International Code Snippets

How to change Input Language programmatically?

Vitaly Zayko — Wed, 31 Dec 2008 13:26:03 GMT

Do you know that your Windows Forms App could switch between installed languages at run-time?

An Input language is a Culture/Keyboard layout pair that determines how the physical keys on a keyboard map or plot to characters in a language (read more about Input Language in MSDN Library). Microsoft Windows allows installing more than one input language but international users usually use two: English and a national.

Since version 1.0 .NET Framework supports a special public sealed class - InputLanguage (in System.Windows.Forms namespace, assembly – System.Windows.Forms.dll). The property we are going to use today is CurrentInputLanguage of the InputLanguage type.

Enforcing to use a particular input language could be useful in many cases but please note that this function changes CurrentInputLanguage for the whole App and not just for a TextBox or any other selected control.

I created four overloaded functions that demonstrate this functionality. Actually only 4^th function (the only one in VB example) does change input language, first demonstrates how to switch between languages and two others - how to create a InputLanguage class based on string or integer language codes (please see code comments for more details).

C# code:

/// <summary>

/// Changing Current Input Language to a next installed language

/// </summary>

public void ChangeInputLanguage()

   // Nothing to do if there is only one Input Language supported:

    if (InputLanguage.InstalledInputLanguages.Count == 1)

       return;

   // Get index of current Input Language

    int currentLang = InputLanguage.InstalledInputLanguages.IndexOf(InputLanguage.CurrentInputLanguage);

   // Calculate next Input Language

    InputLanguage nextLang = ++currentLang == InputLanguage.InstalledInputLanguages.Count ?

       InputLanguage.InstalledInputLanguages[0] : InputLanguage.InstalledInputLanguages[currentLang];

   // Change current Language to the calculated:

    ChangeInputLanguage(nextLang);

/// <summary>

/// Changing current Input Language to a new one passed in the param

/// </summary>

/// <param name="ISOLang">ISO Culture name string code e.g. "en" for English</param>

public void ChangeInputLanguage(string ISOLang)

   // Convert ISO Culture name to InputLanguage object. Be aware: if ISO is not supported

    // ArgumentException will be invoked here

    InputLanguage nextLang = InputLanguage.FromCulture(new System.Globalization.CultureInfo(ISOLang));

   ChangeInputLanguage(nextLang);

/// <summary>

/// Changing current Input Language to a new one passed in the param

/// </summary>

/// <param name="LangID">Integer Culture code e.g. 1033 for English</param>

public void ChangeInputLanguage(int LangID)

   // Convert Integer Culture code to InputLanguage object. Be aware: if Culture code is not supported

    // ArgumentException will be invoked here

    InputLanguage nextLang = InputLanguage.FromCulture(new System.Globalization.CultureInfo(LangID));

   ChangeInputLanguage(nextLang);

/// <summary>

/// Changing current Input Language to a new one passed in the param

/// </summary>

/// <param name="InputLang">New Input Language as InputLanguage object</param>

public void ChangeInputLanguage(InputLanguage InputLang)

   // Check is this Language really installed. Raise exception to warn if it is not:

    if (InputLanguage.InstalledInputLanguages.IndexOf(InputLang) == -1)

       throw new ArgumentOutOfRangeException();

   // InputLAnguage changes here:

    InputLanguage.CurrentInputLanguage = InputLang;

VB.NET code:

Public Sub ChangeInputLanguage(ByVal InputLang As InputLanguage)

   If InputLanguage.InstalledInputLanguages.IndexOf(InputLang) = -1 Then

        Throw New ArgumentOutOfRangeException()

   End If

    InputLanguage.CurrentInputLanguage = InputLang

End Sub

Happy New Year!

Technorati Tags: Globalization

How to get list of all installed input locales?

Vitaly Zayko — Thu, 18 Dec 2008 10:07:46 GMT

In the last post we spoke about how to find what locale is currently selected as active. Now it's time to find how many and what input locales are installed on a PC.

Here are two overloaded functions: one returns locale IDs as integer values (e.g. 1049) and the second – as two characters ISO strings (e.g. "en"):

/// <summary>

/// Returns list of installed locales

/// </summary>

/// <param name="LangList">Contains integer values of installed locales</param>

public void GetInstalledLanguages(out IList<int> LangList)

   LangList = new List<int>(InputLanguage.InstalledInputLanguages.Count);

   foreach (InputLanguage lng in InputLanguage.InstalledInputLanguages)

       LangList.Add(lng.Culture.KeyboardLayoutId);

/// <summary>

/// Returns list of installed locales

/// </summary>

/// <param name="LangList">Contains string values of installed locales</param>

public void GetInstalledLanguages(out IList<string> LangList)

   LangList = new List<string>(InputLanguage.InstalledInputLanguages.Count);

   foreach (InputLanguage lng in InputLanguage.InstalledInputLanguages)

       LangList.Add(lng.Culture.TwoLetterISOLanguageName);

How to get user's current input locale?

Vitaly Zayko — Fri, 28 Nov 2008 11:03:00 GMT

Windows supports number of locales installed on the same computer. Current input locale could be important in some cases, for example in password request dialogs. Here is how you can find active locale in your WinForms App to warn user and prevent wrong submitting.

