/** Reading and writing of Blu-Ray captions demuxed from M2TS transport streams (BD-SUP). */
public class SupBD implements SubtitleStream {
private static final Configuration configuration = Configuration.getInstance();
private static final Logger logger = Logger.getInstance();
private FileBuffer buffer;
private List<SubPictureBD> subPictures = new ArrayList<SubPictureBD>();
private int forcedFrameCount;
/** color palette of the last decoded caption */
private Palette palette;
/** bitmap of the last decoded caption */
private Bitmap bitmap;
/** index of dominant color for the current caption */
private int primaryColorIndex;
public SupBD(String filename) throws CoreException {
SupBDParser parser = new SupBDParser(filename);
buffer = parser.getBuffer();
subPictures = parser.getSubPictures();
forcedFrameCount = parser.getForcedFrameCount();
}
/**
* Decode caption from the input stream.
*
* @param subPictureBD SubPicture object containing info about the caption
* @param transparentColorIndex index of the transparent color
* @return bitmap of the decoded caption
* @throws CoreException
*/
private Bitmap decodeImage(SubPictureBD subPictureBD, int transparentColorIndex)
throws CoreException {
int width = subPictureBD.getImageWidth();
int height = subPictureBD.getImageHeight();
// always decode image obj 0, start with first entry in fragment list
ImageObjectFragment imageObjectFragment =
subPictureBD.getImageObject().getFragmentList().get(0);
long startOfs = imageObjectFragment.getImageBufferOfs();
if (width > subPictureBD.getWidth() || height > subPictureBD.getHeight()) {
throw new CoreException(
"Subpicture too large: "
+ width
+ "x"
+ height
+ " at offset "
+ ToolBox.toHexLeftZeroPadded(startOfs, 8));
}
Bitmap bm = new Bitmap(width, height, (byte) transparentColorIndex);
int b;
int index = 0;
int ofs = 0;
int size;
int xpos = 0;
try {
// just for multi-packet support, copy all of the image data in one common buffer
byte[] buffer = new byte[subPictureBD.getImageObject().getBufferSize()];
index = 0;
for (ImageObjectFragment fragment : subPictureBD.getImageObject().getFragmentList()) {
// copy data of all packet to one common buffer
imageObjectFragment = fragment;
for (int i = 0; i < imageObjectFragment.getImagePacketSize(); i++) {
buffer[index + i] =
(byte) this.buffer.getByte(imageObjectFragment.getImageBufferOfs() + i);
}
index += imageObjectFragment.getImagePacketSize();
}
index = 0;
do {
b = buffer[index++] & 0xff;
if (b == 0) {
b = buffer[index++] & 0xff;
if (b == 0) {
// next line
ofs = (ofs / width) * width;
if (xpos < width) {
ofs += width;
}
xpos = 0;
} else {
if ((b & 0xC0) == 0x40) {
// 00 4x xx -> xxx zeroes
size = ((b - 0x40) << 8) + (buffer[index++] & 0xff);
for (int i = 0; i < size; i++) {
bm.getInternalBuffer()[ofs++] = 0; /*(byte)b;*/
}
xpos += size;
} else if ((b & 0xC0) == 0x80) {
// 00 8x yy -> x times value y
size = (b - 0x80);
b = buffer[index++] & 0xff;
for (int i = 0; i < size; i++) {
bm.getInternalBuffer()[ofs++] = (byte) b;
}
xpos += size;
} else if ((b & 0xC0) != 0) {
// 00 cx yy zz -> xyy times value z
size = ((b - 0xC0) << 8) + (buffer[index++] & 0xff);
b = buffer[index++] & 0xff;
for (int i = 0; i < size; i++) {
bm.getInternalBuffer()[ofs++] = (byte) b;
}
xpos += size;
} else {
// 00 xx -> xx times 0
for (int i = 0; i < b; i++) {
bm.getInternalBuffer()[ofs++] = 0;
}
xpos += b;
}
}
} else {
bm.getInternalBuffer()[ofs++] = (byte) b;
xpos++;
}
} while (index < buffer.length);
return bm;
} catch (FileBufferException ex) {
throw new CoreException(ex.getMessage());
} catch (ArrayIndexOutOfBoundsException ex) {
