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 : PdfDictionary {
// membervariables
/** is the stream compressed? */
protected bool compressed = false;
protected MemoryStream streamBytes = null;
protected Stream inputStream;
protected PdfIndirectReference iref;
protected int inputStreamLength = -1;
protected PdfWriter writer;
protected int rawLength;
internal static byte[] STARTSTREAM = DocWriter.GetISOBytes("stream\n");
internal static byte[] ENDSTREAM = DocWriter.GetISOBytes("\nendstream");
internal static 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) : base() {
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(Stream inputStream, PdfWriter writer) {
type = STREAM;
this.inputStream = inputStream;
this.writer = writer;
iref = writer.PdfIndirectReference;
Put(PdfName.LENGTH, iref);
}
/**
* Constructs a PdfStream-object.
*/
protected PdfStream() : base() {
type = STREAM;
}
// methods overriding some methods of PdfObject
/**
* 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() {
if (inputStream == null)
throw new PdfException("WriteLength() can only be called in a contructed PdfStream(InputStream,PdfWriter).");
if (inputStreamLength == -1)
throw new PdfException("WriteLength() can only be called after output of the stream body.");
writer.AddToBody(new PdfNumber(inputStreamLength), iref, false);
}
public int RawLength {
get {
return rawLength;
}
}
// methods
/**
* Compresses the stream.
*
* @throws PdfException if a filter is allready defined
*/
public void FlateCompress() {
if (!Document.Compress)
return;
// check if the flateCompress-method has allready been
if (compressed) {
return;
}
if (inputStream != null) {
compressed = true;
return;
}
// check if a filter allready exists
PdfObject filter = PdfReader.GetPdfObject(Get(PdfName.FILTER));
if (filter != null) {
if (filter.IsName()) {
if (PdfName.FLATEDECODE.Equals(filter))
return;
}
else if (filter.IsArray()) {
if (((PdfArray) filter).Contains(PdfName.FLATEDECODE))
return;
}
else {
throw new PdfException("Stream could not be compressed: filter is not a name or array.");
}
}
// compress
MemoryStream stream = new MemoryStream();
ZDeflaterOutputStream zip = new ZDeflaterOutputStream(stream);
if (streamBytes != null)
streamBytes.WriteTo(zip);
else
zip.Write(bytes, 0, bytes.Length);
//zip.Close();
zip.Finish();
// update the object
streamBytes = stream;
bytes = null;
Put(PdfName.LENGTH, new PdfNumber(streamBytes.Length));
if (filter == null) {
Put(PdfName.FILTER, PdfName.FLATEDECODE);
}
else {
PdfArray filters = new PdfArray(filter);
filters.Add(PdfName.FLATEDECODE);
Put(PdfName.FILTER, filters);
}
compressed = true;
}
protected virtual void SuperToPdf(PdfWriter writer, Stream os) {
base.ToPdf(writer, os);
}
public override void ToPdf(PdfWriter writer, Stream os) {
if (inputStream != null && compressed)
Put(PdfName.FILTER, PdfName.FLATEDECODE);
PdfEncryption crypto = null;
if (writer != null)
crypto = writer.Encryption;
if (crypto != null) {
PdfObject filter = Get(PdfName.FILTER);
if (filter != null) {
if (PdfName.CRYPT.Equals(filter))
crypto = null;
else if (filter.IsArray()) {
ArrayList af = ((PdfArray)filter).ArrayList;
if (af.Count > 0 && PdfName.CRYPT.Equals(af[0]))
crypto = null;
}
}
}
PdfObject nn = Get(PdfName.LENGTH);
if (crypto != null && nn != null && nn.IsNumber()) {
int sz = ((PdfNumber)nn).IntValue;
Put(PdfName.LENGTH, new PdfNumber(crypto.CalculateStreamSize(sz)));
SuperToPdf(writer, os);
Put(PdfName.LENGTH, nn);
}
else
SuperToPdf(writer, os);
os.Write(STARTSTREAM, 0, STARTSTREAM.Length);
if (inputStream != null) {
rawLength = 0;
ZDeflaterOutputStream def = null;
OutputStreamCounter osc = new OutputStreamCounter(os);
OutputStreamEncryption ose = null;
Stream fout = osc;
if (crypto != null)
fout = ose = crypto.GetEncryptionStream(fout);
if (compressed)
fout = def = new ZDeflaterOutputStream(fout);
byte[] buf = new byte[4192];
while (true) {
int n = inputStream.Read(buf, 0, buf.Length);
if (n <= 0)
break;
fout.Write(buf, 0, n);
rawLength += n;
}
if (def != null)
def.Finish();
if (ose != null)
ose.Finish();
inputStreamLength = osc.Counter;
}
else {
if (crypto == null) {
if (streamBytes != null)
streamBytes.WriteTo(os);
else
os.Write(bytes, 0, bytes.Length);
}
else {
byte[] b;
if (streamBytes != null) {
b = crypto.EncryptByteArray(streamBytes.ToArray());
}
else {
b = crypto.EncryptByteArray(bytes);
}
os.Write(b, 0, b.Length);
}
}
os.Write(ENDSTREAM, 0, ENDSTREAM.Length);
}
/**
* Writes the data content to an Stream.
* @param os the destination to write to
* @throws IOException on error
*/
public void WriteContent(Stream os) {
if (streamBytes != null)
streamBytes.WriteTo(os);
else if (bytes != null)
os.Write(bytes, 0, bytes.Length);
}
/**
* @see com.lowagie.text.pdf.PdfObject#toString()
*/
public override String ToString() {
if (Get(PdfName.TYPE) == null) return "Stream";
return "Stream of type: " + Get(PdfName.TYPE);
}
}
}