// As a string (e.g. "en"):

string currentISOLangStr = InputLanguage.CurrentInputLanguage.Culture.TwoLetterISOLanguageName;

// As an integer (e.g. 1033)

int currentLangId = InputLanguage.CurrentInputLanguage.Culture.KeyboardLayoutId;

By the way, Windows does that in login window.

Technorati Tags: Globalization,C#

Detect user writing system in run-time

Vitaly Zayko — Wed, 12 Nov 2008 10:46:14 GMT

As you know, some languages use left-to-right writing system and some – right-to-left. It is good pattern (and besides so easy in .NET Framework) to make other users to feel comfortable using your App even if no other localization is planned.

Here is how to detect current writing system:

if (System.Globalization.CultureInfo.CurrentCulture.TextInfo.IsRightToLeft)

   MessageBox.Show("This is Right-to-Left Writing system.");

else

    MessageBox.Show("This is Left-to-Right Writing system.");

You can easily adopt your App to work with any system dynamically if you put this snippet to each of your form's Form_Load event:

this.RightToLeft = System.Globalization.CultureInfo.CurrentCulture.TextInfo.IsRightToLeft ?

   RightToLeft.Yes : RightToLeft.No;

Technorati Tags: Globalization,C#,CultureInfo

What we should know about CurrentCulture and CurrentUICulture?

Vitaly Zayko — Mon, 10 Nov 2008 13:04:52 GMT

From the first version .NET Framework has rich set of functions that allow you to make your Application to be World ready. And the most interesting place to start is System.Globalization namespace which contains CultureInfo class. But if you have explored this class already, you probably found that it has two very similar properties both return values of CultureInfo type: CurrentCulture and CurrentUICulture. So what is the difference between them?

The short answer is MUI (Multilingual User Interface): If on your or your customer's PC is installed a single language of Windows OS, these properties contains equal data, no matter what language is it. But some editions of Windows (Windows Vista Ultimate, for example) allow installing any number of additional languages (and whole bunch of locale settings like date and number formats) and switching between them.

Let's look closer what if an additional UI language support is installed and activated. I bolded the last word because if a MUI pack has been just installed but not switch to, both properties still keep the same data even if user has customized his locale settings. I ran the code below on Windows Vista en-US version with has customized date and time parameters as "dd/MM/yy HH:mm:ss" instead of traditional US formats:

// CurrentCulture demo:

System.Globalization.CultureInfo currentCulture = System.Globalization.CultureInfo.CurrentCulture;

MessageBox.Show(

   String.Format("currentCulture.DateTimeFormat.FullDateTimePattern: {0}\r\ncurrentCulture.NumberFormat.CurrencySymbol: {1}\r\nDateTime.Now.ToString(currentCulture): {2}",

       currentCulture.DateTimeFormat.FullDateTimePattern,

       currentCulture.NumberFormat.CurrencySymbol,

       DateTime.Now.ToString(currentCulture)),

   currentCulture.EnglishName);

// CurrentUICulture demo:

System.Globalization.CultureInfo currentUICulture = System.Globalization.CultureInfo.CurrentUICulture;

MessageBox.Show(

   String.Format("currentUICulture.DateTimeFormat.FullDateTimePattern: {0}\r\ncurrentUICulture.NumberFormat.CurrencySymbol: {1}\r\nDateTime.Now.ToString(currentUICulture)): {2}",

       currentUICulture.DateTimeFormat.FullDateTimePattern,

       currentUICulture.NumberFormat.CurrencySymbol,

       DateTime.Now.ToString(currentUICulture)),

   currentUICulture.EnglishName);

and here are results I got:

As you can see, both CurrentCulture and CurrentUICulture return exactly the same locale name (at the title bar) and date/time formats.

Now I'm going to activate preinstalled Russian MUI and re-run the test.

And here are new results:

CurrentCulture in second test wasn't changed although CurrentUICulture was: the UI culture contains default formats for Russian language and even my customization has no any affect.

Why it is so important?

If your App just output some data (let say from a database) then using wrong Culture info settings could confuse your users (say "1/3/08 – is it January or March?) but no runtime exception will happen.

But if you expect some user input when you should take a string, parse it into correct format and store or operate with it, wrong locale settings could break your App if format exceptions won't be correctly handled.

Fortunately every culture-critical function in .NET Framework like ToString() or Parse() has several overloads where default (without any parameters) function takes CurrentCulture as a locale information. If I run the code below on my MUI system, the first line will be able to parse my input string successfully:

string inputDate = "15/11/2008 12:00";

DateTime parseDateCurrentCulture = DateTime.Parse(inputDate);

but this one:

DateTime parseDateUICulture = DateTime.Parse(inputDate,

   System.Globalization.CultureInfo.CurrentUICulture);

fails with FormatException.

So based on these experiments, it's more safe and preferred to use CurrentCulture and try..catch blocks to handle possible exceptions especially when you expect some locale-critical user input:

try

   DateTime parseDateCurrentCulture = DateTime.Parse(inputDate);

catch (FormatException)

   MessageBox.Show("Wrong input format!");

Technorati Tags: localization