FramePositioningAdapter.java

/*
 * @(#)FramePositioningAdapter.java	1.5 02/08/21
 *
 * Copyright (c) 1996-2002 Sun Microsystems, Inc.  All rights reserved.
 */

package com.sun.media.controls;

import java.awt.Component;
import javax.media.Time;
import javax.media.Track;
import javax.media.Player;
import javax.media.control.FramePositioningControl;
import javax.media.Format;
import javax.media.format.VideoFormat;
import com.sun.media.Reparentable;



/**
 * The <code>FramePositioningControl</code> is the interface to control 
 * precise positioning to a video frame for <code>Players</code> 
 * and <code>Processors</code>.
 */
public class FramePositioningAdapter implements FramePositioningControl, Reparentable {

    static public Track getMasterTrack(Track tracks[]) {
	Track master = null;
	Format f;
	float rate = Format.NOT_SPECIFIED;

	for (int i = 0; i < tracks.length; i++) {

	    if (tracks[i] == null || ((f = tracks[i].getFormat()) == null))
		continue;

	    if (!(f instanceof VideoFormat))
		continue;

	    master = tracks[i];

	    if ((rate = ((VideoFormat)f).getFrameRate()) != Format.NOT_SPECIFIED &&
		rate != 0f) {

		return master;
	    }
	}

	if (master != null &&
	    master.mapTimeToFrame(new Time(0)) != FramePositioningControl.FRAME_UNKNOWN)
	    return master;
	else
	    return null;
    }


    Object owner;
    Player player;
    Track master = null;
    long frameStep = -1;


    public FramePositioningAdapter(Player p, Track track) {
	this.player = p;
	this.master = track;

	// Base on the frame rate, compute the inter-frame duration.
	// This is not very accurate since the frame rate reported is not
	// very accurate anyway.
	Format f = track.getFormat();
	if (f instanceof VideoFormat) {
	    float rate = ((VideoFormat)f).getFrameRate();
	    if (rate != Format.NOT_SPECIFIED && rate != 0f)
		frameStep = (long)(Time.ONE_SECOND / rate);
	}
    }


    /**
     * Seek to a given video frame.
     * @param frameNumber the frame to seek to.
     * @return the actual frame that the Player has seeked to. 
     */
    public int seek(int frameNumber) {
	Time seekTo = master.mapFrameToTime(frameNumber);
	if (seekTo != null && seekTo != FramePositioningControl.TIME_UNKNOWN) {
	    player.setMediaTime(seekTo);
	    return master.mapTimeToFrame(seekTo);
	} else {
	    // Can't do any thing if mapFrameToTime fails.
	    return FramePositioningControl.FRAME_UNKNOWN;
	}
    }

    /**
     * Skip a given number of frames from the current position.
     * @param framesToSkip the number of frames to skip from the current
     *   position.  If framesToSkip is positive, it will seek forward
     *   by framesToSkip number of frames.  If framesToSkip is negative, 
     *   it will seek backward by framesToSkip number of frames.
     *   e.g. skip(-1) will step backward one frame.
     * @return the actual number of frames skipped.  
     */
    public int skip(int framesToSkip) {
	if (frameStep != -1) {
	    // Use interframe duration.
	    long t = player.getMediaNanoseconds() + (framesToSkip * frameStep);
	    player.setMediaTime(new Time(t));
	    return framesToSkip;

	} else {
	    int currentFrame = master.mapTimeToFrame(player.getMediaTime());
	    if (currentFrame != 0 &&
		currentFrame != FramePositioningControl.FRAME_UNKNOWN) {
		int newFrame = seek(currentFrame+framesToSkip);
		return newFrame - currentFrame;
	    } else {
		// Ran out of options.
		return FramePositioningControl.FRAME_UNKNOWN;
	    }
	}
    }

    /**
     * Converts the given frame number to the corresponding media time.
     * <p>
     * @param frameNumber the input frame number for the conversion.
     * @return the converted media time for the given frame.  If the
     *   conversion fails, TIME_UNKNOWN is returned.
     */
    public Time mapFrameToTime(int frameNumber) {
	return master.mapFrameToTime(frameNumber);
    }

    /**
     * Converts the given media time to the corresponding frame number.
     * <p>
     * The frame returned is the nearest frame that has a media time
     * less than or equal to the given media time.
     * <p>
     * @param mediaTime the input media time for the conversion.
     * @return the converted frame number the given media time.  If the
     *   conversion fails, FRAME_UNKNOWN is returned.
     */
    public int mapTimeToFrame(Time mediaTime) {
	return master.mapTimeToFrame(mediaTime);
    }


    public Component getControlComponent() {
	return null;
    }

    public Object getOwner() {
	if (owner == null)
	    return this;
	else
	    return owner;
    }

    public void setOwner(Object newOwner) {
	owner = newOwner;
    }
}