Display of International Characters in MapServer

Author:

Jeff McKenna

Contact:

jmckenna at gatewaygeomatics.com

Last Updated:

2020-10-28

Credit

Initial functionality was added to MapServer 4.4.0 as a part of a project sponsored by the Information-technology Promotion Agency (IPA), in Japan. Project members included: Venkatesh Raghavan, Masumoto Shinji, Nonogaki Susumu, Nemoto Tatsuya, Hirai Naoki (Osaka City University, Japan), Mario Basa, Hagiwara Akira, Niwa Makoto, Mori Toru (Orkney Inc., Japan), and Hattori Norihiro (E-Solution Service, Inc., Japan).

Requirements

  • MapServer >= 4.4.0 (MapServer >= 7.0 for layer-level encoding)

  • MapServer compiled with the libiconv library

Σημείωση

In terms of map labels with international characters, since the MapServer 7.0 release, other important dependant libaries besides libiconv are Freetype (to get information about glyph sizes), Fribidi (to handle bidirectional text), and Harfbuzz (for text shaping).

How to Enable in Your Mapfile (MapServer >= 7.0)

The MapServer 7.0 release contained changes in how MapServer handles encoding; new in 7.0 is that encoding is set at the LAYER level. This makes it much easier to manage having multiple layers in different encodings, in the same mapfile. The reason for this change was that the encoding of a dataset affects the whole layer, not only the labels. MapServer 7 will also convert any strings into UTF8 in the background, and any output (such as through OGC GetCapabilities, GetFeature, or queries) will be returned in UTF8.

The mapfile LAYER object’s ENCODING parameter accepts the encoding name as its parameter.

MapServer uses GNU’s libiconv library to deal with encodings. The libiconv web site has a list of supported encodings. One can also use the «iconv -l» command on a system with libiconv installed to get the complete list of supported encodings on that specific system.

Σημείωση

The label object’s ENCODING parameter is deprecated, but some logic still exists to handle that use in that scenario, in MapServer 7.

Step 1: Verify ICONV Support and MapServer Version

Execute mapserv -v at the commandline, and verify that your MapServer version >= 7.0 and it includes SUPPORTS=ICONV, such as:

> mapserv -v

  MapServer version 7.7.0-dev (MS4W 4.0.4) OUTPUT=PNG OUTPUT=JPEG
  OUTPUT=KML SUPPORTS=PROJ SUPPORTS=AGG SUPPORTS=FREETYPE
  SUPPORTS=CAIRO SUPPORTS=SVG_SYMBOLS SUPPORTS=SVGCAIRO
  SUPPORTS=ICONV SUPPORTS=FRIBIDI SUPPORTS=WMS_SERVER
  SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT
  SUPPORTS=WCS_SERVER SUPPORTS=SOS_SERVER SUPPORTS=FASTCGI
  SUPPORTS=THREADS SUPPORTS=GEOS SUPPORTS=POINT_Z_M SUPPORTS=PBF
  INPUT=JPEG INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE

Step 2: Verify That Your Files” Encoding is Supported by ICONV

Since MapServer uses the libiconv library to handle encodings, you can check the list of supported encodings here: https://www.gnu.org/software/libiconv/

Unix users can also use the iconv -l command on a system with libiconv installed to get the complete list of supported encodings on that specific system.

Step 3: Add ENCODING Parameter to your LAYER Object

Now you can simply add the ENCODING parameter to your mapfile LAYER object, such as:

MAP
 ...
 LAYER
   ...
   ENCODING "SHIFT_JIS"
   CLASS
     ...
   END #class
 END #layer
END #map

Σημείωση

Make sure you save your mapfile in the «UTF-8» encoding in your text editor.

LAYER
  NAME "地名"
  DATA "chimei.shp"
  STATUS DEFAULT
  TYPE POINT

  ENCODING "SHIFT_JIS"
  LABELITEM "NAMAE"

  CLASS
    NAME "地名"
    STYLE
      COLOR 10 100 100
    END
    LABEL
      TYPE TRUETYPE
      FONT "pgothic"
      COLOR 220 20 20
      SIZE 7
      POSITION CL
      PARTIALS FALSE
      BUFFER 3
    END
  END
END

Σημείωση

The MapServer 7.6.0 release included an important fix to allow special characters such as «ä» (umlauts) in filenames and paths in a mapfile.

Step 4: Test with the map2img utility

../_images/encoding.png

How to Enable in Your Mapfile (MapServer < 7.0)

Older MapServer versions only allowed encoding to be set at the LABEL level in the mapfile.

Add ENCODING Parameter to your LABEL Object

Add the ENCODING parameter to your mapfile LABEL object, such as:

MAP
 ...
 LAYER
   ...
   CLASS
     ...
     LABEL
       ...
       ENCODING "SHIFT_JIS"
     END
   END
 END
END

Here is an example layer using the encoding set at the LABEL level:

LAYER
  NAME "chimei"
  DATA "chimei.shp"
  STATUS DEFAULT
  TYPE POINT
  LABELITEM "NAMAE"
  CLASS
    NAME "CHIMEI"
    STYLE
      COLOR 10 100 100
    END
    LABEL
      TYPE TRUETYPE
      FONT "kochi-gothic"
      COLOR 220 20 20
      SIZE 10
      POSITION CL
      PARTIALS FALSE
      BUFFER 0
      ENCODING "SHIFT_JIS"
    END
  END
END

Example Using PHP MapScript

For PHP Mapscript, the Encoding parameter is included in the LabelObj Class (for MapServer < 7), so that the encoding parameter of a layer can be modified such as:

// Loading the php_mapscript library
dl("php_mapscript.so");

// Loading the map file
$map = ms_newMapObj("example.map");

// get the desired layer
$layer = $map->getLayerByName("chimei");

// get the layer's class object
$class = $layer->getClass(0);

// get the class object's label object
$clabel= $class->label;

// get encoding parameter
$encode_str = $clabel->encoding;
print "Encoding = ".$encode_str."\n";

// set encoding parameter
$clabel->set("encoding","UTF-8");

Notes

Σημείωση

During initial implementation, this functionality was tested using the different Japanese encoding systems: Shift-JIS, EUC-JP, UTF-8, as well as Thai’s TIS-620 encoding system.

Examples of encodings for the Latin alphabet supported by libiconv are: ISO-8859-1 (Latin alphabet No. 1 - also known as LATIN-1 - western European languages), ISO-8859-2 (Latin alphabet No. 2 - also known as LATIN-2 - eastern European languages), CP1252 (Microsoft Windows Latin alphabet encoding - English and some other Western languages).