Filter (PDFTron PDFNet SDK API Reference)

java.lang.Object
- pdftron.Filters.Filter

Direct Known Subclasses:

ASCII85Encode, CustomFilter, FlateEncode, Image2RGB, Image2RGBA, MemoryFilter, StdFile
```
public class Filter
extends java.lang.Object
```
Provides a generic view of a sequence of bytes. A Filter is the abstract base class of all filters. A filter is an abstraction of a sequence of bytes, such as a file, an input/output device, an inter-process communication pipe, or a TCP/IP socket. The Filter class and its derived classes provide a generic view of these different types of input and output, isolating the programmer from the specific details of the operating system and the underlying devices. Besides providing access to input/output sources Filters can be also to transform the data (e.g. to compress the data stream, to normalize the image data, to encrypt data, etc). Filters can also be attached to each other to form pipelines. For example, a filter used to open an image data file can be attached to a filter that decompresses the data, which is attached to another filter that will normalize the image data. Depending on the underlying data source or repository, filters might support only some of these capabilities. An application can query a stream for its capabilities by using the IsInputFilter() and CanSeek() properties.

Note:

To read or write data to a filter, a user will tipically use FilterReader/FilterWriter class. instead of using Filter methods For example:

Field Summary

Fields
Modifier and Type Field and Description

protected Filter attached

protected long impl

protected java.lang.Object ref

Fields
Modifier and Type	Field and Description
`protected Filter`	`attached`
`protected long`	`impl`
`protected java.lang.Object`	`ref`

Constructor Summary

Constructors
Modifier Constructor and Description

protected Filter(long impl, Filter attached)

Constructors
Modifier	Constructor and Description
`protected`	`Filter(long impl, Filter attached)`

Method Summary

Methods
Modifier and Type	Method and Description
`static Filter`	`__Create(long impl, Filter attached)`
`long`	`__GetHandle()`
`void`	`__SetRefHandle(java.lang.Object ref)`
`void`	`attachFilter(Filter attach_filter)` Attaches a filter to the this filter.
`boolean`	`canSeek()` determine whether the stream supports seeking
`Filter`	`createInputIterator()` Create Filter iterator.
`void`	`destroy()` Frees the native memory of the object.
`protected void`	`finalize()`
`void`	`flush()` Forces any data remaining in the buffer to be written to input or output filter.
`void`	`flushAll()` Forces any data remaining in the filter chain to the source or destination.
`Filter`	`getAttachedFilter()` Get the attached filter.
`java.lang.String`	`getDecodeName()` Get the decode name.
`java.lang.String`	`getFilePath()` Get the file path.
`java.lang.String`	`getName()` Get the name.
`Filter`	`getSourceFilter()` Get the source filter.
`boolean`	`isInputFilter()` Checks if is input filter.
`Filter`	`releaseAttachedFilter()` Release the ownership of the attached filter.
`void`	`seek(long offset, int origin)` When overridden in a derived class, sets the position within the current stream.
`void`	`setStreamLength(long bytes)` The functions specifies the length of the data stream.
`long`	`tell()` Reports the current read position in the stream relative to the stream origin.

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - impl
```
protected long impl
```
  - attached
```
protected Filter attached
```
  - ref
```
protected java.lang.Object ref
```
- Constructor Detail
  - Filter
```
protected Filter(long impl,
      Filter attached)
```
- Method Detail
  - destroy
```
public void destroy()
             throws PDFNetException
```
    Frees the native memory of the object. This can be explicity called to control the deallocation of native memory and avoid situations where the garbage collector does not free the object in a timely manner.
    
    Throws:
    
    PDFNetException
  - finalize
```
protected void finalize()
                 throws java.lang.Throwable
```
    Overrides:
    
    finalize in class java.lang.Object
    
    Throws:
    
    java.lang.Throwable
  - attachFilter
```
public void attachFilter(Filter attach_filter)
                  throws PDFNetException
```
    Attaches a filter to the this filter. If this filter owns another filter it will be deleted. This filter then becomes the owner of the attached filter.
    
    Parameters:
    attach_filter - the attach_filter
    
    Throws:
    
    PDFNetException
  - releaseAttachedFilter
```
public Filter releaseAttachedFilter()
                             throws PDFNetException
```
    Release the ownership of the attached filter. After the attached filter is released this filter points to NULL filter.
    
    Returns:
    - Previously attached filter.
    
