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|
;;; emms-info.el --- Retrieving track information
;; Copyright (C) 2005, 2006 Free Software Foundation Inc.
;; Author: Jorgen Schaefer <forcer@forcix.cx>
;; This program 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
;; of the License, or (at your option) any later version.
;; This program 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 this program; if not, write to the Free Software
;; Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
;; 02110-1301 USA
;;; Commentary:
;; This EMMS module provides a way to add information for a track.
;; This can use an ID3 or OGG comment like syntax.
;; The code will add info symbols to the track. The following symbols
;; are defined:
;; info-artist - string naming the artist
;; info-title - string naming the title of the song
;; info-album - string naming the album
;; info-tracknumber - string(?) naming the track number
;; info-year - string naming the year
;; info-note - string of free-form entry
;; info-genre - string naming the genre
;; info-playing-time - number giving the seconds of playtime
;;; Code:
(require 'emms)
(require 'later-do)
(defgroup emms-info nil
"*Track information. ID3, OGG, etc."
:group 'emms)
(defcustom emms-info-auto-update t
"*Non-nil when EMMS should update track information if the file changes.
This will cause hard drive activity on track loading. If this is
too annoying for you, set this variable to nil."
:type 'boolean
:group 'emms-info)
(defcustom emms-info-asynchronously t
"*Non-nil when track information should be loaded asynchronously.
This requires `later-do', which should come with EMMS."
:type 'boolean
:group 'emms-info)
(defcustom emms-info-functions nil
"*Functions which add information to tracks.
Each is called with a track as argument."
:type 'hook
:group 'emms-info)
(defvar emms-info-asynchronous-tracks 0
"Number of tracks we're waiting for to be done.")
;; cache support (break into a separate file and make
;; emms-info-really-initialize-track into a variable controlling which
;; function to use)?
;; The cache is invalidated when track names are changed. It also does
;; not differenciate between file or uri tracks, and relies on the
;; uniqueness of the name.
;; usage - in your .emacs
;; (add-hook 'after-init-hook 'emms-info-cache-restore)
;; (add-hook 'kill-emacs-hook 'emms-info-cache-save)
;; this is works much better with a later-do-interval of something
;; like 0.001
(define-hash-table-test 'string-hash 'string= 'sxhash)
(defvar emms-info-cache (make-hash-table :test 'string-hash)
"A mapping of paths to file info.
This is used to cache file info over emacs sessions.")
(defvar emms-info-cache-file "~/.emms-cache"
"A file used to store cached file info information over sessions")
(defvar emms-info-cache-dirty nil
"True if the cache has been updated since init.")
(defun emms-info-initialize-track (track)
"Initialize TRACK with emms-info information.
This is a suitable value for `emms-track-initialize-functions'."
(if (not emms-info-asynchronously)
(emms-info-really-initialize-track track)
(setq emms-info-asynchronous-tracks (1+ emms-info-asynchronous-tracks))
(later-do 'emms-info-really-initialize-track track)))
(defun emms-info-really-initialize-track (track)
"Really initialize TRACK.
Return t when the track got changed."
(let ((file-mtime (when emms-info-auto-update
(emms-info-track-file-mtime track)))
(name (emms-track-get track 'name))
cached-track
updated)
(when (setq cached-track (gethash name emms-info-cache))
;; We need to modify TRACK. This way we lose information already
;; present in TRACK, which is not necessarily what we want, but
;; it's efficient.
(setcar track (car cached-track))
(setcdr track (cdr cached-track)))
;; if uncached, or cached and the time has changed
(when (or (not cached-track)
(and cached-track
emms-info-auto-update
(emms-time-less-p
(emms-track-get track 'info-mtime) file-mtime)))
(setq updated t)
(run-hook-with-args 'emms-info-functions track))
(emms-track-set track 'info-mtime file-mtime)
(emms-track-updated track)
(when (or (not cached-track)
updated)
(puthash name track emms-info-cache)
(setq emms-info-cache-dirty t))
(when emms-info-asynchronously
(setq emms-info-asynchronous-tracks (1- emms-info-asynchronous-tracks))
(when (zerop emms-info-asynchronous-tracks)
(message "EMMS: All track information loaded.")))
t))
(defun emms-info-cache-save ()
"Save the info cache to a file."
(when emms-info-cache-dirty
(message "Saving emms info cache...")
(set-buffer (get-buffer-create " emms-info-cache "))
(erase-buffer)
(maphash (lambda (k v)
(insert (format
"(puthash %S '%S emms-info-cache)\n" k v)))
emms-info-cache)
(set-buffer-file-coding-system 'mule-utf-8)
(write-region (point-min) (point-max) emms-info-cache-file)
(kill-buffer (current-buffer))
(message "Saving emms info cache...done")
(setq emms-info-cache-dirty nil)))
(defun emms-info-cache-restore ()
"Restore the info cache from a file."
(load emms-info-cache-file t nil t)
(setq emms-info-cache-dirty nil))
(defun emms-info-track-file-mtime (track)
"Return the mtime of the file of TRACK, if any.
Return zero otherwise."
(if (eq (emms-track-type track)
'file)
(nth 5 (file-attributes (emms-track-name track)))
0))
(defun emms-info-track-description (track)
"Return a description of the current track."
(let ((artist (emms-track-get track 'info-artist))
(title (emms-track-get track 'info-title)))
(if (and artist title)
(format "%s - %s" artist title)
(emms-track-simple-description track))))
(provide 'emms-info)
;;; emms-info.el ends here
|
