PDFStream Class Documentation
class PDFStream : PDFObjectNamespace:Datalogics::PDFL
- Inherits from:
PDFObject
Detailed Description
Represents a stream of data within a PDF document.
All objects in a PDF document are built from a collection of simpler objects that represent fundamental datatypes like numbers, strings and arrays.
PDFObject and its subclasses allow direct access and manipulation of these simple objects. Some subclasses represent single data elements (e.g. PDFInteger represents a single integer value); other subclasses represent a collection of PDFObjects (e.g. PDFArray is an indexed array of data elements).
A PDFStream represents a stream of unsigned bytes, and may be inserted into any collection object. It includes a dictionary that describes how the data in the stream is encoded and other useful information about the stream. A PDFStream is always an indirect object.
PDFStreams can be encoded using built-in filters. These filters include compression schemes for most popular image formats, and text encoding translators to permit safe transmission of the document over the Internet. The data in a PDFStream will be automatically encoded when it is created; the user can read either the encoded (raw) or decoded (filtered) data.
PDFStreams can be used for any large collection of data that need not be read into memory all at once, including image data, multimedia data or XML markup.
Constructor & Destructor Documentation
PDFStream
Parameters
stream: System.IO.StreamSystem.IO.Stream which will provide data for this PDFStream
doc: DocumentDocument object containing this PDFStream
encoding_dict: PDFDictPDFDict describing properties of this stream, including the encoding
encoding_params: PDFArrayPDFArray describing parameters for encoding this stream
General constructor
PDFStream
Parameters
stream: System.IO.StreamSystem.IO.Stream which will provide data for this PDFStream
docFromObj: PDFObjectThe new PDFArray will be created in the same document as this object.
encoding_dict: PDFDictPDFDict describing properties of this stream, including the encoding
encoding_params: PDFArrayPDFArray describing parameters for encoding this stream
General constructor
Property Documentation
Dict
PDFDict Dict[get]The encoding dictionary for the stream. This includes all required information for decoding the stream, such as filter names and decode parameters.
Document
Document Document[get]The Document of which this object is a member.
Returns null if the Document is not known by PDFL, or if it is a temporary document.
If the Document is not null, then it shares the same internal data with other Document objects that refer to the same file. Document objects returned this way do not contribute to the internal count that keeps the Document open, and will become invalid if the main reference to the document is disposed.
FilteredStream
System.IO.Stream FilteredStream[get]Generation
int Generation[get]The generation number for this object.
Only indirect objects have a generation number.
Exceptions
- ApplicationException —
direct objects do not have a generation number.
ID
int ID[get]The ID number for this object.
Only indirect objects have an ID number.
Exceptions
- ApplicationException —
direct objects do not have an ID number.
Indirect
bool Indirect[get]Indicates if this object is indirect or direct.
Length
int Length[get]The encoded length of the stream in bytes.
PDFHashValue
int PDFHashValue[get]The 32-bit hash value for this object.
The hash value is used internally to quickly access the object, and is not generally useful for PDFObject users. Note that two PDFObjects with equal hash values are not necessarily equal; use Equals() to check for equality.
StreamPos
int StreamPos[get]The byte offset of this stream in the PDF file.
Exceptions
- ApplicationException —
will be thrown if the document has not been saved since creating the stream
UnfilteredStream
System.IO.Stream UnfilteredStream[get]Member Function Documentation
Clone
PDFObject Clone()Returns:
PDFObjectA new PDFObject that is a copy of this object.
Makes a new copy of this PDFObject in memory, in the same document and using same direct/indirect setting as this PDFObject.
Clone
Parameters
doc: DocumentThe target document in which to create the copy.
Returns:
PDFObjectA new PDFObject that is a copy of this object in the specified document.
Makes a new copy of this PDFObject in memory, in the supplied document, using the same direct/indirect setting as this PDFObject.
Clone
Parameters
doc: DocumentThe target document in which to create the copy.
indirect: boolIf true, the copy will be an indirect object; if false, it will be direct.
Returns:
PDFObjectA new PDFObject that is a copy of this object in the specified document.
Makes a new copy of this PDFObject in memory, in the supplied document, using supplied direct/indirect setting.
Clone
Parameters
obj: PDFObjectThe reference object whose document will be used for the copy.
Returns:
PDFObjectA new PDFObject that is a copy of this object in the same document as obj.
Makes a new copy of this PDFObject in memory, in the same document as another object, using the same direct/indirect setting as this PDFObject.
Clone
Parameters
obj: PDFObjectThe reference object whose document will be used for the copy.
indirect: boolIf true, the copy will be an indirect object; if false, it will be direct.
Returns:
PDFObjectA new PDFObject that is a copy of this object in the same document as obj.
Makes a new copy of this PDFObject in memory, in the same document as another object, using supplied direct/indirect setting.
CompareTo
PDFObjectComparison CompareTo(PDFObject rhs)Parameters
rhs: PDFObjectthe other PDFObject to compare.
Returns:
PDFObjectComparisonA PDFObjectComparison value that relates this object to the rhs object
Compares this object to another object. The result is useful for ordering or sorting PDFObjects. No other significance should be attached to the result. In particular, an unequal result indicates nothing about the type of either object.
The result is valid only within a single instance of the document.
Destroy
void Destroy()Returns:
voidDestroys this object.
This method does nothing if this object is a direct scalar object.
If a composite object (an array, dictionary or stream) is destroyed:
• All the direct objects in it are automatically destroyed.
• The indirect objects in it are not destroyed.
Dispose
void Dispose()Returns:
voidEnumPDFObjects
bool EnumPDFObjects(PDFObjectEnumProc enumProc)Parameters
enumProc: PDFObjectEnumProcA user-supplied callback to call for each element of the object. of obj. Neither proc nor any routine called by proc may modify the object. Doing so can produce undefined results or errors. For example, if the object is an array, enumProc must not call Remove(); if the object is a dictionary, enumProc must not call Put().
Returns:
boolReturns true if every call to enumProc returned true. As soon as any call to enumProc returns false, the enumeration stops and EnumPDFObject() returns false.
Enumerates the elements of a PDFObject by calling a user-supplied procedure for each component of the object.
• For scalars or strings, the proc is not called, and CosObjEnum() returns true.
• For dictionaries, proc is called for each key-value pair. The order in which the key-value pairs are enumerated is undefined.
• For arrays, proc is called with each element as the first paramater to proc, and the NULL object as the second parameter. Array elements are enumerated in ascending order of index.
• For streams, proc is called once, with the stream's dictionary as the first parameter to the proc and the NULL object as the second parameter.
Equals
override bool Equals(object obj)Parameters
obj: object
Returns:
override boolGetFilteredStream
System.IO.Stream GetFilteredStream()Returns:
System.IO.StreamThe stream data of this object, decoded according to the filter data in its dictionary.
GetStream
System.IO.Stream GetStream(PDFStreamOpenMode mode)Parameters
mode: PDFStreamOpenMode
Returns:
System.IO.StreamThe stream data of this object, processed according to the mode
GetUnfilteredStream
System.IO.Stream GetUnfilteredStream()Returns:
System.IO.StreamThe unfiltered data of this stream object.
SetData
Parameters
Returns:
voidReplace the data in this PDFStream
ToString
override string ToString()Returns:
override stringA string describing this PDFStream, including its indirect/direct status and ID.
Returns a string representation of this PDFStream.