如何从Xamarin.Forms UWP打印pdf文档？

var printManager = PrintManager.GetForCurrentView();

printManager.PrintTaskRequested += PrintManager_PrintTaskRequested;

private void PrintManager_PrintTaskRequested(PrintManager sender, PrintTaskRequestedEventArgs args)
{
    var printTask = args.Request.CreatePrintTask("Print PDF", OnPrintTaskSourceRequested);

    // 设置打印任务的设置和内容
    printTask.Options.Orientation = PrintOrientation.Portrait;
    printTask.Options.MediaSize = PrintMediaSize.IsoA4;

    // 设置打印内容
    printTask.SetSource(printDocumentSource);
}

private void OnPrintTaskSourceRequested(PrintTaskSourceRequestedArgs args)
{
    var deferral = args.GetDeferral();

    var printDocument = new PrintDocument();
    printDocument.Paginate += PrintDocument_Paginate;
    printDocument.GetPreviewPage += PrintDocument_GetPreviewPage;
    printDocument.AddPages += PrintDocument_AddPages;

    args.SetSource(printDocument.DocumentSource);

    deferral.Complete();
}

private void PrintDocument_Paginate(object sender, PaginateEventArgs e)
{
    // 设置打印内容的页面布局和数量
    printDocument.SetPreviewPageCount(1, PreviewPageCountType.Final);
}

private void PrintDocument_GetPreviewPage(object sender, GetPreviewPageEventArgs e)
{
    // 生成打印内容的预览页面
    var previewPage = new PrintPreviewPage();
    e.SetPreviewPage(previewPage);
}

private void PrintDocument_AddPages(object sender, AddPagesEventArgs e)
{
    // 将打印内容添加到打印文档中
    printDocument.AddPage(previewPage);

    // 打印文档完成
    printDocument.AddPagesComplete();
}

private async void PrintButton_Click(object sender, EventArgs e)
{
    await PrintManager.ShowPrintUIAsync();
}