logger.warn(
"Problems during RLE decoding of picture OBJ at offset "
+ ToolBox.toHexLeftZeroPadded(startOfs + index, 8)
+ "\n");
return bm;
}
}
/**
* decode palette from the input stream
*
* @param pic SubPicture object containing info about the current caption
* @return
* @throws CoreException
*/
private Palette decodePalette(SubPictureBD pic) throws CoreException {
boolean fadeOut = false;
int paletteIndex;
List<PaletteInfo> paletteInfos = pic.getPalettes().get(pic.getImageObject().getPaletteID());
if (paletteInfos == null) {
throw new CoreException("Palette ID out of bounds.");
}
Palette palette = new Palette(256, Core.usesBT601());
// by definition, index 0xff is always completely transparent
// also all entries must be fully transparent after initialization
try {
for (PaletteInfo paletteInfo : paletteInfos) {
int index = paletteInfo.getPaletteOffset();
for (int i = 0; i < paletteInfo.getPaletteSize(); i++) {
// each palette entry consists of 5 bytes
paletteIndex = buffer.getByte(index);
int y = buffer.getByte(++index);
int cr, cb;
if (configuration.isSwapCrCb()) {
cb = buffer.getByte(++index);
cr = buffer.getByte(++index);
} else {
cr = buffer.getByte(++index);
cb = buffer.getByte(++index);
}
int alpha = buffer.getByte(++index);
int alphaOld = palette.getAlpha(paletteIndex);
// avoid fading out
if (alpha >= alphaOld) {
if (alpha
< configuration
.getAlphaCrop()) { // to not mess with scaling algorithms, make transparent
// color black
y = 16;
cr = 128;
cb = 128;
}
palette.setAlpha(paletteIndex, alpha);
} else {
fadeOut = true;
}
palette.setYCbCr(paletteIndex, y, cb, cr);
index++;
}
}
if (fadeOut) {
logger.warn("fade out detected -> patched palette\n");
}
return palette;
} catch (FileBufferException ex) {
throw new CoreException(ex.getMessage());
}
}
/**
* decode given picture
*
* @param pic SubPicture object containing info about caption
* @throws CoreException
*/
private void decode(SubPictureBD pic) throws CoreException {
palette = decodePalette(pic);
bitmap = decodeImage(pic, palette.getIndexOfMostTransparentPaletteEntry());
primaryColorIndex =
bitmap.getPrimaryColorIndex(
palette.getAlpha(), configuration.getAlphaThreshold(), palette.getY());
}
/* (non-Javadoc)
* @see SubtitleStream#decode(int)
*/
public void decode(int index) throws CoreException {
if (index < subPictures.size()) {
decode(subPictures.get(index));
} else {
throw new CoreException("Index " + index + " out of bounds\n");
}
}
/* (non-Javadoc)
* @see SubtitleStream#getPalette()
*/
public Palette getPalette() {
return palette;
}
/* (non-Javadoc)
* @see SubtitleStream#getBitmap()
*/
public Bitmap getBitmap() {
return bitmap;
}
/* (non-Javadoc)
* @see SubtitleStream#getImage()
*/
public BufferedImage getImage() {
return bitmap.getImage(palette.getColorModel());
}
/* (non-Javadoc)
* @see SubtitleStream#getImage(Bitmap)
*/
public BufferedImage getImage(Bitmap bm) {
return bm.getImage(palette.getColorModel());
}
/* (non-Javadoc)
* @see SubtitleStream#getPrimaryColorIndex()
*/
public int getPrimaryColorIndex() {
return primaryColorIndex;
}
/* (non-Javadoc)
* @see SubtitleStream#getSubPicture(int)
*/
public SubPicture getSubPicture(int index) {
return subPictures.get(index);
}
/* (non-Javadoc)
* @see SubtitleStream#getNumFrames()
*/
public int getFrameCount() {
return subPictures.size();
}
/* (non-Javadoc)
* @see SubtitleStream#getForcedFrameCount()
*/
public int getForcedFrameCount() {
return forcedFrameCount;
}
/* (non-Javadoc)
* @see SubtitleStream#close()
*/
public void close() {
if (buffer != null) {
buffer.close();
}
}
/* (non-Javadoc)
* @see SubtitleStream#getEndTime(int)
