From 8cd96eae645a2cf16332c1f674bec16c0bfadf2e Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Sat, 13 Apr 2019 02:40:58 +1000
Subject: [PATCH] nodes can now be connected through the node editor

---
 effects/effectrow.cpp        |  57 +++++++++++++++++-
 effects/effectrow.h          |  83 ++++++++++++++++++++++----
 nodes/inputs/boolinput.cpp   |   2 +-
 nodes/inputs/colorinput.cpp  |   2 +-
 nodes/inputs/comboinput.cpp  |   2 +-
 nodes/inputs/fileinput.cpp   |   2 +-
 nodes/inputs/fontinput.cpp   |   2 +-
 nodes/inputs/stringinput.cpp |   2 +-
 nodes/inputs/vecinput.cpp    |   8 +--
 nodes/node.cpp               |  26 +++++++++
 nodes/node.h                 |   9 ++-
 nodes/nodeedge.cpp           |  21 +++++++
 nodes/nodeedge.h             |  39 +++++++++++++
 nodes/nodeplug.cpp           |  11 ----
 nodes/nodeplug.h             |  13 -----
 nodes/nodes/nodemedia.cpp    |   2 +
 olive.pro                    |  10 ++--
 panels/nodeeditor.cpp        |  49 +++++++++++++---
 panels/nodeeditor.h          |   5 ++
 ui/nodeedgeui.cpp            |  67 +++++++++++++++++++++
 ui/nodeedgeui.h              |  26 +++++++++
 ui/nodeui.cpp                | 109 ++++++++++++++++++++++++++++-------
 ui/nodeui.h                  |  16 ++++-
 ui/nodeview.cpp              |   2 +-
 24 files changed, 480 insertions(+), 85 deletions(-)
 create mode 100644 nodes/nodeedge.cpp
 create mode 100644 nodes/nodeedge.h
 delete mode 100644 nodes/nodeplug.cpp
 delete mode 100644 nodes/nodeplug.h
 create mode 100644 ui/nodeedgeui.cpp
 create mode 100644 ui/nodeedgeui.h

diff --git a/effects/effectrow.cpp b/effects/effectrow.cpp
index 7e2abaa7c..e60bea8b1 100644
--- a/effects/effectrow.cpp
+++ b/effects/effectrow.cpp
@@ -65,13 +65,54 @@ void EffectRow::AddField(EffectField *field)
   fields_.append(field);
 }
 
-void EffectRow::AddNodeInput(olive::nodes::DataType type)
+void EffectRow::AddAcceptedNodeInput(olive::nodes::DataType type)
 {
   Q_ASSERT(output_type_ == olive::nodes::kInvalid);
 
   accepted_inputs_.append(type);
 }
 
+void EffectRow::ConnectEdge(EffectRow *output, EffectRow *input)
+{
+  Q_ASSERT(output->IsNodeOutput());
+  Q_ASSERT(input->IsNodeInput());
+
+  if (!input->node_edges_.isEmpty()) {
+    DisconnectEdge(input->node_edges_.first());
+  }
+
+  NodeEdgePtr edge = std::make_shared<NodeEdge>(output, input);
+
+  output->node_edges_.append(edge);
+  input->node_edges_.append(edge);
+
+  emit output->EdgesChanged();
+  emit input->EdgesChanged();
+}
+
+void EffectRow::DisconnectEdge(NodeEdgePtr edge)
+{
+  EffectRow* output = edge->output();
+  EffectRow* input = edge->input();
+
+  output->node_edges_.removeAll(edge);
+  input->node_edges_.removeAll(edge);
+
+  emit output->EdgesChanged();
+  emit input->EdgesChanged();
+}
+
+QVector<NodeEdge*> EffectRow::edges()
+{
+  QVector<NodeEdge*> edges;
+
+  for (int i=0;i<node_edges_.size();i++) {
+    edges.append(node_edges_.at(i).get());
+  }
+
+  return edges;
+}
+
 bool EffectRow::IsKeyframing() {
   return keyframing_;
 }
@@ -121,6 +162,20 @@ void EffectRow::SetOutputDataType(olive::nodes::DataType type)
   output_type_ = type;
 }
 
+bool EffectRow::CanAcceptDataType(olive::nodes::DataType type)
+{
+  if (!IsNodeInput()) {
+    return false;
+  }
+
+  return accepted_inputs_.contains(type);
+}
+
+olive::nodes::DataType EffectRow::OutputDataType()
+{
+  return output_type_;
+}
+
 bool EffectRow::IsNodeInput()
 {
   return !accepted_inputs_.isEmpty();
diff --git a/effects/effectrow.h b/effects/effectrow.h
index cbdf2256b..c991d52c3 100644
--- a/effects/effectrow.h
+++ b/effects/effectrow.h
@@ -35,6 +35,7 @@ class KeyframeNavigator;
 class ClickableLabel;
 
