gui.framework.ps1

# (c) Nabil Redmann 2019

# based on https://stackoverflow.com/a/52416973/1644202
function LoadXamlFile
{
    Param
    (
        [Parameter(Mandatory=$true)] $xamlFile
    )

    $xamlString = Get-Content -Path $xamlFile
    $Form,$Elements =  LoadXamString($xamlString)
    return $Form, $Elements
}

function LoadXamString
{
    Param
    (
        [Parameter(Mandatory=$true)] $xamlString
    )

    Add-Type -AssemblyName PresentationFramework,PresentationCore,WindowsBase

    If (!$knownEvents) { $knownEvents = @(
        # Some major events. There are way more.
        # Window
        "Initialized", "Loaded", "Unloaded", "Activated", "Closed", "Closing", "GotFocus", "LostFocus", "SizeChanged",
        # Checkbox, Buttons etc
        "Click", "Checked", "MouseDoubleClick", "MouseEnter", "MouseLeave", "MouseDown", "MouseUp", "MouseLeftButtonDown", "MouseLeftButtonUp", "MouseRightButtonDown", "MouseRightButtonUp", "MouseMove", "MouseWheel",
        # Text
        "KeyDown", "KeyUp", "PreviewKeyDown", "PreviewKeyUp"
    ) }

    # store window class
    $windowClass = [Regex]::Match($xamlString, '^<Window[^>]*x:Class="([^"]*)').Captures.Groups[1].Value

    #===========================================================================
    # fix XAML markup for powershell
    #===========================================================================
    $xamlString = $xamlString -replace 'mc:Ignorable="d"','' -replace "x:N",'N' -replace '^<Win.*', '<Window' -replace "x:Bind", "Binding"
    [xml]$XAML = $xamlString

    #===========================================================================
    # storing events
    #===========================================================================
    $eventElements = @()
    Foreach ($event in $knownEvents) {
        Foreach ($node in $XAML.SelectNodes("//*[@$event]")) {
            If (!$node.Name) { $node.AddAttribute("Name", "el_$(Get-Random)") }
            $eventElements += @{
                e = $node
                ev = $event
                fn = $node.$event
                name = $node.Name
            }
            $node.RemoveAttribute($event)
        }
    }


    #===========================================================================
    #Read XAML
    #===========================================================================
    $reader = (New-Object System.Xml.XmlNodeReader $XAML)

    try{ $Form = [Windows.Markup.XamlReader]::Load($reader) }
    catch [System.Management.Automation.MethodInvocationException] {
        Write-Warning "We ran into a problem with the XAML code.  Check the syntax for this control..."
        write-host $error[0].Exception.Message -ForegroundColor Red
    }
    catch{#if it broke some other way
        Write-Host "Unable to load Windows.Markup.XamlReader. Double-check syntax and ensure .net is installed."
    }


    #===========================================================================
    # attaching click handlers
    #===========================================================================
    Write-Host "Form class: $windowClass "
    Foreach ($evData in $eventElements) {
        $fnName = $evData.fn
        if ($windowClass) {
            $fnName = "$windowClass.$fnName"
        }

        Write-Host "Linking event $($evData.ev) on element $($evData.name) -> function $fnName()"
        $fns = Get-ChildItem function: | Where-Object { $_.Name -like $fnName } # function namespace.windowclassname.function_name($Sender, $EventArgs)

        If (!$fns.Count) {
            Write-Host ".. handler function does not exist: $fnName(`$Sender,`$EventArgs)" -ForegroundColor Red
        }
        else {
            Invoke-Expression ('$Form.FindName($evData.name).Add_' + $evData.ev + '( $fns[0].ScriptBlock )')
        }
    }

    #===========================================================================
    # Store named elements to be acessable through $Elements
    #===========================================================================
    $Elements = @{}
    $xaml.SelectNodes("//*[@Name]") | %{ $Elements[$_.Name] = $Form.FindName($_.Name) }


    $Elements["_Window"] = $Form

    return $Elements, $Elements._Window
}

gui.xaml

<Window x:Class="WpfApp2.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:WpfApp2"
    mc:Ignorable="d"
    Title="MainWindow" Height="450" Width="800">
    <Grid>
        <ListView SelectionMode="Multiple" x:Name="lvApps" Height="371" VerticalAlignment="Top">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <StackPanel Orientation="Horizontal" Height="64" AutomationProperties.Name="{Binding Name}">
                        <Ellipse Height="48" Width="48" VerticalAlignment="Center">
                            <Ellipse.Fill>
                                <ImageBrush ImageSource="{Binding ButtonImage}"/>
                            </Ellipse.Fill>
                        </Ellipse>
                        <StackPanel Orientation="Vertical" VerticalAlignment="Center" Margin="12,0,0,0">
                            <TextBlock Text="{Binding Name}" />
                            <TextBlock Text="{Binding Description}" />
                        </StackPanel>
                    </StackPanel>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>
        <Button x:Name="doInstallAll" Content="install all" Width="75" VerticalAlignment="Center" Click="DoInstallAll_Click" />
    </Grid>
</Window>

run.cmd

start powershell.exe -ExecutionPolicy Bypass -Command .\start.ps1;Read-Host  "Press Enter to continue ..."

start.ps1

# import logic
. .\gui.framework.ps1

# define handler to be auto attached - window.class + ckick-handler --> before loading the GUI !
function WpfApp2.MainWindow.DoInstallAll_Click($Sender, $EventArgs) { 
    #write-host $Sender,$EventArgs 
    Write-Host "WORKS !"$Elements.lvApps.Items.Count  # $Elements will be available at the time of execution
}

# load main gui
$Elements, $Form = LoadXamlFile .\gui.xaml

# add some element
$Elements.lvApps.AddChild([pscustomobject]@{Name='Ben';Description="sdsd 343"})

# show ui
$Form.ShowDialog() | out-null

# add handler manually (alternative)
$Elements.doInstall.Add_Click({
    Write-Host "!"
})

#
# Use `Invoke-All` to start work intensive stuff in a seperate thread to not block the UI
#
. .\z.helper.ps1
$return = Start-Await-Job {
    Write-Host "doing prog.."
    sleep 3
    return "..done"
}
Write-Host $return

z.helper.ps1

# await a job
Add-Type -AssemblyName System.Windows.Forms
Function Await-Job {
    Param
    (
        [Parameter(Mandatory=$true)] $job
    )

    while ($job.state -eq 'Running') {
        [System.Windows.Forms.Application]::DoEvents()  # keep form responsive
    }
    # will wait on job
    #$consume = Wait-Job $job

    # Captures and throws any exception in the job output -> '-ErrorAction stop' --- otherwise returns result
    return Receive-Job $job -ErrorAction Continue
}

# start and await a job
Function Start-Await-Job {

    Param
    (
        [Parameter(Mandatory=$true)] $scriptBlock
    )

    $job = Start-Job -ScriptBlock $scriptBlock

    return Await-Job $job
}