GIS.m: Fancy Map Display statusbar coords in Lat/Lon

[hamish]

This was code request # 401 over at the old Gforge bug tracker. Moving it here. ​http://wald.intevation.org/tracker/index.php?func=detail&aid=401&group_id=21&atid=188

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Hi,

I would love for Lat/Lon locations to format the Map Display statusbar x,y string into 45°59.9999'S 170°59.9999'W.

Hamish:

>>>        set mapunits [MapCanvas::get_mapunits]
>>>         if { [string first "degree" $mapunits ] >= 0 } {
>>>             set outfmt_coords {%.6f}
>>>         } else {
>>>             set outfmt_coords {%.3f}
>>>         }

Michael:

This is a procedure I didn't know about. Did you write it? Seems handy. I might write something similar in wxgrass.

H:

Yes, I wrote it to stabilize the x,y coords in the bottom right corner of the GIS.m Map Display window. I would love for Lat/Lon locations to munge the string into 45°59.9999'S 170°59.9999'W.

M:

Why can't this just be built into your get_mapunits procedure? I can add it to the statusbar easily enough.

because that calls g.proj to get the units. You only need to do that once at init to set a global variable. You really don't want to be calling a module twice every time the mouse moves 1 pixel.

Python/SWIG:

# test the string made by   (eg "degrees")
python_grass6.G_database_unit_name(int plural)   # ie 0 or 1

BUT is there a way to get the degree symbol that works on all platforms?

Does this show a degree symbol on the Mac?

$ echo "puts \xB0; exit" | wish

here is some non-functional demo Tcl code:

init {
   global is_ll
   set mapunits [MapCanvas::get_mapunits]

   if {string first "degree" $mapunits ] >= 0 } {
      set is_ll 1
   } else {
      set is_ll 0
   }
   if { is_ll } {
       # failsafe, will try for fancy fmt later
       set outfmt_coords {%.6f}
   } else {
       set outfmt_coords {%.3f}
   }
}


.....
bind $can($mon) <Motion> {
  global mon
  global is_ll

  set scrxmov %x
  set scrymov %y
  if { is_ll } {
     set eastcoord  [fmt_latlon [eval MapCanvas::scrx2mape $mon %x] 0]
     set northcoord [fmt_latlon [eval MapCanvas::scry2mapn $mon %y] 1]
  } else {
     set eastcoord  [format $outfmt_coords [eval MapCanvas::scrx2mape $mon %x] ]
     set northcoord [format $outfmt_coords [eval MapCanvas::scry2mapn $mon %y] ]
  }
  set coords($mon) "$eastcoord $northcoord"
}
......



proc fmt_latlon { num, is_latitude } {
     global is_ll
     # units are degrees
     # _d means integer, _f means float
     set deg_d [expr num - (num%1) ]
     set min_f [expr (num%1)*60 ]
     set min_d [expr min_d - (min_d%1) ]
     set sec_f [expr (min_f%1)*60 ]

     if { is_latitude } {
       if { num > 0 } {
	  set hem_str "N"
       } elif { num == 0 } {
	  set hem_str ""
       } else {
	  set hem_str "S"
       }
     } else {
       if { num > 0 } {
	  set hem_str "E"
       } elif { num == 0 } {
	  set hem_str ""
       } else {
	  set hem_str "W"
       }
     }

     set num_fmt [concat [format {%3d} deg] "\xB0" \
	[format {%02d} min_d] {'} \
	[format {%.5} sec_f]  {"" } $hem_str ]

    return num_fmt
}

Hamish

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Date: 2007-05-22

Sender: Hamish B

slight adjustment:

set coords($mon) "$eastcoord $northcoord"

move that into the {is_ll} bit and if LL put $northcoord first.

Hamish

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I guess if the degree symbol is not portable for display a "d " or just a space could be used, but its not as nice.

Hamish

[hamish]

I'd like to see this happen for the 6.4.0 release.

Hamish

[hamish]

note the wxPython GUI includes this feature, so only relevant to the Tcl/Tk GUI.

Hamish

[hamish]

committed to devbr6 in r37710.

TODO:

• add a UI control to switch between DMS, DMM.MMM, and D.DDD (all there in the code now, just modify the dms_format setting to change)
• learn via feedback how portable ° symbol is.

Hamish