Added preview of first selected node in inspector

MaterialGraphProject/Assets/GraphFramework/SerializableGraph/Editor/Drawing/AbstractGraphInspector.cs

     {
         private readonly TypeMapper m_DataMapper = new TypeMapper(typeof(BasicNodeInspector));
 
-        [SerializeField] private List<AbstractNodeInspector> m_Inspectors = new List<AbstractNodeInspector>();
+        [SerializeField] protected List<AbstractNodeInspector> m_Inspectors = new List<AbstractNodeInspector>();
 
         protected abstract void AddTypeMappings(Action<Type, Type> map);
 
             }
         }
 
-        private void UpdateInspectors()
+        protected virtual void UpdateInspectors()
         {
             var asset = target as IGraphAsset;
             if (asset == null)
             return CreateInstance(type) as AbstractNodeInspector;
         }
 
-        public void OnEnable()
+        public virtual void OnEnable()
         {
             m_DataMapper.Clear();
             AddTypeMappings(m_DataMapper.AddMapping);

MaterialGraphProject/Assets/UnityShaderEditor/Editor/Drawing/MaterialGraphInspector.cs

 using System.Linq;
 using UnityEditor.Graphing.Drawing;
 using UnityEditor.MaterialGraph.Drawing.NodeInspectors;
+using UnityEngine;
+using UnityEngine.Graphing;
 using UnityEngine.MaterialGraph;
 
 namespace UnityEditor.MaterialGraph.Drawing
     {
+        private AbstractMaterialNode m_PreviewNode;
+        private NodePreviewDrawData m_NodePreviewPresenter;
+
+        public override void OnEnable()
+        {
+            base.OnEnable();
+            m_NodePreviewPresenter = CreateInstance<NodePreviewDrawData>();
+        }
+
+        }
+
+        protected override void UpdateInspectors()
+        {
+            base.UpdateInspectors();
+            var newPreviewNode = m_Inspectors.Select(i => i.node).OfType<AbstractMaterialNode>().FirstOrDefault();
+            if (newPreviewNode != m_PreviewNode)
+            {
+                m_PreviewNode = newPreviewNode;
+                m_NodePreviewPresenter.Initialize(m_PreviewNode);
+            }
+        }
+
+        public override bool HasPreviewGUI()
+        {
+            return m_PreviewNode != null;
+        }
+
+        public override void OnPreviewGUI(Rect r, GUIStyle background)
+        {
+            if (Event.current.type == EventType.Repaint)
+            {
+                var size = Mathf.Min(r.width, r.height);
+                var previewDimension = new Vector2(size, size);
+                var previewPosition = new Vector2(r.x + r.width*0.5f - size*0.5f, r.y + r.height*0.5f - size*0.5f);
+                var image = m_NodePreviewPresenter.Render(previewDimension);
+                GUI.DrawTexture(new Rect(previewPosition, previewDimension), image);
+                m_NodePreviewPresenter.modificationScope = ModificationScope.Node;
+            }
+        }
+
+        public override bool RequiresConstantRepaint()
+        {
+            return true;
+        }
+
+        public override GUIContent GetPreviewTitle()
+        {
+            return new GUIContent(m_Inspectors.Select(i => i.node.name).FirstOrDefault());
         }
     }
 }