/**************************************************************
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 *************************************************************/


// __________ Imports __________

import java.awt.*;
import java.lang.*;
import java.awt.event.*;

// __________ Implementation __________

/**
 * Class to pass the system window handle to the OpenOffice.org toolkit.
 * It use special JNI methods to get the system handle of used java window.
 *
 * Attention!
 * Use JNI functions on already visible canvas objects only!
 * Otherwise they can make some trouble.
 *
 * @author  Andreas Schl&uuml;ns
 * @created 22.02.2002 08:47
 */

public class NativeView extends java.awt.Canvas
{
    // ____________________

    /**
     * ctor
     * Does nothing really.
     * We can use our JNI mechanism for an already visible
     * canvas only. So we overload the method for showing ("setVisible()")
     * and make our initialization there. BUt we try to show an empty clean
     * window till there.
     */
    public NativeView()
    {
        maHandle = null;
        maSystem = 0;
        this.setBackground(Color.white);
	}

    // ____________________

    /**
     * Overload this method to make necessary initializations here.
     * (e.g. get the window handle and necessary system informations)
     *
     * Why here?
     * Because the handle seems to be available for already visible windows
     * only. So it's the best place to get it. Special helper method
     * can be called more then ones - but call native code one times only
     * and safe the handle and the system type on our members maHandle/maSystem!
     */
    public void setVisible(boolean bState)
    {
        getHWND();
    }

    // ____________________

    /**
     * to guarantee right resize handling inside a swing container
     * (e.g. JSplitPane) we must provide some informations about our
     * preferred/minimum and maximum size.
     */
    public Dimension getPreferredSize()
    {
        return new Dimension(500,300);
    }

    public Dimension getMaximumSize()
    {
        return new Dimension(1024,768);
    }

    public Dimension getMinimumSize()
    {
        return new Dimension(100,100);
    }

    // ____________________

    /**
     * overload paint routine to show provide against
     * repaint errors if no office view is really plugged
     * into this canvas.
     * If handle is present - we shouldn't paint anything further.
     * May the remote window is already plugged. In such case we
     * shouldn't paint it over.
     */
    public void paint(Graphics aGraphic)
    {
        if(maHandle==null)
        {
            Dimension aSize = getSize();
            aGraphic.clearRect(0,0,aSize.width,aSize.height);
        }
    }

    // ____________________

    /**
     * JNI interface of this class
     * These two methods are implemented by using JNI mechanism.
     * The will be used to get the platform dependent window handle
     * of a java awt canvas. This handle can be used to create an office
     * window as direct child of it. So it's possible to plug Office
     * windows in a java UI container.
     *
     * Note:
     * Native code for windows register special function pointer to handle
     * window messages ... But if it doesn't check for an already registered
     * instance of this handler it will do it twice and produce a stack overflow
     * because such method call herself in a never ending loop ...
     * So we try to use the JNI code one times only and safe already getted
     * informations inside this class.
     */
    public  native int  getNativeWindowSystemType();
    private native long getNativeWindow(); // private! => use getHWND() with cache mechanism!

    public Integer getHWND()
    {
        if(maHandle==null)
        {
            maHandle = new Integer((int)getNativeWindow());
            maSystem = getNativeWindowSystemType();
        }
        return maHandle;
    }

    // ____________________

    /**
     * for using of the JNI methods it's necessary to load
     * system library which exports it.
     */
    static
    {
        System.loadLibrary("nativeview");
    }

    // ____________________

    /**
     * @member  maHandle    system window handle
     * @member  maSystem    info about currently used platform
     */
    public Integer maHandle ;
    public int     maSystem ;
}