*/
public long getEndTime(int index) {
return subPictures.get(index).getEndTime();
}
/* (non-Javadoc)
* @see SubtitleStream#getStartTime(int)
*/
public long getStartTime(int index) {
return subPictures.get(index).getStartTime();
}
/* (non-Javadoc)
* @see SubtitleStream#isForced(int)
*/
public boolean isForced(int index) {
return subPictures.get(index).isForced();
}
/* (non-Javadoc)
* @see SubtitleStream#getStartOffset(int)
*/
public long getStartOffset(int index) {
SubPictureBD pic = subPictures.get(index);
return pic.getImageObject().getFragmentList().get(0).getImageBufferOfs();
}
/**
* Get frame rate for given caption
*
* @param index index of caption
* @return frame rate
*/
public double getFps(int index) {
return Framerate.valueForId(subPictures.get(index).getType());
}
}
/** Reading and writing of Blu-Ray captions in Xml/Png format. */
public class SupXml implements SubtitleStream {
private static final Configuration configuration = Configuration.getInstance();
private static final Logger logger = Logger.getInstance();
/** ArrayList of captions contained in the current file */
private List<SubPictureXml> subPictures = new ArrayList<SubPictureXml>();
/** color palette of the last decoded caption */
private Palette palette;
/** bitmap of the last decoded caption */
private Bitmap bitmap;
/** index of dominant color for the current caption */
private int primaryColorIndex;
/** number of forced captions in the current file */
private int numForcedFrames;
/** path of the input stream */
private String pathName;
/** file name of XML file used as title */
private String title;
/** language id read from the xml */
private String language = "eng";
/** resolution read from the xml */
private Resolution resolution = Resolution.HD_1080;
/** frame rate read from the stream */
private double fps = Framerate.FPS_23_976.getValue();
/** converted xml frame rate read from the stream */
private double fpsXml = XmlFps(fps);
/**
* Constructor (for reading)
*
* @param filename file name of Xml file to read
* @throws CoreException
*/
public SupXml(String filename) throws CoreException {
this.pathName = FilenameUtils.addSeparator(FilenameUtils.getParent(filename));
this.title = FilenameUtils.removeExtension(FilenameUtils.getName(filename));
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser;
try {
saxParser = factory.newSAXParser();
DefaultHandler handler = new XmlHandler();
saxParser.parse(new File(filename), handler);
} catch (ParserConfigurationException e) {
throw new CoreException(e.getMessage());
} catch (SAXException e) {
throw new CoreException(e.getMessage());
} catch (IOException e) {
throw new CoreException(e.getMessage());
}
logger.trace("\nDetected " + numForcedFrames + " forced captions.\n");
}
/**
* Return an integer frame rate in BDN XML style
*
* @param fps source frame rate
* @return next integer frame rate (yet returned as double)
*/
private static double XmlFps(double fps) {
if (fps == Framerate.FPS_23_975.getValue()) {
return Framerate.FPS_24.getValue();
} else if (fps == Framerate.FPS_23_976.getValue()) {
return Framerate.FPS_24.getValue();
} else if (fps == Framerate.NTSC.getValue()) {
return 30.0;
} else if (fps == Framerate.NTSC_I.getValue()) {
return 60.0;
} else {
return fps;
}
}
/* (non-Javadoc)
* @see deadbeef.SupTools.SubtitleStream#close()
*/
@Override
public void close() {}
/* (non-Javadoc)
* @see deadbeef.SupTools.SubtitleStream#decode(int)
*/
@Override
public void decode(int index) throws CoreException {
try {
File f = new File(subPictures.get(index).getFileName());
if (!f.exists()) {
