node: provide convenience function for signing hashes with ID

app/node/distort/transform/transformdistortnode.cpp

@@ -335,7 +335,7 @@ void TransformDistortNode::Hash(const QString &output, QCryptographicHash &hash,
 
     if (!matrix.isIdentity()) {
       // Add fingerprint
-      hash.addData(id().toUtf8());
+      HashAddNodeSignature(hash, output);
       hash.addData(reinterpret_cast<const char*>(&matrix), sizeof(matrix));
     }
   }

app/node/math/merge/merge.cpp

@@ -123,7 +123,7 @@ void MergeNode::Hash(const QString &output, QCryptographicHash &hash, const rati
 
     if (!passthrough_base && !passthrough_blend) {
       // This merge will actually do something so we add a fingerprint
-      hash.addData(id().toUtf8());
+      HashAddNodeSignature(hash, output);
     }
 
     if (!passthrough_base) {

app/node/node.cpp

@@ -1253,6 +1253,12 @@ bool Node::AreLinked(Node *a, Node *b)
   return a->links_.contains(b);
 }
 
+void Node::HashAddNodeSignature(QCryptographicHash &hash, const QString &output) const
+{
+  hash.addData(id().toUtf8());
+  hash.addData(output.toUtf8());
+}
+
 void Node::InsertInput(const QString &id, NodeValue::Type type, const QVariant &default_value, Node::InputFlags flags, int index)
 {
   if (id.isEmpty()) {
@@ -1446,11 +1452,8 @@ void Node::SetLabel(const QString &s)
 
 void Node::Hash(const QString &output, QCryptographicHash &hash, const rational& time, const VideoParams &video_params) const
 {
-  Q_UNUSED(output)
-
   // Add this Node's ID and output being used
-  hash.addData(id().toUtf8());
-  hash.addData(output.toUtf8());
+  HashAddNodeSignature(hash, output);
 
   auto inputs = inputs_for_output(output);
   foreach (const QString& input, inputs) {

app/node/node.h

@@ -852,6 +852,8 @@ protected:
 
   };
 
+  void HashAddNodeSignature(QCryptographicHash &hash, const QString &output) const;
+
   void InsertInput(const QString& id, NodeValue::Type type, const QVariant& default_value, InputFlags flags, int index);
 
   void PrependInput(const QString& id, NodeValue::Type type, const QVariant& default_value, InputFlags flags = InputFlags(kInputFlagNormal))