all the items from this <code>Form</code>, leaving
	 * it with zero items.
	 * This method does nothing if the <code>Form</code> is already empty.
	 * 
	 * @since  MIDP 2.0
	 */
	public void deleteAll()
	{
		this.container.clear();
		if (this.isShown() ) {
			repaint();
		}

	}

	/**
	 * Sets the item referenced by <code>itemNum</code> to the
	 * specified item,
	 * replacing the previous item. The previous item is removed
	 * from this <code>Form</code>.
	 * The <code>itemNum</code> parameter must be
	 * within the range <code>[0..size()-1]</code>, inclusive.
	 * 
	 * <p>The end result is equal to
	 * <code>insert(n, item); delete(n+1);</code><br>
	 * although the implementation may optimize the repainting
	 * and usage of the array that stores the items. <P>
	 * 
	 * @param itemNum the index of the item to be replaced
	 * @param item the new item to be placed in the Form
	 * @throws IndexOutOfBoundsException if itemNum is invalid
	 * @throws IllegalStateException if the item is already owned by a container
	 * @throws NullPointerException if item is null
	 */
	public void set(int itemNum, Item item)
	{
		this.container.set( itemNum, item );
	}

	/**
	 * Gets the item at given position.  The contents of the
	 * <code>Form</code> are left
	 * unchanged.
	 * The <code>itemNum</code> parameter must be
	 * within the range <code>[0..size()-1]</code>, inclusive.
	 * 
	 * @param itemNum the index of item
	 * @return the item at the given position
	 * @throws IndexOutOfBoundsException - if itemNum is invalid
	 */
	public Item get(int itemNum)
	{
		return this.container.get( itemNum );
	}

	/**
	 * Sets the <code>ItemStateListener</code> for the
	 * <code>Form</code>, replacing any previous
	 * <code>ItemStateListener</code>. If
	 * <code>iListener</code> is <code>null</code>, simply
	 * removes the previous <code>ItemStateListener</code>.
	 * 
	 * @param iListener the new listener, or null to remove it
	 */
	public void setItemStateListener( ItemStateListener iListener)
	{
		this.itemStateListener = iListener;
	}

	/**
	 * Gets the number of items in the <code>Form</code>.
	 * 
	 * @return the number of items
	 */
	public int size()
	{
		return this.container.size();
	}

	//#ifdef polish.useDynamicStyles	
	/* (non-Javadoc)
	 * @see de.enough.polish.ui.Screen#getCssSelector()
	 */
	protected String createCssSelector() {
		return "form";
	}
	//#endif	
	
	/**
	 * Adds the given item to the queue for state notifications.
	 * The ItemStateListener will be called at the next possibility.
	 * 
	 * @param item the item which contents have been edited.
	 */
	protected void addToStateNotifyQueue( Item item ) {
		if (this.itemStateListener != null) {
			if (this.stateNotifyQueue == null) {
				this.stateNotifyQueue = new ArrayList();
			}
			synchronized (this.stateNotifyQueue) {
				this.stateNotifyQueue.add( item );
			}
			//#debug
			System.out.println("added item " + item + " to stateNotifyQueue with listener " + this.itemStateListener + ", size of queue=" + this.stateNotifyQueue.size() + " to form " + this  );
		}
	}
	
	/**
	 * Notifies the ItemStateListener about the changes which occurred to the items.
	 */
	protected void notifyStateListener() {
		if (this.stateNotifyQueue != null && this.itemStateListener != null) {
			Item lastItem = null;
			while (this.stateNotifyQueue.size() > 0) {
				Item item;
				synchronized (this.stateNotifyQueue) {
					item = (Item) this.stateNotifyQueue.remove(0);
				}
				if (item != lastItem) {
					//#debug
					System.out.println("notifying ItemStateListener for item " + item + " and form " + this ); 
					this.itemStateListener.itemStateChanged(item);
					lastItem = item;
				}
			}
			//#debug
			System.out.println("done notifying ItemStateListener."); 
		}
	}
	

	/* (non-Javadoc)
	 * @see de.enough.polish.ui.Screen#animate()
	 */
	public boolean animate() {
		boolean animated = false;
		if ( (this.itemStateListener != null) 
				&& (this.stateNotifyQueue != null) 
				&& (this.stateNotifyQueue.size() > 0 ) ) {
			notifyStateListener();
			animated = true;
		}
		return animated | super.animate();
	}
}