is there a way to know ui element is visible in the scroll view?

Questions & Answers
1

I was use the UGUI,
65731-1.jpg

one page is show six itemelement,
when I drop the scroll view, is there a way to know which itemelement is visible in the scroll view?

3

Well, I have reached some good utility exist in Unity3d, I hope this helps:

RectTransformUtility.RectangleContainsScreenPoint

2

myself fix this question,
first: Get the count to show in the scroll view.

private int CalculateCurElementShowCount()
{
    float offsetCellX = 10.0f;
    float offsetCellY = 10.0f;

    ColumnElementCount = -1;
    RowElementCount = -1;

    if (UI_GridGroup.constraint == GridLayoutGroup.Constraint.FixedColumnCount)
    {
        ColumnElementCount = UI_GridGroup.constraintCount;
    }
    else if(UI_GridGroup.constraint == GridLayoutGroup.Constraint.FixedRowCount)
    {
        RowElementCount = UI_GridGroup.constraintCount;
    }
    
    if(ColumnElementCount == -1)
    {
        ColumnElementCount = (int)( (rectComponent.rect.width + offsetCellX)/(UI_GridGroup.cellSize.x + UI_GridGroup.spacing.x) );
    }
    if(RowElementCount == -1)
    {
        RowElementCount = (int)( (rectComponent.rect.height + offsetCellY) / (UI_GridGroup.cellSize.y + UI_GridGroup.spacing.y) );
    }

    int Count = ColumnElementCount * RowElementCount;
    if(Count < 0)
    {
        Count = 0;
    }

    return Count;
}

second:

float showPercent = 1 - ScrollRectConl.verticalNormalizedPosition;
int centerIndex = (int)(CurAssetList.Count * showPercent);
int halfOffsetIndex = (int)(ScrollShowCount / 2.0f);

    downloadLogoStartIndex = ((centerIndex + halfOffsetIndex) >= CurAssetList.Count) ? (centerIndex - ScrollShowCount - ColumnElementCount) : (centerIndex - halfOffsetIndex - ColumnElementCount);
    downloadLogoEndIndex = (centerIndex < halfOffsetIndex) ? (centerIndex + ScrollShowCount + ColumnElementCount) : (centerIndex + halfOffsetIndex + ColumnElementCount);

    if (downloadLogoStartIndex < 0)
    {
        downloadLogoStartIndex = 0;
    }

    if (downloadLogoEndIndex >= CurAssetList.Count)
    {
        downloadLogoEndIndex = CurAssetList.Count - 1;
    }