About Colors.md

When I'm having a bad day, I can spend hours just fiddling with colors and recursion ...

Today I wrote an HslEnumerator class which is fun because if you output it to the PowerShell terminal it just goes on producing colors forever:

[HslEnumerator][PoshCode.Pansies.RgbColor]"Goldenrod" | Format-Wide 30 # I do have a wide screen

But I also made something more fun. Out-Colors will colorize tables or lists with fun HSL rainbows...

HslEnumerator.ps1

#requires -Modules Pansies
using namespace System
using namespace System.IO
using namespace System.Collections
using namespace System.Collections.Generic
using namespace System.Linq

class HslEnumerator : IEnumerator[PoshCode.Pansies.RgbColor] {
  hidden [PoshCode.Pansies.RgbColor]$Start = "White"
  [int]$HueStep = 1
  [int]$LightStep = 1
  [int]$SatStep = 1

  # Default constructor so we can cast hashtables
  HslEnumerator() {}

  HslEnumerator([PoshCode.Pansies.RgbColor]$Start) {
    $this.Start = $Start
  }

  # Implement IEnumerator.
  [PoshCode.Pansies.RgbColor]$Current = $null

  [object] get_Current() {
    return $this.Current
  }

  [bool] MoveNext() {
    if ($null -eq $this.Current) {
      $this.Current = $this.Start
      return $true
    }

    $next = $this.Current.ToHsl();
    $next.H += $this.HueStep;
    $next.H %= 360;

    if ($next.S + $this.SatStep -gt 100) {
      $next.S = 20;
    } else {
      $next.S += $this.SatStep;
    }
    if ($next.L + $this.LightStep -gt 80) {
      $next.L = 20;
    } else {
      $next.L += $this.LightStep
    }

    $this.Current = $next.ToRgb();

    return $true;
  }

  [void] Reset() {
    $this.Current = $null;
  }

  # IDisposable is required by IEnumerator
  [void] Dispose() {}
}

Out-Colors.ps1

filter Out-Colors {
    [CmdletBinding()]
    param(
        [HslEnumerator]$Colors = @{ Start = "GoldenRod"; HueStep = 18},

        [Parameter(ValueFromPipeline)]
        $FormatInfoData
    )
    # Only color the data (not the headers)
    if ($_.GetType().Name -eq "FormatEntryData") {
        # Listview
        @($_.FormatEntryInfo.ListViewFieldList).Where{ $_ }.ForEach{
            $null = $Colors.MoveNext()
            $_.FormatPropertyField.propertyValue = $Colors.Current.ToVt() + $_.FormatPropertyField.propertyValue
        }
        # Tableview
        @($_.FormatEntryInfo.FormatPropertyFieldList).Where{ $_ }.ForEach{
            $null = $Colors.MoveNext()
            $_.propertyValue = $Colors.Current.ToVt() + $_.propertyValue
        }
    }
    # Pass through everything
    $_
}