EditorWindow, draggable GUI.Window and dragging to pan [SOLVED]

User unimechanic posted a couple years ago a snippet of C# code to create a simple Node Editor, which he later updated to add a simple pan functionality. The thread is here: http://forum.unity3d.com/threads/simple-node-editor.189230/

I've been trying to figure out a way to drag the EditorWindow background instead of using buttons to pan. This little snippet seemed to do the trick:

Code (CSharp):

1.         if (Event.current.button == 1 && Event.current.type == EventType.MouseDrag) {
2.             panX += Event.current.delta.x;
3.             panY += Event.current.delta.y;
4.         }

...except when we attempt to drag the GUI.Windows that we use as the nodes, both the window and the whole group will drag.

I've been trying to figure out a way to detect if the GUI.Window is being dragged, or if the mouse is within the rect of the windows, but after a lot of browsing in the documentation I can't figure out how to achieve either.

The whole script for testing:

Code (CSharp):

1. using UnityEngine;
2. using UnityEditor;
3.  
4. public class NodeEditor : EditorWindow {
5.  
6.     Rect window1;
7.     Rect window2;
8.     float panX = 0;
9.     float panY = 0;
10.    
11.     [MenuItem("Window/Node Editor")]
12.     static void ShowEditor() {
13.         NodeEditor editor = EditorWindow.GetWindow<NodeEditor>();
14.         editor.Show();
15.     }
16.    
17.     public void Awake() {
18.         window1 = new Rect(10, 10, 100, 100);
19.         window2 = new Rect(210, 210, 100, 100);
20.     }
21.    
22.     void OnGUI() {
23.         bool didPan = false;
24.         if (Event.current.type == EventType.MouseDrag) {
25.             panX += Event.current.delta.x;
26.             panY += Event.current.delta.y;
27.             didPan = true;
28.         }
29.        
30.         GUI.BeginGroup(new Rect(panX, panY, 100000, 100000));
31.        
32.         DrawNodeCurve(window1, window2); // Here the curve is drawn under the windows
33.        
34.         BeginWindows();
35.         window1 = GUI.Window(2, window1, DrawNodeWindow, "Node A");   // Updates the Rect's when these are dragged
36.         window2 = GUI.Window(3, window2, DrawNodeWindow, "Node B");
37.         EndWindows();
38.        
39.         GUI.EndGroup();
40.        
41.         if (didPan) Repaint();
42.     }
43.    
44.     void DrawNodeWindow(int id) {
45.         GUI.DragWindow();
46.     }
47.    
48.     void DrawNodeCurve(Rect start, Rect end) {
49.         Vector3 startPos = new Vector3(start.x + start.width, start.y + start.height / 2, 0);
50.         Vector3 endPos = new Vector3(end.x, end.y + end.height / 2, 0);
51.         Vector3 startTan = startPos + Vector3.right * 50;
52.         Vector3 endTan = endPos + Vector3.left * 50;
53.         Handles.DrawBezier(startPos, endPos, startTan, endTan, Color.white, null, 4);
54.     }
55. }

 

Derp! I figured it out! I'm very new to Unity, so I didn't realize that GUI.Window returns the window Rect - the current one, accounting for the windows being dragged.

With that, I simply need to check each window rect for Rect.Contain(Event.Current.mousePosition). If neither window rect contains the mouse position, that means the user is dragging the background.

 

I know this is more than a year old and it's probably way irrelevant to you by now but you can simply move the panning code below GUI.EndGroup ().

I don't quite understand why it works, maybe something to do with the windows already being serialized before the panning code, I will try to look into it. Anyways, this should simplify the code and I hope this helps.

P.S. no need for the didPan bool check simply replace it with repaint.

 

yes you are right! simple way to solve it