/***************************************************************************/
typedef struct {
  char   *unit;
  double mm;
} unit_type;

static unit_type units[] = {
  { "mm",                1.0     },
  { "cm",               10.0     },
  { "dm",              100.0     },
  { "m",              1000.0     },
  { "km",          1000000.0     },
  { "inch",             25.4     },
  { "ft",              304.8     },
  { "yard",            914.4     },
  { "mile",        1609300.0     },
  { "NM",          1853200.0     },
  { "tuuma(s)",         24.742   },
  { "kortteli",        148.45    },
  { "jalka(s)",        296.9     },
  { "kyynärä",         593.8     },
  { "syli",           1781.4     },
  { "virsta",      1068800.0     },
  { "peninkulma", 10688000.0     },
  { NULL,                0.0     } 
};

#define MM 0
#define KM 4

#define DO_SHOW_OUT 1991
#define DO_SHOW_MAP 1992


/***************************************************************************/
BOOL do_command(HWND hDlg,WPARAM wParam)
{
  SendMessage(hDlg,WM_COMMAND,wParam,0);
  return TRUE;
}

/***************************************************************************/
BOOL CALLBACK_E Scaling(HWND hDlg,unsigned message,WPARAM wParam,LPARAM lParam)
{
#pragma argsused
  static int    map_unit     = MM;          /* mm */
  static double map_dist     = 10.0;
  static int    out_unit     = KM;          /* km */
  static double out_dist     = 2.0;
  static double scale        = 200000.0;
  static int    change_other = 1;
  int i;

  switch (message) {

  case WM_PAINT:
    return FALSE;

  case WM_INITDIALOG:
    for (i=0; units[i].unit; i++) {  /* Täytetään combo-listat */
      SendDlgItemMessage(hDlg,ID_MAP_UNIT,CB_INSERTSTRING,i,
         (LPARAM) ((LPSTR)units[i].unit));
      SendDlgItemMessage(hDlg,ID_OUT_UNIT,CB_INSERTSTRING,i,
         (LPARAM) ((LPSTR)units[i].unit));
    }

    SendDlgItemMessage(hDlg,ID_MAP_UNIT,CB_SETCURSEL,map_unit,0); /* oletus yks  */
    SendDlgItemMessage(hDlg,ID_OUT_UNIT,CB_SETCURSEL,out_unit,0); /* oletus yks  */
    SendDlgItemMessage(hDlg,IDR_OTHER,BM_SETCHECK,change_other=1,0);/*oletus muut*/

    ShowDouble(hDlg,ID_SCALE,scale);
    ShowDouble(hDlg,ID_MAP_DIST,map_dist);
    ShowDouble(hDlg,ID_OUT_DIST,out_dist);

    return (TRUE);

  case WM_COMMAND:
    switch ( wParam ) {

      case DO_SHOW_OUT:
        out_dist = map_dist*units[map_unit].mm*scale/units[out_unit].mm;
        ShowDouble(hDlg,ID_OUT_DIST,out_dist);
        return TRUE;

      case DO_SHOW_MAP:
        map_dist = out_dist/(units[map_unit].mm*scale/units[out_unit].mm);
        ShowDouble(hDlg,ID_MAP_DIST,map_dist);
        return TRUE;

      case ID_SCALE:
        if ( HIWORD(lParam) == EN_CHANGE ) {
          scale = GetDouble(hDlg,wParam);
          if ( scale <=0 ) scale = 1;
          return do_command(hDlg,DO_SHOW_OUT);
        }
        break;

      case ID_MAP_DIST:
        if ( HIWORD(lParam) == EN_CHANGE ) {
          map_dist = GetDouble(hDlg,wParam);
          return do_command(hDlg,DO_SHOW_OUT);
        }
        break;

      case ID_OUT_DIST:
        if ( HIWORD(lParam) == EN_CHANGE ) {
          out_dist = GetDouble(hDlg,wParam);
          return do_command(hDlg,DO_SHOW_MAP);
        }
        break;

      case ID_MAP_UNIT:
        if ( HIWORD(lParam) == CBN_SELCHANGE ) {
            map_unit = (int)SendDlgItemMessage(hDlg,ID_MAP_UNIT,CB_GETCURSEL,0,0);
            if ( change_other ) return do_command(hDlg,DO_SHOW_OUT);
            return do_command(hDlg,DO_SHOW_MAP);
        }
        break;

      case ID_OUT_UNIT:
        if ( HIWORD(lParam) == CBN_SELCHANGE ) {
            out_unit = (int)SendDlgItemMessage(hDlg,ID_OUT_UNIT,CB_GETCURSEL,0,0);
            if ( change_other ) return do_command(hDlg,DO_SHOW_MAP);
            return do_command(hDlg,DO_SHOW_OUT);
        }
        break;

      case IDR_THIS:
        change_other = 0;
        return TRUE;

      case IDR_OTHER:
        change_other = 1;
        return FALSE;

      case IDOK:
        SetFocus(GetDlgItem(hDlg,ID_MAP_DIST));
        SendDlgItemMessage(hDlg,ID_MAP_DIST,EM_SETSEL,0,MAKELONG(0,-1));
        return TRUE;

      case IDCANCEL:
        DestroyDialog(hDlg, TRUE);
        return (TRUE);
      default: break;
    }
    break;
  }
  return (FALSE);
}