SWMM5 Delphi GUI Dmapexp.pas Summary

 Below is an overview of Dmapexp.pas, a Delphi unit from SWMM 5.2 that provides a dialog (TMapExportForm) to export the current study area map into one of three file formats:

1. MAP (a plain text format containing map coordinates)
2. EMF (Enhanced Metafile, a vector-based image format)
3. DXF (Drawing Exchange Format, often used by CAD applications)

---

1. Purpose and Context

When a user wants to save or share the spatial layout of a SWMM model’s map (as opposed to the entire SWMM input file), TMapExportForm provides a convenient interface to choose the export format and file location. The user can then:

• Generate a MAP file, which is an internal SWMM text-based format containing only the graphical layout (node/link coordinates, etc.).
• Produce an EMF file (vector image) for high-quality printing or embedding in documents.
• Create a DXF file for importing the geometry into CAD or GIS software.

---

2. Main Form: TMapExportForm

2.1 Controls

• Radio Buttons (1) MAP, (2) EMF, (3) DXF:
  Let the user pick which file format to export.

• RadioGroup1:
  Visible only if DXF is chosen. Provides additional drawing choices (e.g., “Circle” vs. “Square” for node symbols) for how junctions appear in the DXF file.

• Buttons:

  • OK (Button1): Executes the export.
  • Cancel (Button2): Closes the dialog with no export.
  • Help (Button3): Opens the help topic for exporting.

• SaveDialog1:
  A standard Windows save-file dialog, controlled at runtime.

2.2 Variables and Constants

const
  MAP_FILE = 0;
  EMF_FILE = 1;
  DXF_FILE = 2;

  FilterTxt: array[MAP_FILE..DXF_FILE] of PChar =
    ('Map files (*.MAP)|*.MAP|All files|*.*',
     'EMF files (*.EMF)|*.EMF|All files|*.*',
     'DXF files (*.DXF)|*.DXF|All files|*.*');

  ExtensionTxt: array[MAP_FILE..DXF_FILE] of PChar =
    ('map','emf','dxf');

  TXT_SAVE_MAP_TITLE = 'Save Map As';

• These definitions let the code manage SaveDialog1’s filter text and file extension automatically, based on which format is selected.

---

3. Workflow

1. User Chooses Format
   By default, RadioButton1 (MAP) is checked. The user can switch to EMF or DXF.

2. (Optional) Adjust DXF Node Style
   If RadioButton3 (DXF) is checked, RadioGroup1 is revealed, letting the user pick how junctions will be drawn in the DXF.

3. OK Button

   • The form is hidden.
   • SaveDialog1 is configured with the relevant filter and extension.
   • If the user picks a file name and clicks Save, the form processes the file in the chosen format:
     1. MAP => calls ExportMapFile
     2. EMF => calls MapForm.CopyToMetaFile
     3. DXF => calls Udxf.DXFexport, passing the chosen “junction style” index from RadioGroup1.ItemIndex.

4. ExportMapFile

   • For a MAP format, the code calls Uexport.ExportMap(S) to retrieve a text representation of the map’s layout in a TStringList (S).
   • Then S.SaveToFile(Fname) writes it out.

5. Help Button

   • Invokes the help topic for exporting the map (HELP_CONTEXT, 211850).

6. FormKeyDown

   • If F1 is pressed, calls the Help routine.

---

4. Key Routines

4.1 ExportMapFile

procedure TMapExportForm.ExportMapFile(const Fname: String);
var
  S: TStringlist;
begin
  S := TStringlist.Create;
  try
    Uexport.ExportMap(S);
    S.SaveToFile(Fname);
  finally
    S.Free;
  end;
end;

• Leverages the function in Uexport.pas that builds a text-based representation of map coordinates and object placements.
• This text is saved in a .MAP file, which can be re-imported by SWMM as a partial reference for the map layout.

4.2 MapForm.CopyToMetaFile

• When exporting to EMF, MapForm.CopyToMetaFile(Filename) captures a vector “screenshot” of the model map.
• The user can place this .emf into other applications with no loss of resolution.

4.3 Udxf.DXFexport

• If the user chooses DXF, Udxf.DXFexport(Filename, JuncStyle) writes a standard 2D CAD format file.
• JuncStyle typically controls how nodes are drawn (circles, squares, etc.) in the resulting DXF.

---

5. Summary

Dmapexp.pas is a concise unit enabling SWMM to export the model’s map as:

1. MAP: SWMM’s text layout format (doesn’t include data on subcatchment polygons beyond their vertices, nor does it store hydraulic/hydrologic parameters—only geometry).
2. EMF: A Windows Enhanced Metafile (vector image).
3. DXF: A universal CAD format for geometry-based outlines of subcatchments, links, nodes, etc.

By allowing multiple formats, SWMM provides flexibility for both graphical presentation and for transferring geometry to other software tools.