PowerShell ProgressBar -- Part 1

The Series

Making PowerShell progress bars has always been a handy feature of PowerShell. End users and admins alike love to see that bar progressing just so they know the script is going somewhere. Write-Progress is a great tool built into Windows but sometimes you want to hide that black scary screen and surface a beautiful shiny bar of progress that will make your end user oooo and ahhhhh and your PowerShell prowess.

What I am going to do over the next few posts is create a decent PowerShell progress bar that will have the following feautures:

  1. Update asynchronous from the script (credit goes to Boe Prox1 and Rhys W Edwards 2)
  2. Awesome styles (Material Design and MahApps)

The Basics

This module will be made up of three cmdlets:

  1. New-ProgressBar - Used to create a ProgressBar variable attached to progressbar in separaterunspace. Select styling.
  2. Write-ProgressBar - Used to send progress events to the ProgressBar. Attempts to modify the variable directly will fail due to runspace security
  3. Close-ProgressBar - Used to close out the ProgressBar safely and cleanly to prevent memory issues.

New-ProgressBar

Let’s start with implementing the New-ProgressBar cmdlet and see what all that entails. I strongly recommend reading the referenced article from Boe Prox on managing runspaces before continuing (It’s short).

In order to have the progress bar run without interrupting the current process we need to create it in a separate runspace.

    $SyncHash = [hashtable]::Synchronized(@{})
    $newRunspace =[runspacefactory]::CreateRunspace()
    $SyncHash.Runspace = $newRunspace
    $newRunspace.ApartmentState = "STA"
    $newRunspace.ThreadOptions = "ReuseThread"
    $newRunspace.Open()
    $newRunspace.SessionStateProxy.SetVariable("syncHash",$syncHash)

The $SyncHash variable is going to be used to manage the progress bar from the current thread as we’ll see later in the Write-Progress cmdlet.

The next step is to create the command that will run in this alternate runspace which creates a very basic xaml progress bar and adds the elements of the progressbar to the $SyncHash for later modification.

    $PowerShellCommand = [PowerShell]::Create().AddScript({
        [xml]$xaml = @"
        <Window
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Name="Window" Title="Progress..." WindowStartupLocation = "CenterScreen"
            Width = "300" Height = "100" ShowInTaskbar = "True">
            <StackPanel Margin="20">
               <ProgressBar Name="ProgressBar" Value="40"/>
               <TextBlock Text="{Binding ElementName=ProgressBar, Path=Value, StringFormat={}{0:0}%}" HorizontalAlignment="Center" VerticalAlignment="Center" />
            </StackPanel>
        </Window>
"@

        $reader=(New-Object System.Xml.XmlNodeReader $xaml)
        $syncHash.Window=[Windows.Markup.XamlReader]::Load( $reader )
        #===========================================================================
        # Store Form Objects In PowerShell
        #===========================================================================
        $xaml.SelectNodes("//*[@Name]") | %{ $SyncHash."$($_.Name)" = $SyncHash.Window.FindName($_.Name)}


        $syncHash.Window.ShowDialog() | Out-Null
        $syncHash.Error = $Error

    })
    $PowerShellCommand.Runspace = $newRunspace
    $data = $PowerShellCommand.BeginInvoke()

At this point we should have a progress bar running asynchronously in a separate runspace. Now all we have to do is wrap this in a function and return the $SyncHash as the result for future modification.

I did, however, just in case someone sent it to the pipeline without storing it in a variable a sort of safeguard to close the runspace if it became orphaned or the progress bar was closed.

Register-ObjectEvent -InputObject $SyncHash.Runspace `
            -EventName 'AvailabilityChanged' `
            -Action {

                    if($Sender.RunspaceAvailability -eq "Available")
                    {
                        $Sender.Closeasync()
                        $Sender.Dispose()
                    }

                }

This will basically listen for when the availability (typically busy while the progress bar is running) to change and if it is Available go ahead and close out the runspace and dispose it.

The full function appears here:

Function New-ProgressBar {

    [void][System.Reflection.Assembly]::LoadWithPartialName('presentationframework')
    $syncHash = [hashtable]::Synchronized(@{})
    $newRunspace =[runspacefactory]::CreateRunspace()
    $syncHash.Runspace = $newRunspace
    $newRunspace.ApartmentState = "STA"
    $newRunspace.ThreadOptions = "ReuseThread"
    $newRunspace.Open()
    $newRunspace.SessionStateProxy.SetVariable("syncHash",$syncHash)
    $PowerShellCommand = [PowerShell]::Create().AddScript({
        [xml]$xaml = @"
        <Window
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Name="Window" Title="Progress..." WindowStartupLocation = "CenterScreen"
            Width = "300" Height = "100" ShowInTaskbar = "True">
            <StackPanel Margin="20">
               <ProgressBar Name="ProgressBar" Value="40"/>
               <TextBlock Text="{Binding ElementName=ProgressBar, Path=Value, StringFormat={}{0:0}%}" HorizontalAlignment="Center" VerticalAlignment="Center" />
            </StackPanel>
        </Window>
"@

        $reader=(New-Object System.Xml.XmlNodeReader $xaml)
        $syncHash.Window=[Windows.Markup.XamlReader]::Load( $reader )
        #===========================================================================
        # Store Form Objects In PowerShell
        #===========================================================================
        $xaml.SelectNodes("//*[@Name]") | %{ $SyncHash."$($_.Name)" = $SyncHash.Window.FindName($_.Name)}


        $syncHash.Window.ShowDialog() | Out-Null
        $syncHash.Error = $Error

    })
    $PowerShellCommand.Runspace = $newRunspace
    $data = $PowerShellCommand.BeginInvoke()


    Register-ObjectEvent -InputObject $SyncHash.Runspace `
            -EventName 'AvailabilityChanged' `
            -Action {

                    if($Sender.RunspaceAvailability -eq "Available")
                    {
                        $Sender.Closeasync()
                        $Sender.Dispose()
                    }

                }

    return $SyncHash

}

Write-ProgressBar

Now to build your starting Write-ProgressBar function. To start out we aren’t going to want to mess with re-creating every functionality of Write-Progress, so we are just going to add the ability to pass in an updated Activity which will update the title of the progress bar window and PercentComplete.

