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api:dk11:net:tatukgis.ndk.tgis_layervector.findfirst_tgis_extent_string_tgis_shape_string_boolean

TGIS_LayerVector.FindFirst(TGIS_Extent, string, TGIS_Shape, string, bool) method

DK11 for .NET | TatukGIS.NDK.TGIS_LayerVector.FindFirst | Overloads | Constructors | Fields | Methods | Properties | Events

Find first occurrence of an item which meets extent and query. Will use RTree if available.

Available also on: Delphi | Java | ActiveX.

Syntax

// C#
public TGIS_Shape FindFirst(
  TGIS_Extent _extent,
  string _query,
  TGIS_Shape _shape,
  string _de9im,
  bool _skipDeleted
);
' VisualBasic
Public Function FindFirst(
  ByVal _extent As TGIS_Extent,
  ByVal _query As String,
  ByVal _shape As TGIS_Shape,
  ByVal _de9im As String,
  ByVal _skipDeleted As Boolean
) As TGIS_Shape
// Oxygene
public
  function FindFirst(
    _extent : TGIS_Extent;
    _query : String;
    _shape : TGIS_Shape;
    _de9im : String;
    _skipDeleted : Boolean
  ) : 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
_query string
String
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 TGIS_Shape if not nil, then only shapes matched _de9im matrix with _shape will be found
_de9im string
String
DE-9IM matrix of comparison
_skipDeleted bool
Boolean
set a skip deleted treatment; by default deleted items will be ignored

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 desirable shape.

To locate a shape, simply choose an existing layer and use FindFirst method of with a proper extent and SQL query as a WHERE clause.

References

2018/02/17 00:26