 #include "effectfields.h"
+#include "nodes/nodeedge.h"
 
 /**
  * @brief The EffectRow class
@@ -245,6 +246,64 @@ public:
    */
   void SetOutputDataType(olive::nodes::DataType type);
 
+  /**
+   * @brief Check if this row can accept the data type specified in type
+   *
+   * @return
+   *
+   * TRUE if this row can accept this data type. If this row is not an input, this function will always return FALSE.
+   */
+  bool CanAcceptDataType(olive::nodes::DataType type);
+
+  /**
+   * @brief Get this row's output data type
+   *
+   * @return
+   *
+   * If this is not an output, this will always return olive::nodes::kInvalid
+   */
+  olive::nodes::DataType OutputDataType();
+
+  /**
+   * @brief Adds a node data type that can be accepted by this input
+   *
+   * Allows this input to take a node connection from a data type specified by type. An input can take several data
+   * types.
+   *
+   * @param type
+   *
+   * The data type to add
+   */
+  void AddAcceptedNodeInput(olive::nodes::DataType type);
+
+  /**
+   * @brief Connect two node sockets together
+   *
+   * For outputs, the maximum amount of edges is unlimited and this will continually add to a list of edges. For inputs,
+   * there can only be one edge and adding a second will destroy the first.
+   *
+   * @param edge
+   *
+   * The edge to add (output) or replace the current edge (input).
+   */
+  static void ConnectEdge(EffectRow* output, EffectRow* input);
+
+  /**
+   * @brief Disconnect an edge
+   *
+   * Disconnects two nodes and destroys the edge object connecting them together
+   *
+   * @param edge
+   *
+   * Edge to be removed
+   */
+  static void DisconnectEdge(NodeEdgePtr edge);
+
+  /**
+   * @brief Get a list of references to all edges currently connected to this row
+   */
+  QVector<NodeEdge *> edges();
+
 protected:
   /**
    * @brief Add a field to this row
@@ -258,18 +317,6 @@ protected:
    */
   void AddField(EffectField* Field);
 
-  /**
-   * @brief Adds a node data type that can be accepted by this input
-   *
-   * Allows this input to take a node connection from a data type specified by type. An input can take several data
-   * types.
-   *
-   * @param type
-   *
-   * The data type to add
-   */
-  void AddNodeInput(olive::nodes::DataType type);
-
 public slots:
   /**
    * @brief Go to previous keyframe
@@ -332,6 +379,13 @@ signals:
    */
   void Clicked();
 
+  /**
+   * @brief Edges changed signal
+   *
+   * Signal emitted any time an edge is connected or disconnected from this row
+   */
+  void EdgesChanged();
+
 private slots:
   /**
    * @brief Set keyframing enabled state
@@ -402,6 +456,11 @@ private:
    * this.
    */
   olive::nodes::DataType output_type_;
+
+  /**
+   * @brief Internal array of node edges. Access with AddEdge() and RemoveEdge().
+   */
+  QVector<NodeEdgePtr> node_edges_;
 };
 
 #endif // EFFECTROW_H
diff --git a/nodes/inputs/boolinput.cpp b/nodes/inputs/boolinput.cpp
index ff58c005a..aa98181d6 100644
--- a/nodes/inputs/boolinput.cpp
+++ b/nodes/inputs/boolinput.cpp
@@ -7,7 +7,7 @@ BoolInput::BoolInput(Node* parent, const QString& id, const QString& name, bool
   connect(bool_field, SIGNAL(Toggled(bool)), this, SIGNAL(Toggled(bool)));
   AddField(bool_field);
 
-  AddNodeInput(olive::nodes::kBoolean);
+  AddAcceptedNodeInput(olive::nodes::kBoolean);
 }
 
 bool BoolInput::GetBoolAt(double timecode)
diff --git a/nodes/inputs/colorinput.cpp b/nodes/inputs/colorinput.cpp
index 6c12129d6..ade47dbd2 100644
--- a/nodes/inputs/colorinput.cpp
+++ b/nodes/inputs/colorinput.cpp
@@ -5,7 +5,7 @@ ColorInput::ColorInput(Node* parent, const QString& id, const QString& name, boo
 {
   AddField(new ColorField(this));
 
-  AddNodeInput(olive::nodes::kColor);
+  AddAcceptedNodeInput(olive::nodes::kColor);
 }
 
