Unity UGUI ScrollView positioning function

/// <summary>
/// 获取ScrollView对应VerticalNormalizedPosition或者HorizontalNormalizedPosition
/// 不考虑vertical和horizontal同时勾选的情况
/// </summary>
/// <param name="currentChildIndex">物体在数组中的index</param>
/// <param name="inverse">是否反着来，从上而下、从右往左要反着来</param>
/// <param name="pixelOffset">像素偏移，向下向右为正</param>
/// <returns>0 ~ 1，VerticalNormalizedPosition或者HorizontalNormalizedPosition</returns>
public static float GetScrollViewNormalizedPosition(ScrollRect scrollRect, int currentChildIndex, bool inverse = false, float pixelOffset = 0)
{
    
    
	if (scrollRect.viewport == null || scrollRect.content == null)
	{
    
    
		Debugger.EO_LogError("ScrollView的Content或Viewport为空");
		return inverse ? 1 : 0;
	}
	var childTrans = scrollRect.content.GetChild(0) as RectTransform;
	if (childTrans == null)
	{
    
    
		Debugger.EO_LogError("Content下面没有物体或不是RectTransform");
		return inverse ? 1 : 0;
	}
	
	Rect viewportRect = scrollRect.viewport.rect;
	Rect contentRect  = scrollRect.content.rect;
	Rect childrenRect = childTrans.rect;
	
	if (scrollRect.vertical && scrollRect.horizontal)
	{
    
    
		Debugger.EO_LogError("暂时不考虑ScrollView的vertical、horizontal同时勾选的情况");
		return inverse ? 1 : 0;
	}

	if (scrollRect.vertical)
	{
    
    
		VerticalLayoutGroup group = scrollRect.content.GetComponent<VerticalLayoutGroup>();
		if (group == null)
		{
    
    
			Debugger.EO_LogError("获取VerticalLayoutGroup失败");
			return inverse ? 1 : 0;
		}

		var diff = contentRect.height - viewportRect.height;
		float elementLength = childrenRect.height + group.spacing;

		if(inverse)
			return Mathf.Clamp01(1 - (currentChildIndex * elementLength + pixelOffset) / diff);
		else
			return Mathf.Clamp01((currentChildIndex * elementLength - pixelOffset) / diff);
	}

	if (scrollRect.horizontal)
	{
    
    
		HorizontalLayoutGroup group = scrollRect.content.gameObject.GetComponent<HorizontalLayoutGroup>();
		if (group == null)
		{
    
    
			Debugger.EO_LogError("获取HorizontalLayoutGroup失败");
			return inverse ? 1 : 0;
		}

		var diff = contentRect.width - viewportRect.width;
		float elementLength = childrenRect.width + group.spacing;

		if(inverse)
			return Mathf.Clamp01(1 - (currentChildIndex * elementLength - pixelOffset) / diff);
		else
			return Mathf.Clamp01((currentChildIndex * elementLength + pixelOffset) / diff);
	}

	return inverse ? 1 : 0;
}