Unity超链接：支持点击事件，下划线以及自定义颜色

基于这篇：
zyf2533 - Unity 超链接 Text
修正了一些bug，额外支持了下划线以及自定义颜色。

/*
    https://blog.youkuaiyun.com/zyf2533/article/details/122703640
 */

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using UnityEngine;
using UnityEngine.EventSystems;
//using UnityEngine.UI;

namespace UnityEngine.UI
{
    [AddComponentMenu("UI/UIHyperlinkText")]
    /// <summary>
    /// eg:
    /// 获得了：<a href="Tip#1102201">先锋盾合成卷轴</a> 
    /// </summary>
    public class UIHyperlinkText : Text, IPointerClickHandler
    {
        /// <summary>
        /// 超链接信息类
        /// </summary>
        private class HyperlinkInfo
        {
            //起始Index
            public int StartIndex;
            //结束Index
            public int EndIndex;
            //内容
            public string RefValue;
            public string InnerValue;
            //包围框
            public List<Rect> BoxList = new List<Rect>();
        }

        #region 私有变量
        //超链接正则
        private static Regex hrefRegex = new Regex(@"<a href=([^>\n\s]+)>(.*?)(</a>)", RegexOptions.Singleline);
        //颜色正则
        private static Regex colorRegex = new Regex(@"<color=([^>\n\s]+)>(.*?)(</color>)", RegexOptions.Singleline);
        private static Regex colorPreRegex = new Regex(@"<color=([^>\n\s]+)>", RegexOptions.Singleline);
        private static Regex colorEndRegex = new Regex(@"</color>", RegexOptions.Singleline);
    
        //超链接信息列表
        private List<HyperlinkInfo> hyperlinkInfoList = new List<HyperlinkInfo>();

        private static Action<string, string> clickCallback = null;
        private static Color innerTextColor = Color.blue;
        #endregion

        #region 公有变量

        #endregion

        #region 生命周期
        protected override void OnPopulateMesh(VertexHelper toFill)
        {
            base.OnPopulateMesh(toFill);

            InitHyperlinkInfo();
            InitHyperlinkBox(toFill);
            DrawUnderLine(toFill);
        }
        #endregion

        #region 公有方法

        #endregion

        #region 动作
        public void OnPointerClick(PointerEventData eventData)
        {
            Vector2 localPoint;
            RectTransformUtility.ScreenPointToLocalPointInRectangle(
                rectTransform, eventData.position, eventData.pressEventCamera, out localPoint);

            foreach (HyperlinkInfo hyperlinkInfo in hyperlinkInfoList)
            {
                var boxeList = hyperlinkInfo.BoxList;
                for (var i = 0; i < boxeList.Count; ++i)
                {
                    if (boxeList[i].Contains(localPoint))
                    {
                        if (clickCallback != null)
                        {
                            clickCallback(hyperlinkInfo.RefValue, hyperlinkInfo.InnerValue);
                        }
                        return;
                    }
                }
            }
        }

        public static void RegisterClickCallback(Action<string, string> callback, string innerColor)
        { 
            clickCallback = callback;

            if (!innerColor.StartsWith("#"))
            {
                innerColor = "#" + innerColor;
            }

            Color nowColor;
            ColorUtility.TryParseHtmlString(innerColor, out nowColor);
            innerTextColor = nowColor;
        }
        #endregion

        #region 私有方法
        /// <summary>
        /// 初始化连接信息
        /// </summary>
        private void InitHyperlinkInfo()
        {
			GetOutputText(text);
        }

        /// <summary>
        /// 初始化连接包围框
        /// </summary>
        /// <param name="toFill"></param>
        private void InitHyperlinkBox(VertexHelper toFill)
        {
        	UIVertex vert = new UIVertex();

            // 处理超链接包围框
            foreach (var hrefInfo in hyperlinkInfoList)
            {
                hrefInfo.BoxList.Clear();

                //一个字符是四个顶点，所以Index要乘以4
                int startVertex = hrefInfo.StartIndex * 4;
                int endVertex = hrefInfo.EndIndex * 4;

                if (startVertex >= toFill.currentVertCount)
                {
                    continue;
                }

                // 将超链接里面的文本顶点索引坐标加入到包围框
                toFill.PopulateUIVertex(ref vert, startVertex);

                var pos = vert.position;
                var bounds = new Bounds(pos, Vector3.zero);

                for (int i = startVertex; i < endVertex; i++)
                {
                    if (i >= toFill.currentVertCount)
                    {
                        break;
                    }

                    toFill.PopulateUIVertex(ref vert, i);
                    //toFill.SetUIVertex(vert, i);

                    pos = vert.position;

                    bool needEncapsulate = true;

                    if ((i - startVertex) % 4 == 0)
                    {
                        if (i < 4) continue;

                        UIVertex lastV = new UIVertex();
                        toFill.PopulateUIVertex(ref lastV, i - 4);
                        var lastPos = lastV.position;

