player_thread: disable cross-fading in "single" mode

This commit reimplements the core of the "single" mode.  Instead of
doing the detection in the playlist code from the outside, it is moved
to the player thread, which gets a new option called "border_pause".
It will now pause playback exactly at the beginning of the new song,
making the feature more reliable.

Now that the player thread knows what will happen, it can suppress
cross-fading.

Fixes mantis tickets 0003055 and 0003166.

4 files changed, 47 insertions, 8 deletions

diff --git a/src/player_control.c b/src/player_control.c
index d8d54dfd6..90f616d77 100644
--- a/src/player_control.c
+++ b/src/player_control.c
@@ -211,6 +211,14 @@ pc_set_pause(struct player_control *pc, bool pause_flag)
 }
 
 void
+pc_set_border_pause(struct player_control *pc, bool border_pause)
+{
+	player_lock(pc);
+	pc->border_pause = border_pause;
+	player_unlock(pc);
+}
+
+void
 pc_get_status(struct player_control *pc, struct player_status *status)
 {
 	player_lock(pc);
diff --git a/src/player_control.h b/src/player_control.h
index 5a04ab0f9..a77d31ec5 100644
--- a/src/player_control.h
+++ b/src/player_control.h
@@ -115,6 +115,15 @@ struct player_control {
 	float mixramp_db;
 	float mixramp_delay_seconds;
 	double total_play_time;
+
+	/**
+	 * If this flag is set, then the player will be auto-paused at
+	 * the end of the song, before the next song starts to play.
+	 *
+	 * This is a copy of the queue's "single" flag most of the
+	 * time.
+	 */
+	bool border_pause;
 };
 
 struct player_control *
@@ -207,6 +216,12 @@ pc_set_pause(struct player_control *pc, bool pause_flag);
 void
 pc_pause(struct player_control *pc);
 
+/**
+ * Set the player's #border_pause flag.
+ */
+void
+pc_set_border_pause(struct player_control *pc, bool border_pause);
+
 void
 pc_kill(struct player_control *pc);
 
diff --git a/src/player_thread.c b/src/player_thread.c
index eaf6df303..707fb27ae 100644
--- a/src/player_thread.c
+++ b/src/player_thread.c
@@ -842,6 +842,16 @@ player_song_border(struct player *player)
 	if (!player_wait_for_decoder(player))
 		return false;
 
+	struct player_control *const pc = player->pc;
+	player_lock(pc);
+
+	if (pc->border_pause) {
+		player->paused = true;
+		pc->state = PLAYER_STATE_PAUSE;
+	}
+
+	player_unlock(pc);
+
 	return true;
 }
 
@@ -957,7 +967,10 @@ static void do_play(struct player_control *pc, struct decoder_control *dc)
 			player_dc_start(&player, music_pipe_new());
 		}
 
-		if (player_dc_at_next_song(&player) &&
+		if (/* no cross-fading if MPD is going to pause at the
+		       end of the current song */
+		    !pc->border_pause &&
+		    player_dc_at_next_song(&player) &&
 		    player.xfade == XFADE_UNKNOWN &&
 		    !decoder_lock_is_starting(dc)) {
 			/* enable cross fading in this song?  if yes,
diff --git a/src/playlist.c b/src/playlist.c
index d62865dd1..dc6d8c340 100644
--- a/src/playlist.c
+++ b/src/playlist.c
@@ -109,11 +109,6 @@ playlist_song_started(struct playlist *playlist, struct player_control *pc)
 	playlist->current = playlist->queued;
 	playlist->queued = -1;
 
-	/* Pause if we are in single mode. */
-	if(playlist->queue.single && !playlist->queue.repeat) {
-		pc_set_pause(pc, true);
-	}
-
 	if(playlist->queue.consume)
 		playlist_delete(playlist, pc,
 				queue_order_to_position(&playlist->queue,
@@ -310,7 +305,11 @@ playlist_set_repeat(struct playlist *playlist, struct player_control *pc,
 	if (status == playlist->queue.repeat)
 		return;
 
-	playlist->queue.repeat = status;
+	struct queue *queue = &playlist->queue;
+
+	queue->repeat = status;
+
+	pc_set_border_pause(pc, queue->single && !queue->repeat);
 
 	/* if the last song is currently being played, the "next song"
 	   might change when repeat mode is toggled */
@@ -338,7 +337,11 @@ playlist_set_single(struct playlist *playlist, struct player_control *pc,
 	if (status == playlist->queue.single)
 		return;
 
-	playlist->queue.single = status;
+	struct queue *queue = &playlist->queue;
+
+	queue->single = status;
+
+	pc_set_border_pause(pc, queue->single && !queue->repeat);
 
 	/* if the last song is currently being played, the "next song"
 	   might change when single mode is toggled */