how to stop Drag event in OnBeginDrag() in unity 4.6

Question

I have a script that handles dragging of an items from and to a given slot. But i want to add a function to stop dragging of a specific items. i think the best place to do is in the OnBeginDrag method, but cant seem to figure a way to stop/cancel the drag event itself, here is a bit of my code

public class SlotBehaviour : MonoBehaviour, IDropHandler, IPointerEnterHandler, IPointerExitHandler, IBeginDragHandler, IDragHandler, IEndDragHandler,IPointerClickHandler
{
    public void OnBeginDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left)
        {
            return;
        }
        if (this.Empty) return;
        var canvas = imageItem.canvas;
        if (canvas == null) return;
        GUIManager.mouseBusy = true;
        // We have clicked something that can be dragged.
        // What we want to do is create an icon for this.
        m_DraggingIcon = new GameObject("icon");

        m_DraggingIcon.transform.SetParent(canvas.transform, false);
        m_DraggingIcon.transform.SetAsLastSibling();

        var image = m_DraggingIcon.AddComponent<Image>();
        // The icon will be under the cursor.
        // We want it to be ignored by the event system.
        m_DraggingIcon.AddComponent<IgnoreRaycast>();

        image.sprite = imageItem.sprite;
        image.rectTransform.sizeDelta = imageItem.rectTransform.sizeDelta;


        m_DraggingPlane = transform as RectTransform;

        SetDraggedPosition(eventData);

    }

    public void OnDrag(PointerEventData data)
    {
        if (m_DraggingIcon != null)
            SetDraggedPosition(data);
    }

    private void SetDraggedPosition(PointerEventData data)
    {
        if (data.pointerEnter != null && data.pointerEnter.transform as RectTransform != null)
            m_DraggingPlane = data.pointerEnter.transform as RectTransform;

        var rt = m_DraggingIcon.GetComponent<RectTransform>();
        Vector3 globalMousePos;
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(m_DraggingPlane, data.position, data.pressEventCamera, out globalMousePos))
        {
            rt.position = globalMousePos;
            rt.rotation = m_DraggingPlane.rotation;
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        if (m_DraggingIcon != null)
        {

            Destroy(m_DraggingIcon);
        }
        GUIManager.mouseBusy = false;
        //if you drop it somewhere where its not wanted(or just nowhere)
        if (eventData.used == false)
        {
            if (eventData.pointerCurrentRaycast.gameObject == null)// if its nowhere offer to drop it on ground
            {
                GUIManager.instance.DropItem((int)ItemsDatabase.container[containerID].items[indexInContainer]);
            }
        }
    }
}

I tried returning the method earlier but it doesnt do anything, probably need to do something with the event data...i will be gratefull if you tell me how to deal with it.

Answer 1

You may create flag (for example, IsDragable). For items which you donn't want to drag&drop you have to return from drag event handlers:

public class DragHangler : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler {

public bool IsDragable;

#region IBeginDragHandler implementation
public void OnBeginDrag (PointerEventData eventData)
{
    if (!IsDragable)    return;

    Debug.Log ("OnBeginDrag:Do something");
}
#endregion

#region IDragHandler implementation

public void OnDrag (PointerEventData eventData)
{
    if (!IsDragable)    return;

    Debug.Log ("OnDrag: Do something");
}

#endregion

#region IEndDragHandler implementation

public void OnEndDrag (PointerEventData eventData)
{
    if (!IsDragable) return;

    Debug.Log ("OnEnd: Do something");
}

#endregion
}

Other solution is to disable BlockRaycast in CanvasGroup component.