make-thumbs.ps1

param(
  [string]$FullDir = "assets/awards/full",
  [string]$ThumbDir = "assets/awards/thumbs",
  [int]$Height = 240,
  [long]$Quality = 85,
  [switch]$Force
)

$ErrorActionPreference = "Stop"
Add-Type -AssemblyName System.Drawing

if (-not (Test-Path -LiteralPath $FullDir)) {
  throw "Full image directory not found: $FullDir"
}
if (-not (Test-Path -LiteralPath $ThumbDir)) {
  New-Item -ItemType Directory -Path $ThumbDir | Out-Null
}

$codec = [System.Drawing.Imaging.ImageCodecInfo]::GetImageEncoders() |
  Where-Object { $_.MimeType -eq "image/jpeg" }
$encoder = [System.Drawing.Imaging.Encoder]::Quality
$params = New-Object System.Drawing.Imaging.EncoderParameters(1)
$params.Param[0] = New-Object System.Drawing.Imaging.EncoderParameter($encoder, $Quality)

Get-ChildItem -LiteralPath $FullDir -File |
  Where-Object { $_.Extension -match '^\.(jpg|jpeg|png)$' } |
  ForEach-Object {
    $baseName = $_.BaseName
    if ($baseName.EndsWith("-full")) {
      $thumbName = $baseName.Substring(0, $baseName.Length - 5) + "-thumb.jpg"
    } else {
      $thumbName = $baseName + "-thumb.jpg"
    }

    $thumbPath = Join-Path $ThumbDir $thumbName
    if ((Test-Path -LiteralPath $thumbPath) -and -not $Force) {
      Write-Output "skip $thumbPath"
      return
    }

    $image = [System.Drawing.Image]::FromFile($_.FullName)
    try {
      $width = [int][Math]::Round($image.Width * $Height / $image.Height)
      $bitmap = New-Object System.Drawing.Bitmap($width, $Height)
      $graphics = [System.Drawing.Graphics]::FromImage($bitmap)
      try {
        $graphics.InterpolationMode = [System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic
        $graphics.SmoothingMode = [System.Drawing.Drawing2D.SmoothingMode]::HighQuality
        $graphics.PixelOffsetMode = [System.Drawing.Drawing2D.PixelOffsetMode]::HighQuality
        $graphics.DrawImage($image, 0, 0, $width, $Height)
        $bitmap.Save($thumbPath, $codec, $params)
        Write-Output "wrote $thumbPath ${width}x${Height}"
      } finally {
        $graphics.Dispose()
        $bitmap.Dispose()
      }
    } finally {
      $image.Dispose()
    }
  }