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api:dk11:activex:tatukgis_xdk11.itgis_layervector.findfirst_3_itgis_extent_widestring

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ITGIS_LayerVector.FindFirst_3 method

DK11 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.

Available also on: Delphi | .NET | Java.

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.

2020/05/07 01:04