The following methods allow the customiser/application writer to access and use SIS items as "Blob" strings. The term Blob is used because many databases use Binary Large OBjects to store strings over a certain length.
Blob strings provide a database-independent way of storing SIS items in a database. A Blob string is a string which completely encapsulates a SIS Item, i.e. its geometry and properties. Blob strings in SIS format are not human readable and may only be interpreted by SIS.
A companion string to a Blob string is a Spatial Reference. A Spatial Reference is a sixteen character string which has encoded in it a position and a radius, which together describe an extents circle. The spatial reference allows SISto load only those Blob items whose extents overlap the view extents when viewing Blob items from a database, thus reducing database queries.
Spatial References can also be used in databases which contain an X and Y column and are viewed as Point or Text items. In order to populate an existing database of points with Spatial References, first add a suitable column to the database (i.e. a column of 16 character strings). A GisLink customisation or ActiveX Control application can then be written to create a temporary Point item for each row in the database, get its Spatial Reference, and write the Spatial Reference to the new column, before deleting the Point item. The customisation/application could be written to be run as a batch job.
| CreateItem | Creates an item from a BLOB string. |
| CreateItemB | Creates an item from a BLOB. |
| GetBlob | Gets the BLOB string of the current open item within a coordinate reference system. |
| GetBlobB | Gets the BLOB of the current open item within a coordinate reference system. |
| GetBlobExtent | Gets the extents of a BLOB string, within a coordinate reference system. |
| GetOverlayThemeLegend | Gets an overlay theme legend as a BLOB string within a coordinate reference system. |
| GetSpatialReference | Gets the spatial reference for the current open item within a spanned cube in a coordinate reference system. |
| GetSpatialReferenceFromExtent |
Gets the spatial reference for the given extents within a spanned cube in a coordinate reference system. |
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