throw new CoreException("file " + subPictures.get(index).getFileName() + " not found.");
}
BufferedImage img = ImageIO.read(f);
int w = img.getWidth();
int h = img.getHeight();
this.palette = null;
// first try to read image and palette directly from imported image
if (img.getType() == BufferedImage.TYPE_BYTE_INDEXED) {
IndexColorModel icm = (IndexColorModel) img.getColorModel();
if (icm.getMapSize() < 255 || (icm.hasAlpha() && icm.getAlpha(255) == 0)) {
// create palette
palette = new Palette(256);
for (int i = 0; i < icm.getMapSize(); i++) {
int alpha = (icm.getRGB(i) >> 24) & 0xff;
if (alpha >= configuration.getAlphaCrop()) {
palette.setARGB(i, icm.getRGB(i));
} else {
palette.setARGB(i, 0);
}
}
// copy pixels
WritableRaster raster = img.getRaster();
bitmap =
new Bitmap(
img.getWidth(),
img.getHeight(),
(byte[]) raster.getDataElements(0, 0, img.getWidth(), img.getHeight(), null));
}
}
// if this failed, assume RGB image and quantize palette
if (palette == null) {
// grab int array (ARGB)
int[] pixels = new int[w * h];
img.getRGB(0, 0, w, h, pixels, 0, w);
// quantize image
QuantizeFilter qf = new QuantizeFilter();
bitmap = new Bitmap(img.getWidth(), img.getHeight());
int ct[] = qf.quantize(pixels, bitmap.getInternalBuffer(), w, h, 255, false, false);
int size = ct.length;
if (size > 255) {
logger.warn("Quantizer failed.\n");
size = 255;
}
// create palette
palette = new Palette(256);
for (int i = 0; i < size; i++) {
int alpha = (ct[i] >> 24) & 0xff;
if (alpha >= configuration.getAlphaCrop()) {
palette.setARGB(i, ct[i]);
} else {
palette.setARGB(i, 0);
}
}
}
primaryColorIndex =
bitmap.getPrimaryColorIndex(
palette.getAlpha(), configuration.getAlphaThreshold(), palette.getY());
// crop
BitmapBounds bounds =
bitmap.getCroppingBounds(palette.getAlpha(), configuration.getAlphaCrop());
if (bounds.yMin > 0
|| bounds.xMin > 0
|| bounds.xMax < bitmap.getWidth() - 1
|| bounds.yMax < bitmap.getHeight() - 1) {
w = bounds.xMax - bounds.xMin + 1;
h = bounds.yMax - bounds.yMin + 1;
if (w < 2) {
w = 2;
}
if (h < 2) {
h = 2;
}
bitmap = bitmap.crop(bounds.xMin, bounds.yMin, w, h);
// update picture
SubPictureXml pic = subPictures.get(index);
pic.setImageWidth(w);
pic.setImageHeight(h);
pic.setOfsX(pic.getOriginalXOffset() + bounds.xMin);
pic.setOfsY(pic.getOriginalYOffset() + bounds.yMin);
}
} catch (IOException e) {
throw new CoreException(e.getMessage());
} catch (OutOfMemoryError e) {
JOptionPane.showMessageDialog(
null,
"Out of heap! Use -Xmx256m to increase heap!",
"Error!",
JOptionPane.WARNING_MESSAGE);
throw new CoreException("Out of heap! Use -Xmx256m to increase heap!");
}
}
/**
* Create Xml file
*
* @param fname file name
* @param pics Map of SubPictures and their original indexes which were used to generate the png
* file names
* @throws CoreException
*/
public static void writeXml(String fname, SortedMap<Integer, SubPicture> pics)
throws CoreException {
double fps = configuration.getFpsTrg();
double fpsXml = XmlFps(fps);
BufferedWriter out = null;
String name = FilenameUtils.removeExtension(FilenameUtils.getName(fname));
try {
out = new BufferedWriter(new FileWriter(fname));
out.write("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
out.newLine();
out.write(
"<BDN Version=\"0.93\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:noNamespaceSchemaLocation=\"BD-03-006-0093b BDN File Format.xsd\">");
out.newLine();
out.write(" <Description>");
out.newLine();
out.write(" <Name Title=\"" + name + "\" Content=\"\"/>");
out.newLine();
out.write(" <Language Code=\"" + LANGUAGES[configuration.getLanguageIdx()][2] + "\"/>");
out.newLine();
