Support dragging and dropping between playlists

src/playlist/playlist.cpp

@@ -492,11 +492,31 @@ bool Playlist::dropMimeData(const QMimeData* data, Qt::DropAction action, int ro
 
     // Get the list of rows that were moved
     QList<int> source_rows;
+    Playlist* source_playlist = NULL;
+
     QDataStream stream(data->data(kRowsMimetype));
+    stream >> source_playlist;
     stream >> source_rows;
     qStableSort(source_rows); // Make sure we take them in order
 
-    undo_stack_->push(new PlaylistUndoCommands::MoveItems(this, source_rows, row));
+    if (source_playlist == this) {
+      // Dragged from this playlist - rearrange the items
+      undo_stack_->push(new PlaylistUndoCommands::MoveItems(this, source_rows, row));
+    } else {
+      // Drag from a different playlist
+      PlaylistItemList items;
+      foreach (int row, source_rows)
+        items << source_playlist->item_at(row);
+      undo_stack_->push(new PlaylistUndoCommands::InsertItems(this, items, row));
+
+      // Remove the items from the source playlist if it was a move event
+      if (action == Qt::MoveAction) {
+        foreach (int row, source_rows) {
+          source_playlist->undo_stack()->push(
+              new PlaylistUndoCommands::RemoveItems(source_playlist, row, 1));
+        }
+      }
+    }
   } else if (data->hasUrls()) {
     // URL list dragged from the file list or some other app
     InsertUrls(data->urls(), false, row);
@@ -708,6 +728,7 @@ QMimeData* Playlist::mimeData(const QModelIndexList& indexes) const {
   QBuffer buf;
   buf.open(QIODevice::WriteOnly);
   QDataStream stream(&buf);
+  stream << this;
   stream << rows;
   buf.close();
 
@@ -1099,3 +1120,13 @@ void Playlist::QueueLayoutChanged() {
     emit dataChanged(index, index);
   }
 }
+
+QDataStream& operator <<(QDataStream& s, const Playlist* p) {
+  s.writeRawData(reinterpret_cast<char*>(&p), sizeof(p));
+  return s;
+}
+
+QDataStream& operator >>(QDataStream& s, Playlist*& p) {
+  s.readRawData(reinterpret_cast<char*>(&p), sizeof(p));
+  return s;
+}

src/playlist/playlist.h

@@ -240,4 +240,7 @@ class Playlist : public QAbstractListModel {
   QUndoStack* undo_stack_;
 };
 
+QDataStream& operator <<(QDataStream&, const Playlist*);
+QDataStream& operator >>(QDataStream&, Playlist*&);
+
 #endif // PLAYLIST_H

src/playlist/playlistcontainer.cpp

@@ -110,6 +110,7 @@ void PlaylistContainer::ClearFilter() {
 
 void PlaylistContainer::SetManager(PlaylistManager *manager) {
   manager_ = manager;
+  ui_->tab_bar->SetManager(manager);
 
   connect(ui_->tab_bar, SIGNAL(CurrentIdChanged(int)),
           manager, SLOT(SetCurrentPlaylist(int)));

src/playlist/playlisttabbar.cpp

@@ -14,19 +14,27 @@
    along with Clementine.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include "playlist.h"
+#include "playlistmanager.h"
 #include "playlisttabbar.h"
+#include "songmimedata.h"
+#include "radio/radiomimedata.h"
 #include "ui/iconloader.h"
 
 #include <QContextMenuEvent>
 #include <QMenu>
 #include <QInputDialog>
+#include <QtDebug>
 
 PlaylistTabBar::PlaylistTabBar(QWidget *parent)
   : QTabBar(parent),
+    manager_(NULL),
     menu_(new QMenu(this)),
     menu_index_(-1),
     suppress_current_changed_(false)
 {
+  setAcceptDrops(true);
+
   remove_ = menu_->addAction(IconLoader::Load("list-remove"), tr("Remove playlist"), this, SLOT(Remove()));
   rename_ = menu_->addAction(IconLoader::Load("edit-rename"), tr("Rename playlist..."), this, SLOT(Rename()));
   save_ = menu_->addAction(IconLoader::Load("document-save"), tr("Save playlist..."), this, SLOT(Save()));
@@ -44,6 +52,10 @@ void PlaylistTabBar::SetActions(
   new_ = new_playlist;
 }
 
