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AleixCardona/ScrollRectEnsureVisible

Created December 2, 2019 13:15
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  1. AleixCardona created this gist Dec 2, 2019.
    86 changes: 86 additions & 0 deletions ScrollRectEnsureVisible
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,86 @@
    using UnityEngine;
    using UnityEngine.UI;

    [RequireComponent(typeof(ScrollRect))]
    public class ScrollRectEnsureVisible : MonoBehaviour
    {
    public RectTransform maskTransform;

    private ScrollRect mScrollRect;
    private RectTransform mScrollTransform;
    private RectTransform mContent;

    public void CenterOnItem(RectTransform target)
    {
    // Item is here
    var itemCenterPositionInScroll = GetWorldPointInWidget(mScrollTransform, GetWidgetWorldPoint(target));
    // But must be here
    var targetPositionInScroll = GetWorldPointInWidget(mScrollTransform, GetWidgetWorldPoint(maskTransform));
    // So it has to move this distance
    var difference = targetPositionInScroll - itemCenterPositionInScroll;
    difference.z = 0f;

    //clear axis data that is not enabled in the scrollrect
    if (!mScrollRect.horizontal)
    {
    difference.x = 0f;
    }
    if (!mScrollRect.vertical)
    {
    difference.y = 0f;
    }

    var normalizedDifference = new Vector2(
    difference.x / (mContent.rect.size.x - mScrollTransform.rect.size.x),
    difference.y / (mContent.rect.size.y - mScrollTransform.rect.size.y));

    var newNormalizedPosition = mScrollRect.normalizedPosition - normalizedDifference;
    if (mScrollRect.movementType != ScrollRect.MovementType.Unrestricted)
    {
    newNormalizedPosition.x = Mathf.Clamp01(newNormalizedPosition.x);
    newNormalizedPosition.y = Mathf.Clamp01(newNormalizedPosition.y);
    }

    mScrollRect.normalizedPosition = newNormalizedPosition;
    }
    private void Awake()
    {
    mScrollRect = GetComponent<ScrollRect>();
    mScrollTransform = mScrollRect.transform as RectTransform;
    mContent = mScrollRect.content;
    Reset();
    }
    private void Reset()
    {
    if (maskTransform == null)
    {
    var mask = GetComponentInChildren<Mask>(true);
    if (mask)
    {
    maskTransform = mask.rectTransform;
    }
    if (maskTransform == null)
    {
    var mask2D = GetComponentInChildren<RectMask2D>(true);
    if (mask2D)
    {
    maskTransform = mask2D.rectTransform;
    }
    }
    }
    }
    private Vector3 GetWidgetWorldPoint(RectTransform target)
    {
    //pivot position + item size has to be included
    var pivotOffset = new Vector3(
    (0.5f - target.pivot.x) * target.rect.size.x,
    (0.5f - target.pivot.y) * target.rect.size.y,
    0f);
    var localPosition = target.localPosition + pivotOffset;
    return target.parent.TransformPoint(localPosition);
    }
    private Vector3 GetWorldPointInWidget(RectTransform target, Vector3 worldPoint)
    {
    return target.InverseTransformPoint(worldPoint);
    }
    }