 QColor ColorInput::GetColorAt(double timecode)
diff --git a/nodes/inputs/comboinput.cpp b/nodes/inputs/comboinput.cpp
index b257ea66e..395ff6ebf 100644
--- a/nodes/inputs/comboinput.cpp
+++ b/nodes/inputs/comboinput.cpp
@@ -7,7 +7,7 @@ ComboInput::ComboInput(Node* parent, const QString& id, const QString& name, boo
   connect(combo_field, SIGNAL(DataChanged(const QVariant&)), this, SIGNAL(DataChanged(const QVariant&)));
   AddField(combo_field);
 
-  AddNodeInput(olive::nodes::kCombo);
+  AddAcceptedNodeInput(olive::nodes::kCombo);
 }
 
 void ComboInput::AddItem(const QString &text, const QVariant &data)
diff --git a/nodes/inputs/fileinput.cpp b/nodes/inputs/fileinput.cpp
index 77d2406bf..4f8d5c808 100644
--- a/nodes/inputs/fileinput.cpp
+++ b/nodes/inputs/fileinput.cpp
@@ -5,7 +5,7 @@ FileInput::FileInput(Node* parent, const QString& id, const QString& name, bool
 {
   AddField(new FileField(this));
 
-  AddNodeInput(olive::nodes::kFile);
+  AddAcceptedNodeInput(olive::nodes::kFile);
 }
 
 QString FileInput::GetFileAt(double timecode)
diff --git a/nodes/inputs/fontinput.cpp b/nodes/inputs/fontinput.cpp
index c5a901c7e..ec9ba7077 100644
--- a/nodes/inputs/fontinput.cpp
+++ b/nodes/inputs/fontinput.cpp
@@ -5,7 +5,7 @@ FontInput::FontInput(Node* parent, const QString& id, const QString& name, bool
 {
   AddField(new FontField(this));
 
-  AddNodeInput(olive::nodes::kFont);
+  AddAcceptedNodeInput(olive::nodes::kFont);
 }
 
 QString FontInput::GetFontAt(double timecode)
diff --git a/nodes/inputs/stringinput.cpp b/nodes/inputs/stringinput.cpp
index 0cdfa6922..121051ea8 100644
--- a/nodes/inputs/stringinput.cpp
+++ b/nodes/inputs/stringinput.cpp
@@ -5,7 +5,7 @@ StringInput::StringInput(Node* parent, const QString& id, const QString& name, b
 {
   AddField(new StringField(this, rich_text));
 
-  AddNodeInput(olive::nodes::kString);
+  AddAcceptedNodeInput(olive::nodes::kString);
 }
 
 QString StringInput::GetStringAt(double timecode)
diff --git a/nodes/inputs/vecinput.cpp b/nodes/inputs/vecinput.cpp
index 2626720f0..f99666c6b 100644
--- a/nodes/inputs/vecinput.cpp
+++ b/nodes/inputs/vecinput.cpp
@@ -15,15 +15,15 @@ VecInput::VecInput(Node* parent, const QString& id, const QString& name, int val
     AddField(new DoubleField(this));
   }
 
-  AddNodeInput(olive::nodes::kFloat);
+  AddAcceptedNodeInput(olive::nodes::kFloat);
   if (values > 1) {
-    AddNodeInput(olive::nodes::kVec2);
+    AddAcceptedNodeInput(olive::nodes::kVec2);
   }
   if (values > 2) {
-    AddNodeInput(olive::nodes::kVec3);
+    AddAcceptedNodeInput(olive::nodes::kVec3);
   }
   if (values > 3) {
-    AddNodeInput(olive::nodes::kVec4);
+    AddAcceptedNodeInput(olive::nodes::kVec4);
   }
 }
 
diff --git a/nodes/node.cpp b/nodes/node.cpp
index efb3146e3..a2d6b7d9b 100644
--- a/nodes/node.cpp
+++ b/nodes/node.cpp
@@ -148,6 +148,11 @@ void Node::AddRow(EffectRow *row)
   rows.append(row);
 }
 
+int Node::IndexOfRow(EffectRow *row)
+{
+  return rows.indexOf(row);
+}
+
 void Node::copy_field_keyframes(NodePtr e) {
   for (int i=0;i<rows.size();i++) {
     EffectRow* row = rows.at(i);
@@ -191,6 +196,17 @@ int Node::gizmo_count() {
   return gizmos.size();
 }
 
+QVector<NodeEdge *> Node::GetAllEdges()
+{
+  QVector<NodeEdge*> edges;
+
+  for (int i=0;i<row_count();i++) {
+    edges.append(row(i)->edges());
+  }
+
+  return edges;
+}
+
 void Node::refresh() {}
 
 void Node::FieldChanged() {
@@ -310,6 +326,11 @@ void Node::SetExpanded(bool e)
   expanded_ = e;
 }
 
