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Java binding for the Gstreamer framework (0.10 compatible)
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/* 
 * Copyright (C) 2009 Levente Farkas 
 * 
 * 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.swt.overlay;

import java.lang.reflect.Field;

import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;

import org.gstreamer.Element;
import org.gstreamer.GstException;
import org.gstreamer.interfaces.XOverlay;

import com.sun.jna.NativeLong;
import com.sun.jna.Platform;

import static org.gstreamer.lowlevel.GstXOverlayAPI.GSTXOVERLAY_API;

/**
 * Interface for elements providing tuner operations
 */
public class SWTOverlay extends XOverlay {
    /**
     * Wraps the {@link Element} in a SWTOverlay interface
     * 
     * @param element the element to use as a SWTOverlay
     * @return a SWTOverlay for the element
     */
    public static SWTOverlay wrap(Element element) {
        return new SWTOverlay(element);
    }
    
    /**
     * Creates a new SWTOverlay instance
     * 
     * @param element the element that implements the tuner interface
     */
    private SWTOverlay(Element element) {
        super(element);
    }

    /**
     * Helper function to get the proper handle for a given SWT Control on Linux.
     *
     * @param control the SWT control for what i like to get the handle.
     * @return the handle of the control or 0 if the handle is not available.
     */
    public static long getLinuxHandle(Composite composite) 
             throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
        Class compositeClass = composite.getClass();
        Field embedHandleField = compositeClass.getField("embeddedHandle");
        Class t = embedHandleField.getType();
        if (t.equals(long.class))
            return embedHandleField.getLong(composite);
        else if (t.equals(int.class))
            return embedHandleField.getInt(composite);
        return 0L;
    }
    
    /**
     * Helper function to get the proper handle for a given SWT Composite.
     *
     * @param composite the SWT Composite for what i like to get the handle.
     * @return the handle of the Composite or 0 if the handle is not available.
     */
    public static long handle(Composite composite) {
        // Composite style must be embedded
        if (composite == null || ((composite.getStyle() | SWT.EMBEDDED) == 0))
            return 0L;
        if (Platform.isWindows())
            return composite.handle;
        else if (Platform.isLinux())
            try {
            	return getLinuxHandle(composite);
            } catch (Exception e) {
                //e.printStackTrace();
            }
        return 0L;
    }

    /**
     * Sets the native window for the {@link Element} to use to display video.
     *
     * @param window A native window to use to display video, or null to
     * stop using the previously set window.
     */
    public void setWindowID(Composite composite) {
        // composite style must be embedded
        if (composite == null || ((composite.getStyle() | SWT.EMBEDDED) == 0))
            throw new GstException("Cannot set window ID, in XOverlay interface, composite is null or not SWT.EMBEDDED");
        if (Platform.isWindows())
            GSTXOVERLAY_API.gst_x_overlay_set_xwindow_id(this, new NativeLong(composite.handle));
        else if (Platform.isLinux())
            try {
                GSTXOVERLAY_API.gst_x_overlay_set_xwindow_id(this, new NativeLong(getLinuxHandle(composite)));
            } catch (Exception e) {
                throw new GstException("Cannot set window ID, in XOverlay interface, can't get embeddedHandle. " + e.getLocalizedMessage());
            }
        else
            throw new GstException("Cannot set window ID, in XOverlay interface: not supported sink element on platform");
    }
}