CADSoftTools

Posted: **14 Jun 2006, 18:42**

I have been trying to create several entities in loop while exporting a vector drawing to DXF. The entities depend on actual contents of the onscreen drawing in a Delphi application.

Sometimes the first entity required to be created in DXF file (and sometime the only entity required) is a HATCH. In this case the exported file seems to be corrupt and while trying to open it in AutoCAD I get the following error message:

"The following error was encountered while reading
in HATCH starting at line 340:
Error: expected group code 91
Invalid or incomplete DXF input -- drawing discarded."

The simplimfied Delphi code being used for above is as below:

Code: Select all

<b>procedure</b> TForm1.FormCreate(Sender: TObject);
<b>var</b>
  e: TsgDXFExport;
<b>begin</b>
  e := TsgDXFExport.create;
  <b>try</b>
    DrawSubbasins(e);
  <b>finally</b>
  e.free ;
  <b>end</b>;
<b>end</b>;

<b>procedure</b> TForm1.DrawSubbasins(E:TsgDXFExport);
  <b>var</b>
    Data: TdxfExportData;
    vLayer: TsgExpDXFLayer;
    Pt: PDXFPoint;
  
  <b>procedure</b> FreeDataPoints;
  <b>var</b>
    J, K: Integer;
  <b>begin
    for</b> K := 0 <b>to</b> Data.Points.Count - 1 <b>do
    begin
      for</b> J := 0 <b>to</b> TList(Data.Points[K]).Count - 1 <b>do</b>
        Dispose(TList(Data.Points[K]).Items[J]);
      TList(Data.Points[K]).Free;
    <b>end</b>;
  <b>end</b>;

<b>begin</b>
  vLayer := TsgExpDXFLayer.Create('StormNET Subbasins Fill');
  e.CurrentLayer := vLayer;

  Data.Color := ColorToDXF(clteal);
  Data.Count := 4;
  Data.Points := TList.Create;
  Data.Points.Add(TList.Create);
  <b>try</b>
    New(Pt);
    Pt^.X := 1000;
    Pt^.Y := 1000;
    Pt^.Z := 0;
    TList(Data.Points[0]).Add(Pt);

    Pt^.X := 1100;
    Pt^.Y := 1000;
    Pt^.Z := 0;
    TList(Data.Points[0]).Add(Pt);

    Pt^.X := 1100;
    Pt^.Y := 2000;
    Pt^.Z := 0;
    TList(Data.Points[0]).Add(Pt);

    Pt^.X := 1500;
    Pt^.Y := 1500;
    Pt^.Z := 0;
    TList(Data.Points[0]).Add(Pt);

    e.CurrentLayer := vLayer;
    e.AddHatch(Data);
    e.savetofile('C:\sampleHatch.dxf');

  <b>finally</b>
    FreeDataPoints;
    Data.Points.Free;
  <b>end</b>;
<b>end</b>;

Please review the above code and tell me if I am doing something wrong or what.

Also sometime I encounter a delphi error message for invalid pointer operation while freeing the points (it can be seen through above code also. Maybe I am doing something in wrong manner. Please help.

thanking you in anticipation

SK Arora

Posted: **15 Jun 2006, 13:00**

Hello,

Important: current version (v.5.2.5) of DXFExportVCL (http://www.cadsofttools.com/download/dxfexportvcl.zip) supports double precision. It is necessary to use <b>PexpPoint</b> instead of <b>PDXFPoint</b>.
The following code works:

Code: Select all

<b>procedure</b> TForm1.Button3Click(Sender: TObject);

  <b>procedure</b> DrawSubbasins(AExport: TsgDXFExport);
  <b>var</b>
    Data: TdxfExportData;
    vLayer: TsgExpDXFLayer;
    Pt: PexpPoint;
    vList: TList;

    <b>procedure</b> FreeDataPoints;
    <b>var</b>
      J, K: Integer;
      vList: TList;
    <b>begin
      for</b> K := 0 <b>to</b> Data.Points.Count - 1 <b>do
      begin</b>
        vList := TList(Data.Points[K]);
        Data.Points[K] := <b>nil</b>;
        <b>for</b> J := vList.Count - 1 <b>downto</b> 0 <b>do</b>
          Dispose(vList[J]);
        vList.Free;
      <b>end</b>;
    <b>end</b>;

  <b>begin</b>
    vLayer := TsgExpDXFLayer.Create('StormNET Subbasins Fill');
    AExport.CurrentLayer := vLayer;

    Data.Color := ColorToDXF(clteal);
    Data.Count := 4;
    Data.Scale := cnstFPointSingle;
    Data.Points := TList.Create;
    vList := TList.Create;
    Data.Points.Add(vList);
    <b>try</b>
      New(Pt);
      Pt^.X := 1000;
      Pt^.Y := 1000;
      Pt^.Z := 0;
      vList.Add(Pt);

      New(Pt);
      Pt^.X := 1100;
      Pt^.Y := 1000;
      Pt^.Z := 0;
      vList.Add(Pt);

      New(Pt);
      Pt^.X := 1100;
      Pt^.Y := 2000;
      Pt^.Z := 0;
      vList.Add(Pt);

      New(Pt);
      Pt^.X := 1500;
      Pt^.Y := 1500;
      Pt^.Z := 0;
      vList.Add(Pt);

      AExport.CurrentLayer := vLayer;
      AExport.AddHatch(Data);
      AExport.SaveToFile('C:\sampleHatch.dxf');
    <b>finally</b>
      FreeDataPoints;
      Data.Points.Free;
    <b>end</b>;
  <b>end</b>;

<b>var</b>
  vExport: TsgDXFExport;
<b>begin</b>
  vExport := TsgDXFExport.Create;
  <b>try</b>
    DrawSubbasins(vExport);
  <b>finally</b>
    vExport.Free;
  <b>end</b>;
<b>end</b>;

Sergey.

please post questions to the forum or write to support@cadsofttools.com

CADSoftTools

Cant create a hatch as first entity , BUG?

Cant create a hatch as first entity , BUG?