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api:dk11:java:tatukgis.jdk.tgis_layervector.findfirst_tgis_extent

TGIS_LayerVector.FindFirst(TGIS_Extent) method

DK11 for Java | tatukgis.jdk.TGIS_LayerVector.FindFirst | Overloads | Constructors | Fields | Methods | Properties | Events

Finds the first occurrence of an item which meets an extent. Will use RTree if available.

Available also on: Delphi | .NET | ActiveX.

Syntax

// Java
public TGIS_Shape FindFirst(
  TGIS_Extent _extent
);
// Oxygene
public
  function FindFirst(
    _extent : TGIS_Extent
  ) : TGIS_Shape; virtual;

Parameters

Name Type Description
_extent TGIS_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

Result

Type Description
TGIS_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.

References

2020/05/07 01:13

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