Public Member Functions | Protected Attributes

GDALAsyncReader Class Reference

Class used as a session object for asynchronous requests. More...

#include <gdal_priv.h>

Inherited by GDALDefaultAsyncReader.

List of all members.

Public Member Functions

GDALDatasetGetGDALDataset ()
int GetXOffset ()
int GetYOffset ()
int GetXSize ()
int GetYSize ()
void * GetBuffer ()
int GetBufferXSize ()
int GetBufferYSize ()
GDALDataType GetBufferType ()
int GetBandCount ()
int * GetBandMap ()
int GetPixelSpace ()
int GetLineSpace ()
int GetBandSpace ()
virtual GDALAsyncStatusType GetNextUpdatedRegion (double dfTimeout, int *pnBufXOff, int *pnBufYOff, int *pnBufXSize, int *pnBufYSize)=0
 Get async IO update.
virtual int LockBuffer (double dfTimeout=-1.0)
 Lock image buffer.
virtual void UnlockBuffer ()
 Unlock image buffer.

Protected Attributes

GDALDatasetpoDS
int nXOff
int nYOff
int nXSize
int nYSize
void * pBuf
int nBufXSize
int nBufYSize
GDALDataType eBufType
int nBandCount
int * panBandMap
int nPixelSpace
int nLineSpace
int nBandSpace

Detailed Description

Class used as a session object for asynchronous requests.

They are created with GDALDataset::BeginAsyncReader(), and destroyed with GDALDataset::EndAsyncReader().


Member Function Documentation

GDALAsyncStatusType GDALAsyncReader::GetNextUpdatedRegion ( double  dfTimeout,
int *  pnBufXOff,
int *  pnBufYOff,
int *  pnBufXSize,
int *  pnBufXSize 
) [pure virtual]

Get async IO update.

Provide an opportunity for an asynchronous IO request to update the image buffer and return an indication of the area of the buffer that has been updated.

The dfTimeout parameter can be used to wait for additional data to become available. The timeout does not limit the amount of time this method may spend actually processing available data.

The following return status are possible.

  • GARIO_PENDING: No imagery was altered in the buffer, but there is still activity pending, and the application should continue to call GetNextUpdatedRegion() as time permits.
  • GARIO_UPDATE: Some of the imagery has been updated, but there is still activity pending.
  • GARIO_ERROR: Something has gone wrong. The asynchronous request should be ended.
  • GARIO_COMPLETE: An update has occured and there is no more pending work on this request. The request should be ended and the buffer used.
Parameters:
dfTimeout the number of seconds to wait for additional updates. Use -1 to wait indefinately, or zero to not wait at all if there is no data available.
pnBufXOff location to return the X offset of the area of the request buffer that has been updated.
pnBufYOff location to return the Y offset of the area of the request buffer that has been updated.
pnBufXSize location to return the X size of the area of the request buffer that has been updated.
pnBufYSize location to return the Y size of the area of the request buffer that has been updated.
Returns:
GARIO_ status, details described above.
int GDALAsyncReader::LockBuffer ( double  dfTimeout = -1.0  )  [virtual]

Lock image buffer.

Locks the image buffer passed into GDALDataset::BeginAsyncReader(). This is useful to ensure the image buffer is not being modified while it is being used by the application. UnlockBuffer() should be used to release this lock when it is no longer needed.

Parameters:
dfTimeout the time in seconds to wait attempting to lock the buffer. -1.0 to wait indefinately and 0 to not wait at all if it can't be acquired immediately. Default is -1.0 (infinite wait).
Returns:
TRUE if successful, or FALSE on an error.
void GDALAsyncReader::UnlockBuffer (  )  [virtual]

Unlock image buffer.

Releases a lock on the image buffer previously taken with LockBuffer().


The documentation for this class was generated from the following files:

Generated for GDAL by doxygen 1.7.1.