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package org.apache.poi.hpsf;

import org.apache.poi.hpsf.littleendian.DWord;
/**
 * <p>Class to manipulate  data in the Clipboard Variant
 * ({@link Variant#VT_CF VT_CF}) format.</p>
 *
 * @see SummaryInformation#getThumbnail()
 *
 * @author Drew Varner (Drew.Varner inOrAround sc.edu)
 * @version $Id$
 * @since 2002-04-29
 */
public class Thumbnail
{



    /**
     * <p>Offset in bytes where the Clipboard Format Tag
     * starts in the <code>byte[]</code> returned by
     * {@link SummaryInformation#getThumbnail()}</p>
     */
    public static int OFFSET_CFTAG = 4;



    /**
     * <p>Offset in bytes where the Clipboard Format
     * starts in the <code>byte[]</code> returned by
     * {@link SummaryInformation#getThumbnail()}</p>
     *
     * <p>This is only valid if the Clipboard Format Tag
     * is {@link #CFTAG_WINDOWS} </p>
     */
    public static int OFFSET_CF = 8;



    /**
     * <p>Offset in bytes where the Windows Metafile
     * (WMF) image data starts in the <code>byte[]</code>
     * returned by {@link SummaryInformation#getThumbnail()}</p>
     *
     * <p>There is only WMF data at this point in the
     * <code>byte[]</code> if the Clipboard Format Tag is
     * {@link #CFTAG_WINDOWS} and the Clipboard Format is
     * {@link #CF_METAFILEPICT}.</p>
     *
     * <p>Note: The <code>byte[]</code> that starts at
     * <code>OFFSET_WMFDATA</code> and ends at
     * <code>getThumbnail().length - 1</code> forms a
     * complete WMF image. It can be saved to disk with a
     * <code>.wmf</code> file type and read using a WMF-capable
     * image viewer.</p>
     */
    public static int OFFSET_WMFDATA = 20;



    /**
     * <p>Clipboard Format Tag - Windows clipboard format</p>
     * <p>A <code>DWORD</code> indicating a built-in Windows clipboard
     * format value</p>
     *
     * <p>See:
     * <a href="http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp"
     * target="_blank">
     * http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp</a>
     */
    public static int CFTAG_WINDOWS = -1;



    /**
     * <p>Clipboard Format Tag - Macintosh clipboard format</p>
     * <p>A <code>DWORD</code> indicating a Macintosh clipboard format value</p>
     *
     * <p>See:
     * <a href="http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp"
     * target="_blank">
     * http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp</a>
     */
    public static int CFTAG_MACINTOSH = -2;



    /**
     * <p>Clipboard Format Tag - Format ID</p>
     * <p>A GUID containing a format identifier (FMTID). This is rarely used.</p>
     *
     * <p>See:
     * <a href="http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp"
     * target="_blank">
     * http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp</a>
     */
    public static int CFTAG_FMTID = -3;



    /**
     * <p>Clipboard Format Tag - No Data</p>
     * <p>a <code>DWORD</code> indicating No data. This is rarely used.</p>
     *
     * <p>See:
     * <a href="http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp"
     * target="_blank">
     * http://msdn.microsoft.com/library/en-us/dnolegen/html/msdn_propset.asp</a>
     */
    public static int CFTAG_NODATA = 0;



    /**
     * <p>Clipboard Format - Windows metafile format.
     * This is the recommended way to store thumbnails
     * in Property Streams.</p>
     * <p> <strong>Note:</strong> this is not the same
     * format used in regular WMF images. The clipboard
     * version of this format has an extra clipboard-specific
     * header</p>
     */
    public static int CF_METAFILEPICT = 3;



    /**
     * <p>Clipboard Format - Device Independent Bitmap</p>
     */
    public static int CF_DIB = 8;



    /**
     * <p>Clipboard Format - Enhanced Windows metafile format</p>
     */
    public static int CF_ENHMETAFILE = 14;



    /**
     * <p>Clipboard Format - Bitmap</p>
     * <p>Obsolete, See:
     * <a href="msdn.microsoft.com/library/en-us/dnw98bk/html/clipboardoperations.asp
     *    target="_blank">
     * msdn.microsoft.com/library/en-us/dnw98bk/html/clipboardoperations.asp
     * </a>
     * </p>
     */
    public static int CF_BITMAP = 2;



    /**
     * <p> A <code>byte[]</code> to hold a thumbnail image in
     * ({@link Variant#VT_CF VT_CF}) format. </p>
     */
    private byte[] thumbnailData = null;



    /**
     * <p>Default Constructor. If you use then one you'll have to add
     * the thumbnail <code>byte[]</code> from {@link
     * SummaryInformation#getThumbnail()} to do any useful
     * manipulations, otherwise you'll get a
     * <code>NullPointerException</code>.</p>
     */
    public Thumbnail()
    {
        super();
    }



