/**
   * This implementation of <code>javaToNative</code> converts an ImageData object represented by
   * java <code>ImageData</code> to a platform specific representation.
   *
   * @param object a java <code>ImageData</code> containing the ImageData to be converted
   * @param transferData an empty <code>TransferData</code> object that will be filled in on return
   *     with the platform specific format of the data
   * @see Transfer#nativeToJava
   */
  public void javaToNative(Object object, TransferData transferData) {
    if (!checkImage(object) || !isSupportedType(transferData)) {
      DND.error(DND.ERROR_INVALID_DATA);
    }
    if (OS.GTK_VERSION < OS.VERSION(2, 4, 0)) return;

    ImageData imgData = (ImageData) object;
    if (imgData == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
    Image image = new Image(Display.getCurrent(), imgData);
    long /*int*/ pixbuf = ImageList.createPixbuf(image);
    if (pixbuf != 0) {
      String typeStr = "";
      if (transferData.type == JPEG_ID) typeStr = "jpeg";
      else if (transferData.type == PNG_ID) typeStr = "png";
      else if (transferData.type == BMP_ID) typeStr = "bmp";
      else if (transferData.type == EPS_ID) typeStr = "eps";
      else if (transferData.type == PCX_ID) typeStr = "pcx";
      else if (transferData.type == PPM_ID) typeStr = "ppm";
      else if (transferData.type == RGB_ID) typeStr = "rgb";
      else if (transferData.type == TGA_ID) typeStr = "tga";
      else if (transferData.type == XBM_ID) typeStr = "xbm";
      else if (transferData.type == XPM_ID) typeStr = "xpm";
      else if (transferData.type == XV_ID) typeStr = "xv";
      byte[] type = Converter.wcsToMbcs(null, typeStr, true);
      long /*int*/[] buffer = new long /*int*/[1];
      long /*int*/[] len = new long /*int*/[1];
      if (type == null) return;
      OS.gdk_pixbuf_save_to_bufferv(pixbuf, buffer, len, type, null, null, null);
      OS.g_object_unref(pixbuf);
      transferData.pValue = buffer[0];
      transferData.length = (int) (len[0] + 3) / 4 * 4;
      transferData.result = 1;
      transferData.format = 32;
    }
    image.dispose();
  }