+void Node::SetPos(const QPointF &pos)
+{
+  pos_ = pos;
+}
+
 void Node::SetEnabled(bool b) {
   enabled_ = b;
   emit EnabledChanged(b);
@@ -615,6 +636,11 @@ void Node::setIterations(int i) {
   iterations = i;
 }
 
+const QPointF &Node::pos()
+{
+  return pos_;
+}
+
 void Node::process_image(double, uint8_t *, uint8_t *, int){}
 
 NodePtr Node::copy(Clip *c) {
diff --git a/nodes/node.h b/nodes/node.h
index c67a317af..b58fa1d78 100644
--- a/nodes/node.h
+++ b/nodes/node.h
@@ -127,7 +127,7 @@ public:
   virtual NodePtr Create(Clip *c) = 0;
 
   void AddRow(EffectRow* row);
-
+  int IndexOfRow(EffectRow* row);
   EffectRow* row(int i);
   int row_count();
 
@@ -135,6 +135,8 @@ public:
   EffectGizmo* gizmo(int i);
   int gizmo_count();
 
+  QVector<NodeEdge*> GetAllEdges();
+
   bool IsEnabled();
   bool IsExpanded();
 
@@ -168,6 +170,8 @@ public:
   int getIterations();
   void setIterations(int i);
 
+  const QPointF& pos();
+
   virtual void process_image(double timecode, uint8_t* input, uint8_t* output, int size);
   virtual void process_shader(double timecode, GLTextureCoords&, int iteration);
   virtual void process_coords(double timecode, GLTextureCoords& coords, int data);
@@ -225,6 +229,7 @@ public slots:
   void FieldChanged();
   void SetEnabled(bool b);
   void SetExpanded(bool e);
+  void SetPos(const QPointF& pos);
 signals:
   void EnabledChanged(bool);
 private slots:
@@ -264,6 +269,8 @@ private:
 
   QVector<KeyframeDataChange*> gizmo_dragging_actions_;
 
+  QPointF pos_;
+
   // superimpose functions
   virtual void redraw(double timecode);
   bool valueHasChanged(double timecode);
diff --git a/nodes/nodeedge.cpp b/nodes/nodeedge.cpp
new file mode 100644
index 000000000..da21eaac8
--- /dev/null
+++ b/nodes/nodeedge.cpp
@@ -0,0 +1,21 @@
+#include "nodeedge.h"
+
+#include <QDebug>
+
+#include "effects/effectrow.h"
+
+NodeEdge::NodeEdge(EffectRow *output, EffectRow *input) :
+  output_(output),
+  input_(input)
+{
+}
+
+EffectRow *NodeEdge::output()
+{
+  return output_;
+}
+
+EffectRow *NodeEdge::input()
+{
+  return input_;
+}
diff --git a/nodes/nodeedge.h b/nodes/nodeedge.h
new file mode 100644
index 000000000..a6b49581d
--- /dev/null
+++ b/nodes/nodeedge.h
@@ -0,0 +1,39 @@
+#ifndef NODEEDGE_H
+#define NODEEDGE_H
+
+#include <memory>
+
+class EffectRow;
+
+class NodeEdge;
+using NodeEdgePtr = std::shared_ptr<NodeEdge>;
+
+class NodeEdge
+{
+public:
+  /**
+   * @brief NodeEdge Constructor
+   *
+   * Creates a node edge and stores its two connections.
+   *
+   * This should not be used directly. Use the static function EffectRow::ConnectEdge instead.
+   *
+   * @param output
+   *
+   * Output/from EffectRow that this edge "starts" at
+   *
+   * @param input
+   *
+   * Input/to EffectRow that this edge "ends" at
+   */
+  NodeEdge(EffectRow* output, EffectRow* input);
+
+  EffectRow* output();
+  EffectRow* input();
+
+private:
+  EffectRow* output_;
+  EffectRow* input_;
+};
+
+#endif // NODEEDGE_H
diff --git a/nodes/nodeplug.cpp b/nodes/nodeplug.cpp
deleted file mode 100644
index bb60f8397..000000000
--- a/nodes/nodeplug.cpp
+++ /dev/null
@@ -1,11 +0,0 @@
-#include "nodeplug.h"
-
-NodePlug::NodePlug()
-{
-
-}
-
-bool NodePlug::IsConnected()
-{
-
-}
diff --git a/nodes/nodeplug.h b/nodes/nodeplug.h
deleted file mode 100644
index 764afc716..000000000
--- a/nodes/nodeplug.h
+++ /dev/null
@@ -1,13 +0,0 @@
-#ifndef NODEPLUG_H
-#define NODEPLUG_H
-
-
-class NodePlug
-{
-public:
-  NodePlug();
-
-  bool IsConnected();
-};
-
-#endif // NODEPLUG_H
diff --git a/nodes/nodes/nodemedia.cpp b/nodes/nodes/nodemedia.cpp
index 0035e900c..e835a884a 100644
--- a/nodes/nodes/nodemedia.cpp
+++ b/nodes/nodes/nodemedia.cpp
@@ -3,6 +3,8 @@
 NodeMedia::NodeMedia(Clip* c) :
   Node(c)
 {
+  EffectRow* matrix_input = new EffectRow(this, "matrix", tr("Matrix"), true, false);
+  matrix_input->AddAcceptedNodeInput(olive::nodes::kMatrix);
 }
 
