Allow drag and drop of songs to favorite playlists

- allows adding songs from active playlist
to any favorite by drag & drop
- after 500msec hovering with the songs over
desired playlist it becomes current
- drag & drop multiple songs is supported

src/playlist/playlistlistcontainer.cpp

@@ -44,6 +44,7 @@
 #include <QToolButton>
 #include <QShowEvent>
 #include <QContextMenuEvent>
+#include <QMimeData>
 
 #include "core/application.h"
 #include "core/iconloader.h"
@@ -110,6 +111,7 @@ PlaylistListContainer::PlaylistListContainer(QWidget *parent)
 
   QObject::connect(ui_->tree, &PlaylistListView::ItemsSelectedChanged, this, &PlaylistListContainer::ItemsSelectedChanged);
   QObject::connect(ui_->tree, &PlaylistListView::doubleClicked, this, &PlaylistListContainer::ItemDoubleClicked);
+  QObject::connect(ui_->tree, &PlaylistListView::ItemMimeDataDroppedSignal, this, &PlaylistListContainer::ItemMimeDataDropped);
 
   model_->invisibleRootItem()->setData(PlaylistListModel::Type_Folder, PlaylistListModel::Role_Type);
 
@@ -348,6 +350,19 @@ void PlaylistListContainer::ItemDoubleClicked(const QModelIndex &proxy_idx) {
 
 }
 
+void PlaylistListContainer::ItemMimeDataDropped(const QModelIndex &proxy_idx, const QMimeData *q_mimedata) {
+
+  const QModelIndex idx = proxy_->mapToSource(proxy_idx);
+  if (!idx.isValid()) return;
+
+  // Drop playlist rows if type is playlist and it's not active, to prevent selfcopy
+  int playlis_id = idx.data(PlaylistListModel::Role_PlaylistId).toInt();
+  if (idx.data(PlaylistListModel::Role_Type).toInt() == PlaylistListModel::Type_Playlist && playlis_id != app_->playlist_manager()->active_id()) {
+    app_->playlist_manager()->playlist(playlis_id)->dropMimeData(q_mimedata, Qt::CopyAction, -1, 0, QModelIndex());
+  }
+
+}
+
 void PlaylistListContainer::CopyToDevice() {
 
 #ifndef Q_OS_WIN

src/playlist/playlistlistcontainer.h

@@ -63,6 +63,7 @@ class PlaylistListContainer : public QWidget {
   // From the UI
   void NewFolderClicked();
   void ItemDoubleClicked(const QModelIndex &proxy_idx);
+  void ItemMimeDataDropped(const QModelIndex &proxy_idx, const QMimeData *q_mimedata);
 
   // From the model
   void PlaylistPathChanged(const int id, const QString &new_path);

src/playlist/playlistlistview.cpp

@@ -23,6 +23,7 @@
 
 #include <QWidget>
 #include <QFont>
+#include <QMimeData>
 #include <QPainter>
 #include <QPalette>
 #include <QRect>
@@ -30,6 +31,7 @@
 
 #include "widgets/autoexpandingtreeview.h"
 #include "playlistlistview.h"
+#include "playlist.h"
 
 PlaylistListView::PlaylistListView(QWidget *parent) : AutoExpandingTreeView(parent) {}
 
@@ -64,3 +66,72 @@ bool PlaylistListView::ItemsSelected() const {
 void PlaylistListView::selectionChanged(const QItemSelection&, const QItemSelection&) {
   emit ItemsSelectedChanged(selectionModel()->selectedRows().count() > 0);
 }
+
+void PlaylistListView::dragEnterEvent(QDragEnterEvent *e) {
+
+  if (e->mimeData()->hasFormat(Playlist::kRowsMimetype)) {
+    e->acceptProposedAction();
+  }
+  else {
+    AutoExpandingTreeView::dragEnterEvent(e);
+  }
+
+}
+
+void PlaylistListView::dragMoveEvent(QDragMoveEvent *e) {
+
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+    QModelIndex drag_hover_tab_ = indexAt(e->position().toPoint());
+#else
+    QModelIndex drag_hover_tab_ = indexAt(e->pos());
+#endif
+
+  if (e->mimeData()->hasFormat(Playlist::kRowsMimetype)) {
+    if (drag_hover_tab_ != currentIndex()) {
+      e->setDropAction(Qt::CopyAction);
+      e->accept(visualRect(drag_hover_tab_));
+      setCurrentIndex(drag_hover_tab_);
+      if (drag_hover_timer_.isActive()) {
+        drag_hover_timer_.stop();
+      }
+      drag_hover_timer_.start(kDragHoverTimeout, this);
+    }
+  }
+  else {
+    AutoExpandingTreeView::dragMoveEvent(e);
+  }
+
+}
+
+void PlaylistListView::dragLeaveEvent(QDragLeaveEvent *e) {
+
+  if (drag_hover_timer_.isActive()) {
+    drag_hover_timer_.stop();
+  }
+  AutoExpandingTreeView::dragLeaveEvent(e);
+
+}
+
+void PlaylistListView::timerEvent(QTimerEvent *e) {
+
+  QTreeView::timerEvent(e);
+  if (e->timerId() == drag_hover_timer_.timerId()) {
+    drag_hover_timer_.stop();
+    emit doubleClicked(currentIndex());
+  }
+
+}
+
+void PlaylistListView::dropEvent(QDropEvent *e) {
+
+  if (e->mimeData()->hasFormat(Playlist::kRowsMimetype)) {
+    if (drag_hover_timer_.isActive()) {
+      drag_hover_timer_.stop();
+    }
+    emit ItemMimeDataDroppedSignal(currentIndex(), e->mimeData());
+  }
+  else  {
+    AutoExpandingTreeView::dropEvent(e);
+  }
+
+}

src/playlist/playlistlistview.h

@@ -24,6 +24,7 @@
 
 #include "config.h"
 
+#include <QBasicTimer>
 #include <QObject>
 #include <QWidget>
 #include <QString>
@@ -31,6 +32,11 @@
 #include "widgets/autoexpandingtreeview.h"
 
 class QPaintEvent;
+class QDragEnterEvent;
+class QDragLeaveEvent;
+class QDragMoveEvent;
+class QDropEvent;
+class QTimerEvent;
 
 class PlaylistListView : public AutoExpandingTreeView {
   Q_OBJECT
@@ -42,11 +48,23 @@ class PlaylistListView : public AutoExpandingTreeView {
 
  signals:
   void ItemsSelectedChanged(const bool);
+  void ItemMimeDataDroppedSignal(const QModelIndex &proxy_idx, const QMimeData *q_mimedata);
 
  protected:
   // QWidget
   void paintEvent(QPaintEvent *event) override;
   void selectionChanged(const QItemSelection&, const QItemSelection&) override;
+
+  void dragEnterEvent(QDragEnterEvent *e) override;
+  void dragMoveEvent(QDragMoveEvent *e) override;
+  void dragLeaveEvent(QDragLeaveEvent *e) override;
+  void dropEvent(QDropEvent *e) override;
+  void timerEvent(QTimerEvent *e) override;
+
+ private:
+  static const int kDragHoverTimeout = 500;
+
+  QBasicTimer drag_hover_timer_;
 };
 
 #endif  // PLAYLISTVIEW_H