Unity UI Selection problem of Toggles/Buttons in a draggable ScrollRect

Hello all,

I've searched for a while but haven't found a solution for me.

I am creating a mobile application with 2D elements on a canvas.
On some panels I will have a ScrollRect with dynamic content, meaning the amount of items in there varies. I already managed to scale the content size with the content size fitter. What I now wanted to achieve is the possibility to drag this ScrollRect even if I touch a Button or Toggle.

I achieved this also by attaching a script which implements IPointerDownHandler, IPointerUpHandler, IBeginDragHandler, IDragHandler, IEndDragHandler.

I have also implemented the ability to press or hold either Toggles or Buttons. When I click my Toggles, they work as intended and change their color, when they are turned on.

The problem I am facing is:

Whenever I want to drag the ScrollRect view, the Selectable Object keeps getting selected when I re-enter the gameobject. With Buttons it was acceptable, but using toggles introduces the issue of changing the value of isOn, when I release the touch after a drag on this same Toggle. What I want is:
The moment I begin to drag the content area, I want to deselect the pressed item and simply continue with dragging, regardless where I stop. If I release the touch outside of the starting element, nothing is changed like it should be.

I hope the following images make this more understandable. The mouse pointer's position is shown with the star symbol.

Beginning to hold down over a Toggle.


Beginning to drag.


Moving the mouse outside of the selected object.


Reentering the Toggle. (This should react like any other Toggle being hovered over.)


Releasing the touch/press over this Toggle. (Should not happen!)


The code of this toggle is basically this:

Code (CSharp):

1.  
2. [RequireComponent(typeof(Toggle))]
3. public class HoldButtonOrderTableItem : MonoBehaviour, IPointerDownHandler, IPointerUpHandler, IBeginDragHandler, IDragHandler, IEndDragHandler
4. {
5.     private Toggle thisToggle;
6.  
7.     private bool isDown;
8.     private bool isDrag;
9.  
10.     private float downTime;
11.     private ScrollRect parentScrollRect;
12.  
13.     [...]
14.  
15.     void Update()
16.     {
17.         if (!isDown) return;
18.         if (!isDrag && Time.realtimeSinceStartup - downTime > 1f)
19.         {
20.             HandleLongTap();
21.         }
22.     }
23.  
24.     private void HandleLongTap()
25.     {
26.         print("Handle Long Tap");
27.         isDown = false;
28.         // some functionality ...
29.     }
30.  
31.     private void HandleShortTap()
32.     {
33.         Debug.Log("Handle Short Tap");
34.         // some functionality ...
35.     }
36.  
37.     public void OnPointerDown(PointerEventData eventData)
38.     {
39.         Debug.Log("Pointer Down!");
40.  
41.         isDrag = false;
42.         isDown = true;
43.         downTime = Time.realtimeSinceStartup;
44.     }
45.  
46.     public void OnPointerUp(PointerEventData eventData)
47.     {
48.         Debug.Log("Pointer Up!");
49.  
50.         isDown = false;
51.  
52.         if (!isDrag && Time.realtimeSinceStartup - downTime <= 1f)
53.         {
54.             HandleShortTap();
55.         }
56.     }
57.  
58.     public void OnBeginDrag(PointerEventData eventData)
59.     {
60.         Debug.Log("Begin Drag!");
61.         isDrag = true;
62.  
63.         // thisToggle.OnPointerExit(eventData);  <-- I tried different things here, nothing worked yet.
64.  
65.         parentScrollRect.OnBeginDrag(eventData);
66.     }
67.  
68.     public void OnDrag(PointerEventData eventData)
69.     {
70.         parentScrollRect.OnDrag(eventData);
71.     }
72.  
73.     public void OnEndDrag(PointerEventData eventData)
74.     {
75.         Debug.Log("End Drag.");
76.  
77.         parentScrollRect.OnEndDrag(eventData);
78.     }
79.  

The received console output until the last image is this one, which shows it doesn't call any of my methods (HandleLong/ShortTap). So the Toggle is using the OnPointerUp Event and changes its ON-state.