 QString NodeMedia::name()
diff --git a/olive.pro b/olive.pro
index 9d4b6542d..404cee082 100644
--- a/olive.pro
+++ b/olive.pro
@@ -191,7 +191,6 @@ SOURCES += \
     ui/nodeui.cpp \
     panels/effectspanel.cpp \
     nodes/nodedatatypes.cpp \
-    nodes/nodeplug.cpp \
     nodes/inputs/boolinput.cpp \
     nodes/inputs/comboinput.cpp \
     nodes/inputs/colorinput.cpp \
@@ -207,7 +206,9 @@ SOURCES += \
     nodes/nodes/nodeshader.cpp \
     decoders/ffmpegdecoder.cpp \
     decoders/decoder.cpp \
-    nodes/node.cpp
+    nodes/node.cpp \
+    nodes/nodeedge.cpp \
+    ui/nodeedgeui.cpp
 
 HEADERS += \
         ui/mainwindow.h \
@@ -353,7 +354,6 @@ HEADERS += \
     ui/nodeui.h \
     panels/effectspanel.h \
     nodes/nodedatatypes.h \
-    nodes/nodeplug.h \
     nodes/inputs.h \
     nodes/inputs/boolinput.h \
     nodes/inputs/comboinput.h \
@@ -372,7 +372,9 @@ HEADERS += \
     decoders/ffmpegdecoder.h \
     decoders/decoder.h \
     nodes/node.h \
-    timeline/tracktypes.h
+    timeline/tracktypes.h \
+    nodes/nodeedge.h \
+    ui/nodeedgeui.h
 
 FORMS +=
 
diff --git a/panels/nodeeditor.cpp b/panels/nodeeditor.cpp
index 73d24bd30..af7a1c89d 100644
--- a/panels/nodeeditor.cpp
+++ b/panels/nodeeditor.cpp
@@ -24,6 +24,8 @@ NodeEditor::NodeEditor(QWidget *parent) :
 
   view_.setInteractive(true);
   view_.setDragMode(QGraphicsView::RubberBandDrag);
+
+  connect(&scene_, SIGNAL(changed(const QList<QRectF>&)), this, SLOT(ItemsChanged()));
 }
 
 void NodeEditor::Retranslate()
@@ -32,9 +34,9 @@ void NodeEditor::Retranslate()
 
 void NodeEditor::LoadEvent()
 {
-  nodes_.resize(open_effects_.size());
-
   if (!open_effects_.isEmpty()) {
+    QVector<NodeEdge*> added_edges;
+
     Clip* first_clip = open_effects_.first()->GetEffect()->parent_clip;
 
     for (int i=0;i<open_effects_.size();i++) {
@@ -48,20 +50,53 @@ void NodeEditor::LoadEvent()
 
         node_ui->SetWidget(effect_ui);
         node_ui->AddToScene(&scene_);
+        node_ui->setPos(effect_ui->GetEffect()->pos());
 
-        nodes_[i] = node_ui;
+        nodes_.append(node_ui);
+
+        // Get node edges
+        QVector<NodeEdge*> edges = open_effects_.at(i)->GetEffect()->GetAllEdges();
+        for (int j=0;j<edges.size();j++) {
+
+          NodeEdge* edge = edges.at(j);
+
+          if (!added_edges.contains(edge)) {
+            NodeEdgeUI* edge_ui = new NodeEdgeUI(edge);
+            scene_.addItem(edge_ui);
+            edges_.append(edge_ui);
+
+            added_edges.append(edge);
+          }
+        }
       }
     }
+
+    ItemsChanged();
   }
 }
 
 void NodeEditor::ClearEvent()
 {
-  NodeUI* node;
-
-  foreach (node, nodes_) {
-    delete node;
+  foreach (NodeUI* node, nodes_) {
+    scene_.removeItem(node);
   }
 
