DoAction.java

/*
 * DoAction.java
 * Transform
 *
 * Copyright (c) 2001-2010 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;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import com.flagstone.transform.action.Action;
import com.flagstone.transform.action.ActionData;
import com.flagstone.transform.coder.Coder;
import com.flagstone.transform.coder.Context;
import com.flagstone.transform.coder.SWFDecoder;
import com.flagstone.transform.coder.SWFEncoder;
import com.flagstone.transform.coder.SWFFactory;

/**
 * DoAction is used to add a set of actions to a frame in a movie. The actions
 * will be triggered when the Flash Player executes the ShowFrame command.
 *
 * <p>
 * Only one DoAction object can be used to specify the actions for a given
 * frame. If more than one DoAction object is added in a single frame only the
 * actions contained in the last DoAction object (before the ShowFrame object)
 * will be executed when the frame is displayed. The other DoAction objects will
 * be ignored.
 * </p>
 *
 * <p>
 * IMPORTANT: The last action in the list must be BasicAction.END otherwise
 * the object will not be encoded correctly.
 * </p>
 *
 * <p>
 * When decoding a movie, if the decode actions flag is set to false then the
 * actions will be decoded as a single ActionData object containing the encoded
 * actions.
 * </p>
 *
 * <p>
 * DoAction can only be used in movies that contain Actionscript 1.x or
 * Actionscript 2.x code. For Actionscript 3.0 use the DoABC class.
 * </p>
 */
public final class DoAction implements MovieTag {

    /** Format string used in toString() method. */
    private static final String FORMAT = "DoAction: { actions=%s}";
    /** The actions executed when the current frame is displayed. */
    private List<Action> actions;

    /** The length of the object, minus the header, when it is encoded. */
    private transient int length;

    /**
     * Creates and initialises a DoAction object using values encoded in the
     * Flash binary format.
     *
     * @param coder
     *            an SWFDecoder object that contains the encoded Flash data.
     * @param context
     *            a Context object used to pass values when decoding objects.
     * @throws IOException
     *             if an error occurs while decoding the data.
     */
    public DoAction(final SWFDecoder coder, final Context context)
            throws IOException {

        final SWFFactory<Action> decoder = context.getRegistry()
        .getActionDecoder();
        actions = new ArrayList<Action>();

        length = coder.readUnsignedShort() & Coder.LENGTH_FIELD;
        if (length == Coder.IS_EXTENDED) {
            length = coder.readInt();
        }
        coder.mark();

        if (decoder == null) {
            actions.add(new ActionData(coder.readBytes(new byte[length])));
        } else {
            while (coder.bytesRead() < length) {
                decoder.getObject(actions, coder, context);
            }
        }
        coder.check(length);
        coder.unmark();
    }

    /**
     * Creates a new DoAction class with an empty list.
     */
    public DoAction() {
        actions = new ArrayList<Action>();
    }

    /**
     * Creates a DoAction object with a list of actions.
     *
     * @param list
     *            the list of action objects. Cannot be null.
     */
    public DoAction(final List<Action> list) {
        setActions(list);
    }

    /**
     * Creates a DoAction object with a copy of the actions from another
     * DoAction object.
     *
     * @param object
     *            a DoAction object to copy.
     */
    public DoAction(final DoAction object) {
        actions = new ArrayList<Action>(object.actions);
    }

    /**
     * Adds the action object to the list of actions. If the object already
     * contains encoded actions then they will be deleted.
     *
     * @param anAction
     *            an object belonging to a class derived from Action. The
     *            argument cannot be null.
     *
     * @return this object.
     */
    public DoAction add(final Action anAction) {
        if (anAction == null) {
            throw new IllegalArgumentException();
        }
        actions.add(anAction);
        return this;
    }

    /**
     * Returns the list of actions that are executed when the frame is
     * displayed.
     *
     * @return the list of action objects.
     */
    public List<Action> getActions() {
        return actions;
    }

    /**
     * Set the list of actions that will be executed when the next ShowFrame
     * tag is executed by the Flash Player. If the object already contains
     * encoded actions then they will be deleted.
     *
     * @param list
     *            the list of action objects. May be empty but cannot be null.
     */
    public void setActions(final List<Action> list) {
        if (list == null) {
            throw new IllegalArgumentException();
        }
        actions = list;
    }

    /** {@inheritDoc} */
    public DoAction copy() {
        return new DoAction(this);
    }

    /** {@inheritDoc} */
    @Override
    public String toString() {
        return String.format(FORMAT, actions.toString());
    }

    /** {@inheritDoc} */
    public int prepareToEncode(final Context context) {
        length = 0;

        for (final Action action : actions) {
            length += action.prepareToEncode(context);
        }

        return (length > Coder.HEADER_LIMIT ? Coder.LONG_HEADER
                : Coder.SHORT_HEADER) + length;
    }

    /** {@inheritDoc} */
    public void encode(final SWFEncoder coder, final Context context)
            throws IOException {

        if (length > Coder.HEADER_LIMIT) {
            coder.writeShort((MovieTypes.DO_ACTION
                    << Coder.LENGTH_FIELD_SIZE) | Coder.IS_EXTENDED);
            coder.writeInt(length);
        } else {
            coder.writeShort((MovieTypes.DO_ACTION
                    << Coder.LENGTH_FIELD_SIZE) | length);
        }
        if (Constants.DEBUG) {
            coder.mark();
        }
        for (final Action action : actions) {
            action.encode(coder, context);
        }
        if (Constants.DEBUG) {
            coder.check(length);
            coder.unmark();
        }
    }
}