fix async promise, to load image at first frame.

Runtime/async/coroutine.cs

         internal volatile Exception lastError;
         internal bool isDone;
 
-        readonly Promise<object> _promise = new Promise<object>();
+        readonly Promise<object> _promise = new Promise<object>(isSync: true);
 
         public IPromise<object> promise {
             get { return this._promise; }
 
             this._routine = routine;
             this._window = window;
+            this._isBackground = isBackground;
 
             if (isBackground && BackgroundCallbacks.getInstance() != null) {
                 this._unhook = BackgroundCallbacks.getInstance().addCallback(this._moveNext);
+                this._moveNext(true); // try to run the first enumeration in the current loop.
-
-            this._isBackground = isBackground;
+            this._moveNext(false);
+        }
+
+        void _moveNext(bool firstTime) {
             D.assert(!this.isDone);
 
             var lastError = this.lastError;
                 return;
             }
 
-            bool hasNext;
+            bool hasNext = true;
-                hasNext = this._processIEnumeratorRecursive(this._routine);
+                if (firstTime) {
+                    hasNext = this._routine.MoveNext();
+                }
+                if (hasNext) {
+                    hasNext = this._processIEnumeratorRecursive(this._routine);
+                }
             }
             catch (Exception ex) {
                 this.stop(ex);

Runtime/material/button_theme.cs

                 return 0.0f;
             }
 
-            if (button is OutlineButton)
+            if (button is OutlineButton) {
+            }
             return 8.0f;
         }
 

Runtime/painting/image_provider.cs

         IEnumerator _loadAssetAsync(AssetBundleImageKey key) {
             if (key.bundle == null) {
                 ResourceRequest request = Resources.LoadAsync(key.name);
-                yield return request;
-                yield return request.asset;
+                if (request.asset) {
+                    yield return request.asset;
+                } else {
+                    yield return request;
+                    yield return request.asset;
+                }
-                yield return request;
-                yield return request.asset;
+                if (request.asset) {
+                    yield return request.asset;
+                } else {
+                    yield return request.asset;
+                }
             }
         }
     }

Runtime/painting/image_resolution.cs

 using System;
-using System.Collections;
-using Unity.UIWidgets.async;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.ui;
 using UnityEngine;
         public readonly string assetName;
         public readonly AssetBundle bundle;
 
-        protected override
-            IPromise<AssetBundleImageKey> obtainKey(ImageConfiguration configuration) {
+        protected override IPromise<AssetBundleImageKey> obtainKey(ImageConfiguration configuration) {
             AssetImageConfiguration assetConfig = new AssetImageConfiguration(configuration, this.assetName);
             AssetBundleImageKey key;
             var cache = AssetBundleCache.instance.get(configuration.bundle);
 
             AssetBundle chosenBundle = this.bundle ? this.bundle : configuration.bundle;
             var devicePixelRatio = configuration.devicePixelRatio ?? Window.instance.devicePixelRatio;
-            var coroutine = Window.instance.startCoroutine(this._loadAssetAsync(chosenBundle, devicePixelRatio));
-            return coroutine.promise.Then(result => {
-                D.assert(result != null);
-
-                key = (AssetBundleImageKey) result;
-                cache[assetConfig] = key;
-                return key;
-            });
+            key = this._loadAsset(chosenBundle, devicePixelRatio);
+            cache[assetConfig] = key;
+            
+            return Promise<AssetBundleImageKey>.Resolved(key);
-        IEnumerator _loadAssetAsync(AssetBundle bundle, float devicePixelRatio) {
+        AssetBundleImageKey _loadAsset(AssetBundle bundle, float devicePixelRatio) {
-            var upper = devicePixelRatio.ceil();
+            var upper = Mathf.Min(3, devicePixelRatio.ceil());
-                    ResourceRequest request = Resources.LoadAsync(assetName);
-                    yield return request;
-                    asset = request.asset;
-                }
-                else {
-                    AssetBundleRequest request = bundle.LoadAssetAsync(assetName);
-                    yield return request;
-                    asset = request.asset;
+                    asset = Resources.Load(assetName);
+                } else {
+                    asset = bundle.LoadAsset(assetName);
-                    }
-                    else {
+                    } else {
-                    yield return new AssetBundleImageKey(
+                    return new AssetBundleImageKey(
-                    yield break;
-            yield return new AssetBundleImageKey(
+            return new AssetBundleImageKey(
                 bundle,
                 this.assetName,
                 scale: 1.0f

