TurtleGraphics

New-Window -AsJob -Title "ShowUI - Turtle Graphics" -WindowStartupLocation "CenterScreen" -Width 500 -Height 500 -On_Loaded {
    . $Window.Resources.Code | Import-Module
    Set-Window $Window
} -Resource @{
    Code = {
        New-Module TurtleGraphics {
            [double] $Script:X = 0
            [double] $Script:Y = 0
            [bool]   $Script:PenDown = $false

            $Script:Stroke = [System.Windows.Media.Brushes]::Violet
            $Script:StrokeThickness = 2
            $Script:Fill = [System.Windows.Media.Brushes]::LightBlue
            $Script:Window = ""

            $Script:PointCollection = New-Object System.Windows.Media.PointCollection

            function Set-Window    ($Window) {$Script:Window = $Window}
            function Set-PenWidth  ($StrokeThickness) {$Script:StrokeThickness = $StrokeThickness}
            function Set-PenColor  ($Color) { $Script:Stroke = [System.Windows.Media.Brushes]::$color }
            function Set-FillColor ($Color) { $Script:Fill = [System.Windows.Media.Brushes]::$color }

            function New-Point {
                param([double]$x, [double]$y)
                New-Object System.Windows.Point $x, $y
            }

            function PenDown {
                $Script:PointCollection.Add((New-Point $X $y))
                $Script:PenDown = $true
            }

            function PenUp {
                if($Script:PointCollection.Count -ge 2) {
                    $Polyline = New-Polyline

                    $PointCollection | ForEach { $Polyline.Points.Add($_) }

                    $Polyline.Stroke = $Script:Stroke
                    $Polyline.StrokeThickness = $Script:StrokeThickness
                    $Polyline.Fill = $Script:Fill

                    $TheCanvas = $Script:Window | Get-ChildControl -ByName TheCanvas
                    $TheCanvas.Children.Add($Polyline)
                }

                $Script:PointCollection.Clear()
                $Script:PenDown = $false
            }

            function MoveTo ($X, $Y) {
                if($Script:PenDown) {
                    $Script:PointCollection.Add((New-Point $X $y))
                }

                $Script:X = $X
                $Script:Y = $Y
            }

            function ClearCanvas {
                $TheCanvas = $Script:Window | Get-ChildControl -ByName TheCanvas
                $TheCanvas.Children.Clear()
                $Script:X = 0
                $Script:Y = 0
            }
        }
    }
} {
    $tbStype = @{
        Margin = 5
        VerticalScrollBarVisibility = "Auto"
        AcceptsReturn = $true
        HorizontalScrollBarVisibility = "Auto"
    }

    $targetScript = @"
ClearCanvas

Set-PenWidth 3

function Do-It (`$x, `$y, `$max) {
    PenUp
    MoveTo `$x `$y

    PenDown
    MoveTo `$max `$y
    MoveTo `$max `$max
    MoveTo `$x `$max
    MoveTo `$x `$y

    PenUp
}

1..10 | ForEach { `$y=`$x=10; `$max=230 } {
    `$y=`$x+=10; `$max-=10
    Do-It `$x `$y `$max
}

"@
    Grid -Columns 2 -Rows 100*, Auto {
        Canvas  -Row 0 -Column 1 -RowSpan 2 -Name TheCanvas
        TextBox -Row 0 -Column 0 -Name TB -Text $targetScript @tbStype

        StackPanel -Orientation Horizontal -Row 1 -Column 0 {
            Button _Run -Margin 5 -MinWidth 75 -On_Click {
                $TB.Text | Invoke-Expression
            }

            Button _Clear -Margin 5 -MinWidth 75 -On_Click { ClearCanvas }
        }
    }
}