NGUI中UIWidget提供了錨點(diǎn)Anchor選項(xiàng)谁鳍，可以方便地設(shè)置一個(gè)Widget相對(duì)于另一個(gè)Widget的位置和大小筹裕。
我用的Unity版本：3.5.6知押；NGUI版本：3.5.9
今天做項(xiàng)目時(shí)遇到一個(gè)問(wèn)題：在SceneA和SceneB中都有UIRoot淤刃，由于某些原因砸逊，我必須以LoadLevelAdditiveAsync的方式加載SceneB，并在進(jìn)入SceneB后銷毀SceneA赤屋。我們知道在一個(gè)場(chǎng)景下最多只能存在一個(gè)UIRoot立镶，但從SceneA跳轉(zhuǎn)到SceneB后，場(chǎng)景中同時(shí)存在了兩個(gè)UIRoot类早，這導(dǎo)致某些使用了Anchor的UI的位置和大小不正確（實(shí)測(cè)Unity Editor中不會(huì)出問(wèn)題媚媒，但在手機(jī)上基本都會(huì)出問(wèn)題）。
此時(shí)有兩種解決辦法：
1.在SceneA銷毀后再呈現(xiàn)SceneB涩僻，也就是不要用Additive的方式加載缭召，但由于我的項(xiàng)目中兩個(gè)Scene的耦合太高了（接的前人的盤(pán)）栈顷，這么做會(huì)非常費(fèi)時(shí)，老板一直在催版本嵌巷，沒(méi)時(shí)間重構(gòu)萄凤。
2.自己實(shí)現(xiàn)Anchor功能。
代碼很簡(jiǎn)單搪哪，大致思路如下：1.根據(jù)Target的位置和大小計(jì)算出Target的左右上下四個(gè)點(diǎn)坐標(biāo)（實(shí)際上只需要用到左tLeftBoardPos和下tBottomBoardPos）靡努；2.根據(jù)輸入的左右上下的偏移量，計(jì)算出當(dāng)前Widget的左右X坐標(biāo)（mLeftBoardX, mRightBoardX）和上下Y坐標(biāo)（mTopBoardY, mBottomBoardY）晓折；3.根據(jù)2求得的四個(gè)值計(jì)算當(dāng)前Widget的位置和大小惑朦。
需要注意的是：這里用的始終是世界坐標(biāo)，且需要考慮UIRoot本身的縮放系數(shù)scaleRatio漓概。
==注：暫時(shí)沒(méi)有考慮Center的情況漾月，有需要了再加上。==
下面是具體實(shí)現(xiàn)：
SimpleAnchor.cs
using UnityEngine;
using System.Collections;
[RequireComponent(typeof(UIWidget))]
public class SimpleAnchor : MonoBehaviour
{
public enum HorizPivot
{
Left,
Right,
Center
}
public enum VertPivot
{
Top,
Bottom,
Center
}
public Transform Target;
public int Left;
public HorizPivot LeftPivot;
public int Right;
public HorizPivot RightPivot;
public int Bottom;
public VertPivot BottomPivot;
public int Top;
public VertPivot TopPivot;
void OnEnable()
{
if(!Target)return;
UIWidget targetWidget = Target.GetComponent<UIWidget>();
UIPanel targetPanel = Target.GetComponent<UIPanel>();
if(!targetPanel && !targetWidget) return;
if (targetWidget)
{
SetPosAndSize(targetWidget.transform.position, targetWidget.width, targetWidget.height);
}
else
{
SetPosAndSize(targetPanel.transform.position, (int)targetPanel.width, (int)targetPanel.height);
}
}
void SetPosAndSize(Vector3 targetPos, int targetWidth, int targetHeight)
{
Debug.LogError("Target width: " + targetWidth);
Debug.LogError("Target height: " + targetHeight);
float scaleRatio = NGUITools.FindInParents<UIRoot>(transform).transform.localScale.x;
Vector3 tLeftBoardPos = new Vector3(targetPos.x - scaleRatio * targetWidth / 2, targetPos.y, targetPos.z);
Vector3 tRightBoardPos = new Vector3(targetPos.x + scaleRatio * targetWidth / 2, targetPos.y, targetPos.z);
Vector3 tTopBoardPos = new Vector3(targetPos.x, targetPos.y + scaleRatio * targetHeight / 2, targetPos.z);
Vector3 tBottomBoardPos = new Vector3(targetPos.x, targetPos.y - scaleRatio * targetHeight / 2, targetPos.z);
float mLeftBoardX = 0;
if (LeftPivot == HorizPivot.Left)
{
mLeftBoardX = tLeftBoardPos.x + scaleRatio * Left;
}
else if (LeftPivot == HorizPivot.Right)
{
mLeftBoardX = tLeftBoardPos.x + scaleRatio * (targetWidth + Left);
}
float mRightBoardX = 0;
if (RightPivot == HorizPivot.Left)
{
mRightBoardX = tLeftBoardPos.x + scaleRatio * Right;
}
else if (LeftPivot == HorizPivot.Right)
{
mRightBoardX = tLeftBoardPos.x + scaleRatio * (targetWidth + Right);
}
float mBottomBoardY = 0;
if (BottomPivot == VertPivot.Bottom)
{
mBottomBoardY = tBottomBoardPos.y + scaleRatio * Bottom;
}
else if (BottomPivot == VertPivot.Top)
{
mBottomBoardY = tBottomBoardPos.y + scaleRatio * (targetHeight + Bottom);
}
float mTopBoardY = 0;
if (TopPivot == VertPivot.Bottom)
{
mTopBoardY = tBottomBoardPos.y + scaleRatio * Top;
}
else if (TopPivot == VertPivot.Top)
{
mTopBoardY = tBottomBoardPos.y + scaleRatio * (targetHeight + Top);
}
transform.position = new Vector3((mLeftBoardX + mRightBoardX) / 2, (mTopBoardY + mBottomBoardY) / 2, targetPos.z);
UIWidget mWidget = GetComponent<UIWidget>();
if (mWidget)
{
mWidget.width = (int)(Mathf.Abs(mLeftBoardX - mRightBoardX) / scaleRatio);
mWidget.height = (int)(Mathf.Abs(mTopBoardY - mBottomBoardY) / scaleRatio);
}
}
}
使用方法：將SimpleAnchor掛載到需要打錨點(diǎn)的Widget上垛耳，為方便填寫(xiě)數(shù)值栅屏，可以先使用UIWidget自帶的Anchor調(diào)好數(shù)值，再Copy到SimpleAnchor對(duì)應(yīng)項(xiàng)即可堂鲜，最后別忘了把自帶Anchor的Type調(diào)整為None栈雳。
見(jiàn)下面兩個(gè)圖：
目前還不完善，后續(xù)會(huì)將Center的情況考慮進(jìn)去缔莲，并寫(xiě)個(gè)Editor腳本方便調(diào)整相應(yīng)數(shù)值哥纫。
