v0.1.5: sidebar playlist tree auto-scrolls when dragging near its edges

lintunes/gui/sidebar.py

@@ -2,12 +2,14 @@ from PyQt6.QtWidgets import (
     QWidget, QVBoxLayout, QPushButton, QTreeWidget, QTreeWidgetItem, QMenu,
     QInputDialog, QMessageBox, QAbstractItemView,
 )
-from PyQt6.QtCore import Qt, QTimer, pyqtSignal
+from PyQt6.QtCore import Qt, QTimer, QPoint, pyqtSignal
 from PyQt6.QtGui import QBrush, QPainter, QPixmap
 
 from lintunes.models import PlaylistType
 from lintunes import tagging
-from lintunes.gui.track_table import parse_tracks_mime, TRACKS_MIME
+from lintunes.gui.track_table import (
+    parse_tracks_mime, TRACKS_MIME, autoscroll_direction,
+)
 from lintunes.gui.playlist_ops import add_tracks_with_dup_check
 from lintunes.gui.art_window import ArtWindow
 from lintunes.gui import drag_ghost
@@ -166,6 +168,15 @@ class PlaylistTree(QTreeWidget):
         self.currentItemChanged.connect(self._on_selection_changed)
         self.itemChanged.connect(self._on_item_renamed)
 
+        # Edge auto-scroll during a drag (Qt's built-in autoscroll never runs
+        # because our dragMoveEvent accepts the event itself). Mirrors
+        # track_table's Round 13 machinery.
+        self._autoscroll_dir = 0
+        self._autoscroll_pos: QPoint | None = None
+        self._autoscroll_timer = QTimer(self)
+        self._autoscroll_timer.setInterval(40)
+        self._autoscroll_timer.timeout.connect(self._autoscroll_tick)
+
         manager.playlists_changed.connect(self.rebuild)
         self.rebuild()
 
@@ -377,31 +388,41 @@ class PlaylistTree(QTreeWidget):
             event.ignore()
 
     def dragMoveEvent(self, event):
-        drag_ghost.move(self.viewport().mapToGlobal(event.position().toPoint()))
+        pos = event.position().toPoint()
+        drag_ghost.move(self.viewport().mapToGlobal(pos))
         if event.source() is self:
-            # Moving a playlist into/out of folders
+            # Moving a playlist into/out of folders. The tree accepts an
+            # internal move somewhere no matter what (empty area = top level),
+            # so edge auto-scroll stays live even over non-folder rows —
+            # otherwise scrolling down to a distant folder would be nearly
+            # impossible past the playlists in between.
             self._clear_drop_target()
-            target = self.itemAt(event.position().toPoint())
+            target = self.itemAt(pos)
             kind = target.data(0, KIND_ROLE) if target else ""
             if kind in ("folder", "") or target is None:
                 event.acceptProposedAction()
             else:
                 event.ignore()
+            self._update_autoscroll(pos, accepted=True)
             return
         if not event.mimeData().hasFormat(TRACKS_MIME):
             self._clear_drop_target()
+            self._update_autoscroll(pos, accepted=False)
             event.ignore()
             return
-        target = self.itemAt(event.position().toPoint())
+        target = self.itemAt(pos)
         if target and target.data(0, KIND_ROLE) == "playlist":
             self._set_drop_target(target)
             event.acceptProposedAction()
+            self._update_autoscroll(pos, accepted=True)
         else:
             self._clear_drop_target()
             event.ignore()
+            self._update_autoscroll(pos, accepted=False)
 
     def dragLeaveEvent(self, event):
         self._clear_drop_target()
+        self._stop_autoscroll()
         super().dragLeaveEvent(event)
 
     def _set_drop_target(self, item):
@@ -422,8 +443,43 @@ class PlaylistTree(QTreeWidget):
             self._drop_target.setForeground(0, self._drop_target_fg)
             self._drop_target = None
 
+    # ---- drag auto-scroll ----
+
+    def _update_autoscroll(self, pos: QPoint, accepted: bool):
+        """Start/stop edge auto-scroll based on the drag's position."""
+        self._autoscroll_pos = pos
+        self._autoscroll_dir = autoscroll_direction(
+            pos.y(), self.viewport().height(), accepted)
+        if self._autoscroll_dir and not self._autoscroll_timer.isActive():
+            self._autoscroll_timer.start()
+        elif not self._autoscroll_dir and self._autoscroll_timer.isActive():
+            self._autoscroll_timer.stop()
+
+    def _autoscroll_tick(self):
+        bar = self.verticalScrollBar()
+        before = bar.value()
+        bar.setValue(before + self._autoscroll_dir)
+        if bar.value() == before:  # reached the top/bottom — nothing more to do
+            self._autoscroll_timer.stop()
+            return
+        # The cursor may be held still while rows scroll under it, so keep the
+        # drop-target highlight on the row now beneath it (track drags only;
+        # internal playlist moves never set a drop target).
+        if self._autoscroll_pos is not None and self._drop_target is not None:
+            target = self.itemAt(self._autoscroll_pos)
+            if target and target.data(0, KIND_ROLE) == "playlist":
+                self._set_drop_target(target)
+            else:
+                self._clear_drop_target()
+
+    def _stop_autoscroll(self):
+        self._autoscroll_dir = 0
+        self._autoscroll_pos = None
+        self._autoscroll_timer.stop()
+
     def dropEvent(self, event):
         self._clear_drop_target()
+        self._stop_autoscroll()
         target = self.itemAt(event.position().toPoint())
         if event.source() is self:
             item = self.currentItem()