   nodes_.clear();
+
+  foreach (NodeEdgeUI* edge, edges_) {
+    scene_.removeItem(edge);
+  }
+
+  edges_.clear();
+}
+
+void NodeEditor::ItemsChanged()
+{
+  foreach (NodeEdgeUI* edge, edges_) {
+    edge->adjust();
+  }
+
+  foreach (NodeUI* node, nodes_) {
+    node->Widget()->GetEffect()->SetPos(node->pos());
+  }
 }
diff --git a/panels/nodeeditor.h b/panels/nodeeditor.h
index a404629c3..fd3ed0967 100644
--- a/panels/nodeeditor.h
+++ b/panels/nodeeditor.h
@@ -6,6 +6,7 @@
 #include "effectspanel.h"
 #include "ui/nodeview.h"
 #include "ui/nodeui.h"
+#include "ui/nodeedgeui.h"
 
 class NodeEditor : public EffectsPanel {
   Q_OBJECT
@@ -22,6 +23,10 @@ private:
   QGraphicsScene scene_;
   NodeView view_;
   QVector<NodeUI*> nodes_;
+  QVector<NodeEdgeUI*> edges_;
+
+private slots:
+  void ItemsChanged();
 
 };
 
diff --git a/ui/nodeedgeui.cpp b/ui/nodeedgeui.cpp
new file mode 100644
index 000000000..61c0bde8c
--- /dev/null
+++ b/ui/nodeedgeui.cpp
@@ -0,0 +1,67 @@
+#include "nodeedgeui.h"
+
+#include <QPen>
+#include <QGraphicsScene>
+
+#include "global/math.h"
+#include "ui/effectui.h"
+
+NodeEdgeUI::NodeEdgeUI(NodeEdge* edge) :
+  edge_(edge),
+  output_node_(nullptr),
+  input_node_(nullptr)
+{
+  setPen(QPen(Qt::white, 2));
+}
+
+void NodeEdgeUI::adjust()
+{
+  if (output_node_ == nullptr) {
+    // Locate the output and input nodes' UIs
+
+    QList<QGraphicsItem*> all_items = scene()->items();
+
+    for (int j=0;j<all_items.size();j++) {
+      NodeUI* node = dynamic_cast<NodeUI*>(all_items.at(j));
+      if (node != nullptr) {
+
+        // Check if this node has the output row
+        int row_index = node->Widget()->GetEffect()->IndexOfRow(edge_->output());
+
+        if (row_index > -1) {
+          output_node_ = node;
+          output_index_ = row_index;
+        }
+
+        // Check if this node has the input row
+        row_index = node->Widget()->GetEffect()->IndexOfRow(edge_->input());
+
+        if (row_index > -1) {
+          input_node_ = node;
+          input_index_ = row_index;
+        }
+      }
+    }
+  }
+
+  setPath(GetEdgePath(output_node_->pos() + output_node_->GetNodeSocketRects().at(output_index_).center(),
+                      input_node_->pos() + input_node_->GetNodeSocketRects().at(input_index_).center()));
+}
+
+NodeEdge *NodeEdgeUI::edge()
+{
+  return edge_;
+}
+
+QPainterPath NodeEdgeUI::GetEdgePath(const QPointF &start_pos, const QPointF &end_pos)
+{
+  double mid_x = double_lerp(start_pos.x(), end_pos.x(), 0.5);
+
+  QPainterPath path_;
+  path_.moveTo(start_pos);
+  path_.cubicTo(QPointF(mid_x, start_pos.y()),
+                QPointF(mid_x, end_pos.y()),
+                end_pos);
+
+  return path_;
+}
diff --git a/ui/nodeedgeui.h b/ui/nodeedgeui.h
new file mode 100644
index 000000000..3634334d2
--- /dev/null
+++ b/ui/nodeedgeui.h
@@ -0,0 +1,26 @@
+#ifndef NODEEDGEUI_H
+#define NODEEDGEUI_H
+
+#include <QGraphicsPathItem>
+
+#include "nodeui.h"
+
+class NodeEdgeUI : public QGraphicsPathItem {
+public:
+  NodeEdgeUI(NodeEdge* edge);
+
+  static QPainterPath GetEdgePath(const QPointF& start_pos, const QPointF& end_pos);
+
+  void adjust();
+  NodeEdge* edge();
+
+private:
+  NodeEdge* edge_;
+
+  NodeUI* output_node_;
+  int output_index_;
+  NodeUI* input_node_;
+  int input_index_;
+};
+
+#endif // NODEEDGEUI_H
diff --git a/ui/nodeui.cpp b/ui/nodeui.cpp
index de263e07d..6b433bf84 100644
--- a/ui/nodeui.cpp
+++ b/ui/nodeui.cpp
@@ -12,13 +12,15 @@
 #include <QPainter>
 
