From 53f85a5d227763aa5c8374dd177ff7c2bd86adb1 Mon Sep 17 00:00:00 2001
From: Thor Brigsted <thorbrigsted@gmail.com>
Date: Sat, 8 Jun 2019 14:25:07 +0200
Subject: [PATCH] Improved zoom with the help of Jeroenimoo0's PR

---
 Scripts/Editor/NodeEditorGUI.cs | 56 ++++++++++++++++++++++-----------
 1 file changed, 37 insertions(+), 19 deletions(-)

diff --git a/Scripts/Editor/NodeEditorGUI.cs b/Scripts/Editor/NodeEditorGUI.cs
index c9c460f..2bf3945 100644
--- a/Scripts/Editor/NodeEditorGUI.cs
+++ b/Scripts/Editor/NodeEditorGUI.cs
@@ -10,10 +10,13 @@ namespace XNodeEditor {
         public NodeGraphEditor graphEditor;
         private List<UnityEngine.Object> selectionCache;
         private List<XNode.Node> culledNodes;
+        /// <summary> 19 if docked, 22 if not </summary>
         private int topPadding { get { return isDocked() ? 19 : 22; } }
         /// <summary> Executed after all other window GUI. Useful if Zoom is ruining your day. Automatically resets after being run.</summary>
         public event Action onLateGUI;
 
+        private Matrix4x4 prevGuiMatrix;
+
         private void OnGUI() {
             Event e = Event.current;
             Matrix4x4 m = GUI.matrix;
@@ -38,24 +41,40 @@ namespace XNodeEditor {
             GUI.matrix = m;
         }
 
-        public static void BeginZoomed(Rect rect, float zoom, float topPadding) {
-            GUI.EndClip();
+        public void BeginZoomed() {
+            GUI.EndGroup();
 
-            GUIUtility.ScaleAroundPivot(Vector2.one / zoom, rect.size * 0.5f);
-            Vector4 padding = new Vector4(0, topPadding, 0, 0);
-            padding *= zoom;
-            GUI.BeginClip(new Rect(-((rect.width * zoom) - rect.width) * 0.5f, -(((rect.height * zoom) - rect.height) * 0.5f) + (topPadding * zoom),
-                rect.width * zoom,
-                rect.height * zoom));
+            Rect position = new Rect(this.position);
+            position.x = 0;
+            position.y = topPadding;
+
+            Vector2 topLeft = new Vector2(position.xMin, position.yMin - topPadding);
+            Rect clippedArea = ScaleSizeBy(position, zoom, topLeft);
+            GUI.BeginGroup(clippedArea);
+
+            prevGuiMatrix = GUI.matrix;
+            Matrix4x4 translation = Matrix4x4.TRS(Vector3.zero, Quaternion.identity, Vector3.one);
+            Matrix4x4 scale = Matrix4x4.Scale(new Vector3(1.0f / zoom, 1.0f / zoom, 1.0f));
+            GUI.matrix = translation * scale * translation.inverse * GUI.matrix;
         }
 
-        public static void EndZoomed(Rect rect, float zoom, float topPadding) {
-            GUIUtility.ScaleAroundPivot(Vector2.one * zoom, rect.size * 0.5f);
-            Vector3 offset = new Vector3(
-                (((rect.width * zoom) - rect.width) * 0.5f),
-                (((rect.height * zoom) - rect.height) * 0.5f) + (-topPadding * zoom) + topPadding,
-                0);
-            GUI.matrix = Matrix4x4.TRS(offset, Quaternion.identity, Vector3.one);
+        public void EndZoomed() {
+            GUI.matrix = prevGuiMatrix;
+            GUI.EndGroup();
+            GUI.BeginGroup(new Rect(0.0f, topPadding - (topPadding * zoom), Screen.width, Screen.height));
+        }
+
+        public static Rect ScaleSizeBy(Rect rect, float scale, Vector2 pivotPoint) {
+            Rect result = rect;
+            result.x -= pivotPoint.x;
+            result.y -= pivotPoint.y;
+            result.xMin *= scale;
+            result.xMax *= scale;
+            result.yMin *= scale;
+            result.yMax *= scale;
+            result.x += pivotPoint.x;
+            result.y += pivotPoint.y;
+            return result;
         }
 
         public void DrawGrid(Rect rect, float zoom, Vector2 panOffset) {
@@ -136,8 +155,7 @@ namespace XNodeEditor {
 
                             p = new Vector2(-p.y, p.x) * Mathf.Sign(side) * tangentLength;
                             inputTangent = p;
-                        }
-                        else {
+                        } else {
                             inputTangent = Vector2.left * Vector2.Distance(windowPoints[i], windowPoints[i + 1]) * 0.01f * zoom;
                         }
 
@@ -258,7 +276,7 @@ namespace XNodeEditor {
                 if (onValidate != null) EditorGUI.BeginChangeCheck();
             }
 
-            BeginZoomed(position, zoom, topPadding);
+            BeginZoomed();
 
             Vector2 mousePos = Event.current.mousePosition;
 
@@ -389,7 +407,7 @@ namespace XNodeEditor {
             }
 
             if (e.type != EventType.Layout && currentActivity == NodeActivity.DragGrid) Selection.objects = preSelection.ToArray();
-            EndZoomed(position, zoom, topPadding);
+            EndZoomed();
 
             //If a change in is detected in the selected node, call OnValidate method. 
             //This is done through reflection because OnValidate is only relevant in editor,