winform with `.DownloadFileAsync` and progress bar

formstuff.ps1

Add-Type -Assembly System.Windows.Forms

[System.Windows.Forms.Application]::EnableVisualStyles()

$form = [System.Windows.Forms.Form]@{
    Size            = '500, 150'
    FormBorderStyle = 'Fixed3d'
}
$btn = [System.Windows.Forms.Button]@{
    Name     = 'MyButton'
    Text     = 'Click Me!'
    Size     = '90, 30'
    Location = '370, 70'
    Anchor   = 'Bottom, Right'
}
$btn.Add_Click({
    $this.Enabled = $false
    $downloader.DownloadFileAsync('https://www.7-zip.org/a/7z2301-x64.exe', "$pwd\7Zip.exe")
})
$progress = [System.Windows.Forms.ProgressBar]@{
    Name     = 'MyProgressBar'
    Size     = '460, 40'
    Location = '10, 10'
}
$form.Controls.AddRange(($btn, $progress))

$downloader = [System.Net.WebClient]::new()
$rs = [runspacefactory]::CreateRunspace($Host)
$rs.Open()
$rs.SessionStateProxy.PSVariable.Set([psvariable]::new('form', $form))
$ps = [powershell]::Create().AddScript({
    $registerObjectEventSplat = @{
        InputObject      = $args[0]
        EventName        = 'DownloadProgressChanged'
        SourceIdentifier = 'WebMainDownloadProgressChanged'
        Action           = {
            [System.Threading.Monitor]::Enter($form)
            $progress = $form.Controls.Find('MyProgressBar', $false)[0]
            $eventArgs.ProgressPercentage | Out-Host
            $progress.Value = $eventArgs.ProgressPercentage
            [System.Threading.Monitor]::Exit($form)
        }
    }
    Register-ObjectEvent @registerObjectEventSplat
    $registerObjectEventSplat['EventName'] = 'DownloadFileCompleted'
    $registerObjectEventSplat['SourceIdentifier'] = 'WebMainDownloadFileCompleted'
    $registerObjectEventSplat['Action'] = {
        [System.Threading.Monitor]::Enter($form)
        $form.Controls.Find('MyButton', $false)[0].Enabled = $true
        Write-Host 'Download Completed!'
        [System.Threading.Monitor]::Exit($form)
    }
    Register-ObjectEvent @registerObjectEventSplat
}).AddArgument($downloader)
$ps.Runspace = $rs
$task = $ps.BeginInvoke()
$form.ShowDialog()