WPF/Add-EventHandler.ps1
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function Add-EventHandler { <# .Synopsis Adds an event handler to an object .Description Adds an event handler to an object. If the object has a resource dictionary, it will add an eventhandlers hashtable to that object and it will store the event handler, so it can be removed later. .Example $window = New-Window $window | Add-EventHandler Loaded { $this.Top = 100 } .Parameter Object The Object to add an event handler to .Parameter EventName The name of the event (i.e. Loaded) .Parameter Handler The script block that will handle the event .Parameter SourceType For RoutedEvents, the type that originates the event .Parameter PassThru If this is set, the delegate that is added to the object will be returned from the function. #> param( [Parameter(ValueFromPipeline=$true, Mandatory=$true, Position = 0, ParameterSetName="SimpleEvents")] [ValidateNotNull()] [Alias("Object")] $InputObject, [Parameter(Mandatory=$true, Position=1)] [String] $EventName, [Parameter(Mandatory=$true, Position=2)] [ScriptBlock] $Handler, [Parameter(Mandatory=$false)] [String] $SourceType, [Switch] $PassThru ) process { if($SourceType) { $Type = $SourceType -as [Type] if(!$Type) { $Type = (Get-Command $SourceType).OutputType[0].Type } if(!$Type) { Write-Error "Can't determine type from '$SourceType', you should pass either a Type or the name of a ShowUI command that outputs a UI Element. We will try the InputObject(s)" $Type = $InputObject.GetType() } } else { $Type = $InputObject.GetType() } if ($eventName.StartsWith("On_")) { $eventName = $eventName.Substring(3) } $Event = $Type.GetEvent($EventName, [Reflection.BindingFlags]"IgnoreCase, Public, Instance") if (-not $Event) { Write-Error "Handler $EventName does not exist on $InputObject" return } $realHandler = ([ScriptBlock]::Create(@" `$eventName = 'On_$eventName'; `$parent = . Get-ParentControl -Control `$this . Initialize-EventHandler -parent `$parent `$ErrorActionPreference = [Management.Automation.ActionPreference]::Stop $Handler trap { . Write-WPFError `$_ continue } "@)) -as $event.EventHandlerType if($realHandler -is [System.Windows.RoutedEventHandler] -and $Type::"${EventName}Event" ) { $InputObject.AddHandler( $Type::"${EventName}Event", $realHandler ) } else { if ($InputObject.Resources) { if (-not $InputObject.Resources.EventHandlers) { $InputObject.Resources.EventHandlers = @{} } $InputObject.Resources.EventHandlers."On_$EventName" = $realHandler } $event.AddEventHandler($InputObject, $realHandler) } if ($passThru) { $RealHandler } } } |