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TGIS_DataSet.Open method

DK11 for Delphi | GisDataSet.TGIS_DataSet.Open | Constructors | Methods | Properties | Events

Open the database which meets extent and query. Will use RTree if available.

Available also on: .NET | Java.


// Delphi
  procedure Open(
    const _layer : TGIS_LayerVector;
    const _extent : TGIS_Extent;
    const _query : String = '';
    const _shape : TGIS_Shape = nil;
    const _de9im : String = '';
    const _skipDeleted : Boolean = True;
    const _maxRecords : Integer = -1
  ); virtual;
// C++ Builder
  virtual void Open(
    TGIS_LayerVector* const _layer,
    TGIS_Extent* const _extent,
    const UnicodeString _query,
    TGIS_Shape* const _shape,
    const UnicodeString _de9im,
    const bool _skipDeleted,
    const int _maxRecords


Name Type Description
_layer TGIS_LayerVector source layer for the dataset
_extent TGIS_Extent extent of items to be found; expected _extent units are in a Layer coordinate space
_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 items will match.
_shape TGIS_Shape if not nil, then only shapes matched dm9 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
_maxRecords Integer maximum number of records to be returned; default is -1 which means no limit; 0 means that only structure will be filled


Use this method to fill the dataset with all shapes 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 01:06

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