String res = configuration.getOutputResolution().getResolutionNameForXml();
out.write(
" <Format VideoFormat=\""
+ res
+ "\" FrameRate=\""
+ ToolBox.formatDouble(fps)
+ "\" DropFrame=\"False\"/>");
out.newLine();
long t = pics.get(pics.firstKey()).getStartTime();
if (fps != fpsXml) {
t = (t * 2000 + 1001) / 2002;
}
String ts = ptsToTimeStrXml(t, fpsXml);
t = pics.get(pics.lastKey()).getEndTime();
if (fps != fpsXml) {
t = (t * 2000 + 1001) / 2002;
}
String te = ptsToTimeStrXml(t, fpsXml);
out.write(
" <Events Type=\"Graphic\" FirstEventInTC=\""
+ ts
+ "\" LastEventOutTC=\""
+ te
+ "\" NumberofEvents=\""
+ pics.size()
+ "\"/>");
out.newLine();
out.write(" </Description>");
out.newLine();
out.write(" <Events>");
out.newLine();
for (int idx : pics.keySet()) {
SubPicture p = pics.get(idx);
t = p.getStartTime();
if (fps != fpsXml) {
t = (t * 2000 + 1001) / 2002;
}
ts = ptsToTimeStrXml(t, fpsXml);
t = p.getEndTime();
if (fps != fpsXml) {
t = (t * 2000 + 1001) / 2002;
}
te = ptsToTimeStrXml(t, fpsXml);
String forced = p.isForced() ? "True" : "False";
out.write(" <Event InTC=\"" + ts + "\" OutTC=\"" + te + "\" Forced=\"" + forced + "\">");
out.newLine();
String pname = getPNGname(name, idx + 1);
out.write(
" <Graphic Width=\""
+ p.getImageWidth()
+ "\" Height=\""
+ p.getImageHeight()
+ "\" X=\""
+ p.getXOffset()
+ "\" Y=\""
+ p.getYOffset()
+ "\">"
+ pname
+ "</Graphic>");
out.newLine();
out.write(" </Event>");
out.newLine();
}
out.write(" </Events>");
out.newLine();
out.write("</BDN>");
out.newLine();
} catch (IOException ex) {
throw new CoreException(ex.getMessage());
} finally {
try {
if (out != null) {
out.close();
}
} catch (IOException ex) {
}
}
}
/* (non-Javadoc)
* @see SubtitleStream#getBitmap()
*/
public Bitmap getBitmap() {
return bitmap;
}
/* (non-Javadoc)
* @see SubtitleStream#getImage()
*/
public BufferedImage getImage() {
return bitmap.getImage(palette.getColorModel());
}
/* (non-Javadoc)
* @see SubtitleStream#getImage(Bitmap)
*/
public BufferedImage getImage(final Bitmap bm) {
return bm.getImage(palette.getColorModel());
}
/* (non-Javadoc)
* @see SubtitleStream#getForcedFrameCount()
*/
public int getForcedFrameCount() {
return numForcedFrames;
}
/* (non-Javadoc)
* @see SubtitleStream#getNumFrames()
*/
public int getFrameCount() {
return subPictures.size();
}
/* (non-Javadoc)
* @see SubtitleStream#getPalette()
*/
public Palette getPalette() {
return palette;
}
/* (non-Javadoc)
* @see SubtitleStream#getPrimaryColorIndex()
*/
public int getPrimaryColorIndex() {
return primaryColorIndex;
}
/* (non-Javadoc)
* @see deadbeef.SupTools.SubtitleStream#getStartOffset(int)
*/
public long getStartOffset(int index) {
// dummy
return 0;
}
/* (non-Javadoc)
* @see SubtitleStream#getSubPicture(int)
*/
public SubPicture getSubPicture(int index) {
return subPictures.get(index);
}
/* (non-Javadoc)
* @see SubtitleStream#getEndTime(int)
*/
public long getEndTime(int index) {
return subPictures.get(index).getEndTime();
}
/* (non-Javadoc)
* @see SubtitleStream#getStartTime(int)
*/
public long getStartTime(final int index) {
return subPictures.get(index).getStartTime();
}
/* (non-Javadoc)
* @see SubtitleStream#isForced(int)
*/
public boolean isForced(int index) {
return subPictures.get(index).isForced();
}
/**
* Create PNG name from (xml) file name and index
*
* @param fn file name
* @param idx index
* @return PNG name
*/
public static String getPNGname(String fn, int idx) {
return fn + "_" + ToolBox.leftZeroPad(idx, 4) + ".png";
}
/**
* get language read from Xml
*
* @return language as String
*/
public String getLanguage() {
return language;
}