If you didn’t read Boe’s article you may have already attempted to update the progressbar using the $SyncHash Variable. This will sadly not work. Something about security or something. So what we are going to do is modify the properties in the second runspace by using the dispatcher which is exposed in our $SyncHash variable.

function Write-ProgressBar
{

    Param (
        [Parameter(Mandatory=$true)]
        [System.Object[]]$ProgressBar,
        [Parameter(Mandatory=$true)]
        [String]$Activity,
        [int]$PercentComplete
    )

   # This updates the control based on the parameters passed to the function
   $ProgressBar.Window.Dispatcher.Invoke([action]{

      $ProgressBar.Window.Title = $Activity

   }, "Normal")

   if($PercentComplete)
   {

       $ProgressBar.Window.Dispatcher.Invoke([action]{

          $ProgressBar.ProgressBar.Value = $PercentComplete

       }, "Normal")

   }

}

Close-ProgressBar

The Close-ProgressBar function is going to be very similar.

function Close-ProgressBar
{

    Param (
        [Parameter(Mandatory=$true)]
        [System.Object[]]$ProgressBar
    )

    $ProgressBar.Window.Dispatcher.Invoke([action]{

      $ProgressBar.Window.Close()

    }, "Normal")

}

Hope you enjoy! The next posting we will get into replicating the exact functionality of the write-progress function as well as dealing with some of the performance issues you will see when running the below demo. The third we will get into styling our progress bars.

Below is the full code so far and a demo:

Full Code


# Function to facilitate updates to controls within the window
Function New-ProgressBar {

    [void][System.Reflection.Assembly]::LoadWithPartialName('presentationframework')
    $syncHash = [hashtable]::Synchronized(@{})
    $newRunspace =[runspacefactory]::CreateRunspace()
    $syncHash.Runspace = $newRunspace
    $newRunspace.ApartmentState = "STA"
    $newRunspace.ThreadOptions = "ReuseThread"
    $newRunspace.Open()
    $newRunspace.SessionStateProxy.SetVariable("syncHash",$syncHash)
    $PowerShellCommand = [PowerShell]::Create().AddScript({
        [xml]$xaml = @"
        <Window
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            Name="Window" Title="Progress..." WindowStartupLocation = "CenterScreen"
            Width = "300" Height = "100" ShowInTaskbar = "True">
            <StackPanel Margin="20">
               <ProgressBar Name="ProgressBar" />
               <TextBlock Text="{Binding ElementName=ProgressBar, Path=Value, StringFormat={}{0:0}%}" HorizontalAlignment="Center" VerticalAlignment="Center" />
            </StackPanel>
        </Window>
"@

        $reader=(New-Object System.Xml.XmlNodeReader $xaml)
        $syncHash.Window=[Windows.Markup.XamlReader]::Load( $reader )
        #===========================================================================
        # Store Form Objects In PowerShell
        #===========================================================================
        $xaml.SelectNodes("//*[@Name]") | %{ $SyncHash."$($_.Name)" = $SyncHash.Window.FindName($_.Name)}


        $syncHash.Window.ShowDialog() | Out-Null
        $syncHash.Error = $Error

    })
    $PowerShellCommand.Runspace = $newRunspace
    $data = $PowerShellCommand.BeginInvoke()


    Register-ObjectEvent -InputObject $SyncHash.Runspace `
            -EventName 'AvailabilityChanged' `
            -Action {

                    if($Sender.RunspaceAvailability -eq "Available")
                    {
                        $Sender.Closeasync()
                        $Sender.Dispose()
                    }

                }

    return [System.Collections.Hashtable]$SyncHash

}


function Write-ProgressBar
{

    Param (
        [Parameter(Mandatory=$true)]
        [System.Object[]]$ProgressBar,
        [Parameter(Mandatory=$true)]
        [String]$Activity,
        [String]$Status,
        [int]$Id,
        [int]$PercentComplete,
        [int]$SecondsRemaining,
        [String]$CurrentOperation,
        [int]$ParentId,
        [Switch]$Completed,
        [int]$SourceID
    )

   # This updates the control based on the parameters passed to the function
   $ProgressBar.Window.Dispatcher.Invoke([action]{

      $ProgressBar.Window.Title = $Activity

   }, "Normal")

   if($PercentComplete)
   {

       $ProgressBar.Window.Dispatcher.Invoke([action]{

          $ProgressBar.ProgressBar.Value = $PercentComplete

       }, "Normal")

   }

}


function Close-ProgressBar
{

    Param (
        [Parameter(Mandatory=$true)]
        [System.Object[]]$ProgressBar
    )

    $ProgressBar.Window.Dispatcher.Invoke([action]{

      $ProgressBar.Window.Close()

    }, "Normal")

}

Demo

Run this after creating the above functions

$ProgressBar = New-ProgressBar

1..100 | foreach {Write-ProgressBar -ProgressBar $ProgressBar -Activity "Counting $_ out of 100" -PercentComplete $_; Start-Sleep -Milliseconds 250}

Close-ProgressBar $ProgressBar

  1. http://learn-powershell.net/2012/10/14/powershell-and-wpf-writing-data-to-a-ui-from-a-different-runspace/ ↩

  2. https://gallery.technet.microsoft.com/scriptcenter/New-ProgressBar-8468da5c ↩

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