;;; acss-structure.el --- CSS -- Cascaded Speech Style structure
;;; $Id$
;;; $Author: tv.raman.tv $
;;; Description: DTK Interface for Cascaded Speech Style Sheets
;;; Keywords:emacspeak, audio interface to emacs CSS
;;{{{  LCD Archive entry:

;;; LCD Archive Entry:
;;; emacspeak| T. V. Raman |raman@cs.cornell.edu
;;; A speech interface to Emacs |
;;; $Date: 2007-08-25 18:28:19 -0700 (Sat, 25 Aug 2007) $ |
;;;  $Revision: 4532 $ |
;;; Location undetermined
;;;

;;}}}
;;{{{  Copyright:

;;;Copyright (C) 1995 -- 2007, T. V. Raman 
;;; Copyright (c) 1996 by T. V. Raman
;;; All Rights Reserved.
;;;
;;; This file is not part of GNU Emacs, but the same permissions apply.
;;;
;;; GNU Emacs is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 2, or (at your option)
;;; any later version.
;;;
;;; GNU Emacs is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Emacs; see the file COPYING.  If not, write to
;;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;}}}

;;{{{  Introduction:

;;; Commentary:
;;; The CSS Speech Style Sheet specification defines a number of
;;; abstract device independent voice properties.
;;; A setting conforming to the CSS speech specification can be
;;; represented in elisp as a structure.

;;; We will refer to this structure as a "speech style".
;;; This structure needs to be mapped to device dependent codes to
;;; produce the desired effect.
;;; This module forms a bridge between User Agents e.g. Emacs-w3 that
;;; wish to implement a speech style sheet
;;; and Emacspeak's dectalk-voices module.
;;; Emacspeak produces voice change effects by examining the value of
;;; text-property 'personality.

;;; Think of a buffer of formatted text along with the text-property
;;; 'personality appropriately set as a "aural display list".
;;; Applications like W3 that produce such formatted buffers  call function
;;; acss-personality-from-speech-style  with a  "speech-style"
;;; --a structure as defined in this module and get back a symbol that
;;; they then assign to the value of property 'personality.
;;;Emacspeak's rendering engine then does the needful at the time
;;;speech is produced.
;;; Function acss-personality-from-speech-style does the following:
;;; Takes as input a "speech style"
;;;(1)  Computes a symbol that will be used henceforth to refer to this
;;; specific speech style.
;;; (2) Examines emacspeak's internal voice table to see if this
;;; speech style has a voice already defined.
;;; If so it returns immediately.
;;; Otherwise, it does the additional work of defining a dectalk-voice for
;;; future use.
;;; See module dectalk-voices.el to see how voices are defined.

;;}}}
;;{{{  Required modules

;;; Code:
(require 'cl)
(declaim  (optimize  (safety 0) (speed 3)))

;;}}}
;;{{{ tts common vars 
(defvar tts-default-voice 'paul 
  "Default voice used. ")

;;}}}
;;{{{  A speech style structure

(defstruct  acss
  family
  gain left-volume right-volume
  average-pitch
  pitch-range
  stress
  richness
  punctuations
  )

;;}}}
;;{{{  define from style

;;; may be redefined at runtime when alternative tts engine is
;;; configured.
(defalias 'tts-voice-defined-p 'dectalk-voice-defined-p)
(defalias 'tts-define-voice-from-speech-style
  'dectalk-define-voice-from-speech-style)

(defun acss-personality-from-speech-style (style)
  "First compute a symbol that will be name for this STYLE.
Then see if a voice defined for it.
Finally return the symbol"
  (cond
   ((and (acss-gain style)
         (= 0 (acss-gain style)))
    'inaudible)
   (t
    (let ((f (acss-family style))
          (a (acss-average-pitch style))
          (p (acss-pitch-range style))
          (s (acss-stress style))
          (r (acss-richness style))
          (m (acss-punctuations style))
          (name nil))
      (setq name 
            (intern
             (format "acss%s%s%s%s%s%s"
                     (if f
                         (format "-%s" f)
                       "")
                     (if a
                         (format "-a%s" a)
                       "")
                     (if p
                         (format "-p%s" p)
                       "")
                     (if s
                         (format "-s%s" s)
                       "")
                     (if r
                         (format "-r%s" r)
                       "")
                     (if m
                         (format "-%s" m)
                       ""))))
      (unless (tts-voice-defined-p name)
        (tts-define-voice-from-speech-style name style))
      name))))

;;}}}
(provide  'acss-structure)
;;{{{  emacs local variables

;;; local variables:
;;; folded-file: t
;;; byte-compile-dynamic: nil
;;; end:

;;}}}