Reworks to the shuffle system to improve performance and allow fast shuffling from a big library (but this work for all database views)

This improvement brings a huge performance improvement to start a random mix of your library. Previously, the only way to do this was to increase the size of a playlist with absurd sizes number. Now it will respect the limitation but will insert random songs from the current view.

Database: Add true random songs in playlist if it is gonna exceed its maximum capacity

More context is available here : https://www.reddit.com/r/rockbox/comments/1ez0mq4/i_developped_true_full_library_shuffle_for/

Also :
- Improved layout in the DB browser
- New default max playlists capacity is now 2000 on old PortalPlayer targets to give a better user experience and not having to wait dozens of seconds while creating a playlist
- "Show insert shuffled" option is now true by default
- Add a new shortcut to play all songs shuffled in the DB browser
- Now the feature is fully optional and enabled only on targets that have more than 2MB of RAM
- Add entries about this feature in the manual to explain it to the users
Change-Id: I1aebaf7ebcff2bf907080f1861027d530619097c

Change-Id: I3354923b148eeef1975171990e814a1a505d1df0

1 files changed, 10 insertions, 3 deletions

diff --git a/apps/onplay.c b/apps/onplay.c
index 4f748204df..045af275bc 100644
--- a/apps/onplay.c
+++ b/apps/onplay.c
@@ -302,7 +302,7 @@ static int add_to_playlist(void* arg)
 
     /* warn if replacing the playlist */
     if (new_playlist && !warn_on_pl_erase())
-        return 0;
+        return 1;
 
     splash(0, ID2P(LANG_WAIT));
 
@@ -340,7 +340,7 @@ static int add_to_playlist(void* arg)
     }
 
     playlist_set_modified(NULL, true);
-    return false;
+    return 0;
 }
 
 static bool view_playlist(void)
@@ -1255,7 +1255,7 @@ static int execute_hotkey(bool is_wps)
 }
 #endif /* HOTKEY */
 
-int onplay(char* file, int attr, int from_context, bool hotkey)
+int onplay(char* file, int attr, int from_context, bool hotkey, int customaction)
 {
     const struct menu_item_ex *menu;
     onplay_result = ONPLAY_OK;
@@ -1294,6 +1294,13 @@ int onplay(char* file, int attr, int from_context, bool hotkey)
 #else
     (void)hotkey;
 #endif
+    if (customaction == ONPLAY_CUSTOMACTION_SHUFFLE_SONGS) {
+        int returnCode = add_to_playlist(&addtopl_replace_shuffled);
+        if (returnCode == 1)
+            // User did not want to erase his current playlist, so let's show again the database main menu
+            return ONPLAY_RELOAD_DIR;
+        return ONPLAY_START_PLAY;
+    }
 
     push_current_activity(ACTIVITY_CONTEXTMENU);
     if (from_context == CONTEXT_WPS)