All Cadcorp SIS API Methods

GetBlob Method

Description

Gets a Blob string of the current open Item within a Coordinate Reference System

Syntax

Visual Basic 
Public Function GetBlob( _
   ByVal projection As String, _
   ByVal fmt As Integer, _
   ByVal precision As Integer _
) As String

Parameters

projection
The named Coordinate Reference System of the returned Blob string. This can be defined as:
  • OGC URNs (eg 'urn:ogc:def:crs:OGC:1.3:CRS84')
  • EPSG URNs (eg 'urn:ogc:def:crs:EPSG::27700')
  • EPSG code strings (eg 'EPSG:27700')
  • EPSG URLs (eg 'http://www.example.com/epsg#27700' or 'http://www.example.com/epsg.xml#27700')
  • EPSG codes as a simple string (eg '27700')

If blank, this will default to the CRS of the current Item’s Dataset.

 
fmt
The format of the stored Item Blob.

SIS_BLOB_OGIS_WKT2 = OGC Well-Known-Text format
SIS_BLOB_OGIS_GML3 = OGC Geographic Markup Language
SIS_BLOB_GEOJSON6 = Geographic Objects for JSON format
 
precision
This parameter is ignored and will always return 64-bit precision.

Return Type

A string describing the current open Item in the chosen format. SIS format strings are encoded and can only be interpreted by SIS.

Remarks

There is no limit on the length of Blob strings generated by SIS.

There are however limits elsewhere: GisLink can only handle strings of a few Kb (this does not apply to the SIS Control); SIS datasets which read Blobs from data sources can use a fixed size communication buffer (use the Cadcorp OGC SQL92 Database Maximum Blob size, and Cadcorp View Geometry Maximum Blob size properties to change the size of the communication buffer).

Available: GEO  OD SISpy

Groups:

Example

sis.GetBlob ( "*APrjNatGrid", 0, 0 )

Returns the Blob string of the current item within the National Grid coordinate reference system.