hythmbox-2.98/shell/rb-play-order-random-by-age-and-rating.c

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  1 /*
  2  *  Copyright (C) 2003 Jeffrey Yasskin <jyasskin@mail.utexas.edu>
  3  *
  4  *  This program is free software; you can redistribute it and/or modify
  5  *  it under the terms of the GNU General Public License as published by
  6  *  the Free Software Foundation; either version 2 of the License, or
  7  *  (at your option) any later version.
  8  *
  9  *  The Rhythmbox authors hereby grant permission for non-GPL compatible
 10  *  GStreamer plugins to be used and distributed together with GStreamer
 11  *  and Rhythmbox. This permission is above and beyond the permissions granted
 12  *  by the GPL license by which Rhythmbox is covered. If you modify this code
 13  *  you may extend this exception to your version of the code, but you are not
 14  *  obligated to do so. If you do not wish to do so, delete this exception
 15  *  statement from your version.
 16  *
 17  *  This program is distributed in the hope that it will be useful,
 18  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 20  *  GNU General Public License for more details.
 21  *
 22  *  You should have received a copy of the GNU General Public License
 23  *  along with this program; if not, write to the Free Software
 24  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA.
 25  *
 26  */
 27 
 28 #include "config.h"
 29 
 30 #include "rb-play-order-random-by-age-and-rating.h"
 31 
 32 #include "rhythmdb.h"
 33 #include <time.h>
 34 #include <math.h>
 35 
 36 static void rb_random_play_order_by_age_and_rating_class_init (RBRandomPlayOrderByAgeAndRatingClass *klass);
 37 
 38 static double rb_random_by_age_and_rating_get_entry_weight (RBRandomPlayOrder *rorder,
 39 						 RhythmDB *db, RhythmDBEntry *entry);
 40 
 41 G_DEFINE_TYPE (RBRandomPlayOrderByAgeAndRating,
 42 	       rb_random_play_order_by_age_and_rating,
 43 	       RB_TYPE_RANDOM_PLAY_ORDER)
 44 
 45 static void
 46 rb_random_play_order_by_age_and_rating_class_init (RBRandomPlayOrderByAgeAndRatingClass *klass)
 47 {
 48 	RBRandomPlayOrderClass *rorder;
 49 
 50 	rorder = RB_RANDOM_PLAY_ORDER_CLASS (klass);
 51 	rorder->get_entry_weight = rb_random_by_age_and_rating_get_entry_weight;
 52 }
 53 
 54 RBPlayOrder *
 55 rb_random_play_order_by_age_and_rating_new (RBShellPlayer *player)
 56 {
 57 	RBRandomPlayOrderByAgeAndRating *rorder;
 58 
 59 	rorder = g_object_new (RB_TYPE_RANDOM_PLAY_ORDER_BY_AGE_AND_RATING,
 60 			"player", player,
 61 			NULL);
 62 
 63 	return RB_PLAY_ORDER (rorder);
 64 }
 65 
 66 static void
 67 rb_random_play_order_by_age_and_rating_init (RBRandomPlayOrderByAgeAndRating *porder)
 68 {
 69 }
 70 
 71 static double
 72 rb_random_by_age_and_rating_get_entry_weight (RBRandomPlayOrder *rorder, RhythmDB *db, RhythmDBEntry *entry)
 73 {
 74 	time_t now;
 75 	gulong last_play;
 76 	gulong seconds_since_last_play = 0;
 77 	gdouble rating;
 78 	RhythmDBEntry *playing_entry;
 79 
 80 	/* This finds the log of the number of seconds since the last play.
 81 	 * It handles never played automatically, since now-0 is a valid
 82 	 * argument to log(). */
 83 	time (&now);
 84 
 85 	playing_entry = rb_play_order_get_playing_entry (RB_PLAY_ORDER (rorder));
 86 	if (playing_entry != entry) {
 87 		last_play = rhythmdb_entry_get_ulong (entry, RHYTHMDB_PROP_LAST_PLAYED);
 88 		seconds_since_last_play = now - last_play;
 89 	}
 90 	if (playing_entry != NULL)
 91 		rhythmdb_entry_unref (playing_entry);
 92 
 93 	/* The lowest weight should be 0. */
 94 	if (seconds_since_last_play < 1)
 95 		seconds_since_last_play = 1;
 96 
 97 	rating = rhythmdb_entry_get_double (entry, RHYTHMDB_PROP_RATING);
 98 
 99 	/* treat unrated as 2.5 for the purposes of probabilities */
100 	if (rating < 0.01)
101 		rating = 2.5;
102 
103 	return log (seconds_since_last_play) * (rating + 1.0);
104 }