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api:dk11:delphi:gislayervector.tgis_layervector.findfirst_void

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TGIS_LayerVector.FindFirst method

DK11 for Delphi | GisLayerVector.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: .NET | Java | ActiveX.

Syntax

// Delphi
public
  function FindFirst : TGIS_Shape; overload; virtual;
// C++ Builder
public:
  virtual TGIS_Shape* FindFirst(void) /* overload */;

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 00:09