    Throws:
    
    PDFNetException
  - getAttachedFilter
```
public Filter getAttachedFilter()
                         throws PDFNetException
```
    Get the attached filter.
    
    Returns:
    - returns attached Filter or a NULL filter if no filter is attached.
    
    Throws:
    
    PDFNetException
  - getSourceFilter
```
public Filter getSourceFilter()
                       throws PDFNetException
```
    Get the source filter.
    
    Returns:
    - returns the first filter in the chain (usually a file filter)
    
    Throws:
    
    PDFNetException
  - getName
```
public java.lang.String getName()
                         throws PDFNetException
```
    Get the name.
    
    Returns:
    - descriptive name of the filter.
    
    Throws:
    
    PDFNetException
  - getDecodeName
```
public java.lang.String getDecodeName()
                               throws PDFNetException
```
    Get the decode name.
    
    Returns:
    - string representing the name of corresponding decode filter as it should appear in document (e.g. both ASCIIHexDecode and ASCIIHexEncode should return ASCIIHexDecode).
    
    Throws:
    
    PDFNetException
  - setStreamLength
```
public void setStreamLength(long bytes)
                     throws PDFNetException
```
    The functions specifies the length of the data stream. The default implementation does not do anything. For some derived filters such as file segment filter it may be useful to override this function in order to limit the stream.
    
    Parameters:
    bytes - the new stream length
    
    Throws:
    
    PDFNetException
  - flush
```
public void flush()
           throws PDFNetException
```
    Forces any data remaining in the buffer to be written to input or output filter.
    
    Throws:
    
    PDFNetException
  - flushAll
```
public void flushAll()
              throws PDFNetException
```
    Forces any data remaining in the filter chain to the source or destination.
    
    Throws:
    
    PDFNetException
  - isInputFilter
```
public boolean isInputFilter()
                      throws PDFNetException
```
    Checks if is input filter.
    
    Returns:
    - boolean indicating whether this is an input filter.
    
    Throws:
    
    PDFNetException
  - canSeek
```
public boolean canSeek()
                throws PDFNetException
```
    determine whether the stream supports seeking
    
    Returns:
    - true if the stream supports seeking; otherwise, false. default is to return false.
    
    Throws:
    
    PDFNetException
  - seek
```
public void seek(long offset,
        int origin)
          throws PDFNetException
```
    When overridden in a derived class, sets the position within the current stream.
    
    Parameters:
    offset - - A byte offset relative to origin. If offset is negative, the new position will precede the position specified by origin by the number of bytes specified by offset. If offset is zero, the new position will be the position specified by origin. If offset is positive, the new position will follow the position specified by origin by the number of bytes specified by offset.
    origin - - A value of type ReferencePos indicating the reference point used to obtain the new position
    
    Throws:
    
    PDFNetException
    Note:
    
    - After each Seek() operation the number of consumed bytes (i.e. Count()) is set to 0.
  - tell
```
public long tell()
          throws PDFNetException
```
    Reports the current read position in the stream relative to the stream origin.
    
    Returns:
    - The current position in the stream
    
    Throws:
    
    PDFNetException
  - createInputIterator
```
public Filter createInputIterator()
                           throws PDFNetException
```
    Create Filter iterator. Filter iterator similar to a regular filter. However, there can be only one owner of the attached filter.
    
    Returns:
    the filter
    
    Throws:
    
    PDFNetException
    Note:
    
    - Derived classes should make sure that there is only one owner of the attached stream. Otherwise the attached stream may be deleted several times.
  - getFilePath
```
public java.lang.String getFilePath()
                             throws PDFNetException
```
    Get the file path.
    
    Returns:
    the file path to the underlying file stream. Default implementation returns empty string.
    
    Throws:
    
    PDFNetException
  - __Create
```
public static Filter __Create(long impl,
              Filter attached)
```
  - __GetHandle
```
public long __GetHandle()
```
  - __SetRefHandle
```
public void __SetRefHandle(java.lang.Object ref)
```

Class Filter

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

impl

attached

ref

Constructor Detail

Filter

Method Detail

destroy

finalize

attachFilter

releaseAttachedFilter

getAttachedFilter

getSourceFilter

getName

getDecodeName

setStreamLength

flush

flushAll

isInputFilter

canSeek

seek

tell

createInputIterator

getFilePath

__Create

__GetHandle

__SetRefHandle