create new folder added

app/project/item/item.cpp

@@ -39,6 +39,10 @@ void Item::add_child(Item* c)
     return;
   }
 
+  if (c->parent_ != nullptr) {
+    c->parent_->remove_child(c);
+  }
+
   children_.append(c);
   c->parent_ = this;
 }

app/project/projectviewmodel.cpp

@@ -376,6 +376,21 @@ bool ProjectViewModel::dropMimeData(const QMimeData *data, Qt::DropAction action
   return false;
 }
 
+void ProjectViewModel::AddChild(Item *parent, Item *child)
+{
+  QModelIndex parent_index;
+
+  if (parent != project_->root()) {
+    parent_index = CreateIndexFromItem(parent);
+  }
+
+  beginInsertRows(parent_index, parent->child_count(), parent->child_count());
+
+  parent->add_child(child);
+
+  endInsertRows();
+}
+
 int ProjectViewModel::IndexOfChild(Item *item) const
 {
   // Find parent's index within its own parent

app/project/projectviewmodel.h

@@ -91,6 +91,9 @@ public:
   virtual QStringList mimeTypes() const override;
   virtual QMimeData * mimeData(const QModelIndexList &indexes) const override;
   virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) override;
+
+  /** Other model functions */
+  void AddChild(Item* parent, Item* child);
 private:
   /**
    * @brief Retrieve the index of `item` in its parent