CreateDbBlobOverlay Method
Description
Creates an overlay which views Blobs stored in a database.
Syntax
Visual Basic |
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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.
- 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 current 'axes' CRS.
- rs
- A named recordset previously created using DefineRecordset.
- fmt
-
The format of the Item Blob.
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).
Remarks
Example
Creates a View Blobs overlay at position 2 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. |