api:dk11:activex:tatukgis_xdk11.itgis_layervector.findfirst_3_itgis_extent_widestring
Table of Contents
ITGIS_LayerVector.FindFirst_3 method
DK for ActiveX | TatukGIS_XDK11.ITGIS_LayerVector.FindFirst_3 | Methods | Properties
Finds the first occurrence of an item which meets an extent and query. Will use RTree if available.
Syntax
// C# public ITGIS_Shape FindFirst_3( ITGIS_Extent _extent, WideString _query );
' VisualBasic Public Function FindFirst_3( ByVal _extent As ITGIS_Extent, ByVal _query As WideString ) As ITGIS_Shape
// Oxygene public function FindFirst_3( _extent : ITGIS_Extent; _query : WideString ) : ITGIS_Shape;
Parameters
| Name | Type | Description |
|---|---|---|
| _extent | ITGIS_Extent | extent of items to be found; the layer has been attached to the Viewer then expected _extent units are in a Viewer coordinate space; otherwise expected _extent units are in a Layer coordinate space |
| _query | WideString | query which must be matched by item; closely mimics SQL WHERE clause; for examples you can use 'AGE >= 18'; empty (default) means that no items will match. |
Result
| Type | Description |
|---|---|
| ITGIS_Shape | Shape itself or nil. |
Remarks
See: FindNext
Use this method to find to the first shape in the layer matching given criteria. Using _query param we can narrow the result of the shape searching down to the minimum. This should speed up our process of locating a desired shape.
To locate a shape, simply choose an existing layer and use FindFirst method of with a proper extent and a SQL query as a WHERE clause.
2025/01/31 01:04