+void PlaylistTabBar::SetManager(PlaylistManager *manager) {
+  manager_ = manager;
+}
+
 void PlaylistTabBar::contextMenuEvent(QContextMenuEvent* e) {
   menu_index_ = tabAt(e->pos());
   rename_->setEnabled(menu_index_ != -1);
@@ -156,3 +168,52 @@ void PlaylistTabBar::TabMoved() {
   }
   emit PlaylistOrderChanged(ids);
 }
+
+void PlaylistTabBar::dragEnterEvent(QDragEnterEvent* e) {
+  if (e->mimeData()->hasUrls() ||
+      e->mimeData()->hasFormat(Playlist::kRowsMimetype) ||
+      qobject_cast<const SongMimeData*>(e->mimeData()) ||
+      qobject_cast<const RadioMimeData*>(e->mimeData())) {
+    e->acceptProposedAction();
+  }
+}
+
+void PlaylistTabBar::dragMoveEvent(QDragMoveEvent* e) {
+  drag_hover_tab_ = tabAt(e->pos());
+
+  if (drag_hover_tab_ == -1) {
+    e->setDropAction(Qt::IgnoreAction);
+    e->ignore();
+    drag_hover_timer_.stop();
+  } else {
+    e->setDropAction(Qt::CopyAction);
+    e->accept(tabRect(drag_hover_tab_));
+
+    if (!drag_hover_timer_.isActive())
+      drag_hover_timer_.start(kDragHoverTimeout, this);
+  }
+}
+
+void PlaylistTabBar::dragLeaveEvent(QDragLeaveEvent*) {
+  drag_hover_timer_.stop();
+}
+
+void PlaylistTabBar::timerEvent(QTimerEvent* e) {
+  QTabBar::timerEvent(e);
+
+  if (e->timerId() == drag_hover_timer_.timerId()) {
+    drag_hover_timer_.stop();
+    if (drag_hover_tab_ != -1)
+      setCurrentIndex(drag_hover_tab_);
+  }
+}
+
+void PlaylistTabBar::dropEvent(QDropEvent* e) {
+  if (drag_hover_tab_ == -1) {
+    e->ignore();
+    return;
+  }
+
+  setCurrentIndex(drag_hover_tab_);
+  manager_->current()->dropMimeData(e->mimeData(), e->proposedAction(), -1, 0, QModelIndex());
+}

src/playlist/playlisttabbar.h

@@ -17,8 +17,11 @@
 #ifndef PLAYLISTTABBAR_H
 #define PLAYLISTTABBAR_H
 
+#include <QBasicTimer>
 #include <QTabBar>
 
+class PlaylistManager;
+
 class QMenu;
 
 class PlaylistTabBar : public QTabBar {
@@ -27,7 +30,10 @@ class PlaylistTabBar : public QTabBar {
 public:
   PlaylistTabBar(QWidget *parent = 0);
 
+  static const int kDragHoverTimeout = 500;
+
   void SetActions(QAction* new_playlist, QAction* load_playlist);
+  void SetManager(PlaylistManager* manager);
 
   // We use IDs to refer to tabs so the tabs can be moved around (and their
   // indexes change).
@@ -49,6 +55,16 @@ signals:
   void Save(int id);
   void PlaylistOrderChanged(const QList<int>& ids);
 
+protected:
+  void contextMenuEvent(QContextMenuEvent* e);
+  void mouseReleaseEvent(QMouseEvent* e);
+  void mouseDoubleClickEvent(QMouseEvent* e);
+  void dragEnterEvent(QDragEnterEvent* e);
+  void dragMoveEvent(QDragMoveEvent* e);
+  void dragLeaveEvent(QDragLeaveEvent* e);
+  void dropEvent(QDropEvent* e);
+  void timerEvent(QTimerEvent *);
+
 private slots:
   void CurrentIndexChanged(int index);
   void Rename();
@@ -56,12 +72,9 @@ private slots:
   void TabMoved();
   void Save();
 
-protected:
-  void contextMenuEvent(QContextMenuEvent* e);
-  void mouseReleaseEvent(QMouseEvent* e);
-  void mouseDoubleClickEvent(QMouseEvent* e);
-
 private:
+  PlaylistManager* manager_;
+
   QMenu* menu_;
   int menu_index_;
   QAction* new_;
@@ -69,6 +82,9 @@ private:
   QAction* remove_;
   QAction* save_;
 
+  QBasicTimer drag_hover_timer_;
+  int drag_hover_tab_;
+
   bool suppress_current_changed_;
 };