 #include "ui/effectui.h"
-#include "global/math.h"
+#include "ui/nodeedgeui.h"
 
 const int kRoundedRectRadius = 5;
 const int kNodePlugSize = 12;
 
 NodeUI::NodeUI() :
   central_widget_(nullptr),
+  proxy_(nullptr),
+  drag_destination_(nullptr),
   clicked_socket_(-1)
 {
   setFlag(QGraphicsItem::ItemIsMovable, true);
@@ -29,7 +31,6 @@ NodeUI::~NodeUI()
 {
   if (scene() != nullptr) {
     scene()->removeItem(proxy_);
-    scene()->removeItem(this);
   }
 }
 
@@ -55,8 +56,8 @@ void NodeUI::Resize(const QSize &s)
 
   rectangle.setWidth(rectangle.width() + kNodePlugSize);
 
-  path_ = QPainterPath();
-  path_.addRoundedRect(inner_rect, kRoundedRectRadius, kRoundedRectRadius);
+  drag_path_ = QPainterPath();
+  drag_path_.addRoundedRect(inner_rect, kRoundedRectRadius, kRoundedRectRadius);
 
   setRect(rectangle);
 }
@@ -66,6 +67,11 @@ void NodeUI::SetWidget(EffectUI *widget)
   central_widget_ = widget;
 }
 
+EffectUI *NodeUI::Widget()
+{
+  return central_widget_;
+}
+
 void NodeUI::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
   Q_UNUSED(widget)
@@ -88,7 +94,7 @@ void NodeUI::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QW
     painter->setPen(palette.base().color());
   }
   painter->setBrush(palette.window());
-  painter->drawPath(path_);
+  painter->drawPath(drag_path_);
 }
 
 void NodeUI::mousePressEvent(QGraphicsSceneMouseEvent *event)
@@ -96,6 +102,7 @@ void NodeUI::mousePressEvent(QGraphicsSceneMouseEvent *event)
   QVector<QRectF> sockets = GetNodeSocketRects();
 
   clicked_socket_ = -1;
+  drag_destination_ = nullptr;
 
   for (int i=0;i<sockets.size();i++) {
     if (sockets.at(i).contains(event->pos())) {
@@ -106,8 +113,7 @@ void NodeUI::mousePressEvent(QGraphicsSceneMouseEvent *event)
 
   if (clicked_socket_ > -1) {
     drag_line_start_ = pos() + sockets.at(clicked_socket_).center();
-    drag_line_ = scene()->addPath(GetEdgePath(drag_line_start_, event->scenePos()),
-                                  QPen(Qt::white, 2));
+    drag_line_ = scene()->addPath(NodeEdgeUI::GetEdgePath(drag_line_start_, event->scenePos()));
 
     event->accept();
   } else {
@@ -119,7 +125,65 @@ void NodeUI::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 {
   if (clicked_socket_ > -1) {
 
-    drag_line_->setPath(GetEdgePath(drag_line_start_, event->scenePos()));
+    bool line_is_touching_node = false;
+
+    QPointF drag_line_end = event->scenePos();
+
+    // Get all the graphics items at this mouse position
+    QList<QGraphicsItem *> mouse_items = scene()->items(event->scenePos());
+    for (int j=0;j<mouse_items.size();j++) {
+
+      // See if the graphics item here is a node
+      NodeUI* mouse_node = dynamic_cast<NodeUI*>(mouse_items.at(j));
+
+      if (mouse_node != nullptr) {
+        // If so, get this node's sockets and loop through them
+        QVector<QRectF> mouse_nodes_sockets = mouse_node->GetNodeSocketRects();
+        for (int i=0;i<mouse_nodes_sockets.size();i++) {
+
+          // See if this socket contains the mouse cursor
+          if (mouse_nodes_sockets.at(i).contains(event->scenePos() - mouse_node->pos())) {
+
+            // If so, see if the two rows can be connected
+
+            EffectRow* local_row = central_widget_->GetEffect()->row(clicked_socket_);
+            EffectRow* remote_row = mouse_node->GetRowFromIndex(i);
+
+            // Ensure one is an input and one is an output and whether their data types are compatible
+            if (local_row->IsNodeInput() != remote_row->IsNodeInput()) {
+
+              // Determine which row is the input and which row is the output
+              EffectRow* input_row = (local_row->IsNodeInput()) ? local_row : remote_row;
+              EffectRow* output_row = (local_row->IsNodeInput()) ? remote_row : local_row;
+
+              if (input_row->CanAcceptDataType(output_row->OutputDataType())) {
+                // This is a valid connection
+                line_is_touching_node = true;
+
+                // Snap drag line to this socket
+                drag_line_end = mouse_node->pos() + mouse_nodes_sockets.at(i).center();
+
+                // Cancel loop since we have a connection now
+                j = mouse_items.size();
+
+                // Cache destination row
+                drag_destination_ = remote_row;
+              }
+            }
+
+            break;
+          }
+        }
+      }
+    }
+
+    if (line_is_touching_node) {
+      drag_line_->setPen(QPen(Qt::white, 2));
+    } else {
+      drag_line_->setPen(QPen(Qt::gray, 2));
+    }
+
+    drag_line_->setPath(NodeEdgeUI::GetEdgePath(drag_line_start_, drag_line_end));
 
