Convert ISO 3166-1 alpha-2 Country Code to localized Country Name - delphi

Question

Is there a way to convert the two-letter Country Codes into their readable counterparts without using external ressources?
e.g. DE -> Germany, AD -> Andorra
It would be great if I could select the target language or it's using the system language, because I'd like to have them in German.

Answer 1

As #Uwe mentioned in his comment, you can use the EnumSystemGeoID and GetGeoInfo functions. The principle is that with EnumSystemGeoID function you'll enumerate geographical location identifiers and by the GetGeoInfo function query if the enumerated identifier's ISO 2-letter country / region code (info type GEO_ISO2) equals to the one of your interest. If so, then you can query for this identifier with the same function either a friendly name (info type GEO_FRIENDLYNAME), or the official name (info type GEO_OFFICIALNAME), return the result and stop the enumeration.
Here is an example code, which might do that (unfortunately, the enumeration function does not support passing custom data, so I've used a global record variable for passing values):
type
TEnumData = record
GeoCode: string;
GeoName: string;
Success: Boolean;
end;
GEOID = type LONG;
GEOTYPE = type DWORD;
GEOCLASS = type DWORD;
SYSGEOTYPE = (
GEO_NATION = $0001,
GEO_LATITUDE = $0002,
GEO_LONGITUDE = $0003,
GEO_ISO2 = $0004,
GEO_ISO3 = $0005,
GEO_RFC1766 = $0006,
GEO_LCID = $0007,
GEO_FRIENDLYNAME= $0008,
GEO_OFFICIALNAME= $0009,
GEO_TIMEZONES = $000A,
GEO_OFFICIALLANGUAGES = $000B,
GEO_ISO_UN_NUMBER = $000C,
GEO_PARENT = $000D
);
SYSGEOCLASS = (
GEOCLASS_NATION = 16,
GEOCLASS_REGION = 14,
GEOCLASS_ALL = 0
);
GEO_ENUMPROC = function(GeoId: GEOID): BOOL; stdcall;
function EnumSystemGeoID(GeoClass: GEOCLASS;
ParentGeoId: GEOID; lpGeoEnumProc: GEO_ENUMPROC): BOOL; stdcall;
external kernel32 name 'EnumSystemGeoID';
function GetGeoInfo(Location: GEOID; GeoType: GEOTYPE;
lpGeoData: LPTSTR; cchData: Integer; LangId: LANGID): Integer; stdcall;
external kernel32 name {$IFDEF UNICODE}'GetGeoInfoW'{$ELSE}'GetGeoInfoA'{$ENDIF};
implementation
var
// I have used this global variable due to a lack of user data parameter for the callback function
EnumData: TEnumData;
function TryGetGeoInfo(GeoId: GEOID; GeoType: GEOTYPE; out Value: string): Boolean;
var
Buffer: string;
BufferLen: Integer;
begin
Result := False;
BufferLen := GetGeoInfo(GeoId, GeoType, LPTSTR(Buffer), 0, 0);
if BufferLen <> 0 then
begin
SetLength(Buffer, BufferLen);
Result := GetGeoInfo(GeoId, GeoType, LPTSTR(Buffer), BufferLen, 0) <> 0;
if Result then
Value := Trim(Buffer);
end;
end;
function EnumGeoInfoProc(GeoId: GEOID): BOOL; stdcall;
var
S: string;
begin
Result := TryGetGeoInfo(GeoId, GEOTYPE(GEO_ISO2), S);
if Result and (S = EnumData.GeoCode) then
begin
// stop the enumeration since we've found the country by its ISO code
Result := False;
// return the success flag and try to return the friendly name of the country to the
// EnumData.GeoName record field; you can optionally query the GEO_OFFICIALNAME
EnumData.Success := TryGetGeoInfo(GeoId, GEOTYPE(GEO_FRIENDLYNAME), EnumData.GeoName);
end;
end;
function TryGetCountryNameByISO2(const Code: string; out Name: string): Boolean;
begin
// here is the brainless part using global record variable (because the function used
// here with its callback does not support passing user data); no, you cannot tune it
// up by making the callback function nested
EnumData.GeoCode := Code;
EnumData.Success := False;
if not EnumSystemGeoID(GEOCLASS(GEOCLASS_NATION), 0, EnumGeoInfoProc) then
RaiseLastOSError;
Result := EnumData.Success;
if Result then
Name := EnumData.GeoName;
end;
And a possible usage:
var
S: string;
begin
if TryGetCountryNameByISO2('DE', S) then
ShowMessage(S);
end;

Answer 2

You can iterate Languages (from Sysutils) and check the Ext property. The corresponding Name property will give you the localized language name.
for I := 0 to Languages.Count - 1 do begin
Writeln(Languages.Ext[I], '=', Languages.Name[I]);
end;

Answer 3

The sublanguage element suggested by Uwe Raabe is helping, but the results aren't that good, because It won't find all ISO codes and sometimes returns something different to a country name, like Simplified Chinese.
function _GetCountryFromISO(const aISO: string): string;
const
cStatement1 = '-(.*)';
cStatement2 = '\((.*?)\)';
var
i: Integer;
match: TMatch;
begin
Result := aISO; // default result if not found
for i := 0 to Languages.Count - 1 do begin
match := TRegEx.Match(Languages.LocaleName[i], cStatement1);
if not match.Success then
Assert(False, '');
if (aISO.Equals(match.Groups[1].Value)) then begin
match := TRegEx.Match(Languages.Name[i], cStatement2);
if not match.Success then
Assert(False, '');
Exit(match.Groups[1].Value);
end;
end;
end;