Change InvokeRequired to True

[Bender2010]

Hello,

I have a GUI with a label which is not visible ($false). I would like to visible the item with BeginInvoke(). So long the task is running, the item is visible and when finished not.

When I have understand, then I must change InvokeRequired to True, so I could change objects outsite my task.
https://docs.microsoft.com/en-us/dotnet ... keRequired

How I could change this settings for my label and other items? When I do this in my script ($label.InvokeRequired = $true), it´s not working while it´s a read only property.

PowerShell Studio 2019. 5.6.170
64 Bit

Best thanks for your assitent

Code: Select all

	# Runspace 
	$runspaceSpace = [RunspaceFactory]::CreateRunspace()
	$runspaceSpace.ApartmentState = 'STA'
	$runspaceSpace.ThreadOptions = 'UseNewThread'
	$runspaceSpace.Open()
	
	# PSInstance
	$PsInstanceSpace = [PowerShell]::Create()
	$PsInstanceSpace.Runspace = $runspace
	
	# Space
	$PsInstanceSpace.Runspace.SessionStateProxy.SetVariable("labelSpaceStatus", $labelSpaceStatus)
	$PsInstanceSpace.Runspace.SessionStateProxy.SetVariable("labelSpaceOK", $labelSpaceOK)
	$PsInstanceSpace.Runspace.SessionStateProxy.SetVariable("labelSpaceX", $labelSpaceX)
	$PsInstanceSpace.Runspace.SessionStateProxy.SetVariable("progressbarSpace", $progressbarSpace)
	
	#$labelSpaceOK.InvokeRequired = $true
	#$labelSpaceX.InvokeRequired = $true
	
	[void]$PsInstanceSpace.AddScript({
			#Place Code Here
			If ((Get-WMIObject -Class Win32_Logicaldisk -Namespace Root\CIMV2 -Filter "deviceid='C:'").FreeSpace -gt 31457280000)
			{
				$labelSpaceStatus.Text = "Success"
				$labelSpaceOK.Visible = $true #Show my label now
				$labelSpaceX.Visible = $false
			}
			else
			{
				$labelSpaceStatus.Text = "Failed"
				$labelSpaceOK.Visible = $false
				$labelSpaceX.Visible = $true
			}
			[System.Windows.Forms.MessageBox]::Show("Script is running", "Running")
			$progressbarSpace.Visible = $false
			$PsInstanceSpace.EndInvoke()
			$PsInstanceSpace.Dispose()
			$runspaceSpace.Close()
			[System.GC]::Collect()
		}).BeginInvoke()

[jvierra]

Invoke is not required to change properties. It is only required for calling delegates. Just set the property. The synchash will handle threading issues.

You must use a synchash and not just assigned variables.

[jvierra]

Here is the way to create a basic invokable script that builds and manages the runspace for you with correct default values and a synchash.

Since the "Visible" property is not really a simple property you would have tocreate a delegate that can calll the "Show()" method on the control. I can't remember the syntax for that in PowerShell right now.

The "InvokeRequired" is not needed here and is not a settable property. It is used so a thread can decide whether to directly access a control or if an "Invoke" is required.

See attached demo for how to code this.

[jvierra]

Ok. I remembered the trick with PS. Here is how to call a delegate from a runspace and set the visible property to true.

Code: Select all

$buttonStart_Click={
    $synchash = @{
        Label = $label1
        Show = [action]{$label1.Visible = $true}
    }
    $psscript = {
        $synchash.Label.Invoke($synchash.Show)
        1..100 |
            ForEach-Object{
                $synchash.Label.Text = "$_ Runspace here"
                sleep 1
            }
    }
    
    # create a new PowerShell runspace
    $ps = [PowerShell]::Create()
    $ps.Runspace.SessionStateProxy.SetVariable('synchash',$synchash)
    $ps.AddScript($psscript)
    $ps.BeginInvoke()
}

[jvierra]

Here is a full example of how to manage a runspace including how to detect when it is complete and how to detect errors.