PdfStream is the Pdf stream object.
*
* A stream, like a string, is a sequence of characters. However, an application can
* read a small portion of a stream at a time, while a string must be read in its entirety.
* For this reason, objects with potentially large amounts of data, such as images and
* page descriptions, are represented as streams.
* A stream consists of a dictionary that describes a sequence of characters, followed by
* the keyword stream, followed by zero or more lines of characters, followed by
* the keyword endstream.
* All streams must be PdfIndirectObjects. The stream dictionary must be a direct
* object. The keyword stream that follows the stream dictionary should be followed by
* a carriage return and linefeed or just a linefeed.
* Remark: In this version only the FLATEDECODE-filter is supported.
* This object is described in the 'Portable Document Format Reference Manual version 1.3'
* section 4.8 (page 41-53).
*
* @see PdfObject
* @see PdfDictionary
*/
public class PdfStream extends PdfDictionary {
// membervariables
/** is the stream compressed? */
protected boolean compressed = false;
protected ByteArrayOutputStream streamBytes = null;
protected InputStream inputStream;
protected PdfIndirectReference ref;
protected int inputStreamLength = -1;
protected PdfWriter writer;
protected int rawLength;
static final byte STARTSTREAM[] = DocWriter.getISOBytes("stream\n");
static final byte ENDSTREAM[] = DocWriter.getISOBytes("\nendstream");
static final int SIZESTREAM = STARTSTREAM.length + ENDSTREAM.length;
// constructors
/**
* Constructs a PdfStream-object.
*
* @param bytes content of the new PdfObject as an array of byte.
*/
public PdfStream(byte[] bytes) {
super();
type = STREAM;
this.bytes = bytes;
rawLength = bytes.length;
put(PdfName.LENGTH, new PdfNumber(bytes.length));
}
/**
* Creates an efficient stream. No temporary array is ever created. The InputStream
* is totally consumed but is not closed. The general usage is:
*
*
* InputStream in = ...;
* PdfStream stream = new PdfStream(in, writer);
* stream.flateCompress();
* writer.addToBody(stream);
* stream.writeLength();
* in.close();
*
* @param inputStream the data to write to this stream
* @param writer the PdfWriter for this stream
*/
public PdfStream(InputStream inputStream, PdfWriter writer) {
super();
type = STREAM;
this.inputStream = inputStream;
this.writer = writer;
ref = writer.getPdfIndirectReference();
put(PdfName.LENGTH, ref);
}
/**
* Constructs a PdfStream-object.
*/
protected PdfStream() {
super();
type = STREAM;
}
/**
* Writes the stream length to the PdfWriter.
*
* This method must be called and can only be called if the contructor {@link #PdfStream(InputStream,PdfWriter)}
* is used to create the stream.
* @throws IOException on error
* @see #PdfStream(InputStream,PdfWriter)
*/
public void writeLength() throws IOException {
if (inputStream == null)
throw new UnsupportedOperationException("writeLength() can only be called in a contructed PdfStream(InputStream,PdfWriter).");
if (inputStreamLength == -1)
throw new IOException("writeLength() can only be called after output of the stream body.");
writer.addToBody(new PdfNumber(inputStreamLength), ref, false);
}
/**
* Gets the raw length of the stream.
* @return the raw length of the stream
*/
public int getRawLength() {
return rawLength;
}
/**
* Compresses the stream.
*/
public void flateCompress() {
if (!Document.compress)
return;
// check if the flateCompress-method has already been
if (compressed) {
return;
}
if (inputStream != null) {
compressed = true;
return;
}
// check if a filter already exists
PdfObject filter = get(PdfName.FILTER);
if (filter != null) {
if (filter.isName() && ((PdfName) filter).compareTo(PdfName.FLATEDECODE) == 0) {
return;
}
else if (filter.isArray() && ((PdfArray) filter).contains(PdfName.FLATEDECODE)) {
return;
}
else {
throw new RuntimeException("Stream could not be compressed: filter is not a name or array.");
}
}
try {
// compress
ByteArrayOutputStream stream = new ByteArrayOutputStream();
DeflaterOutputStream zip = new DeflaterOutputStream(stream);
if (streamBytes != null)
streamBytes.writeTo(zip);
else
zip.write(bytes);
zip.close();
// update the object
streamBytes = stream;
bytes = null;
put(PdfName.LENGTH, new PdfNumber(streamBytes.size()));
if (filter == null) {
put(PdfName.FILTER, PdfName.FLATEDECODE);
}
else {
PdfArray filters = new PdfArray(filter);
filters.add(PdfName.FLATEDECODE);
put(PdfName.FILTER, filters);
}
compressed = true;
}
catch(IOException ioe) {
throw new ExceptionConverter(ioe);
}
}
// public int getStreamLength(PdfWriter writer) {
// if (dicBytes == null)
// toPdf(writer);
// if (streamBytes != null)
// return streamBytes.size() + dicBytes.length + SIZESTREAM;
// else
// return bytes.length + dicBytes.length + SIZESTREAM;
// }
protected void superToPdf(PdfWriter writer, OutputStream os) throws IOException {
super.toPdf(writer, os);
}
/**
* @see com.lowagie.text.pdf.PdfDictionary#toPdf(com.lowagie.text.pdf.PdfWriter, java.io.OutputStream)
*/
public void toPdf(PdfWriter writer, OutputStream os) throws IOException {
if (inputStream != null && compressed)
put(PdfName.FILTER, PdfName.FLATEDECODE);
superToPdf(writer, os);
os.write(STARTSTREAM);
PdfEncryption crypto = null;
if (writer != null)
crypto = writer.getEncryption();
if (crypto != null)
crypto.prepareKey();
if (inputStream != null) {
rawLength = 0;
DeflaterOutputStream def = null;
OutputStreamCounter osc = new OutputStreamCounter(os);
OutputStream fout = osc;
if (crypto != null)
fout = new PdfEncryptionStream(fout, crypto);
if (compressed)
fout = def = new DeflaterOutputStream(fout, new Deflater(Deflater.BEST_COMPRESSION), 0x8000);
byte buf[] = new byte[0x10000];
while (true) {
int n = inputStream.read(buf);
if (n <= 0)
break;
fout.write(buf, 0, n);
rawLength += n;
}
if (def != null)
def.finish();
inputStreamLength = osc.getCounter();
}
else {
if (crypto == null) {
if (streamBytes != null)
streamBytes.writeTo(os);
else
os.write(bytes);
}
else {
byte b[];
if (streamBytes != null) {
b = streamBytes.toByteArray();
crypto.encryptRC4(b);
}
else {
b = new byte[bytes.length];
crypto.encryptRC4(bytes, b);
}
os.write(b);
}
}
os.write(ENDSTREAM);
}
/**
* Writes the data content to an OutputStream.
* @param os the destination to write to
* @throws IOException on error
*/
public void writeContent(OutputStream os) throws IOException {
if (streamBytes != null)
streamBytes.writeTo(os);
else if (bytes != null)
os.write(bytes);
}
}