Class PDFNet.Filter
PDFNet.Filter
| Constructor Attributes | Constructor Name and Description |
|---|---|
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PDFNet.Filter(id)
Provides a generic view of a sequence of bytes.
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| Method Attributes | Method Name and Description |
|---|---|
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attachFilter(attach_filter)
Attaches a filter to the this filter.
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begin()
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canSeek()
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consume(num_bytes)
Moves the Begin() pointer num_bytes forward.
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count()
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createASCII85Encode(line_width, buf_sz)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createFlateEncode(input_filter, compression_level, buf_sz)
Constructor for Flate encoder.
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| <static> |
PDFNet.Filter.createImage2RGB(img)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createImage2RGBA(img, premultiply)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createImage2RGBAFromElement(elem, premultiply)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createImage2RGBAFromObj(obj, premultiply)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createImage2RGBFromElement(elem)
[Documentation Not Yet Added]
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| <static> |
PDFNet.Filter.createImage2RGBFromObj(obj)
[Documentation Not Yet Added]
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Create Filter iterator.
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| <static> |
PDFNet.Filter.createMemoryFilter(buf_sz, is_input)
[Documentation Not Yet Added]
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destroy()
Frees the native memory of the object.
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flush()
Forces any data remaining in the buffer to be written to input or
output filter.
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flushAll()
Forces any data remaining in the filter chain to the source or destination.
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getName()
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[Documentation Not Yet Added]
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Release the ownership of the attached filter.
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seek(offset, origin)
When overridden in a derived class, sets the position within the current stream.
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setCount(new_count)
Sets a new counting point for the current filter.
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setStreamLength(bytes)
The functions specifies the length of the data stream.
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size()
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tell()
Reports the current read position in the stream relative to the stream origin.
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Class Detail
PDFNet.Filter(id)
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.
- Parameters:
- id
Method Detail
attachFilter(attach_filter)
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:
- {Filter} attach_filter
- filter object to attach
{number}
begin()
- Returns:
- {number} A promise that resolves to beginning of the buffer of Size() bytes that can be used to read or write data.
{boolean}
canSeek()
- Returns:
- {boolean} A promise that resolves to true if the stream supports seeking; otherwise, false. default is to return false.
consume(num_bytes)
Moves the Begin() pointer num_bytes forward.
- Parameters:
- {number} num_bytes
- number of bytes to consume. num_bytes must be less than or equal to Size().
{number}
count()
- Returns:
- {number} A promise that resolves to the number of bytes consumed since opening the filter or the last Seek operation
{Filter}
createASCII85Encode(line_width, buf_sz)
[Documentation Not Yet Added]
- Parameters:
- {number} line_width
- (generated documentation)
- {number} buf_sz
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createFlateEncode(input_filter, compression_level, buf_sz)
Constructor for Flate encoder.
FlateEncode filter can be used to compress any data stream
using Flate (i.e. ZIP) compression method.
- Parameters:
- {filter = PDFNet.Filter("0")} input_filter
- the input data stream
- {number = -1} compression_level
- compression_level must be a number between 0 and 9: 1 gives best speed, 9 gives best compression, 0 gives no compression at all (the input data is simply copied a block at a time), -1 requests a default compromise between speed and compression (currently equivalent to level 6).
- {number = 256} buf_sz
- filter buffer size (in bytes).
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGB(img)
[Documentation Not Yet Added]
- Parameters:
- {Image} img
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGBA(img, premultiply)
[Documentation Not Yet Added]
- Parameters:
- {Image} img
- (generated documentation)
- {boolean} premultiply
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGBAFromElement(elem, premultiply)
[Documentation Not Yet Added]
- Parameters:
- {Element} elem
- (generated documentation)
- {boolean} premultiply
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGBAFromObj(obj, premultiply)
[Documentation Not Yet Added]
- Parameters:
- {Obj} obj
- (generated documentation)
- {boolean} premultiply
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGBFromElement(elem)
[Documentation Not Yet Added]
- Parameters:
- {Element} elem
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createImage2RGBFromObj(obj)
[Documentation Not Yet Added]
- Parameters:
- {Obj} obj
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
{Filter}
createInputIterator()
Create Filter iterator. Filter iterator similar to a regular filter. However,
there can be only one owner of the attached filter.
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
<static>
{Filter}
PDFNet.Filter.createMemoryFilter(buf_sz, is_input)
[Documentation Not Yet Added]
- Parameters:
- {number} buf_sz
- (generated documentation)
- {boolean} is_input
- (generated documentation)
- Returns:
- {Filter} A promise that resolves to an object of type: "Filter" (generated documentation)
destroy()
Frees the native memory of the object.
flush()
Forces any data remaining in the buffer to be written to input or
output filter.
flushAll()
Forces any data remaining in the filter chain to the source or destination.
{Filter}
getAttachedFilter()
- Returns:
- {Filter} A promise that resolves to returns attached Filter or a NULL filter if no filter is attached.
{string}
getDecodeName()
- Returns:
- {string} A promise that resolves to string representing the name of corresponding decode filter as it should appear in document (e.g. both ASCIIHexDecode and ASCIIHexEncode should return ASCIIHexDecode).
{string}
getFilePath()
- Returns:
- {string} A promise that resolves to the file path to the underlying file stream. Default implementation returns empty string.
{string}
getName()
- Returns:
- {string} A promise that resolves to descriptive name of the filter.
{Filter}
getSourceFilter()
- Returns:
- {Filter} A promise that resolves to returns the first filter in the chain (usually a file filter)
{boolean}
isInputFilter()
- Returns:
- {boolean} A promise that resolves to boolean indicating whether this is an input filter.
{number}
memoryFilterGetBuffer()
- Returns:
- {number} A promise that resolves to a pointer to the beginning of the buffer. Use method Count() to determine the number of bytes written to or read from MemoryFilter.
memoryFilterReset()
[Documentation Not Yet Added]
memoryFilterSetAsInputFilter()
{Filter}
releaseAttachedFilter()
Release the ownership of the attached filter. After the attached filter is
released this filter points to NULL filter.
- Returns:
- {Filter} A promise that resolves to Previously attached filter.
seek(offset, origin)
When overridden in a derived class, sets the position within the current stream.
- Parameters:
- {number} 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.
- {number} origin
- A value of type ReferencePos indicating the reference point used to obtain the new position
{number}
setCount(new_count)
Sets a new counting point for the current filter. All subsequent Consume()
operations will increment this counter.
Make sure that the output filter is flushed before using SetCount().
- Parameters:
- {number} new_count
- number to set the counting point of the filter to.
- Returns:
- {number} A promise that resolves to the value of previous counter
setStreamLength(bytes)
The functions specifies the length of the data stream. The default
implementation doesn't 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 length.
- Parameters:
- {number} bytes
- the length of stream in bytes
{number}
size()
- Returns:
- {number} A promise that resolves to the size of buffer returned by Begin(). If the Size() returns 0 end of data has been reached.
{number}
tell()
Reports the current read position in the stream relative to the stream origin.
- Returns:
- {number} A promise that resolves to The current position in the stream