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TGIS_LayerVector.cursorFindFirst method

DK11 for Delphi | GisLayerVector.TGIS_LayerVector.cursorFindFirst | 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.


// Delphi
  function cursorFindFirst(
    const _cursor : Integer;
    const _viewerCS : Boolean;
    const _extent : TGIS_Extent;
    const _query : String;
    const _shape : TGIS_Shape;
    const _de9im : String;
    const _skipDeleted : Boolean
  ) : TGIS_Shape; virtual;
// C++ Builder
  virtual TGIS_Shape* cursorFindFirst(
    const int _cursor,
    const bool _viewerCS,
    TGIS_Extent* const _extent,
    const UnicodeString _query,
    TGIS_Shape* const _shape,
    const UnicodeString _de9im,
    const bool _skipDeleted


Name Type Description
_cursor Integer cursor identifier (see TGIS_LayerVector.cursorOpen)
_viewerCS Boolean if True an 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
_extent TGIS_Extent extent of item to be found
_query 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 all items will match.
_shape TGIS_Shape if not nil, then only shapes matched _de9im matrix with _shape will be found
_de9im String DE-9IM matrix of comparison
_skipDeleted Boolean set a skip deleted treatment; by default deleted items will be ignored


Type Description
TGIS_Shape Shape itself or nil.


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.

2020/05/07 01:09

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