批量转换图片大小脚本

param(
	[string]$p="*.jpg",
	[string]$s="800x600",
	[string]$o="out\"
)

if ($MyInvocation.BoundParameters.Count -eq 0) {
	echo "Batch resize image v1.0"
	echo "Usage: resize [filter [WxH [dir]]]"
	echo "  Example: resize *.jpg 800x400 C:\resized"
	echo "  Default: filter = *.jpg, WxH=800x600, dir=.\out"
	echo ""
}

if ($s -match "^(\d+)x(\d+)$") {
	$w=[int]$matches[1]
	$h=[int]$matches[2]
} else {
	echo "Invalid size format."
	exit 1
}

if (-not (Test-Path $o)) {New-Item -ItemType Directory -Path $o | Out-Null}
Add-Type -AssemblyName System.Drawing
foreach ($f in Get-ChildItem -Path . -Filter $p) {
	$i=[System.Drawing.Image]::FromFile($f.FullName)
	if ($i.Width -le $w -and $i.Height -le $h) {
		Copy-Item $f.FullName -Destination (Join-Path -Path $o -ChildPath $f.Name)
		Write-Host "Copied: $($f.Name)"
	} else {
		$rw=$w/$i.Width
		$rh=$h/$i.Height
		$sc=[Math]::Min($rw,$rh)
		$nw=[int]($i.Width*$sc)
		$nh=[int]($i.Height*$sc)
		$ni=New-Object System.Drawing.Bitmap($nw,$nh)
		$g=[System.Drawing.Graphics]::FromImage($ni)
		$g.CompositingQuality=[System.Drawing.Drawing2D.CompositingQuality]::HighQuality
		$g.InterpolationMode=[System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic
		$g.SmoothingMode=[System.Drawing.Drawing2D.SmoothingMode]::HighQuality
		$g.DrawImage($i,0,0,$nw,$nh)
		$ni.Save((Join-Path -Path $o -ChildPath $f.Name),[System.Drawing.Imaging.ImageFormat]::Jpeg)
		$g.Dispose()
		$i.Dispose()
		$ni.Dispose()
		echo "Processed: $($f.Name)"
	}
}
echo "Done."