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Java binding for the Gstreamer framework
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/* 
 * Copyright (C) 2008 Wayne Meissner
 * Copyright (C) 1999,2000 Erik Walthinsen 
 *                    2000 Wim Taymans 
 *                    2005 Wim Taymans 
 *
 * This file is part of gstreamer-java.
 *
 * This code is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License version 3 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * version 3 for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * version 3 along with this work.  If not, see .
 */

package org.gstreamer.query;

import org.gstreamer.Format;
import org.gstreamer.Query;
import org.gstreamer.lowlevel.GstNative;

import com.sun.jna.Pointer;

/**
 * Used to discover information about the currently configured segment for playback.
 */
public class SegmentQuery extends Query {
    private static interface API extends com.sun.jna.Library {
        Pointer ptr_gst_query_new_segment(Format format);
        void gst_query_set_segment(SegmentQuery query, double rate, Format format,
         /* gint64 */ long start_value, /* gint64 */ long stop_value);
        void gst_query_parse_segment(SegmentQuery query, double[] rate, /*GstFormat **/ int[] format,
         /* gint64 * */ long[] start_value, /* gint64 * */ long[] stop_value);

    }
    private static final API gst = GstNative.load(API.class);
    public SegmentQuery(Initializer init) {
        super(init);
    }
    /**
     * Constructs a new segment query object.
     *
     * @param format the {@link Format} for the new query.
     */
    public SegmentQuery(Format format) {
        this(initializer(gst.ptr_gst_query_new_segment(format)));
    }
    
    /**
     * Answers a segment query by setting the requested values. 
     * 
     * The normal playback segment of a pipeline is 0 to duration at the default rate of
     * 1.0. If a seek was performed on the pipeline to play a different
     * segment, this query will return the range specified in the last seek.
     *
     * {@code startValue} and {@code stopValue} will respectively contain the configured 
     * playback range start and stop values expressed in format. 
     * The values are always between 0 and the duration of the media and 
     * {@code startValue <= stopValue}. {@code rate} will contain the playback rate. For
     * negative rates, playback will actually happen from {@code stopValue} to
     * {@code startValue}.
     * 
     * @param rate the rate of the segment.
     * @param format the {@link Format} of the segment values.
     * @param startValue the start value.
     * @param stopValue the stop value.
     */
    public void setSegment(double rate, Format format, long startValue, long stopValue) {
        gst.gst_query_set_segment(this, rate, format, startValue, stopValue);
    }
    
    /**
     * Gets the rate of the segment Query.
     * 
     * @return the rate of the segment.
     */
    public double getRate() {
        double[] rate = new double[1];
        gst.gst_query_parse_segment(this, rate, null, null, null);
        return rate[0];
    }
    
    /**
     * Gets the format of the start and stop values in the segment query.
     * 
     * @return The format for the start and stop values.
     */
    public Format getFormat() {
        int[] fmt = new int[1];
        gst.gst_query_parse_segment(this, null, fmt, null, null);
        return Format.valueOf(fmt[0]);
    }
    
    /**
     * Gets the start of the playback range.
     * 
     * @return the start of the playback range.
     */
    public long getStart() {
        long[] value = new long[1];
        gst.gst_query_parse_segment(this, null, null, value, null);
        return value[0];
    }
    
    /**
     * Gets the end of the playback range.
     * 
     * @return the end of the playback range.
     */
    public long getEnd() {
        long[] value = new long[1];
        gst.gst_query_parse_segment(this, null, null, null, value);
        return value[0];
    }
}