ResourcesTreeModel: support for dragging ResourceItems

Added initial support for dragging ResourceItems. This is achieved by
using drag'n'drop support offered by Qt's model/view technology.

Signed-off-by: Tobias Doerffel <tobias.doerffel@gmail.com>

include/ResourceItem.h

@@ -200,6 +200,11 @@ public:
 
 	Type guessType( void ) const;
 
+	static const char * mimeKey()
+	{
+		return "ResourceItem";
+	}
+
 	static QString getBaseDirectory( BaseDirectory _bd,
 					const ResourceItem * _item = NULL );
 

include/ResourceTreeModel.h

@@ -42,10 +42,7 @@ public:
 	virtual QVariant data( const QModelIndex & _idx,
                                         int _role = Qt::DisplayRole ) const;
 
-	virtual Qt::ItemFlags flags( const QModelIndex & _index ) const
-	{
-		return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
-	}
+	virtual Qt::ItemFlags flags( const QModelIndex & _index ) const;
 
 	int rowCount( const QModelIndex & _parent = QModelIndex() ) const;
 
@@ -58,7 +55,13 @@ public:
 	virtual QModelIndex index( int _row, int _col,
 			const QModelIndex & _parent = QModelIndex() ) const;
 
-	virtual QModelIndex parent ( const QModelIndex & index ) const;
+	virtual QModelIndex parent( const QModelIndex & index ) const;
+
+	// return list of possible MIME types for items in this model
+	virtual QStringList mimeTypes() const;
+
+	// used for drag'n'drop - return proper MIME data for indexes
+	virtual QMimeData * mimeData( const QModelIndexList & _indexes ) const;
 
 	void setFilter( const QString & _s );
 

src/core/ResourceTreeModel.cpp

@@ -25,12 +25,15 @@
 
 #include "ResourceTreeModel.h"
 #include "embed.h"
+#include "string_pair_drag.h"
 
 
 ResourceTreeModel::ResourceTreeModel( ResourceDB * _db, QObject * _parent ) :
 	QAbstractItemModel( _parent ),
 	m_db( _db )
 {
+	setSupportedDragActions( Qt::CopyAction );
+
 	connect( m_db, SIGNAL( itemsChanged() ),
 			this, SIGNAL( itemsChanged() ) );
 }
@@ -105,6 +108,32 @@ default:
 
 
 
+Qt::ItemFlags ResourceTreeModel::flags( const QModelIndex & _index ) const
+{
+	Qt::ItemFlags flags = Qt::ItemIsEnabled | Qt::ItemIsSelectable;
+	if( _index.isValid() )
+	{
+		switch( item( _index )->type() )
+		{
+			case ResourceItem::TypeSample:
+			case ResourceItem::TypePreset:
+			case ResourceItem::TypePluginSpecificPreset:
+			case ResourceItem::TypeProject:
+			case ResourceItem::TypeMidiFile:
+			case ResourceItem::TypeImage:
+			case ResourceItem::TypePlugin:
+				flags |= Qt::ItemIsDragEnabled;
+				break;
+			default:
+				break;
+		}
+	}
+	return flags;
+}
+
+
+
+
 int ResourceTreeModel::rowCount( const QModelIndex & _parent ) const
 {
 	ResourceTreeItem * parentItem;
@@ -182,6 +211,30 @@ QModelIndex ResourceTreeModel::parent( const QModelIndex & _idx ) const
 
 
 
+QStringList ResourceTreeModel::mimeTypes() const
+{
+	return QStringList() << ResourceItem::mimeKey();
+}
+
+
+
+
+QMimeData * ResourceTreeModel::mimeData( const QModelIndexList & _list ) const
+{
+	// we'll only process first item - look whether it is valid
+	if( !_list.first().isValid() )
+	{
+		return NULL;
+	}
+
+	// create a QMimeData object containing hash of current item
+	return stringPairDrag::createMimeData( ResourceItem::mimeKey(),
+					item( _list.first() )->hash() );
+}
+
+
+
+
 void ResourceTreeModel::setFilter( const QString & _s )
 {
 	filterItems( m_db->topLevelNode(),