Child's anchoredPosition to be set based on Canvas (Vector2)

• 
  Scenario
  
  I have a position

  Vector2 targetPosition

  based on the root Canvas of UnityEngine.UI
  
  Now I want to move a UI Element

  RectTransform ShowButton

  within that Canvas to that targetPosition.

  [URL='https://docs.unity3d.com/ScriptReference/RectTransform.html']RectTransform[/URL].anchoredPosition

  
  
  Issue
  
  This

  ShowButton

  is a child of a RectTransform aligned at center & bottom. Hence the vector2 value of

  ShowButton.anchoredPosition

  is relative to that.
  
  Request
  
  Now if I move my

  anchoredPosition

  of

  ShowButton

  , it moves relatively.
  
  1. How can I convert targetPosition to a relative position of ShowButton (or)
  2. How can I move ShowButton on a global scale (Vector2)?
  
  
  Thank you,
  Karsnen

 

Canvas Render mode is https://docs.unity3d.com/ScriptReference/RenderMode.ScreenSpaceOverlay.html

 

SOLUTION

SPOILER: a sort of a hack!

Steps

1. Create an empty gameobject (say "locationCalculator") with RectTransform as it's component
2. Have that gameobject rest under the root canvas
3. Once you have position (Vector2) relative to the root canvas, set the parent locationCalculator to the RectTransform to which you want to calculate. Also use

   
   
   Transform.SetParent (Transform, bool)
   
   

   with worldPositionStays as true
4. Capture the anchoredPosition of locationCalculator. This becomes your target position.
5. Reset locationCalculator position & parent to normal values (check code)

Creation of the Gameobject

Code (CSharp):

1.    [SerializeField]
2.         internal RectTransform MyCanvasTransform;
3.         private RectTransform locationCalculator;
4.  
5.         private void Awake()
6.         {
7.             if(locationCalculator == null)
8.             {
9.                 GameObject _go = new GameObject("locationCalculator");
10.  
11.                 locationCalculator = _go.AddComponent<RectTransform>();
12.                 locationCalculator.SetParent(MyCanvasTransform);
13.                 _go.transform.localScale = Vector3.one;
14.                 _go.transform.rotation = Quaternion.identity;
15.                 _go.transform.position = Vector3.zero;
16.                 _go.transform.SetAsFirstSibling();
17.             }
18.         }

Getting the target positional values

Code (CSharp):

1.         internal Vector2 GetLocal(Vector2 _globalPosition, RectTransform _referenceTransform)
2.         {
3.             Vector2 _positionBuffer = _globalPosition;
4.             locationCalculator.anchoredPosition = _positionBuffer;
5.             locationCalculator.SetParent(_referenceTransform, true);
6.  
7.             _positionBuffer = locationCalculator.anchoredPosition;
8.             locationCalculator.SetParent(MyCanvasTransform);
9.             locationCalculator.anchoredPosition = Vector2.zero;
10.             locationCalculator.SetAsFirstSibling();
11.             _referenceTransform = null;
12.  
13.             return _positionBuffer;
14.         }

NOTE

PLEASE note the above solution does not work when & if the RectTransform for which you are figuring position has a size delta of Vector2.zero. It would happen if you stretch to fit.

Thank you & would like to also any other possible direct solutions.