api:dk11:delphi:gislayervector.tgis_layervector.cursorfindfirst_integer_boolean_tgis_extent_string_tgis_shape_string_boolean
Table of Contents
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.
Syntax
// Delphi protected 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 protected: 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 );
Parameters
| 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 |
Result
| Type | Description |
|---|---|
| TGIS_Shape | Shape itself or nil. |
Remarks
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.
2017/09/04 11:16