Setting a default language with dxgettext

Delphi, dxgettext, dzLib 2 Minutes

By default, if no translation for a language is available, dxgettext will not do any translation but use the strings as they are in the source code. Sometimes this is not desirable. e.g.

  • Your customer does not understand the source language (e.g. your source language is not English but say German)
  • You are using dxgettext to convert special characters from a placeholder (e.g. “(R)” or “[deg]”) to the actual character (“®” or “°”)

In these cases you’d probably want the translation to default to a language that is actually supplied.

dxgettext doesn’t seem to have this feature (I looked quite hard) so I implemented it myself.

unit u_dzTranslator;

interface

// ... other stuff ...

///<summary>
/// Sets the language to use </summary>
procedure UseLanguage(_LanguageCode: string);

///<summary>
/// gets a list of languages for which translations are available </summary>
procedure GetListOfLanguages(const _Domain: string; _Codes: TStrings;
  _Languages: TStrings = nil);

///<summary>
/// Sets the language to use if the desired language is not available,
/// defaults to English </summary>
procedure SetDefaultLanguage(const _LanguageCode: string);

// ... other stuff ...

implementation

uses
  gnugettext;

// ... other stuff ...

const
  DEFAULT_LANGUAGE = 'en';
var
  gblDefaultLanguage: string = DEFAULT_LANGUAGE;

procedure UseLanguage(_LanguageCode: string);
var
  Codes: TStringList;
  CurLang: string;
  i: Integer;
  p: Integer;
begin
  gnugettext.UseLanguage(_LanguageCode);

  CurLang := gnugettext.GetCurrentLanguage;
  Codes := TStringList.Create;
  try
    GetListOfLanguages('default', Codes);
    for i := 0 to Codes.Count - 1 do begin
      if SameText(CurLang, Codes[i]) then begin
        // There is a translation for this language and country, everything is fine
        Exit; //-->
      end;
    end;
    // no translation found, try without the country code
    p := Pos('_', CurLang);
    if p <> 0 then begin
      CurLang := Copy(CurLang, 1, p - 1);
      for i := 0 to Codes.Count - 1 do begin
        if SameText(CurLang, Codes[i]) then begin
          // There is a translation for this language but not country, we can live with that
          Exit; //-->
        end;
      end;
    end;
  finally
    FreeAndNil(Codes);
  end;

  // we found no translation for this language, so we use the default language
  gnugettext.UseLanguage(gblDefaultLanguage);
end;

procedure SetDefaultLanguage(const _LanguageCode: string);
begin
  if _LanguageCode = '' then
    gblDefaultLanguage := DEFAULT_LANGUAGE
  else
    gblDefaultLanguage := _LanguageCode;
  UseLanguage(gnugettext.GetCurrentLanguage);
end;

procedure GetListOfLanguages(const _Domain: string; _Codes: TStrings; _Languages: TStrings = nil);
var
  i: Integer;
begin
  _Codes.Clear;
  gnugettext.DefaultInstance.GetListOfLanguages(_Domain, _Codes);
  if Assigned(_Languages) then begin
    _Languages.Clear;
    for i := 0 to _Codes.Count - 1 do begin
      _Languages.Add(languagecodes.getlanguagename(_Codes[i]));
    end;
  end;
end;

// ... other stuff ...

initialization
  SetDefaultLanguage(DEFAULT_LANGUAGE);
end.

Apart from the obvious, that is, setting a unit global variable to the desired default language, which itself defaults to English, this code changes the way UseLanguageWorks. It now does:

  • Call gnugettext.UseLanguage to let gnugettext do its stuff
  • Call gnugettext.GetCurrentLanguage to get the language that gnugettext uses (just in case gnugettext changes it from what was set with UseLanguage).
  • Gets a list of all supported translations
  • Tries to find a matching translation for the desired language and country.
  • If not found, tries to find a matching translation for the desired language, ignoring the country
  • If not found, changes the language to the default language.

Note that I just wrote this code, it might still contain bugs and is probably far from perfect. I will put it into the unit u_dzTranslator of my dzlib library and will fix any bugs I find in the future there.

Published