MrSID Decode SDK for Raster Reference Manual
9.5.1.4427
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#include <lt_ioSubStream.h>
Public Member Functions | |
Construction, destruction, initialization | |
LTIOSubStream () | |
Default Constructor. More... | |
virtual | ~LTIOSubStream () |
Destructor. More... | |
virtual LT_STATUS | initialize (LTIOStreamInf *stream, lt_int64 start, lt_int64 end, bool takeOwnership=false) |
Initializes the stream. More... | |
Status accessors | |
virtual bool | isEOF () |
Indicates whether the stream is at the end of its data or not. More... | |
Opening and closing | |
virtual bool | isOpen () |
Is the stream open? More... | |
virtual LT_STATUS | open () |
Opens the stream. More... | |
virtual LT_STATUS | close () |
Closes the stream. More... | |
Data access | |
virtual lt_uint32 | read (lt_uint8 *pDest, lt_uint32 numBytes) |
Retrieve the specified number of bytes from the data source and place them in pDest. More... | |
virtual lt_uint32 | write (const lt_uint8 *pSrc, lt_uint32 numBytes) |
Store the specified number of bytes in the data source. More... | |
Positioning | |
virtual LT_STATUS | seek (lt_int64 offset, LTIOSeekDir origin) |
Moves the the data access position to origin + offset. More... | |
virtual lt_int64 | tell () |
Returns the current data access position as an offset from the start of the data. More... | |
Other operations | |
virtual LTIOStreamInf * | duplicate () |
Clone the stream. More... | |
virtual LT_STATUS | getLastError () const |
Clone the stream. More... | |
virtual const char * | getID () const |
Clone the stream. More... | |
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virtual | ~LTIOStreamInf ()=0 |
Protected Member Functions | |
void | cleanup () |
cleanup method More... | |
Protected Attributes | |
LTIOStreamInf * | m_stream |
bool | m_ownsStream |
lt_int64 | m_startOffset |
lt_int64 | m_endOffset |
bool | m_isEOF |
A SubStream is a stream which wraps another stream, but provides access to only a (contiguous) subset of the bytes of the parent stream – without revealing any of the surrounding bytes.
Consider the following situation: the MG2 decoder always assumes byte 0 of the image stream given to it is the start of the image, but you have an image embedded in some larger stream – say from byte offset 100 to 2100. By creating a substream from the larger stream and giving that to the decoder, the decoder will be doing the right thing when it naively issues a "seek-to-beginning" request.
Note that the SubStream does NOT take ownership of the stream given to it. The caller should duplicate() the main stream first, if needed. Closing the substream will close the parent stream, but deleting the substream will not delete the parent stream.
Note that the results might be undefined if the parent or child stream is modified at any point – try to avoid such situations.
Definition at line 46 of file lt_ioSubStream.h.
LTIOSubStream::LTIOSubStream | ( | ) |
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Puts the stream in a state that does not allow data access. May free up resources, but only in such a way that doesn't inhibit successful future calls to open()
LT_STS_Success | On success, or if the stream is already closed. |
LT_STS_Failure | Otherwise. |
Implements LTIOStreamInf.
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Create new stream of the same type with the same initialization parameters. The transmission of these parameters is the responsibility of the derived type. The new stream should initially return false for isOpen().
NULL | the stream could not be duplicated; valid LTIOStreamInf* otherwise. |
Implements LTIOStreamInf.
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Create new stream of the same type with the same initialization parameters. The transmission of these parameters is the responsibility of the derived type. The new stream should initially return false for isOpen().
NULL | the stream could not be duplicated; valid LTIOStreamInf* otherwise. |
Implements LTIOStreamInf.
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Create new stream of the same type with the same initialization parameters. The transmission of these parameters is the responsibility of the derived type. The new stream should initially return false for isOpen().
NULL | the stream could not be duplicated; valid LTIOStreamInf* otherwise. |
Implements LTIOStreamInf.
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stream | the parent stream to be subsetted |
start | the byte offset to be byte 0 of the subset stream |
end | the byte offset to be the last byte of the subset stream: reading or writing past this byte will be handled as an EOF condition |
takeOwnership | if true, this object will take ownership of stream and delete it |
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false | otherwise |
Implements LTIOStreamInf.
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true | the stream is valid and in a state that allows data access. |
false | otherwise |
Implements LTIOStreamInf.
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Opening a stream puts it in a state that allows data access based on cached initialization parameters.
LT_STS_IOStreamUninitialized | The stream has not been initialized with enough information to open the stream |
LT_STS_IOStreamInvalidState | The the stream is already open |
LT_STS_Success | On success. |
LT_STS_Failure | Otherwise. |
Implements LTIOStreamInf.
pDest | buffer in which to store read data |
numBytes | number of bytes to read from stream |
numBytes | The number of bytes actually read |
Implements LTIOStreamInf.
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offset | number of bytes from origin at which to the next read or write will take place |
origin | place in stream from which to seek |
LT_STS_IOStreamUnsupported | The stream is not seekable |
LT_STS_IOStreamInvalidArgs | The offset and origin do not specify a valid location in the stream |
LT_STS_Success | On success |
LT_STS_Failure | Otherwise |
Implements LTIOStreamInf.
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postion | Number of bytes from the start of the data |
-1 | On error. |
Implements LTIOStreamInf.
pSrc | buffer from which to store data |
numBytes | number of bytes to write to stream |
numBytes | number of bytes actually written |
Implements LTIOStreamInf.
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Definition at line 223 of file lt_ioSubStream.h.
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Definition at line 225 of file lt_ioSubStream.h.
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Definition at line 221 of file lt_ioSubStream.h.
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Definition at line 222 of file lt_ioSubStream.h.
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Definition at line 220 of file lt_ioSubStream.h.
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