Getting the Keyboard Layout in WPF C#

Question

I need to get the Current Windows Keyboard Layout for my WPF application to map each key correctly and handle AZERTY as well as QWERTY and QWERTZ (and so on...)

I notic

Answer 1

The following PowerShell¹ script declares Get-KeyboardLayoutForPid function which reliably gets the Current Windows Keyboard Layout for any process².

if ( $null -eq ('Win32Functions.KeyboardLayout' -as [type]) ) {
    Add-Type -MemberDefinition @'
        [DllImport("user32.dll")] 
        public static extern IntPtr GetKeyboardLayout(uint thread);
'@ -Name KeyboardLayout -Namespace Win32Functions
}

Function Get-KeyboardLayoutForPid {
    [cmdletbinding()]
    Param (
        [parameter(Mandatory=$False, ValueFromPipeline=$False)]
        [int]$Id = $PID,
        # used formerly for debugging
        [parameter(Mandatory=$False, DontShow=$True)]
        [switch]$Raw
    )

    $InstalledInputLanguages = [System.Windows.Forms.InputLanguage]::InstalledInputLanguages
    $CurrentInputLanguage    = [System.Windows.Forms.InputLanguage]::DefaultInputLanguage # CurrentInputLanguage
    $CurrentInputLanguageHKL = $CurrentInputLanguage.Handle # just an assumption
    ### Write-Verbose ('CurrentInputLanguage: {0}, 0x{1:X8} ({2}), {3}' -f $CurrentInputLanguage.Culture, ($CurrentInputLanguageHKL -band 0xffffffff), $CurrentInputLanguageHKL, $CurrentInputLanguage.LayoutName)

    Function GetRealLayoutName ( [IntPtr]$HKL ) {
    $regBase = 'Registry::' + 
                'HKLM\SYSTEM\CurrentControlSet\Control\Keyboard Layouts'
    $LayoutHex = '{0:x8}' -f ($hkl -band 0xFFFFFFFF)
    if ( ($hkl -band 0xFFFFFFFF) -lt 0 ) {
        $auxKeyb = Get-ChildItem -Path $regBase | 
            Where-Object { 
            $_.Property -contains 'Layout Id' -and 
                (Get-ItemPropertyValue -Path "Registry::$($_.Name)" `
                    -Name 'Layout Id' `
                    -ErrorAction SilentlyContinue
                ) -eq $LayoutHex.Substring(2,2).PadLeft(4,'0')
        } | Select-Object -ExpandProperty PSChildName
    } else {
        $auxKeyb = $LayoutHex.Substring(0,4).PadLeft(8,'0')
    }
    $KbdLayoutName  = Get-ItemPropertyValue -Path (
        Join-Path -Path $regBase -ChildPath $auxKeyb
    ) -ErrorAction SilentlyContinue -Name 'Layout Text'
    $KbdLayoutName
    # Another option: grab localized string from 'Layout Display Name'
    } # Function GetRealLayoutName

    Function  GetKbdLayoutForPid {
    Param (
        [parameter(Mandatory=$True, ValueFromPipeline=$False)]
        [int]$Id,
        [parameter(Mandatory=$False, DontShow=$True)]
        [string]$Parent = ''
    ) 
    $Processes = Get-Process -Id $Id
    $Weirds  = @('powershell_ise','explorer') # not implemented yet

    $allLayouts = foreach ( $Proces in $Processes ) {
        $LayoutsExtra = [ordered]@{}
        $auxKLIDs = @( for ( $i=0; $i -lt $Proces.Threads.Count; $i++ ) {
            $thread = $Proces.Threads[$i]
            ## The return value is the input locale identifier for the thread:
            $LayoutInt = [Win32Functions.KeyboardLayout]::GetKeyboardLayout( $thread.Id )
            $LayoutsExtra[$LayoutInt] = $thread.Id
        })
        Write-Verbose ('{0,6} ({1,6}) {2}: {3}' -f $Proces.Id, $Parent, 
            $Proces.ProcessName, (($LayoutsExtra.Keys | 
                Select-Object -Property @{ N='Handl';E={('{0:x8}' -f ($_ -band 0xffffffff))}} | 
                Select-Object -ExpandProperty Handl) -join ', '))
        foreach ( $auxHandle in $LayoutsExtra.Keys ) {
            $InstalledInputLanguages | Where-Object { $_.Handle -eq $auxHandle }
        }
        $ConHost = Get-WmiObject Win32_Process -Filter "Name = 'conhost.exe'"
        $isConsoleApp = $ConHost | Where-Object { $_.ParentProcessId -eq $Proces.Id }
        if ( $null -ne $isConsoleApp ) {
            GetKbdLayoutForPid -Id ($isConsoleApp.ProcessId) -Parent ($Proces.Id -as [string])
        }
    }
    if ( $null -eq $allLayouts ) {
        # Write-Verbose ('{0,6} ({1,6}) {2}: {3}' -f $Proces.Id, $Parent, $Proces.ProcessName, '')
    } else {
        $allLayouts
    }
    } # GetKbdLayoutForPid

    $allLayoutsRaw = GetKbdLayoutForPid -Id $Id
    if ( $null -ne $allLayoutsRaw ) {
        if ( ([bool]$PSBoundParameters['Raw']) ) {
            $allLayoutsRaw
        } else {
            $retLayouts = $allLayoutsRaw | 
                Sort-Object -Property Handle -Unique | 
                Where-Object { $_.Handle -ne $CurrentInputLanguageHKL }
            if ( $null -eq $retLayouts ) { $retLayouts = $CurrentInputLanguage }
            $RealLayoutName = $retLayouts.Handle | 
                ForEach-Object { GetRealLayoutName -HKL $_ }
            $ProcessAux = Get-Process -Id $Id
            $retLayouts | Add-Member -MemberType NoteProperty -Name 'ProcessId' -Value "$Id"
            $retLayouts | Add-Member -MemberType NoteProperty -Name 'ProcessName' -Value ($ProcessAux | Select-Object -ExpandProperty ProcessName )
            # $retLayouts | Add-Member -MemberType NoteProperty -Name 'WindowTitle' -Value ($ProcessAux | Select-Object -ExpandProperty MainWindowTitle )
            $retLayouts | Add-Member -MemberType NoteProperty -Name 'RealLayoutName' -Value ($RealLayoutName -join ';')
            $retLayouts
        }
    }
<#

.Synopsis
Get the current Windows Keyboard Layout for a process.

