Unity中UGUI的Text内字符串截断

在unity的界面显示文字的时候，会出现字符串超出给定的范围的情况，比如本来设定的是显示5个字符串，但是由于某种原因，字符串长度变成了10，这样显示就会出现几种异常的情况：

1. 如果加了ContentSizeFilter，并且设置了相应的选项的时候，有可能会出现自动换行，然后Text就会变高，这样显示就不好看；
2. 如果没有添加任何控制Text组件的控制器，那么会莫名的丢掉多出来的字符串。
   一般会将多出的字符串截掉，然后用...去替代。

首先想到的是直接根据字符串长度去截取，但是效果不是很理想，因为不同的字符，渲染的宽度不一样，这样就会造成即便截取了也会达不到效果，所以后来想到根据字符串的宽度来截取替代。

核心部分代码：
Font myFont = text.font;
myFont.RequestCharactersInTexture(message, text.fontSize, text.fontStyle);
CharacterInfo characterInfo = new CharacterInfo();

char[] arr = message.ToCharArray();

foreach (char c in arr)
{
myFont.GetCharacterInfo(c, out characterInfo, text.fontSize);

totalLength += characterInfo.advance;

}

使用：
using UnityEngine;
using System.Collections;
using UnityEngine.UI;

public class TextController :MonoBehaviour
{
public Text text;

private string suffix = "。。。";
int suffixLength = 0;

private string textToShow = "kdjfaliejlkfjlaisdjfklejfiasldkfj;ailjelkfjalskdvkljalkdjfielkjflksdfsdfa";
private string textToShow2 = 
private string textToShow3 = "我咖啡机客队 罚阿里会计法拉克京东方IE了拉进来打开房间啦看到逻辑拉克减肥的拉科技付款啦";

// Use this for initialization
void Start()
{
    Init();
}

// Update is called once per frame
void Update()
{

}

public void ShowText()
{
    text.text = StripLengthWithSuffix(textToShow3);
}

private void Init()
{
    suffixLength = CalculateLengthOfText(suffix);
    Debug.LogFormat("suffix length: {0}", suffixLength);
}

private string StripLengthWithSuffix(string input, int maxWidth = 460)
{
    int len = CalculateLengthOfText(input);
    Debug.LogFormat("input total length = {0}", len);

    if(len > maxWidth)
    {
        return StripLength(input, maxWidth - suffixLength) + suffix;
    }
    else
    {
        return input;
    }
}

private string StripLength(string input, int maxWidth = 460)
{
    int totalLength = 0;
    Font myFont = text.font;

    myFont.RequestCharactersInTexture(input, text.fontSize, text.fontStyle);
    CharacterInfo characterInfo = new CharacterInfo();
    char[] arr = input.ToCharArray();

    int i = 0; 
    foreach(char c in arr)
    {
        myFont.GetCharacterInfo(c, out characterInfo, text.fontSize);

        int newLength = totalLength + characterInfo.advance;
        if(newLength > maxWidth)
        {
            Debug.LogFormat("new length: {0} - total length: {1}", newLength, totalLength);
            if(Mathf.Abs(newLength - maxWidth) > Mathf.Abs(maxWidth - totalLength))
            {
                break;
            }
            else
            {
                totalLength = newLength;
                i++;
                break;
            }
        }
        totalLength += characterInfo.advance;
        i++;
    }
    Debug.LogFormat("total length: {0}", totalLength);
    return input.Substring(0, i);
}

private int CalculateLengthOfText(string message)
{
    int totalLength = 0;
    Font myFont = text.font;
    myFont.RequestCharactersInTexture(message, text.fontSize, text.fontStyle);
    CharacterInfo characterInfo = new CharacterInfo();

    char[] arr = message.ToCharArray();
    foreach(char c in arr)
    {
        myFont.GetCharacterInfo(c, out characterInfo, text.fontSize);
        totalLength += characterInfo.advance;
    }

    return totalLength;
}

}

结果：