Class TFilterBlobStream (unit Fltcback) |
TStream
Object which is used to hide all the nasty reading and seeking of the BDE blob data. Encapsultes it into a read-only stream.
Constructors |
Functions |
** Returns the size of the current blob field
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Constructors |
***************************************************************************** ** TFILTERBLOBSTREAM Component functions/Methods/Procedures ******************************************************************************) (* ** Filter routine for reading blob fields. These are presented as streams. ** When the GetBlobData is used, a temporary stream is created to the Fields ** Blob data (an exception occurs if the field is not a blob field). The stream ** is released before the next record is passed in by the filter mechanism. The ** previous stream is also released if the GetBlobData call is issued again in ** same filter routine. This makes it possible to check multiple blob fields ** data in the same routine. However, only ONE may be open at any one time. *) (* ** Attempts to create a stream into the blob data of the field specified. ** If successful, sets FOpened flag.
Functions |
** Destructor for the FilterBlobStream object. If the Blob data was opened ** (it may fail during the constructor), free the blob field resources.
** Reads the specified amount of data from the blob field into the passed ** buffer area. We need to be careful that we don't cross a segment boundary.
** Changes the current position pointer within the blob data by Offset amount. ** If Origin is: ** 0 - Offset is relative to the beginning of the blob data ** 1 - Offset is relative to the current position in the blob data ** 2 - Offset is relative to the end of the blob data
** Stops attempts at writing to our filtered stream!
Reference to FilterObject
** Returns the size of the current blob field
Properties |
Events |
Variables |
Whether Blob field opened
Position in Blob data
Field No in table