Why ScrollRect delta doesn't change when I modified normalizedPosition?

Unity Engine
1

Hi there,
I changed normalizedPosition value by code when I’m dragging scrollrect (not release finger), but scroll delta doesn’t change, so scrollview come back to before normalizedPosition changed when I keep dragging (still not release finger). Someone help.

2

ScrollRect uses current mouse position - start mouse position to update/calculate normalizedposition (instead of for instance using delta or otherwise handling any updates to normalizedposition).
The source for ScrollRect in 5.1 is here:
https://bitbucket.org/Unity-Technologies/ui/src/ccb946ecc23815d1a7099aee0ed77b0cde7ff278/UnityEngine.UI/UI/Core/ScrollRect.cs?at=5.1

I have the same problem and thinking about overriding the OnDrag function where it calculates the delta (line 256 -
var pointerDelta = localCursor - m_PointerStartLocalCursor;
) to use eventData.delta instead. But havent tried if it would work as expected yet.

3

It worked, Thanks a lot!!!

public class Scroller : ScrollRect
{
    PointerEventData m_beginEventData;
    public override void OnBeginDrag(PointerEventData eventData)
    {
        base.OnBeginDrag(eventData);
        m_beginEventData = eventData;
    }
    public void Reset()
    {
        OnBeginDrag(m_beginEventData);
    }
}

Reset() after modified normalizedposition.