I somehow need to reset this toggle's state. Does anyone have any idea where to begin or how to achieve this?

I need to use Unity 5.5.2f1.

 

Sadly, I haven't been able to solve this yet.

Does anyone have an idea for a possible solution?

 

Because I also searched a while and couldn't find a proper solution, I dig out this old thread and present my solution for the next poor guy.

I extended the StandaloneInputModule and applied some magic to it... works pretty good:

Code (CSharp):

1. public class MyInputModule : StandaloneInputModule
2. {
3.     ScrollRect _draggedScrollRect;
4.     PointerEventData _lastDragPointer;
5.  
6.     public override void Process()
7.     {
8.        
9.         base.Process();
10.  
11.         _mouseState = GetMousePointerEventData();
12.  
13.         // detect release of dragged scroll rect
14.         if(_mouseState != null && _mouseState.AnyReleasesThisFrame() && _draggedScrollRect != null)
15.         {
16.             // only left button is handled by scroll rect (but it is sometimes not detected as left)
17.             _lastDragPointer.button = PointerEventData.InputButton.Left;
18.            
19.             ExecuteEvents.Execute(_draggedScrollRect.gameObject, _lastDragPointer, ExecuteEvents.endDragHandler);
20.             eventSystem.SetSelectedGameObject(null);
21.  
22.             _draggedScrollRect = null;
23.         }
24.     }
25.  
26.     protected override void ProcessDrag(PointerEventData pointerEvent)
27.     {
28.         _lastDragPointer = pointerEvent;
29.         if (pointerEvent.IsPointerMoving() && Cursor.lockState != CursorLockMode.Locked && pointerEvent.pointerDrag != null)
30.         {
31.             if (!pointerEvent.dragging
32.                 && ShouldStartDrag(pointerEvent.pressPosition,     pointerEvent.position,
33.                                    eventSystem.pixelDragThreshold, pointerEvent.useDragThreshold))
34.             {
35.                 #region Try to find a Scroll Rect
36.                 _draggedScrollRect = pointerEvent.pointerDrag.GetComponentInParent<ScrollRect>();
37.                 if(_draggedScrollRect == null)
38.                 {
39.                     List<RaycastResult> raycast = new List<RaycastResult>();
40.                     eventSystem.RaycastAll(pointerEvent, raycast);
41.                     foreach(var hit in raycast)
42.                     {
43.                         if (!hit.isValid)
44.                             continue;
45.  
46.                         var draggable = hit.gameObject.GetComponentInParent<ScrollRect>();
47.                         if(draggable != null)
48.                         {
49.                             _draggedScrollRect = draggable;
50.                             break;
51.                         }
52.                     }
53.                 }
54.  
55.                 eventSystem.SetSelectedGameObject(null);
56.                 #endregion
57.  
58.                 GameObject obj = (_draggedScrollRect != null)
59.                     ? _draggedScrollRect.gameObject
60.                     : pointerEvent.pointerDrag;
61.  
62.                 ExecuteEvents.Execute(obj, pointerEvent, ExecuteEvents.beginDragHandler);
63.                 pointerEvent.dragging = true;
64.             }
65.  
66.             if (pointerEvent.dragging)
67.             {
68.                 if (_draggedScrollRect != null)
69.                 {
70.                     pointerEvent.eligibleForClick = false;
71.                     ExecuteEvents.Execute(_draggedScrollRect.gameObject, pointerEvent, ExecuteEvents.dragHandler);
72.                 }
73.                 else
74.                 {
75.                     // if dragging something different than scroll rect, use the original logic
76.                     base.ProcessDrag(pointerEvent);
77.                 }
78.             }
79.         }
80.     }
81.    
82.     private static bool ShouldStartDrag(Vector2 pressPos, Vector2 currentPos, float threshold, bool useDragThreshold)
83.     {
84.         if (useDragThreshold)
85.         {
86.             Vector2 vector2 = pressPos - currentPos;
87.             return vector2.sqrMagnitude >= threshold * threshold;
88.         }
89.  
90.         return true;
91.     }
92. }