    /**
     * <p></p>
     */
    public Thumbnail(byte[] thumbnailData)
    {
        this.thumbnailData = thumbnailData;
    }



    /**
     * <p>Returns the thumbnail as a <code>byte[]</code> in
     * {@link Variant#VT_CF VT_CF} format.</p>
     *
     * @see SummaryInformation#getThumbnail()
     */
    public byte[] getThumbnail() {
        return thumbnailData;
    }



    /**
     * <p>Sets the Thumbnail's underlying <code>byte[]</code> in
     * {@link Variant#VT_CF VT_CF} format.</p>
     *
     * @see SummaryInformation#getThumbnail()
     */
    public void setThumbnail(byte[] thumbnail) {
        this.thumbnailData = thumbnail;
    }



    /**
     * <p>Returns an <code>int</code> representing the Clipboard
     * Format Tag</p>
     * <p>Possible return values are:
     * <ul>
     *   <li>{@link #CFTAG_WINDOWS CFTAG_WINDOWS}</li>
     *   <li>{@link #CFTAG_MACINTOSH CFTAG_MACINTOSH}</li>
     *   <li>{@link #CFTAG_FMTID CFTAG_FMTID}</li>
     *   <li>{@link #CFTAG_NODATA CFTAG_NODATA}</li>
     * </ul>
     * </p>
     *
     * @return a flag indicating the Clipboard Format Tag
     */
    public int getClipboardFormatTag()
    {
        DWord clipboardFormatTag = new DWord(getThumbnail(),OFFSET_CFTAG);
        return clipboardFormatTag.intValue();
    }



    /**
     * <p>Returns an <code>int</code> representing the Clipboard
     * Format</p>
     *
     * <p>Will throw an exceptionif the Thumbnail's Clipboard
     * Format Tag is not
     * {@link Thumbnail#CFTAG_WINDOWS CFTAG_WINDOWS}
     * </p>
     *
     * <p>Possible return values are:
     * <ul>
     *   <li>{@link #CF_METAFILEPICT CF_METAFILEPICT}</li>
     *   <li>{@link #CF_DIB CF_DIB}</li>
     *   <li>{@link #CF_ENHMETAFILE CF_ENHMETAFILE}</li>
     *   <li>{@link #CF_BITMAP CF_BITMAP}</li>
     * </ul>
     * </p>
     *
     * @return a flag indicating the Clipboard Format
     *
     * @throws HPSFException if the Thumbnail isn't CFTAG_WINDOWS
     *
     */
    public int getClipboardFormat() throws HPSFException
    {
        if ( !(getClipboardFormatTag() == CFTAG_WINDOWS) )
        {
            throw new HPSFException("Clipboard Format Tag of Thumbnail must " +
                                    "be CFTAG_WINDOWS.");
        }

        DWord clipboardFormat = new DWord(getThumbnail(),OFFSET_CF);
        return clipboardFormat.intValue();
    }



    /**
     * <p>Returns the Thumbnail as a <code>byte[]</code>
     * of WMF data if the Thumbnail's Clipboard Format Tag
     * is {@link #CFTAG_WINDOWS CFTAG_WINDOWS}
     * and its Clipboard Format is
     * {@link #CF_METAFILEPICT CF_METAFILEPICT}</p>
     *
     * <p>This <code>byte[]</code> is in the traditional WMF file,
     * not the clipboard-specific version with special headers.</p>
     *
     * <p> See
     * <a href="http://www.wvware.com/caolan/ora-wmf.html"
     *    target="_blank">http://www.wvware.com/caolan/ora-wmf.html</a>
     * for more information on the WMF image format.</p>
     *
     * @throws HPSFException if the Thumbnail isn't CFTAG_WINDOWS
     *                       and CF_METAFILEPICT
     *
     * @return a WMF image of the Thumbnail
     */
    public byte[] getThumbnailAsWMF() throws HPSFException
    {
        if ( !(getClipboardFormatTag() == CFTAG_WINDOWS) )
        {
            throw new HPSFException("Clipboard Format Tag of Thumbnail must " +
                                    "be CFTAG_WINDOWS.");
        }
        if ( !(getClipboardFormat() == CF_METAFILEPICT) )
        {
            throw new HPSFException("Clipboard Format of Thumbnail must " +
                                    "be CF_METAFILEPICT.");
        }
        else
        {
            byte[] thumbnail = getThumbnail();
            int wmfImageLength = thumbnail.length - OFFSET_WMFDATA;
            byte[] wmfImage = new byte[wmfImageLength];
            System.arraycopy(thumbnail,
                             OFFSET_WMFDATA,
                             wmfImage,
                             0,
                             wmfImageLength);
            return wmfImage;
        }
    }

}