Добавил кэширование поскейленных картинок, чтобы расходовать меньше батарейки и сетевого трафика

Assets/Scripts/Cache.cs

@@ -0,0 +1,160 @@
+using System;
+using System.IO;
+using System.Runtime.Serialization.Formatters.Binary;
+
+public class Cache
+{
+	const int MAX_ELEMENTS = 1000;
+	const string CACHE_DESCRIPTION_FILE = "files.dat";
+	const string CACHE_DATA_DIR = "data";
+
+	private string rootPath;
+	private CacheDescription description;
+
+    public Cache(string path)
+	{
+		rootPath = path;
+		if (!Directory.Exists(GetDataPath()))
+		{
+			Directory.CreateDirectory(GetDataPath());
+		}
+		LoadDescription();
+		CleanupDataDirectory();
+	}
+
+	private string GetDataPath()
+	{
+		return rootPath + "/" + CACHE_DATA_DIR;
+	}
+
+	private void CleanupDataDirectory()
+	{
+		var directory = GetDataPath();
+		var di = new DirectoryInfo(directory);
+		var files = di.GetFiles();
+		foreach (var f in files)
+		{
+			if (!description.path.ContainsKey(f.Name))
+			{
+				File.Delete(directory + "/" + f.Name);
+			}
+		}
+	}
+
+	private string RandomName()
+	{
+		string result = "";
+		for (int i = 0; i < 30; i++)
+		{
+			int t = UnityEngine.Random.Range(0, 36);
+			if (t < 10) result += (char)(t + '0');
+			else result += (char)(t - 10 + 'a');
+		}
+		return result;
+	}
+
+	private void LoadDescription()
+	{
+		var path = rootPath + "/" + CACHE_DESCRIPTION_FILE;
+		try
+		{
+			if (File.Exists(path))
+			{
+				Stream openFileStream = File.OpenRead(path);
+				BinaryFormatter deserializer = new BinaryFormatter();
+				description = (CacheDescription)deserializer.Deserialize(openFileStream);
+				openFileStream.Close();
+			}
+			else
+			{
+				description = new CacheDescription();
+			}
+		}
+		catch (Exception) 
+		{
+			description = new CacheDescription();
+		}
+	}
+
+	public void Add(string path, byte[] data)
+	{
+		if (!description.path.ContainsKey(path))
+		{
+			while (true)
+			{
+				var fileName = RandomName();
+				if (!File.Exists(GetDataPath() + "/" + fileName))
+				{
+					description.path[path] = fileName;
+					break;
+				}
+			}
+		}
+		var filePath = GetDataPath() + "/" + description.path[path];
+		File.WriteAllBytes(filePath, data);
+		description.lastUse[path] = DateTime.Now;
+		PurgeCache();
+		SaveDescription();
+	}
+
+	private void SaveDescription()
+	{
+		var path = rootPath + "/" + CACHE_DESCRIPTION_FILE;
+		try
+		{
+			BinaryFormatter serializer = new BinaryFormatter();
+			Stream openFileStream = File.OpenWrite(path);
+			serializer.Serialize(openFileStream, description);
+			openFileStream.Close();
+		}
+		catch (Exception)
+		{
+			description = new CacheDescription();
+		}
+	}
+
+	private void PurgeCache()
+	{
+		// throw away excess elements
+		// for now will use slow implementation
+		while (description.path.Count >= MAX_ELEMENTS)
+		{
+			DateTime min = DateTime.MaxValue;
+			string mpath = null;
+			foreach (var kv in description.lastUse)
+			{
+				if (kv.Value < min)
+				{
+					min = kv.Value;
+					mpath = kv.Key;
+				}
+			}
+			// not found?
+			if (mpath == null) break;
+			try
+			{
+				File.Delete(GetDataPath() + "/" + description.path[mpath]);
+			}
+			catch (IOException) { }
+			description.path.Remove(mpath);
+			description.lastUse.Remove(mpath);
+		}
+	}
+
+	public byte[] Get(string path)
+	{
+		if (!description.path.ContainsKey(path))
+		{
+			return null;
+		}
+		try
+		{
+			description.lastUse[path] = DateTime.Now;
+			return File.ReadAllBytes(GetDataPath() + "/" + description.path[path]);
+		}
+		catch (IOException)
+		{
+			return null;
+		}
+	}
+}

Assets/Scripts/Cache.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: ab7ecde33614955458f63144323618b4
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/Scripts/CacheDescription.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Collections.Generic;
+
+[Serializable]
+public class CacheDescription 
+{
+    public Dictionary<string, string> path;
+    public Dictionary<string, DateTime> lastUse;
+
+    public CacheDescription()
+	{
+        path = new Dictionary<string, string>();
+        lastUse = new Dictionary<string, DateTime>();
+	}
+}

Assets/Scripts/CacheDescription.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 0520a1857b831224aac90f9eac2c5772
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/Scripts/PhotoFrame.cs

@@ -20,6 +20,7 @@ public class PhotoFrame : MonoBehaviour
     InputField url;
 
 	private int currentImage;
+	private Cache cache;
 
 	private Image CurrentImage
 	{
@@ -33,6 +34,7 @@ public class PhotoFrame : MonoBehaviour
 
 	public void Start()
 	{
+		cache = new Cache(Application.persistentDataPath);
 		Screen.sleepTimeout = SleepTimeout.NeverSleep;
 		currentImage = 0;
 		ActivateUI(true);
@@ -89,29 +91,40 @@ public class PhotoFrame : MonoBehaviour
 			int imageIndex = Random.Range(0, loader.images.Count);
 			string imageUrl = loader.images[imageIndex];
 
-			var request = UnityWebRequest.Get(imageUrl);
-			request.downloadHandler = new DownloadHandlerTexture(true);
-			yield return request.SendWebRequest();
-
-			if (request.isNetworkError || request.isHttpError)
+			var bytes = cache.Get(imageUrl);
+			if (bytes != null)
 			{
-				yield return new WaitForSeconds(1f);
-				continue;
+				var tex = new Texture2D(2, 2);
+				tex.LoadImage(bytes);
+				SetImageTexture(NextImage, tex);
 			}
-
-			var downloadTime = Time.realtimeSinceStartup - startTime;
-			if (PHOTO_INTERVAL > downloadTime)
+			else
 			{
-				yield return new WaitForSeconds(PHOTO_INTERVAL - downloadTime);
+				var request = UnityWebRequest.Get(imageUrl);
+				request.downloadHandler = new DownloadHandlerTexture(true);
+				yield return request.SendWebRequest();
+
+				if (request.isNetworkError || request.isHttpError)
+				{
+					yield return new WaitForSeconds(1f);
+					continue;
+				}
+
+				var downloadTime = Time.realtimeSinceStartup - startTime;
+				if (PHOTO_INTERVAL > downloadTime)
+				{
+					yield return new WaitForSeconds(PHOTO_INTERVAL - downloadTime);
+				}
+
+				var dh = request.downloadHandler as DownloadHandlerTexture;
+				var tex = dh.texture;
+
+				SetImageTexture(NextImage, tex);
+				dh.Dispose();
+				request.Dispose();
+				cache.Add(imageUrl, tex.EncodeToJPG());
 			}
 
-			var dh = request.downloadHandler as DownloadHandlerTexture;
-			var tex = dh.texture;
-
-			SetImageTexture(NextImage, tex);
-			dh.Dispose();
-			request.Dispose();
-
 			float currentStart = CurrentImage.color.a;
 			float currentFinish = transparent.a;
 			float nextStart = NextImage.color.a;