Slicer4:Internationalization of Slicer

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This pages contains notes on source code additions and modifications of different modules within Slicer for the internationalization purpose.

QT-based Internationalization

Internationalization is well supported in QT. A lot of modules of Slicer are developed on QT. This has set a good ground for the internationalization of Slicer.

  • basic idea

In Qt, tr() is one of the static public members of QObject class, which returns a translated version of input sourceText.

   QString QObject::tr ( const char * sourceText, const char * disambiguation = 0, int n = -1 ) [static]

tr() will search the translation in a so-called translation file. If nothing is found, then the sourceText instead of the translated version will be displayed directly.

  • translation file template

The following is an example of the translation file, from English to Chinese.

   <?xml version="1.0" encoding="utf-8"?>
   <TS version="2.0" language="zh_CN">
Import Scene
Add Data

In the above example, all the texts are within the scope of qSlicerMainWindow class. That's why 'qSlicerMainWindo' occurs in section 'name'.

  • The following modifications are are needed:

In file \Slicer4\Base\QTCore\qSlicerCoreApplication.h, add the following line:

   #include <QTranslator>

In file \Slicer4\Applications\SlicerQT\main.cxx (around line#230), add the following lines:

   static QTranslator* translator;
   if (translator != NULL)
       delete translator;
       translator = NULL;
   QString langCode= argv[1];
   translator = new QTranslator;
   QString qmFilename = "lang_" + langCode; 
   if (translator->load(qmFilename))
  • To be continued

Scripted Module

Some modules are implemented in Python. Endoscopy is one of the typical examples. In, if we change the code in line#10

   parent.titel = “Endoscopy”


   parent.title =, "Endoscopy")

then "Endoscopy" can be shown in other languages.Similarily, other displayable strings can be handled in the same way.