unity实战 UGUI Text 间距和ContentSizeFitter组件的适配

策划需求：支持text间距，并且要跟ContentSizeFitter的宽度适配适应

网上查了一些博客，https://blog.csdn.net/ls9512/article/details/82980147 发现这篇博客内容有支持text间距，但是使用过程中发现如果再使用ContentSizeFitter组件的话，将不会适应ui的sizedelta宽度。

然后查到了一个工具(虽然最后没用):TextMesh Pro 看起来功能挺多的，但是没有源码，都是dll。我没法进行修改。就放弃了。当前我使用的text是CustomFont，使用静态图片的，可以合图。对于策划还是ok的。

大概解决方案，获取字符的宽度，使用组件LayoutElement，自己计算合适的preferredWidth值。

对上面的代码进行了加工，直接贴代码，初版没有优化，自己可以修改：

using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

[AddComponentMenu("UI/Effects/TextSpacing")]
public class TextSpacing : BaseMeshEffect
{
    #region Struct

    public enum HorizontalAligmentType
    {
        Left,
        Center,
        Right
    }

    public class Line
    {
        // 起点索引
        public int StartVertexIndex { get { return _startVertexIndex; } }
        private int _startVertexIndex = 0;

        // 终点索引
        public int EndVertexIndex { get { return _endVertexIndex; } }
        private int _endVertexIndex = 0;

        // 该行占的点数目
        public int VertexCount { get { return _vertexCount; } }
        private int _vertexCount = 0;

        public Line(int startVertexIndex, int length)
        {
            _startVertexIndex = startVertexIndex;
            _endVertexIndex = length * 6 - 1 + startVertexIndex;
            _vertexCount = length * 6;
        }
    }

    #endregion

    public float Spacing = 1f;

    public override void ModifyMesh(VertexHelper vh)
    {
        if (!IsActive() || vh.currentVertCount == 0)
        {
            return;
        }

        var text = GetComponent<Text>();

        if (text == null)
        {
            Debug.LogError("Missing Text component");
            return;
        }

        // 水平对齐方式
        HorizontalAligmentType alignment;
        if (text.alignment == TextAnchor.LowerLeft || text.alignment == TextAnchor.MiddleLeft || text.alignment == TextAnchor.UpperLeft)
        {
            alignment = HorizontalAligmentType.Left;
        }
        else if (text.alignment == TextAnchor.LowerCenter || text.alignment == TextAnchor.MiddleCenter || text.alignment == TextAnchor.UpperCenter)
        {
            alignment = HorizontalAligmentType.Center;
        }
        else
        {
            alignment = HorizontalAligmentType.Right;
        }

        var vertexs = new List<UIVertex>();
        vh.GetUIVertexStream(vertexs);
        // var indexCount = vh.currentIndexCount;

        var lineTexts = text.text.Split('\n');

        var lines = new Line[lineTexts.Length];

        // 根据lines数组中各个元素的长度计算每一行中第一个点的索引，每个字、字母、空母均占6个点
        for (var i = 0; i < lines.Length; i++)
        {
            // 除最后一行外，vertexs对于前面几行都有回车符占了6个点
            if (i == 0)
            {
                lines[i] = new Line(0, lineTexts[i].Length + 1);
            }
            else if (i > 0 && i < lines.Length - 1)
            {
                lines[i] = new Line(lines[i - 1].EndVertexIndex + 1, lineTexts[i].Length + 1);
            }
            else
            {
                lines[i] = new Line(lines[i - 1].EndVertexIndex + 1, lineTexts[i].Length);
            }
        }

        UIVertex vt;
        float oldlen = 9999;//取最前最后的字符串偏移，适配sizedelta
        float lastlen = 9999;
        float oldrightlen = 9999;
        float lastrightlen = 9999;
        for (var i = 0; i < lines.Length; i++)
        {
            for (var j = lines[i].StartVertexIndex; j <= lines[i].EndVertexIndex; j++)
            {
                if (j < 0 || j >= vertexs.Count)
                {
                    continue;
                }

                vt = vertexs[j];

                var charCount = lines[i].EndVertexIndex - lines[i].StartVertexIndex;
                if (i == lines.Length - 1)
                {
                    charCount += 6;
                }

                if (alignment == HorizontalAligmentType.Left)
                {
                    oldlen = vt.position.x;
                    vt.position += new Vector3(Spacing * ((j - lines[i].StartVertexIndex) / 6), 0, 0);
                    lastlen = vt.position.x;
                }
                else if (alignment == HorizontalAligmentType.Right)
                {
                    if (oldlen >= 9999){
                        oldlen = vt.position.x;
                    }
                    oldrightlen = vt.position.x;
                    vt.position += new Vector3(Spacing * (-(charCount - j + lines[i].StartVertexIndex) / 6 + 1), 0, 0);
                    if (lastlen >= 9999){
                        lastlen = vt.position.x;
                    }
                    lastrightlen = vt.position.x;
                }
                else if (alignment == HorizontalAligmentType.Center)
                {
                    if (oldlen >= 9999){
                        oldlen = vt.position.x;
                    }
                    oldrightlen = vt.position.x;
                    var offset = (charCount / 6) % 2 == 0 ? 0.5f : 0f;
                    vt.position += new Vector3(Spacing * ((j - lines[i].StartVertexIndex) / 6 - charCount / 12 + offset), 0, 0);
                    if (lastlen >= 9999){
                        lastlen = vt.position.x;
                    }
                    lastrightlen = vt.position.x;
                }

                vertexs[j] = vt;
                // 以下注意点与索引的对应关系
                if (j % 6 <= 2)
                {
                    vh.SetUIVertex(vt, (j / 6) * 4 + j % 6);
                }

                if (j % 6 == 4)
                {
                    vh.SetUIVertex(vt, (j / 6) * 4 + j % 6 - 1);
                }
            }
        }
        string message = text.text;
        int totalLength = 0;
        Font myFont = text.font;
        for(int i = 0; i < message.Length; i++){
            Characterinfo ch;
            myFont.GetCharacterInfo(message[i], out ch);
            totalLength += ch.advance;
        }
        LayoutElement le = GetComponent<LayoutElement >();
        if (le != null){
            le.preferredWidth = totalLength +(lastlen - oldlen)+(lastrightlen - oldrightlen);
        }
    }
}