.Description
Gets the current Windows Keyboard Layout for a process. Identify the process
using -Id parameter.

.Parameter Id
A process Id, e.g.
- Id property of System.Diagnostics.Process instance (Get-Process), or
- ProcessId property (an instance of the Win32_Process WMI class), or 
- PID property from "TaskList.exe /FO CSV", …

.Parameter Raw
Parameter -Raw is used merely for debugging. 

.Example
Get-KeyboardLayoutForPid

This example shows output for the current process (-Id $PID). 
Note that properties RealLayoutName and LayoutName could differ (the latter is wrong; a bug in [System.Windows.Forms.InputLanguage] implementation?)

ProcessId      : 2528
ProcessName    : powershell
RealLayoutName : United States-International
Culture        : cs-CZ
Handle         : -268368891
LayoutName     : US

.Example
. D:\PShell\tests\Get-KeyboardLayoutForPid.ps1  # activate the function

Get-Process -Name * | 
    ForEach-Object { Get-KeyboardLayoutForPid -Id $_.Id -Verbose }

This example shows output for each currently running process, unfortunately
even (likely unusable) info about utility/service processes. 

The output itself can be empty for most processes, but the verbose stream
shows (hopefully worthwhile) info where current keboard layout is held.

Note different placement of the current keboard layout ID:
- console application      (cmd, powershell, ubuntu): conhost
- combined GUI/console app (powershell_ise)         : the app itself
- classic  GUI apps        (notepad, notepad++, …)  : the app itself
- advanced GUI apps        (iexplore)               : Id ≘ tab
- "modern" GUI apps        (MicrosoftEdge*)         : Id ≟ tab (unclear)
- combined GUI/service app (explorer)               : indiscernible
- etc…                     (this list is incomplete).

For instance, iexplore.exe creates a separate process for each open window 
or tab, so their identifying and assigning input languages is an easy task.

On the other side, explorer.exe creates the only process, regardless of 
open visible window(s), so they are indistinguishable by techniques used here…

.Example
gps -Name explorer | % { Get-KeyboardLayoutForPid -Id $_.Id } | ft -au

This example shows where the function could fail in a language multifarious environment:

ProcessId ProcessName RealLayoutName Culture     Handle LayoutName 
--------- ----------- -------------- -------     ------ ---------- 
5344      explorer    Greek (220);US el-GR   -266992632 Greek (220)
5344      explorer    Greek (220);US cs-CZ     67699717 US         

- scenario: 
  open three different file explorer windows and set their input languages
  as follows (their order does not matter):
    - 1st window: let default input language   (e.g. Czech, in my case),
    - 2nd window: set different input language (e.g. US English),
    - 3rd window: set different input language (e.g. Greek).
- output:
  an array (and note that default input language window isn't listed).

.Inputs
No object can be piped to the function. Use -Id pameter instead,
named or positional.

.Outputs
[System.Windows.Forms.InputLanguage] extended as follows:
                                     note the <…> placeholder

Get-KeyboardLayoutForPid | Get-Member -MemberType Properties

   TypeName: System.Windows.Forms.InputLanguage

Name           MemberType   Definition
----           ----------   ----------
ProcessId      NoteProperty string ProcessId=<…>
ProcessName    NoteProperty System.String ProcessName=powershell
RealLayoutName NoteProperty string RealLayoutName=<…>
Culture        Property     cultureinfo Culture {get;}
Handle         Property     System.IntPtr Handle {get;}
LayoutName     Property     string LayoutName {get;}

.Notes
To add the `Get-KeyboardLayoutForPid` function to the current scope,
run the script using `.` dot sourcing operator, e.g. as 
. D:\PShell\tests\Get-KeyboardLayoutForPid.ps1

Auhor:     https://stackoverflow.com/users/3439404/josefz
Created:   2019-11-24
Revisions:  

.Link

.Component
P/Invoke

<##>

} # Function Get-KeyboardLayoutForPid

if ( -not ('System.Windows.Forms.InputLanguage' -as [type]) ) {
    Add-Type -AssemblyName System.Windows.Forms
}

The Get-KeyboardLayoutForPid function contains a Comment-Based Help placed at the end of its body.
I hope that its principle is implementable in C# easy.

The main idea of my approach:

1. Suppose that the current keyboard layout (CurrentInputLanguage) for a given process is the (user-dependant) default one (DefaultInputLanguage).
2. Collect keyboard layouts associated with every thread of given process (allLayoutsRaw). Note this trick for a console application: collect keyboard layouts associated with every thread of child conhost process as well.
3. If there is a keyboard layout different from DefaultInputLanguage in the allLayoutsRaw collection then it's the sought-after one (retLayouts).

---

^{1 Does not work in PowerShell Core (pwsh.exe).}

^{2 Might fail for explorer process in a language multifarious environment, see an example of failing scenario in the Comment-Based help.}