public class SegmentedImageInputStream extends ImageInputStreamImpl
SegmentedImageInputStream provides a view of a
subset of another ImageInputStream consiting of a series
of segments with given starting positions in the source stream and
lengths. The resulting stream behaves like an ordinary
ImageInputStream.
For example, given a ImageInputStream containing
data in a format consisting of a number of sub-streams stored in
non-contiguous sectors indexed by a directory, it is possible to
construct a set of SegmentedImageInputStreams, one for
each sub-stream, that each provide a view of the sectors comprising
a particular stream by providing the positions and lengths of the
stream's sectors as indicated by the directory. The complex
multi-stream structure of the original stream may be ignored by
users of the SegmentedImageInputStream, who see a
separate ImageInputStream for each sub-stream and do not
need to understand the directory structure at all.
For further efficiency, a directory structure such as in the
example described above need not be fully parsed in order to build
a SegmentedImageInputStream. Instead, the
StreamSegmentMapper interface allows the association
between a desired region of the output and an input segment to be
provided dynamically. This mapping might be computed by reading
from a directory in piecemeal fashion in order to avoid consuming
memory resources.
bitOffset, byteOrder, flushedPos, streamPos| Constructor and Description |
|---|
SegmentedImageInputStream(ImageInputStream stream,
long[] segmentPositions,
int[] segmentLengths)
Constructs a
SegmentedImageInputStream given a
ImageInputStream as input and a list of the starting
positions and lengths of the segments of the source stream. |
SegmentedImageInputStream(ImageInputStream stream,
long[] segmentPositions,
int segmentLength,
int totalLength)
Constructs a
SegmentedImageInputStream given a
ImageInputStream as input, a list of the starting
positions of the segments of the source stream, the common
length of each segment, and the total length of the segments. |
SegmentedImageInputStream(ImageInputStream stream,
StreamSegmentMapper mapper)
Constructs a
SegmentedImageInputStream
given a ImageInputStream as input
and an instance of StreamSegmentMapper. |
| Modifier and Type | Method and Description |
|---|---|
long |
length() |
int |
read()
Reads the next byte of data from the input stream.
|
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from the input stream into
an array of bytes. |
checkClosed, close, finalize, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, seek, setBitOffset, setByteOrder, skipBytes, skipBytespublic SegmentedImageInputStream(ImageInputStream stream, StreamSegmentMapper mapper)
SegmentedImageInputStream
given a ImageInputStream as input
and an instance of StreamSegmentMapper.stream - A source ImageInputStreammapper - An instance of the StreamSegmentMapper
interface.public SegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int[] segmentLengths)
SegmentedImageInputStream given a
ImageInputStream as input and a list of the starting
positions and lengths of the segments of the source stream.stream - A source ImageInputStreamsegmentPositions - An array of longs
giving the starting positions of the segments in the
source stream.segmentLengths - An array of ints
giving the lengths of segments in the source stream.public SegmentedImageInputStream(ImageInputStream stream, long[] segmentPositions, int segmentLength, int totalLength)
SegmentedImageInputStream given a
ImageInputStream as input, a list of the starting
positions of the segments of the source stream, the common
length of each segment, and the total length of the segments.
This constructor is useful for selecting substreams of sector-oriented file formats in which each segment of the substream (except possibly the final segment) occupies a fixed-length sector.
stream - A source ImageInputStreamsegmentPositions - An array of longs
giving the starting positions of the segments in the
source stream.segmentLength - The common length of each segment.totalLength - The total length of the source segments.public int read()
throws IOException
int in the range 0 to
255. If no byte is available because the end of the stream
has been reached, the value -1 is returned. This method
blocks until input data is available, the end of the stream is detected,
or an exception is thrown.read in interface ImageInputStreamread in class ImageInputStreamImpl-1 if the end of the
stream is reached.IOException - if an I/O error occurs.public int read(byte[] b,
int off,
int len)
throws IOException
len bytes of data from the input stream into
an array of bytes. An attempt is made to read as many as
len bytes, but a smaller number may be read, possibly
zero. The number of bytes actually read is returned as an integer.
This method blocks until input data is available, end of stream is detected, or an exception is thrown.
If b is null, a
NullPointerException is thrown.
If off is negative, or len is negative, or
off+len is greater than the length of the array
b, then an IndexOutOfBoundsException is
thrown.
If len is zero, then no bytes are read and
0 is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at end of
stream, the value -1 is returned; otherwise, at least one
byte is read and stored into b.
The first byte read is stored into element b[off], the
next one into b[off+1], and so on. The number of bytes read
is, at most, equal to len. Let k be the number of
bytes actually read; these bytes will be stored in elements
b[off] through b[off+k-1],
leaving elements b[off+k] through
b[off+len-1] unaffected.
In every case, elements b[0] through
b[off] and elements b[off+len] through
b[b.length-1] are unaffected.
If the first byte cannot be read for any reason other than end of
stream, then an IOException is thrown. In particular, an
IOException is thrown if the input stream has been closed.
read in interface ImageInputStreamread in class ImageInputStreamImplb - the buffer into which the data is read.off - the start offset in array b
at which the data is written.len - the maximum number of bytes to read.-1 if there is no more data because the end of
the stream has been reached.IOException - if an I/O error occurs.public long length()
length in interface ImageInputStreamlength in class ImageInputStreamImplCopyright © 2015–2022 SCIFIO. All rights reserved.