/**
* get fps read from Xml
*
* @return frame rate as double
*/
public double getFps() {
return fps;
}
enum XmlState {
BDN,
DESCRIPT,
NAME,
LANGUAGE,
FORMAT,
EVENTS,
EVENT,
GRAPHIC,
UNKNOWN
}
private static final String xmlStates[] = {
"bdn", "description", "name", "language", "format", "events", "event", "graphic"
};
class XmlHandler extends DefaultHandler {
XmlState state;
StringBuffer txt;
boolean valid;
SubPictureXml pic;
private XmlState findState(final String s) {
for (XmlState x : XmlState.values()) {
if (s.toLowerCase().equals(xmlStates[x.ordinal()])) {
return x;
}
}
return XmlState.UNKNOWN;
}
@Override
public void startElement(String namespaceURI, String localName, String qName, Attributes atts) {
state = findState(qName);
String at;
if (state != XmlState.BDN && !valid) {
logger.error("BDN tag missing");
}
txt = null;
switch (state) {
case UNKNOWN:
logger.error("Unknown tag " + qName + "\n");
break;
case BDN:
if (valid) {
logger.error("BDN must be used only once");
} else {
valid = true;
}
break;
case NAME:
at = atts.getValue("Title");
if (at != null) {
title = at;
logger.trace("Title: " + title + "\n");
}
break;
case LANGUAGE:
at = atts.getValue("Code");
if (at != null) {
language = at;
logger.trace("Language: " + language + "\n");
}
break;
case FORMAT:
at = atts.getValue("FrameRate");
if (at != null) {
fps = SubtitleUtils.getFps(at);
fpsXml = XmlFps(fps);
logger.trace("fps: " + ToolBox.formatDouble(fps) + "\n");
}
at = atts.getValue("VideoFormat");
if (at != null) {
String res = at;
for (Resolution r : Resolution.values()) {
if (res.length() == 4
&& res.charAt(0) != '7') { // hack to rename 480p/576p to 480i/576i
res = res.replace('p', 'i');
}
if (r.getResolutionNameForXml().equalsIgnoreCase(res)) {
resolution = r;
logger.trace("Language: " + r.getResolutionNameForXml() + "\n");
break;
}
}
}
break;
case EVENTS:
at = atts.getValue("NumberofEvents");
if (at != null) {
int n = ToolBox.getInt(at);
if (n > 0) {
/* number of subtitles read from the xml */
Core.setProgressMax(n);
}
}
break;
case EVENT:
pic = new SubPictureXml();
subPictures.add(pic);
int num = subPictures.size();
logger.info("#" + num + "\n");
Core.setProgress(num);
at = atts.getValue("InTC");
if (at != null) {
pic.setStartTime(timeStrXmlToPTS(at, fpsXml));
if (pic.getStartTime() == -1) {
pic.setStartTime(0);
logger.warn("Invalid start time " + at + "\n");
}
}
at = atts.getValue("OutTC");
if (at != null) {
pic.setEndTime(timeStrXmlToPTS(at, fpsXml));
if (pic.getEndTime() == -1) {
pic.setEndTime(0);
logger.warn("Invalid end time " + at + "\n");
}
}
if (fps != fpsXml) {
pic.setStartTime((pic.getStartTime() * 1001 + 500) / 1000);
pic.setEndTime((pic.getEndTime() * 1001 + 500) / 1000);
}
at = atts.getValue("Forced");
pic.setForced(at != null && at.equalsIgnoreCase("true"));
if (pic.isForced()) {
numForcedFrames++;
}
int dim[] = resolution.getDimensions();
pic.setWidth(dim[0]);
pic.setHeight(dim[1]);
break;
case GRAPHIC:
pic.setImageWidth(ToolBox.getInt(atts.getValue("Width")));
pic.setImageHeight(ToolBox.getInt(atts.getValue("Height")));
pic.setOfsX(ToolBox.getInt(atts.getValue("X")));
pic.setOfsY(ToolBox.getInt(atts.getValue("Y")));
pic.storeOriginalOffsets();
txt = new StringBuffer();
break;
}
}
@Override
public void endElement(String namespaceURI, String localName, String qName) {
XmlState endState = findState(qName);
if (state == XmlState.GRAPHIC && endState == XmlState.GRAPHIC) {
pic.setFileName(pathName + txt.toString().trim());
}
}
@Override
public void characters(char[] ch, int start, int length) {
if (txt != null) {
txt.append(ch, start, length);
}
}
}
}