     event->accept();
 
@@ -132,26 +196,16 @@ void NodeUI::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
 {
   if (clicked_socket_ > -1) {
     scene()->removeItem(drag_line_);
-    delete drag_line_;
     event->accept();
+
+    if (drag_destination_ != nullptr) {
+      EffectRow::ConnectEdge(central_widget_->GetEffect()->row(clicked_socket_), drag_destination_);
+    }
   } else {
     QGraphicsItem::mouseReleaseEvent(event);
   }
 }
 
-QPainterPath NodeUI::GetEdgePath(const QPointF &start_pos, const QPointF &end_pos)
-{
-  double mid_x = double_lerp(start_pos.x(), end_pos.x(), 0.5);
-
-  QPainterPath path_;
-  path_.moveTo(start_pos);
-  path_.cubicTo(QPointF(mid_x, start_pos.y()),
-                QPointF(mid_x, end_pos.y()),
-                end_pos);
-
-  return path_;
-}
-
 QVector<QRectF> NodeUI::GetNodeSocketRects()
 {
   QVector<QRectF> rects;
@@ -176,3 +230,14 @@ QVector<QRectF> NodeUI::GetNodeSocketRects()
 
   return rects;
 }
+
+EffectRow *NodeUI::GetRowFromIndex(int i)
+{
+  if (central_widget_ != nullptr) {
+    Node* e = central_widget_->GetEffect();
+    if (i < e->row_count()) {
+      return e->row(i);
+    }
+  }
+  return nullptr;
+}
diff --git a/ui/nodeui.h b/ui/nodeui.h
index 2ac1b0c48..2b1f30696 100644
--- a/ui/nodeui.h
+++ b/ui/nodeui.h
@@ -5,6 +5,8 @@
 #include <QGraphicsItem>
 
 class EffectUI;
+class EffectRow;
+class NodeEdge;
 
 class NodeUI : public QGraphicsRectItem {
 public:
@@ -14,24 +16,32 @@ public:
   void AddToScene(QGraphicsScene* scene);
   void Resize(const QSize& s);
   void SetWidget(EffectUI* widget);
+  EffectUI* Widget();
+
+  QVector<QRectF> GetNodeSocketRects();
+
 protected:
   virtual void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget = nullptr) override;
 
   virtual void mousePressEvent(QGraphicsSceneMouseEvent * event) override;
   virtual void mouseMoveEvent(QGraphicsSceneMouseEvent *event) override;
   virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent *event) override;
+
 private:
-  QVector<QRectF> GetNodeSocketRects();
-  QPainterPath GetEdgePath(const QPointF& start_pos, const QPointF& end_pos);
+  EffectRow *GetRowFromIndex(int i);
 
   EffectUI* central_widget_;
   QGraphicsProxyWidget* proxy_;
-  QPainterPath path_;
 
   QGraphicsPathItem* drag_line_;
   QPointF drag_line_start_;
+  EffectRow* drag_destination_;
+  QPainterPath drag_path_;
 
   int clicked_socket_;
+
 };
 
+
+
 #endif // NODEUI_H
diff --git a/ui/nodeview.cpp b/ui/nodeview.cpp
index 3998fab9c..94366749d 100644
--- a/ui/nodeview.cpp
+++ b/ui/nodeview.cpp
@@ -42,9 +42,9 @@ void NodeView::mouseMoveEvent(QMouseEvent *event)
 void NodeView::mouseReleaseEvent(QMouseEvent *event)
 {
   if (!hand_moving_) {
-    hand_moving_ = false;
     QGraphicsView::mouseReleaseEvent(event);
   }
+  hand_moving_ = false;
 }
 
 void NodeView::wheelEvent(QWheelEvent *event)