Allow wrapping to last track with Previous button. Closes: #1726

When at the first track and "Previous" is pressed, jump to the last
track in the playlist if "Repeat Playlist" is active. This makes the
behavior more intuitive and consistent with the "Next" button.

Author: radioactiveman

src/libaudcore/drct.cc

@@ -217,7 +217,7 @@ EXPORT void aud_drct_pl_prev()
     if (playlist == Playlist())
         playlist = Playlist::active_playlist();
 
-    playlist.prev_song();
+    playlist.prev_song(aud_get_bool("repeat"));
 }
 
 EXPORT void aud_drct_pl_prev_album()

src/libaudcore/playlist-data.cc

@@ -866,12 +866,18 @@ PlaylistData::PosChange PlaylistData::shuffle_pos_random(bool repeat,
     return NO_POS;
 }
 
-int PlaylistData::pos_before(int ref_pos, bool shuffle) const
+int PlaylistData::pos_before(int ref_pos, bool shuffle, bool repeat) const
 {
     if (shuffle)
         return shuffle_pos_before(ref_pos);
 
-    return (ref_pos > 0) ? ref_pos - 1 : -1;
+    if (ref_pos > 0)
+        return ref_pos - 1;
+
+    if (repeat)
+        return m_entries.len() - 1;
+
+    return -1;
 }
 
 PlaylistData::PosChange PlaylistData::pos_after(int ref_pos, bool shuffle,
@@ -1006,9 +1012,14 @@ void PlaylistData::set_position(int entry_num)
 }
 
 bool PlaylistData::prev_song()
+{
+    return prev_song(false);
+}
+
+bool PlaylistData::prev_song(bool repeat)
 {
     bool shuffle = aud_get_bool("shuffle");
-    int pos = pos_before(position(), shuffle);
+    int pos = pos_before(position(), shuffle, repeat);
     if (pos < 0)
         return false;
 
@@ -1030,6 +1041,7 @@ bool PlaylistData::next_song(bool repeat)
 bool PlaylistData::prev_album()
 {
     bool shuffle = aud_get_bool("shuffle");
+    bool repeat = aud_get_bool("repeat");
     int pos = position();
 
     // find the start of the previous album
@@ -1041,7 +1053,7 @@ bool PlaylistData::prev_album()
 
         while (1)
         {
-            auto prev_entry = entry_at(pos_before(pos, shuffle));
+            auto prev_entry = entry_at(pos_before(pos, shuffle, repeat));
             if (!prev_entry || !same_album(entry->tuple, prev_entry->tuple))
                 break;
 
@@ -1053,7 +1065,7 @@ bool PlaylistData::prev_album()
 
         // we're at the start of the current album
         // one more song back puts us in the previous album
-        pos = pos_before(pos, shuffle);
+        pos = pos_before(pos, shuffle, repeat);
         in_prev_album = true;
     }
 

src/libaudcore/playlist-data.h

@@ -101,6 +101,7 @@ class PlaylistData
     void set_position(int entry_num);
 
     bool prev_song();
+    bool prev_song(bool repeat);
     bool next_song(bool repeat);
     bool prev_album();
     bool next_album(bool repeat);
@@ -159,7 +160,7 @@ class PlaylistData
     PosChange shuffle_pos_after(int ref_pos, bool by_album) const;
     PosChange shuffle_pos_random(bool repeat, bool by_album) const;
 
-    int pos_before(int ref_pos, bool shuffle) const;
+    int pos_before(int ref_pos, bool shuffle, bool repeat) const;
     PosChange pos_after(int ref_pos, bool shuffle, bool by_album) const;
     PosChange pos_new(bool repeat, bool shuffle, bool by_album,
                       int hint_pos) const;

src/libaudcore/playlist.cc

@@ -659,6 +659,10 @@ EXPORT bool Playlist::prev_song() const
 {
     SIMPLE_WRAPPER(bool, false, prev_song);
 }
+EXPORT bool Playlist::prev_song(bool repeat) const
+{
+    SIMPLE_WRAPPER(bool, false, prev_song, repeat);
+}
 EXPORT bool Playlist::prev_album() const
 {
     SIMPLE_WRAPPER(bool, false, prev_album);

src/libaudcore/playlist.h

@@ -253,6 +253,12 @@ class Playlist
      * true on success, false if playlist position was not changed. */
     bool prev_song() const;
 
+    /* Returns the playlist position to the previous entry in playback order.
+     * At the beginning of the playlist, wraps around to the end if <repeat>
+     * is true.  Returns true on success, false if playlist position was not
+     * changed. */
+    bool prev_song(bool repeat) const;
+
     /* Returns the playlist position to the first entry in playback order where
      * the album is not the current album.  Does not support wrapping past the
      * beginning of the playlist.  Returns true on success, false if playlist