CreateDbBlobOverlay Method

Syntax

Visual Basic
Public Function CreateDbBlobOverlay( _ ByVal pos As Integer, _ ByVal prj As String, _ ByVal rs As String, _ ByVal fmt As Integer, _ ByVal nfBlob As Integer, _ ByVal nfId As Integer, _ ByVal nfVer As Integer, _ ByVal nfSr As Integer, _ ByVal nfSlMin As Integer, _ ByVal nfSlMax As Integer, _ ByVal span As Double _ ) As Integer

Visual Basic

Public Function CreateDbBlobOverlay( _
   ByVal pos As Integer, _
   ByVal prj As String, _
   ByVal rs As String, _
   ByVal fmt As Integer, _
   ByVal nfBlob As Integer, _
   ByVal nfId As Integer, _
   ByVal nfVer As Integer, _
   ByVal nfSr As Integer, _
   ByVal nfSlMin As Integer, _
   ByVal nfSlMax As Integer, _
   ByVal span As Double _
) As Integer

Parameters

pos

The position in the overlays list at which to insert the overlay. If this argument specifies a position in the existing overlays then the new overlay will not replace the existing overlay at the given position, but will shuffle any other overlays down the list.

prj

The named projection of the stored Item Blobs.

A named recordset previously created using DefineRecordset.

fmt

The format of the Item Blob.

`SIS_BLOB_SIS_V6_ASCII`	0 = Cadcorp SIS format
SIS_BLOB_OGIS_WKB	1 = OGC Well-Known-Binary format
`SIS_BLOB_OGIS_WKT`	2 = OGC Well-Known-Text format
`SIS_BLOB_OGIS_GML`	3 = OGC Geographic Markup Language
SIS_BLOB_ESRI_SHP	4 = ESRI Shape (*.shp)
SIS_BLOB_SIS_BIN_ITEM	5 = Binary item
SIS_BLOB_GEOJSON	6 = Geographic Objects for JSON format

nfBlob

The index in the recordset columns argument of the Item Blob string column. This column must exist.

nfId

The index in the recordset columns argument of the Item id column. A value of -1 will make Cadcorp SIS generate the Item id-s automatically.

nfVer

The index in the recordset columns argument of the Item version column. A value of -1 indicates that no version information is being supplied.

nfSr

The index in the recordset columns argument of the Item spatial reference column. A value of -1 indicates that no spatial reference is being supplied.

nfSlMin

This parameter is currently ignored, please use -1 for future compatibility.

The index in the recordset columns argument of the Item minimum scale threshold column. A value of -1 indicates that no minimum scale threshold is being supplied.

nfSlMax

This parameter is currently ignored, please use -1 for future compatibility.

The index in the recordset columns argument of the Item maximum scale threshold column. A value of -1 indicates that no maximum scale threshold is being supplied.

span

The span used in the spatial reference (see GetSpatialReference).

Example

sis.CreateDbBlobOverlay(0, "*APrjNatGrid", "rsB lobs", SIS_BLOB_SIS, 3, 0, 1, 2, -1, -1, 2000000)

Creates a View Blobs overlay at position 0 in the overlays list

`SIS_BLOB_SIS`	a constant defined in GisLink.bas (and SisConst.vb)
`3`	the binary data (the graphics) are in column 3 of the table
`0`	the item ID is in column 0 of the table
`1`	the item version is in column 1 of the table
`2`	the spatial reference is in column 2 of the table
`-1`	max and min scale thresholds cannot be set in the current release
`2000000`	The spatial reference string encodes a position and a radius which together describe an extents circle. The span used when calculating a spatial reference must be big enough to cover all the possible co-ordinates. A smaller span will give spatial references with a finer resolution. The spatial reference does not affect the accuracy or resolution of the positions of the item it is associated with, only the accuracy of whether or not the item is loaded in a particular view. The worst that can happen with a coarse resolution is that extra items are loaded.

When creating an overlay in this way, it is essential that you know the structure of the database table, so you can set the correct arguments for the DefineRecordset and CreateDbBlobOverlay methods.

CreateDbBlobOverlay Method

Description

Syntax

Parameters

Remarks

Example