WEKF_Scancode (Industry 8.1)

7/8/2014

Review the syntax, members, and examples of the WEKF_Scancode WMI provider class for Windows Embedded 8.1 Industry (Industry 8.1).

This class blocks or unblocks key combinations by using the keyboard scan code, which is an integer number that is generated whenever a key is pressed or released.

Syntax

class WEKF_Scancode {
    [Static] uint32 Add(
        [In] string Modifiers,
        [In] uint16 scancode
    );
    [Static] uint32 Remove(
        [In] string Modifiers,
        [In] uint16 Scancode
    );

    [Key] string Modifiers;
    [Key] uint16 Scancode;
    [Read, Write] boolean Enabled;
}

Members

The following tables list any constructors, methods, fields, and properties that belong to this class.

Methods

Methods	Description
WEKF_Scancode.Add	Adds a new custom scan code combination and enables Keyboard Filter to block the new scan code combination.
WEKF_Scancode.Remove	Removes the specified custom scan code combination. Keyboard Filter stops blocking the scan code combination that was removed.

Properties

Property	Data type	Qualifiers	Description
Modifiers	string	[key]	The modifier keys that are part of the key combination to block.
Scancode	uint16	[key]	The scan code part of the key combination to block.
Enabled	Boolean	[read, write]	Indicates whether the scan code is blocked or unblocked. This property can be one of the following values: ValueDescription trueIndicates that the scan code is blocked. falseIndicates that the scan code is not blocked.

Remarks

Scan codes are generated by the keyboard whenever a key is pressed. The same physical key will always generate the same scan code, regardless of which keyboard layout is currently being used by the system.

You can specify key combinations by including the modifier keys in the Modifiers parameter of the Add method or by modifying the Modifiers property. The most common modifier names are “Ctrl”, “Shift”, “Alt”, and “Win”.

Example

The following code demonstrates how to add or enable a keyboard scan code that Keyboard Filter will block by using the Windows Management Instrumentation (WMI) providers for Keyboard Filter. This example modifies the properties directly, and does not call any of the methods defined in WEKF_Scancode.

<#
.Synopsis
    This script shows how to use the WMI provider to enable and add 
    Keyboard Filter rules through Windows Powershell on the local computer.
.Parameter ComputerName
    Optional parameter to specify a remote machine that this script should
    manage.  If not specified, the script will execute all WMI operations
    locally.
#>
param (
    [String] $ComputerName
)

$CommonParams = @{"namespace"="root\standardcimv2\embedded"}
$CommonParams += $PSBoundParameters


function Enable-Scancode($Modifiers, [int]$Code) {
    <#
    .Synopsis
        Toggle on a Scancode Keyboard Filter Rule
    .Description
        Use Get-WMIObject to enumerate all WEKF_Scancode instances,
        filter against key values of "Modifiers" and "Scancode", and set
        that instance's "Enabled" property to 1/true.

        In the case that the Scancode instance does not exist, add a new
        instance of WEKF_Scancode using Set-WMIInstance.
    .Example
        Enable-Predefined-Key "Ctrl+V"
        
        Enable filtering of the Ctrl + V sequence.
    #>

    $scancode =
        Get-WMIObject -class WEKF_Scancode @CommonParams |
            where {
                ($_.Modifiers -eq $Modifiers) -and ($_.Scancode -eq $Code)
            }

    if($scancode) {
        $scancode.Enabled = 1
        $scancode.Put() | Out-Null
        "Enabled Custom Scancode {0}+{1:X4}" -f $Modifiers, $Code
    } else {
        Set-WMIInstance `
            -class WEKF_Scancode `
            -argument @{Modifiers="$Modifiers"; Scancode=$Code} `
            @CommonParams | Out-Null
 
        "Added Custom Scancode {0}+{1:X4}" -f $Modifiers, $Code
    }
}

# Some example uses of the function defined above.

Enable-Scancode "Ctrl" 37

See Also

Reference

Keyboard Filter WMI provider reference

Concepts

Keyboard Filter