TextLinkHelper.cs

using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using JimmysUnityUtilities;
using FancyInput;
using TMPro;

namespace LogicUI.TextMeshProUtilities
{
    /// <summary>
    /// Allows links in TextMeshPro text objects to be clicked on, and gives them custom colors when they are hovered or clicked.
    /// </summary>
    [RequireComponent(typeof(TMP_Text))]
    public class TextLinkHelper : MonoBehaviour, IPointerClickHandler, IPointerDownHandler, IPointerUpHandler, IPointerEnterHandler, IPointerExitHandler
    {
        private TMP_Text _Text;
        public TMP_Text Text
        {
            get
            {
                if (_Text == null)
                    _Text = GetComponent<TMP_Text>();

                return _Text;
            }
        }

        private void OnValidate()
        {
            SetAllLinksToNormalColor();
        }

        void Start()
        {
            // I've no idea why the frame delay is necessary, but it is.
            CoroutineUtility.RunAfterOneFrame(SetAllLinksToNormalColor);
        }

        [ColorUsage(showAlpha: false), SerializeField]
        Color32 LinkNormalColor = new Color32(0, 0, 255, 255);

        [ColorUsage(showAlpha: false), SerializeField]
        Color32 LinkHoveredColor = new Color32(50, 50, 255, 255);

        [ColorUsage(showAlpha: false), SerializeField]
        Color32 LinkClickColor = new Color32(80, 80, 255, 255);

        public void SetColors(Color32 linkNormalColor, Color32 linkHoveredColor, Color32 linkClickColor)
        {
            LinkNormalColor = linkNormalColor;
            LinkHoveredColor = linkHoveredColor;
            LinkClickColor = linkClickColor;

            SetAllLinksToNormalColor();
        }



        private Dictionary<string, Action> CustomLinks = new Dictionary<string, Action>();

        /// <summary>
        /// Sets some code to be run when a link is clicked on. 
        /// If a link doesn't have a custom action set, we will use <see cref="Application.OpenURL(string)"/> on it.
        /// </summary>
        /// <param name="linkID"></param>
        /// <param name="linkAction"></param>
        public void SetCustomLink(string linkID, Action linkAction)
        {
            CustomLinks[linkID] = linkAction;
        }


        void IPointerClickHandler.OnPointerClick(PointerEventData eventData)
        {
            int linkIndex = TMP_TextUtilities.FindIntersectingLink(Text, eventData.pressPosition, eventData.pressEventCamera);
            if (linkIndex > -1)
            {
                var link = Text.textInfo.linkInfo[linkIndex];
                ClickOnLink(link.GetLinkID());
            }

            void ClickOnLink(string linkID)
            {
                if (CustomLinks.TryGetValue(linkID, out var action))
                    action?.Invoke();
                else
                    Application.OpenURL(linkID);

                Debug.Log($"clicked on link: {linkID}");
            }
        }




        void IPointerDownHandler.OnPointerDown(PointerEventData eventData)
        {
            PointerIsDown = true;
            SetLinkToColor(PreviouslyHoveredLink, LinkClickColor);
        }

        void IPointerUpHandler.OnPointerUp(PointerEventData eventData)
        {
            PointerIsDown = false;
            SetLinkToColor(PreviouslyHoveredLink, LinkNormalColor);
        }

        void IPointerEnterHandler.OnPointerEnter(PointerEventData eventData)
        {
            CurrentlyHoveredOver = true;
            PointerIsDown = false;
            cachedCamera = eventData.enterEventCamera;
        }

        void IPointerExitHandler.OnPointerExit(PointerEventData eventData)
        {
            CurrentlyHoveredOver = false;
        }


        Camera cachedCamera;

        bool CurrentlyHoveredOver;
        bool PointerIsDown;
        TMP_LinkInfo? PreviouslyHoveredLink = null;
        void Update()
        {
            if (!CurrentlyHoveredOver)
                return;

            if (PointerIsDown)
                return;


            SetLinkToColor(PreviouslyHoveredLink, LinkNormalColor);

            int linkIndex = TMP_TextUtilities.FindIntersectingLink(Text, GameInput.MousePosition, cachedCamera);
            if (linkIndex > -1)
            {
                var link = Text.textInfo.linkInfo[linkIndex];
                SetLinkToColor(link, LinkHoveredColor);
                PreviouslyHoveredLink = link;
            }
            else
            {
                PreviouslyHoveredLink = null;
            }
        }


        public void SetAllLinksToNormalColor()
        {
            if (Text.textInfo == null) // Text object isn't initialized yet; required as of TMP 2.1
                return;

            foreach (var link in Text.textInfo.linkInfo.OrEmptyIfNull())
                SetLinkToColor(link, LinkNormalColor);
        }

        private void SetLinkToColor(TMP_LinkInfo? linkInfo, Color32 color)
        {
            if (linkInfo == null)
                return;

            var link = linkInfo.Value;
            if (link.linkTextfirstCharacterIndex + link.linkTextLength - 1 >= Text.textInfo.characterInfo.Length)
                return;

            for (int i = 0; i < link.linkTextLength; i++)
            {
                int characterIndex = link.linkTextfirstCharacterIndex + i;
                var charInfo = Text.textInfo.characterInfo[characterIndex];
                int meshIndex = charInfo.materialReferenceIndex;
                int vertexIndex = charInfo.vertexIndex;

                var characterVertexColors = Text.textInfo.meshInfo[meshIndex].colors32;

                if (charInfo.isVisible)
                {
                    characterVertexColors[vertexIndex + 0] = color;
                    characterVertexColors[vertexIndex + 1] = color;
                    characterVertexColors[vertexIndex + 2] = color;
                    characterVertexColors[vertexIndex + 3] = color;
                }
            }

            Text.UpdateVertexData(TMP_VertexDataUpdateFlags.All);
        }
    }
}