Knowledge Base



KB10331 - Create a polygon or other shape programmatically.

Question from a customer: "Relating to my farming application I am using the DK to develop, I have difficulty making a shape (polygon) programmatically and introducing it into LayerSHP. My code is as follows:

Create Layer:
lb := TGIS_LayerVector.Create ;
lb.Name := 'buffer' ;
lb.AddField('Query',gisFieldTypeString,20,0);
lb.AddField('Min',gisFieldTypeNumber,3,0);
GIS.ADD( lb ) ;


Create Shape:
... from a buffer ...
Add shape:

if Assigned( shp ) then
begin
shp.Params.Area.Color := ZonasCol[i].Color;
shp.Params.Area.OutlineWidth := 1;
shp.Params.Area.OutlineColor := clBlack;
shp.Params.Area.Pattern := bsSolid;

lb.AddShape(shp);
lb.Shape.SetField('Query', q); // <- Error!!
lb.Shape.SetField('Min',ZonasCol[i].LimiteInf); // <- Error!!
end; //buf

But I cannot SetField! What is wrong?"

 

Answer: Operate on the shape itself, not lbShape (which can be undefined outside MoveFirst..MoveNext loop). The following code should help:

  lb.AddShape(shp);

  shp.SetField('Query', q);
  shp.SetField('Min',ZonasCol[i].LimiteInf); // <- Error!!
  end; //buf
Created: November 21, 2003, Modified: August 06, 2015
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