/// <summary>
/// Get a display name for a transliterator. This reimplements the logic from the C++
/// Transliterator::getDisplayName method, since the ICU C API doesn't expose a
/// utrans_getDisplayName() call. (Unfortunately).
/// Note that if no text is found for the given locale, ICU will (by default) fallback to
/// the root locale. However, the root locale's strings for transliterator display names
/// are ugly and not suitable for displaying to the user. Therefore, if we have to
/// fallback, we fallback to the "en" locale instead of the root locale.
/// </summary>
/// <param name="transId">The translator's system ID in ICU.</param>
/// <param name="localeName">The ICU name of the locale in which to calculate the display
/// name.</param>
/// <returns>A name suitable for displaying to the user in the given locale, or in English
/// if no translated text is present in the given locale.</returns>
public static string GetDisplayName(string transId, string localeName)
{
const string translitDisplayNameRBKeyPrefix = "%Translit%%"; // See RB_DISPLAY_NAME_PREFIX in translit.cpp in ICU source code
const string scriptDisplayNameRBKeyPrefix = "%Translit%"; // See RB_SCRIPT_DISPLAY_NAME_PREFIX in translit.cpp in ICU source code
const string translitResourceBundleName = "ICUDATA-translit";
const string translitDisplayNamePatternKey = "TransliteratorNamePattern";
ParseTransliteratorID(transId, out var source, out var target, out var variant);
if (target.Length < 1)
{
return(transId); // Malformed ID? Give up
}
using (var bundle = new ResourceBundle(translitResourceBundleName, localeName))
using (var bundleFallback = new ResourceBundle(translitResourceBundleName, "en"))
{
var pattern = bundle.GetStringByKey(translitDisplayNamePatternKey);
// If we don't find a MessageFormat pattern in our locale, try the English fallback
if (string.IsNullOrEmpty(pattern))
{
pattern = bundleFallback.GetStringByKey(translitDisplayNamePatternKey);
}
// Still can't find a pattern? Then we won't be able to format the ID, so just return it
if (string.IsNullOrEmpty(pattern))
{
return(transId);
}
// First check if there is a specific localized name for this transliterator, and if so, just return it.
// Note that we need to check whether the string we got still starts with the "%Translit%%" prefix, because
// if so, it means that we got a value from the root locale's bundle, which isn't actually localized.
var translitLocalizedName = bundle.GetStringByKey(translitDisplayNameRBKeyPrefix + transId);
if (!string.IsNullOrEmpty(translitLocalizedName) && !translitLocalizedName.StartsWith(translitDisplayNameRBKeyPrefix))
{
return(translitLocalizedName);
}
// There was no specific localized name for this transliterator (which will be true of most cases). Build one.
// Try getting localized display names for the source and target, if possible.
var localizedSource = bundle.GetStringByKey(scriptDisplayNameRBKeyPrefix + source);
if (string.IsNullOrEmpty(localizedSource))
{
localizedSource = source; // Can't localize
}
else
{
// As with the transliterator name, we need to check that the string we got didn't come from the root bundle
// (which just returns a string that still contains the ugly %Translit% prefix). If it did, fall back to English.
if (localizedSource.StartsWith(scriptDisplayNameRBKeyPrefix))
{
localizedSource = bundleFallback.GetStringByKey(scriptDisplayNameRBKeyPrefix + source);
}
if (string.IsNullOrEmpty(localizedSource) || localizedSource.StartsWith(scriptDisplayNameRBKeyPrefix))
{
localizedSource = source;
}
}
// Same thing for target
var localizedTarget = bundle.GetStringByKey(scriptDisplayNameRBKeyPrefix + target);
if (string.IsNullOrEmpty(localizedTarget))
{
localizedTarget = target; // Can't localize
}
else
{
if (localizedTarget.StartsWith(scriptDisplayNameRBKeyPrefix))
{
localizedTarget = bundleFallback.GetStringByKey(scriptDisplayNameRBKeyPrefix + target);
}
if (string.IsNullOrEmpty(localizedTarget) || localizedTarget.StartsWith(scriptDisplayNameRBKeyPrefix))
{
localizedTarget = target;
}
}
var displayName = MessageFormatter.Format(pattern, localeName, out var status,
2.0, localizedSource, localizedTarget);
if (status.IsSuccess())
{
return(displayName + variant); // Variant is either empty string or starts with "/"
}
return(transId); // If formatting fails, the transliterator's ID is still our final fallback
}
}