sked/Assets/Script/Common/UI/TextureDownload.cs

using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using UnityEngine;
using UnityEngine.Networking;
using UnityEngine.UI;

public class TextureDownload : MonoBehaviour
{
    public bool SAVE = true;
    public RectTransform rect;
    public RawImage texture;
    public Image imgLoading;

    public void Download(string path)
    {
        StartCoroutine(ImageDownload(path));
    }
    public void Initialized()
    {
        texture.texture = null;
        imgLoading.gameObject.SetActive(false);
    }
    private void OnDisable()
    {
        Initialized();
    }
    /// <summary>
    /// 이미지를 다운로드 합니다.
    /// </summary>
    /// <param name="path"></param>
    /// <returns></returns>
    IEnumerator ImageDownload(string path)
    {
        imgLoading.gameObject.SetActive(true);

        yield return null;

        string pathSave = $"{Application.temporaryCachePath}/{getMd5Hash(path)}";
        //Debugging.Warning($"{pathSave}");
        texture.texture = ImageFileLoad(pathSave);

        if (texture.texture == null)
        {
            UnityWebRequest www = UnityWebRequestTexture.GetTexture(path);
            yield return www.SendWebRequest();

            if (www.isNetworkError || www.isHttpError)
                Debugging.Error($"ImageDownload Error\n{www.error}");
            else
            {
                texture.texture = DownloadHandlerTexture.GetContent(www);

                if (SAVE)
                    ImageFileSave(pathSave, DownloadHandlerTexture.GetContent(www));
            }
        }
        Resize();

        imgLoading.gameObject.SetActive(false);
    }
    /// <summary>
    /// 문자열의 MD5 를 생성합니다.
    /// 이미지 다운로드 URL 을 MD5 로 변환하여 파일명으로 사용합니다.
    /// </summary>
    /// <param name="input"></param>
    /// <returns></returns>
    string getMd5Hash(string input)
    {
        MD5 md5Hasher = MD5.Create();
        byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));
        StringBuilder sBuilder = new StringBuilder();
        for (int i = 0; i < data.Length; i++)
            sBuilder.Append(data[i].ToString("x2"));
        return sBuilder.ToString();
    }
    /// <summary>
    /// 다운로드 완료한 이미지를 로컬에 저장합니다.
    /// </summary>
    /// <param name="path"></param>
    /// <param name="texture"></param>
    void ImageFileSave(string path, Texture2D texture)
    {
        Texture2D newTexture = new Texture2D(texture.width, texture.height);
        newTexture.SetPixels(0, 0, texture.width, texture.height, texture.GetPixels());
        newTexture.Apply();

        byte[] bytes = newTexture.EncodeToPNG();
        File.WriteAllBytes(path, bytes);
    }
    /// <summary>
    /// 로컬에서 이미지를 불러옵니다.
    /// </summary>
    /// <param name="path"></param>
    /// <returns></returns>
    Texture ImageFileLoad(string path)
    {
        FileInfo fileInfo = new FileInfo(path);
        if (fileInfo.Exists)
        {
            Texture2D tex = new Texture2D(0, 0);
            if (tex.LoadImage(System.IO.File.ReadAllBytes(path)))
                return tex;
        }
        return null;
    }
    /// <summary>
    /// 이미지 크기 를 조절 합니다.
    /// 가로 와 세로 중 큰 쪽을 기준으로 비율을 설정합니다.
    /// </summary>
    void Resize()
    {
        float ratio = 0;
        if (texture.texture.height < texture.texture.width)
            ratio = rect.rect.width / texture.texture.width;
        else
            ratio = rect.rect.height / texture.texture.height;

        texture.transform.localScale = new Vector3(ratio, ratio, 0);
        texture.SetNativeSize();
    }
}