在 Windows 本地批量将 PPT/PPTX/PPTM 文件转换为 PDF，用于课件等文件的批量归档，传到只接受 PDF 的地方

p2pb.ps1

# 使用方式：`powershell -ExecutionPolicy Bypass -File .\p2pb.ps1 -InputDir .\课件 -OutputDir .\课件`，

# 如需覆盖已有 PDF 可加 `-Overwrite` 参数。

# 不加 -Flatten 保留原目录结构输出。
# 加 -Flatten，所有 PDF 都直接放进 OutputDir。
# 如果不同子目录里有同名 PPT，比如 ch4.pptx，会自动输出为 ch4.pdf、ch4 (1).pdf、ch4 (2).pdf。

# 其原理是通过 PowerShell 调用 Microsoft PowerPoint 的 COM 自动化接口，静默打开演示文稿，
# 并使用 PowerPoint 自带的 `SaveAs(..., ppSaveAsPDF)` 导出 PDF，因此转换效果基本与手动用 PowerPoint 导出一致。

param(
    [string]$InputDir = ".",
    [string]$OutputDir = ".\pdf",
    [switch]$Overwrite,
    [switch]$Flatten
)

$ErrorActionPreference = "Continue"

$msoTrue = -1
$msoFalse = 0
$ppAlertsNone = 1
$ppWindowMinimized = 2
$ppSaveAsPDF = 32

function Get-PathKey {
    param([string]$Path)
    return [System.IO.Path]::GetFullPath($Path).ToLowerInvariant()
}

function Get-UniquePdfPath {
    param(
        [string]$Dir,
        [string]$BaseName,
        [hashtable]$UsedPaths,
        [bool]$AllowOverwriteBase
    )

    $candidate = Join-Path $Dir ($BaseName + ".pdf")
    $key = Get-PathKey $candidate

    # 如果允许覆盖，则第一个同名文件可以直接使用 base.pdf；
    # 但同一轮转换里后续重复文件仍然会改名。
    if (-not $UsedPaths.ContainsKey($key)) {
        if ($AllowOverwriteBase -or -not (Test-Path -LiteralPath $candidate)) {
            $UsedPaths[$key] = $true
            return $candidate
        }
    }

    $i = 1
    while ($true) {
        $candidate = Join-Path $Dir ("{0} ({1}).pdf" -f $BaseName, $i)
        $key = Get-PathKey $candidate

        if (-not $UsedPaths.ContainsKey($key) -and -not (Test-Path -LiteralPath $candidate)) {
            $UsedPaths[$key] = $true
            return $candidate
        }

        $i++
    }
}

$InputDir = (Resolve-Path -LiteralPath $InputDir).Path
New-Item -ItemType Directory -Force -Path $OutputDir | Out-Null
$OutputDir = (Resolve-Path -LiteralPath $OutputDir).Path

$logPath = Join-Path $OutputDir "convert-log.txt"
"Start: $(Get-Date)" | Out-File -Encoding UTF8 $logPath

$ppt = $null
$usedPdfPaths = @{}

try {
    $ppt = New-Object -ComObject PowerPoint.Application
    $ppt.DisplayAlerts = $ppAlertsNone

    try {
        $ppt.WindowState = $ppWindowMinimized
    } catch {}

    $files = Get-ChildItem -Path $InputDir -Recurse -File |
        Where-Object {
            $_.Extension.ToLowerInvariant() -in ".pptx", ".pptm", ".ppt" -and
            $_.Name -notlike "~$*"
        }

    foreach ($file in $files) {
        if ($Flatten) {
            $targetDir = $OutputDir
            $pdfPath = Get-UniquePdfPath `
                -Dir $targetDir `
                -BaseName $file.BaseName `
                -UsedPaths $usedPdfPaths `
                -AllowOverwriteBase $Overwrite.IsPresent
        }
        else {
            $relative = $file.FullName.Substring($InputDir.Length).TrimStart('\')
            $relativeDir = Split-Path $relative -Parent

            $targetDir = if ($relativeDir) {
                Join-Path $OutputDir $relativeDir
            } else {
                $OutputDir
            }

            New-Item -ItemType Directory -Force -Path $targetDir | Out-Null
            $pdfPath = Join-Path $targetDir ($file.BaseName + ".pdf")

            if ((Test-Path -LiteralPath $pdfPath) -and -not $Overwrite) {
                "[SKIP] $($file.FullName)" | Tee-Object -FilePath $logPath -Append
                continue
            }
        }

        New-Item -ItemType Directory -Force -Path $targetDir | Out-Null

        $pres = $null

        try {
            Write-Host "Converting: $($file.FullName)"
            Write-Host "        -> $pdfPath"

            $pres = $ppt.Presentations.Open(
                $file.FullName,
                $msoTrue,
                $msoFalse,
                $msoFalse
            )

            $pres.SaveAs($pdfPath, $ppSaveAsPDF)

            "[OK] $($file.FullName) -> $pdfPath" |
                Tee-Object -FilePath $logPath -Append
        }
        catch {
            "[FAIL] $($file.FullName) :: $($_.Exception.Message)" |
                Tee-Object -FilePath $logPath -Append
        }
        finally {
            if ($pres -ne $null) {
                try { $pres.Close() } catch {}
                [System.Runtime.InteropServices.Marshal]::ReleaseComObject($pres) | Out-Null
            }
        }
    }
}
finally {
    if ($ppt -ne $null) {
        try { $ppt.Quit() } catch {}
        [System.Runtime.InteropServices.Marshal]::ReleaseComObject($ppt) | Out-Null
    }

    [GC]::Collect()
    [GC]::WaitForPendingFinalizers()
}

"End: $(Get-Date)" | Out-File -Encoding UTF8 $logPath -Append
Write-Host "Done. Log: $logPath"