Cadcorp SIS API Methods

GetOverlayThemeLegend Method

Description

Gets an overlay Theme legend as a Blob string within a Coordinate Reference System.

Syntax

Visual Basic
Public Function GetOverlayThemeLegend( _ ByVal pos As Integer, _ ByVal nTheme As Integer, _ ByVal projection As String, _ ByVal fmt As Integer, _ ByVal precision As Integer _ ) As String

Parameters

pos

The position in the overlays list of the overlay whose Theme legend is required.

nTheme

The index of the Theme, starting at 0. Use the Number of themes property to find out the number of Theme objects in an overlay.

projection

The named Coordinate Reference System of the returned Blob string.

fmt

The format of the returned Blob string.

`SIS_BLOB_SIS_V6_ASCII`	0 = Cadcorp SIS format
SIS_BLOB_OGIS_WKT	2 = OGC Well-Known-Text format
SIS_BLOB_OGIS_GML	3 = OGC Geographic Markup Language
SIS_BLOB_GEOJSON	6 = Geographic Objects for JSON format

It is recommended that the SIS_BLOB_SIS format is used, since other formats do not fully support text and styles.

precision

This parameter is ignored and will always return 64-bit precision.

Return Type

A string describing the overlay Theme legend item in the chosen format. The string will be blank if no overlay Theme legend exists. SIS format strings are encoded and cannot be interpreted except by SIS.

Remarks

There is no limit on the length of Blob strings generated by Cadcorp 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 MM ME MD OD OM OV SISpy

Groups:

Example

LegendBlob = sis.GetOverlayThemeLegend (0, 0, "*APrjNatGrid", 0, 0, 64)

Returns the blob string for the first theme on the first overlay in the current window, within the National Grid coordinate reference system.

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