api:dk11:activex:tatukgis_xdk11.itgis_layervector.findfirst_4_itgis_extent_widestring_itgis_shape_widestring
Table of Contents
ITGIS_LayerVector.FindFirst_4 method
DK11 for ActiveX | TatukGIS_XDK11.ITGIS_LayerVector.FindFirst_4 | Methods | Properties
Finds the first occurrence of an item which meets an extent, query, and additional parameters. Will use RTree if available.
Syntax
// C# public ITGIS_Shape FindFirst_4( ITGIS_Extent _extent, WideString _query, ITGIS_Shape _shape, WideString _de9im );
' VisualBasic Public Function FindFirst_4( ByVal _extent As ITGIS_Extent, ByVal _query As WideString, ByVal _shape As ITGIS_Shape, ByVal _de9im As WideString ) As ITGIS_Shape
// Oxygene public function FindFirst_4( _extent : ITGIS_Extent; _query : WideString; _shape : ITGIS_Shape; _de9im : 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. |
| _shape | ITGIS_Shape | if not nil, then only shapes matched _de9im matrix with _shape will be found |
| _de9im | WideString | DE-9IM matrix of comparison |
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.
2020/05/07 01:04