實現功能： 1.採用Texture方式截圖； 2.截圖儲存在 Application.persistentDataPath目錄下； 3.圖片轉bsde64碼，易於傳輸；

/****************************************************
*
*  unity螢幕截圖，並轉換成Base64碼
*
*****************************************************/

using System;
using System.IO;
using UnityEngine;
using System.Collections;

public class Tools_TexScreenshot : MonoBehaviour
{
    public delegate void WeChatTexScreenShotDelegate(bool isSucc);
    public WeChatTexScreenShotDelegate WeChatTexScreenShotCallBack;

    private static Tools_TexScreenshot _Instance;
    public static Tools_TexScreenshot Instance
    {
        get { return _Instance; }
    }

    void Awake()
    {
        _Instance = this;
    }

    void OnDestroy()
    {
        _Instance = null;

        Texture_ShotDelete();
    }

    /// <summary>
    /// 截圖圖片儲存路徑
    /// </summary>
    private string texShotPath
    {
        get
        {
            throw new NotImplementedException("TODO 截圖圖片儲存路徑");
            //return projectQ.PathHelper.PersistentPath + "/screencapture.jpg";//TODO 截圖圖片儲存路徑
        }
    }
    /// <summary>
    /// 壓縮後的截圖圖片儲存路徑
    /// </summary>
    private string texZipShotPath
    {
        get
        {
            throw new NotImplementedException("TODO 壓縮後的截圖圖片儲存路徑");
            //return projectQ.PathHelper.PersistentPath + "/texShare.jpg";//TODO 壓縮後的截圖圖片儲存路徑
        }
    }

    public byte[] GetCaptureTexture(Texture2D _tex2d)
    {
        _tex2d.Compress(false);
        Texture2D texZip = Tools_TexGzip.TexGzipBegin(_tex2d, 0.5f);
        return texZip.EncodeToJPG();
    }

    /// <summary>
    /// 螢幕截圖儲存
    /// </summary>
    /// <param name="startPoint">截圖起點座標</param>
    /// <param name="shotSize">截圖大小</param>
    public void Texture_Screenshot(Vector2 startPoint, Vector2 shotSize, WeChatTexScreenShotDelegate shotBack)
    {
        StartCoroutine(GetCapture(startPoint, shotSize, shotBack));
    }
      
    IEnumerator GetCapture(Vector2 startPoint, Vector2 shotSize, WeChatTexScreenShotDelegate shotBack)
    {
        // 截圖之前，刪除截圖快取檔案
        Texture_ShotDelete();

        yield return new WaitForEndOfFrame();

        int width = (int)shotSize.x;

        int height = (int)shotSize.y;

        Texture2D tex = new Texture2D(width, height, TextureFormat.RGB24, false);

        tex.ReadPixels(new Rect(startPoint.x, startPoint.y, width, height), 0, 0, true);

        //對螢幕快取進行壓縮  
        tex.Compress(false);

        //對圖片進行壓縮
        Texture2D texZip = Tools_TexGzip.TexGzipBegin(tex, 0.5f);

        //轉化為jpg圖
        byte[] imagebytes = texZip.EncodeToJPG();

        //儲存png圖
        File.WriteAllBytes(texShotPath, imagebytes);

        yield return null;

        if (shotBack != null)
        {
            shotBack(true);
        }
    }

    /// <summary>
    /// 圖片壓縮
    /// </summary>
    void Texture_Gzip(int height, int width, WeChatTexScreenShotDelegate shotBack)
    {
        if (shotBack != null)
        {
            shotBack(true);
        }
    }

    /// <summary>
    /// 將圖片資料轉換為Base64字串
    /// </summary>
    public string Texture_ToBase64()
    {
        if (!System.IO.File.Exists(texShotPath))
        {
            Debug.Log(" 圖片路徑無效： " + texShotPath);
            return null;
        }

        var base64Img = Convert.ToBase64String(System.IO.File.ReadAllBytes(texShotPath));

        Debug.Log(" #[圖片轉換成Base64]# 成功 圖片資訊" + base64Img);

        // 分享完成，圖片刪除
        Texture_ShotDelete();

        return base64Img.ToString();
    }

    /// <summary>
    /// 將指定路徑圖片轉換為Base64字串
    /// </summary>
    public string Texture_FixedToBase64(string texFixedPath)
    {
        var base64Img = Convert.ToBase64String(System.IO.File.ReadAllBytes(texFixedPath));
        
        return base64Img.ToString();
    }

    /// <summary>
    /// 將本地圖片轉換為Base64字串
    /// </summary>
    public string Texture_LocalToBase64(byte[] _bytes)
    {
        var base64Img = Convert.ToBase64String(_bytes);

        return base64Img.ToString();
    }

    /// <summary>
    /// 將儲存下來的用於分享的圖片刪除掉
    /// </summary>
    public void Texture_ShotDelete()
    {
        if (File.Exists(texShotPath))
        {
            Debug.Log(" #[如果截圖的圖片還在則刪掉]# ");

            File.Delete(texShotPath);
        }

        if (File.Exists(texZipShotPath))
        {
            Debug.Log(" #[圖片轉換成Base64成功後刪除]# ");

            File.Delete(texZipShotPath);
        }
    }
}