'inline' in Content_Disposition rather than 'attachment' tells browser to display pdf directly. With 'attachment' the browser would immediately download playframework

FilenameForDownload.scala

private def generatePdf(implicit request: RequestHeader) = {
  val pdf = generator.createPDF()
  SimpleResult(
    header = ResponseHeader(200),
    body = Enumerator(pdf)).withHeaders(
      (CONTENT_DISPOSITION, "inline; filename=my.pdf"),
      (CONTENT_TYPE, "application/pdf")
    )
}