--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Scene2DViewport/UndoStack.cpp	Tue Jul 07 16:21:02 2020 +0200
@@ -0,0 +1,68 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+#include "UndoStack.h"
+
+#include "MeasureCommands.h"
+
+#include "../StoneException.h"
+
+namespace OrthancStone
+{
+  UndoStack::UndoStack() : numAppliedCommands_(0)
+  {}
+
+  void UndoStack::PushCommand(boost::shared_ptr<MeasureCommand> command)
+  {
+    commandStack_.erase(
+      commandStack_.begin() + numAppliedCommands_,
+      commandStack_.end());
+
+    ORTHANC_ASSERT(std::find(commandStack_.begin(), commandStack_.end(), command)
+      == commandStack_.end(), "Duplicate command");
+    commandStack_.push_back(command);
+    numAppliedCommands_++;
+  }
+
+  void UndoStack::Undo()
+  {
+    ORTHANC_ASSERT(CanUndo(), "");
+    commandStack_[numAppliedCommands_ - 1]->Undo();
+    numAppliedCommands_--;
+  }
+
+  void UndoStack::Redo()
+  {
+    ORTHANC_ASSERT(CanRedo(), "");
+    commandStack_[numAppliedCommands_]->Redo();
+    numAppliedCommands_++;
+  }
+
+  bool UndoStack::CanUndo() const
+  {
+    return numAppliedCommands_ > 0;
+  }
+
+  bool UndoStack::CanRedo() const
+  {
+    return numAppliedCommands_ < commandStack_.size();
+  }
+
+}