                        if (pos.x < lastPos.x && pos.y < lastPos.y) // 换行重新添加包围框
                        {
                            hrefInfo.BoxList.Add(new Rect(bounds.min, bounds.size));
                            bounds = new Bounds(pos, Vector3.zero);
                            needEncapsulate = false;
                        }
                    }

                    if (needEncapsulate)
                    {
                        bounds.Encapsulate(pos); // 扩展包围框
                    }
                }

                hrefInfo.BoxList.Add(new Rect(bounds.min, bounds.size));
            }
        }

        private void DrawUnderLine(VertexHelper vh)
        {
            foreach (var link in hyperlinkInfoList)
            {
                foreach (var rect in link.BoxList)
                {
                    float height = rect.height;
                    // 左下
                    var pos1 = new Vector3(rect.min.x, rect.min.y, 0);
                    // 右下
                    var pos2 = new Vector3(rect.max.x, rect.max.y, 0) - new Vector3(0, height, 0);

                    MeshUnderLine(vh, pos1, pos2);
                }
            }
        }

        private void MeshUnderLine(VertexHelper vh, Vector2 startPos, Vector2 endPos)
        {            
        	Vector2 extents = rectTransform.rect.size;
            var setting = GetGenerationSettings(extents);

            TextGenerator underlineText = new TextGenerator();
            underlineText.Populate("￣", setting);

            IList<UIVertex> lineVer = underlineText.verts; //"￣"的的顶点数组

            Vector3[] pos = new Vector3[4];
            pos[0] = startPos + new Vector2(-8, 0);
            pos[3] = startPos + new Vector2(-8, -4f);
            pos[2] = endPos + new Vector2(8, -4f);
            pos[1] = endPos + new Vector2(8, 0);

            if (lineVer.Count == 4)
            {
                UIVertex[] tempVerts = new UIVertex[4];
                for (int i = 0; i < 4; i++)
                {
                    tempVerts[i] = lineVer[i];
                    tempVerts[i].color = Color.white;
                    tempVerts[i].position = pos[i];
                    tempVerts[i].uv0 = lineVer[i].uv0;
                    tempVerts[i].uv1 = lineVer[i].uv1;
                    tempVerts[i].uv2 = lineVer[i].uv2;
                    tempVerts[i].uv3 = lineVer[i].uv3;
                }

                vh.AddUIVertexQuad(tempVerts);
            }
        }

        /// <summary>
        /// 获取超链接解析后的最后输出文本
        /// </summary>
        /// <returns></returns>
        private string GetOutputText(string outputText)
        {
            StringBuilder stringBuilder = new StringBuilder();

            hyperlinkInfoList.Clear();

            int strIndex = 0;

            foreach (Match match in hrefRegex.Matches(outputText))
            {
                //Debug.Log(match.Value);

                string appendStr = outputText.Substring(strIndex, match.Index - strIndex);

                //空格和回车没有顶点渲染，所以要去掉
                appendStr = appendStr.Replace(" ", "");
                appendStr = appendStr.Replace("\n", "");

                appendStr = RichStringFilter(appendStr);

                stringBuilder.Append(appendStr);

                int startIndex = stringBuilder.Length;

                //第一个是连接url,第二个是连接文本，跳转用url，计算index用文本
                Group urlGroup = match.Groups[1];
                Group titleGroup = match.Groups[2];

                //如果有Color语法嵌套，则还要继续扒，直到把最终文本扒出来
                Match colorMatch = colorRegex.Match(titleGroup.Value);

                if (colorMatch.Groups.Count > 3)
                {
                    titleGroup = colorMatch.Groups[2];
                }

                var inner = titleGroup.Value;
                inner = inner.Replace(" ", "");
                inner = inner.Replace("\n", "");

                stringBuilder.Append(inner);

                HyperlinkInfo hyperlinkInfo = new HyperlinkInfo
                {
                    StartIndex = startIndex,
                    EndIndex = (startIndex + inner.Length),
                    RefValue = urlGroup.Value,
                    InnerValue = titleGroup.Value,
                };

                strIndex = match.Index + match.Length;
                hyperlinkInfoList.Add(hyperlinkInfo);
            }
            stringBuilder.Append(outputText.Substring(strIndex, outputText.Length - strIndex));
            return stringBuilder.ToString();
        }

        private string RichStringFilter(string outputText)
        {
            outputText = colorPreRegex.Replace(outputText, "");
            outputText = colorEndRegex.Replace(outputText, "");

            return outputText;
        }
        #endregion

        /// <summary>
        /// 添加可视包围框（测试用方法）
        /// </summary>
        private void AddVisibleBound()
        {
            int index = 0;

            foreach (Transform item in this.gameObject.transform.transform)
            {
                Destroy(item.gameObject);
            }

            foreach (var hyperLinkInfo in hyperlinkInfoList)
            {
                Color color = new Color(UnityEngine.Random.Range(0f, 1f), UnityEngine.Random.Range(0f, 1f), UnityEngine.Random.Range(0f, 1f), 0.2f);
                index++;
                foreach (Rect rect in hyperLinkInfo.BoxList)
                {
                    GameObject gameObject = new GameObject();
                    gameObject.name = string.Format("GOBoundBox[{0}]", hyperLinkInfo.InnerValue);
                    gameObject.transform.SetParent(this.gameObject.transform);

                    RectTransform rectTransform = gameObject.AddComponent<RectTransform>();
                    rectTransform.sizeDelta = rect.size;
                    rectTransform.localPosition = new Vector3(rect.position.x + rect.size.x / 2, rect.position.y + rect.size.y / 2, 0);

                    Image image = gameObject.AddComponent<Image>();
                    image.color = color;
                    image.raycastTarget = false;
                }
            }
        }
    }
}