Maintain track headers when changing playlists

app/musicmuster.py

@@ -50,9 +50,9 @@ class Window(QMainWindow, Ui_MainWindow):
 
         # Hard code to the first playlist for now
         # TODO
-        if self.playlist.load_playlist(1):
+        self.playlist.load_playlist(1)
-            self.update_headers()
+        self.update_headers()
-            self.enable_play_next_controls()
+        self.enable_play_next_controls()
 
         self.plLabel = QLabel(f"Playlist: {self.playlist.playlist_name}")
         self.statusbar.addPermanentWidget(self.plLabel)

app/playlists.py

@@ -17,6 +17,7 @@ from PyQt5.QtWidgets import (
 
 import helpers
 import music
+import os
 
 from config import Config
 from datetime import datetime, timedelta
@@ -25,7 +26,6 @@ from model import Notes, Playdates, Playlists, PlaylistTracks, Settings, Tracks
 from ui.dlg_search_database_ui import Ui_Dialog
 from ui.dlg_SelectPlaylist_ui import Ui_dlgSelectPlaylist
 
-
 class Playlist(QTableWidget):
     # Column names
     COL_INDEX = 0
@@ -364,6 +364,12 @@ class Playlist(QTableWidget):
     def calculate_next_start_time(self, row, start):
         "Return this row's end time given its start time"
 
+        if start is None:
+            return None
+        if row is None:
+            DEBUG("calculate_next_start_time() called with row=None")
+            return None
+
         duration = Tracks.get_duration(
             int(self.item(row, self.COL_INDEX).text()))
         return start + timedelta(milliseconds=duration)
@@ -387,8 +393,6 @@ class Playlist(QTableWidget):
         Load tracks and notes from playlist id.
 
         Set first track as next track to play.
-
-        Return True if successful else False.
         """
 
         DEBUG(f"load_playlist(plid={plid})")
@@ -416,22 +420,36 @@ class Playlist(QTableWidget):
         for item in sorted(data, key=lambda x: x[0]):
             self.add_to_playlist(item[1], repaint=False)
 
-        # Set the first non-notes row as next track to play
+        # If this is not the first playlist loaded, we may already have
-        notes_rows = self.meta_get_notes()
+        # a next track set in which case don't change it. Otherwise, set
-        for row in range(self.rowCount()):
+        # the first non-notes row as next track to play.
-            if row in notes_rows:
+        if not self.next_track:
-                continue
+            notes_rows = self.meta_get_notes()
-            self.meta_set_next(row)
+            for row in range(self.rowCount()):
-            self.tracks_changed()
+                if row in notes_rows:
-            return True
+                    continue
+                self.cue_next_track(row)
+                break
 
-        return False
+        # Scroll to top
+        scroll_to = self.item(0, self.COL_INDEX)
+        self.scrollToItem(scroll_to, QAbstractItemView.PositionAtTop)
 
     def meta_clear(self, row):
         "Clear metadata for row"
 
         self.meta_set(row, None)
 
+    def meta_clear_current(self):
+        """
+        Clear current row if there is one. There may not be if
+        we've changed playlists
+        """
+
+        current_row = self.meta_get_current()
+        if current_row:
+            self.meta_clear(current_row)
+
     def meta_find(self, metadata, one=True):
         """
         Search rows for metadata.
@@ -568,7 +586,7 @@ class Playlist(QTableWidget):
             if row in notes_rows:
                 continue
             if self.item(row, self.COL_INDEX):
-                self.meta_set_next(row)
+                self.cue_next_track(row)
                 break
 
         # Tell database to record it as played
@@ -579,7 +597,7 @@ class Playlist(QTableWidget):
         self.played_tracks.append(self.current_track.id)
 
         # Update display
-        self.tracks_changed()
+        self.repaint()
 
     def search_database(self):
         dlg = DbDialog(self)
@@ -609,8 +627,7 @@ class Playlist(QTableWidget):
             return False
 
         if self.item(row, self.COL_INDEX):
-            self.meta_set_next(row)
+            self.cue_next_track(row)
-            self.tracks_changed()
             return True
 
         return False
@@ -626,8 +643,8 @@ class Playlist(QTableWidget):
 
         self.previous_track = self.current_track
         self.previous_track_position = 0
-        self.meta_clear(self.meta_get_current())
+        self.meta_clear_current()
-        self.tracks_changed()
+        self.repaint()
 
     def repaint(self, clear_selection=True):
         "Set row colours, fonts, etc, and save playlist"
@@ -850,31 +867,21 @@ class Playlist(QTableWidget):
         item = QTableWidgetItem(time_str)
         self.setItem(row, self.COL_START_TIME, item)
 
-    def tracks_changed(self):
+    def cue_next_track(self, next_row):
         """
-        One or more of current or next track has changed.
+        Set the passed row as the next track to play
-
-        The row metadata is definitive because the same track may appear
-        more than once in the playlist, but only one track may be marked
-        as current or next.
-
-        Update self.current_track and self.next_track.
         """
 
-        # Update instance variables
-        current_row = self.meta_get_current()
-        if current_row is not None:
-            track_id = int(self.item(current_row, self.COL_INDEX).text())
-            if not self.current_track or self.current_track.id != track_id:
-                self.current_track = Tracks.get_track(track_id)
-        else:
-            self.current_track = None
-
-        next_row = self.meta_get_next()
         if next_row is not None:
+            self.meta_set_next(next_row)
             track_id = int(self.item(next_row, self.COL_INDEX).text())
             if not self.next_track or self.next_track.id != track_id:
                 self.next_track = Tracks.get_track(track_id)
+                # Check we can read it
+                if not self.can_read_track(self.next_track):
+                    self.parent().parent().show_warning(
+                        "Can't read next track",
+                        self.next_track.path)
         else:
             self.next_track = None
 
@@ -937,13 +944,11 @@ class DbDialog(QDialog):
     def double_click(self, entry):
         track_id = entry.data(Qt.UserRole)
         self.add_track(track_id)
+        # Select search text to make it easier for next search
+        self.select_searchtext()
 
     def add_track(self, track_id):
         track = Tracks.track_from_id(track_id)
-        # Store in current playlist in database
-        db_playlist = Playlists.get_playlist_by_id(self.parent().playlist_id)
-        db_playlist.add_track(track)
-        # Add to on-screen playlist
         self.parent().add_to_playlist(track)
         # Select search text to make it easier for next search
         self.select_searchtext()