Creates a new pie chart using WPK

New-PieChart.ps1

param([string] $CountProperty = 'Count',
      [string] $NameProperty = 'Name',
      [double] $Width = 400,
      [double] $Height = 300,
      [string] $WindowTitle = 'Pie Graph',
      [string] $ChartTitle = $null,
      [Parameter(ValueFromPipeline = $true)] $Items,
      [switch] $Show = $false)
begin {
    Import-Module wpk

    $total = 0
    $count = 0
    $computed = @()
    
    function Get-Brightness($color) {
        $sum = 0
        foreach($channel in 'R','G','B') { $sum += $color.$channel }
        return $sum / 255 / 3
    }

    $palette = [Windows.Media.Brushes] `
        | gm -Static -MemberType Property `
        | % { [Windows.Media.Brushes]::$($_.Name) } `
        | ? { $brightness = Get-Brightness $_.Color; $brightness -gt 0.5 -and $brightness -lt 0.75 }
}
process {
    if(-not $items) { return }
    if ($items -isnot [Collections.IEnumerable]) { $Items = @($Items) }
    
    foreach($item in $items.GetEnumerator()){
        trap { Write-Error "Error processing item... Skipping "; continue; }
        $computed += New-Object PSObject -Property @{
            Name = $item.$NameProperty
            Count = $item.$CountProperty
            Brush = $palette[$count % $palette.Length]
            Percentage = 0
        }
        $total += $item.$CountProperty
        $count++
    }
}
end {
    if($total -gt 0) { foreach($item in $computed){ $item.Percentage = $item.Count / $total } }
    
    $computed = $computed | sort -Descending Count

    $legendContent = New-Grid `
        -ColumnDefinitions (0..3 | % { New-ColumnDefinition -Width Auto }) `
        -RowDefinitions (1..$computed.Length | % { New-RowDefinition }) `
        -Children ($computed | % { $row = 0 } {
            New-Border  -Row $row -Column 0 -Background $_.Brush -BorderThickness 1 -BorderBrush Black -Width 10 -Height 10 -Margin 5 | Write-Output
            New-TextBlock -Row $row -Column 1 -Text $_.Name -Margin 5 | Write-Output
            New-TextBlock -Row $row -Column 2 -Text $_.Count.ToString('N') -Margin 5 | Write-Output
            New-TextBlock -Row $row -Column 3 -Text $_.Percentage.ToString('P0') -Margin 5 | Write-Output
            $row++
        })
    
    $legend = New-Border -Dock Right -VerticalAlignment Center -BorderBrush Black -BorderThickness 1 -Margin 5 -Child $legendContent

    $canvas = New-Canvas -Margin 20
       
    function Get-PieSlicePaths {
        function New-Point ($x, $y) { return New-Object -TypeName 'System.Windows.Point' -ArgumentList $x, $y }
        
        $size = [Math]::Min($canvas.ActualWidth, $canvas.ActualHeight)
        $arcSize = New-Object -TypeName 'System.Windows.Size' -ArgumentList ($size / 2), ($size /2)
        $origin = New-Point ($canvas.ActualWidth / 2) ($canvas.ActualHeight / 2)
        $radius = $size / 2

        function Convert-ToCartesian($r, $theta) {
            $thetaRadians = $theta * 2 * [Math]::PI
            $x = $origin.X + $r * [Math]::Sin($thetaRadians)
            $y = $origin.Y - $r * [Math]::Cos($thetaRadians)
            
            return New-Point $x $y
        }
        
        $theta = 0
        $previousRadial = New-Point $origin.X ($origin.Y - $arcSize.Height)
        
        foreach($item in $computed) {
            $theta += $item.Percentage
            $nextRadial = Convert-ToCartesian $radius $theta
            $isLargeArc = $item.Percentage -gt 0.5
        
            $geom = New-StreamGeometry
            $ctx = $geom.Open()
            try {
                $ctx.BeginFigure($origin, $true, $true)
                $ctx.LineTo($previousRadial, $true, $false)
                $ctx.ArcTo($nextRadial, $arcSize, 0, $isLargeArc, 'Clockwise', $true, $false)
                $ctx.LineTo($origin, $true, $false)
            } finally { $ctx.Close() }
            
            New-Path -Data $geom -Fill $item.Brush -Stroke ([Windows.Media.Brushes]::Black) -StrokeThickness 1 | Write-Output 
            
            $previousRadial = $nextRadial
        }
    }
    
    if($chartTitle) { $chartTitleTextBlock = New-TextBlock -Text $chartTitle -FontSize 24 -FontWeight 'Bold' -TextAlignment 'Center' -Dock 'Top' }
    
    $container = New-DockPanel -Children ($chartTitleTextBlock, $legend, $canvas | ? { $_ })
    $window = New-Window -Content $container -Title $WindowTitle -Width $width -Height $height
    
    $window.add_Loaded({ Get-PieSlicePaths | % { $canvas.Children.Add($_) } })
    $window.add_SizeChanged({ $canvas.Children.Clear(); Get-PieSlicePaths | % { $canvas.Children.Add($_) } })
    
    if($show) { Show-Window $window }
    else { return $window }
}

http://yfrog.com/h0nyydp
.\New-PieChart.ps1 -CountProperty 'Value' -ChartTitle 'This is a Test Chart' -Items @{ Alpha = 40; Beta = 30; Delta = 20; Gamma = 10 } -Show