/*
 * FSCall.java
 * Transform
 * 
 * Copyright (c) 2001-2008 Flagstone Software Ltd. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright notice, 
 *    this list of conditions and the following disclaimer in the documentation 
 *    and/or other materials provided with the distribution.
 *  * Neither the name of Flagstone Software Ltd. nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.flagstone.transform;

/**
 * FSCall is used to execute the actions previously assigned to a given frame
 * with an FSDoAction object.
 * 
 * <table class="datasheet">
 * 
 * <tr>
 * <th align="left" colspan="2">Attributes</th>
 * </tr>
 * 
 * <tr>
 * <td><a>type</a></td>
 * <td>Identifies the action when it is encoded. Read-only.</td>
 * </tr>
 * 
 * </table>
 * 
 * <p>
 * FSCall is a stack-based action, the value for the <i>frame name</i> or
 * <i>frame number</i> is retrieved from the top of the stack when it is
 * executed.
 * </p>
 * 
 * <p>
 * The following code fragment show how to execute the actions associated with a
 * given frame number from a Flash movie:
 * </p>
 * 
 * <pre>
 * actions.add(new FSPush(12));
 * actions.add(new FSCall());
 * </pre>
 * 
 * <p>
 * Alternatively if the frame has been assigned a name using an FSFrameLabel
 * object then the associated actions may be executed by using the name as a
 * reference:
 * </p>
 * 
 * <pre>
 *  movie.add(new FSFrameLabel(&quot;FirstFrame&quot;));
 *  ...
 *  actions.add(new FSPush(&quot;FirstFrame&quot;));
 *  actions.add(new FSCall());
 * </pre>
 * 
 * <h1 class="datasheet">History</h1>
 * 
 * <p>
 * The FSCall class represents the ActionCall action of the Macromedia Flash
 * (SWF) File Format Specification. It was introduced in Flash 4.
 * </p>
 */
public class FSCall extends FSActionObject
{
	private static final FSCall instance = new FSCall();

	/**
	 * Returns a canonical FSCall object.
	 * 
	 * @return an object that can safely be shared among objects.
	 */
	public static FSCall getInstance()
	{
		return instance;
	}

	/**
	 * Construct an FSCall object, initialising it with values decoded from an
	 * encoded object.
	 * 
	 * @param coder
	 *            an FSCoder containing the binary data.
	 */
	public FSCall(FSCoder coder)
	{
		super(Call);
		decode(coder);
	}

	/**
	 * Constructs an FSCall object.
	 */
	public FSCall()
	{
		super(Call);
	}

	/**
	 * Constructs an FSCall object by copying values from an existing object.
	 * 
	 * @param obj
	 *            an FSCall object.
	 */
	public FSCall(FSCall obj)
	{
		super(obj);
	}

	public void appendDescription(StringBuffer buffer, int depth)
	{
		buffer.append(name());
	}

	public int length(FSCoder coder)
	{
		return super.length(coder);
	}

	public void encode(FSCoder coder)
	{
		super.encode(coder);
		coder.endObject(name());
	}

	public void decode(FSCoder coder)
	{
		super.decode(coder);
		coder.endObject(name());
	}
}
