gizmos: consolidated input param dragging code into reusable class

app/node/inputdragger.h

@@ -0,0 +1,60 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2019 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef NODEINPUTDRAGGER_H
+#define NODEINPUTDRAGGER_H
+
+#include "node/input.h"
+
+OLIVE_NAMESPACE_ENTER
+
+class NodeInputDragger
+{
+public:
+  NodeInputDragger();
+
+  bool IsStarted() const;
+
+  void Start(NodeInput* input, const rational& time, int track);
+
+  void Drag(const QVariant &value);
+
+  void End();
+
+private:
+  NodeInput* input_;
+
+  int track_;
+
+  rational time_;
+
+  QVariant start_value_;
+
+  QVariant end_value_;
+
+  NodeKeyframePtr dragging_key_;
+
+  bool drag_created_key_;
+
+};
+
+OLIVE_NAMESPACE_EXIT
+
+#endif // NODEINPUTDRAGGER_H