KB10718 - How do I use the DK to implement the selection of objects on the map with an extent defined by a selection rectangle?

To find all shapes within a given extent:

GIS.Lock // to avoid multiple refreshed
Shp := layer.FindFirst( selection_extent )
While Assigned( shp ) do begin
   Shp.MakeEdiable.isSelected := True ;
   Shp.Invalidate
End ;
GIS.Unlock // or pending updates will now be forced


The logic to implement a selected extent is to count all the selected shapes:

sel_extent :=GisNoWorld ;

Shp := layer.FindFirst( selection_extent, ‘GIS_SELECTD=TRUE’ ) )
While Assigned( shp ) do begin
   Sel_xtent := GisCommonExtent( sel_extent, shp.Extent ) ;
End ;