Runtime/promise/Promise.cs

         /// Handle errors for the promise.
         /// </summary>
         public IPromise<PromisedT> Catch(Func<Exception, PromisedT> onRejected) {
-            var resultPromise = new Promise<PromisedT>();
+            var resultPromise = new Promise<PromisedT>(isSync: true);
             resultPromise.WithName(this.Name);
 
             Action<PromisedT> resolveHandler = v => resultPromise.Resolve(v);
             // Otherwise there is now way to get the converted value to pass to the resulting promise.
 //            Argument.NotNull(() => onResolved); 
 
-            var resultPromise = new Promise<ConvertedT>();
+            var resultPromise = new Promise<ConvertedT>(isSync: true);
             resultPromise.WithName(this.Name);
 
             Action<PromisedT> resolveHandler = v => {
             var remainingCount = promisesArray.Length;
             var results = new PromisedT[remainingCount];
             var progress = new float[remainingCount];
-            var resultPromise = new Promise<IEnumerable<PromisedT>>();
+            var resultPromise = new Promise<IEnumerable<PromisedT>>(isSync: true);
             resultPromise.WithName("All");
 
             promisesArray.Each((promise, index) => {
                 );
             }
 
-            var resultPromise = new Promise<PromisedT>();
+            var resultPromise = new Promise<PromisedT>(isSync: true);
             resultPromise.WithName("Race");
 
             var progress = new float[promisesArray.Length];
         public static IPromise<PromisedT> Rejected(Exception ex) {
 //            Argument.NotNull(() => ex);
 
-            var promise = new Promise<PromisedT>();
+            var promise = new Promise<PromisedT>(isSync: true);
-            var promise = new Promise<PromisedT>();
+            var promise = new Promise<PromisedT>(isSync: true);
             promise.WithName(this.Name);
 
             this.Then(x => promise.Resolve(x));

Runtime/promise/Promise_NonGeneric.cs

             // Otherwise there is now way to get the converted value to pass to the resulting promise.
 //            Argument.NotNull(() => onResolved);
 
-            var resultPromise = new Promise<ConvertedT>();
+            var resultPromise = new Promise<ConvertedT>(isSync: true);
             resultPromise.WithName(this.Name);
 
             Action resolveHandler = () => {
         public static IPromise Rejected(Exception ex) {
 //            Argument.NotNull(() => ex);
 
-            var promise = new Promise();
+            var promise = new Promise(isSync: true);
-            var promise = new Promise();
+            var promise = new Promise(isSync: true);
             Window.instance.run(duration, () => { promise.Resolve(); });
             
             return promise;

Samples/UIWidgetsGallery/GalleryMain.cs

             return new GalleryApp();
         }
         
-        protected override void Start() {
-            base.Start();
+        protected override void OnEnable() {
+            base.OnEnable();
             FontManager.instance.addFont(Resources.Load<Font>("MaterialIcons-Regular"));
             FontManager.instance.addFont(Resources.Load<Font>("GalleryIcons"));
         }

Samples/UIWidgetsGallery/gallery/example_code_parser.cs

         Dictionary<string, string> _exampleCode;
     
         public string getExampleCode(string tag, AssetBundle bundle) {
-            if (this._exampleCode == null)
+            if (this._exampleCode == null) {
+            }
             return this._exampleCode.getOrDefault(tag);
         }
     

Tests/Resources/ali_landscape.png.meta

 TextureImporter:
   fileIDToRecycleName: {}
   externalObjects: {}
-  serializedVersion: 9
+  serializedVersion: 7
   mipmaps:
     mipMapMode: 0
     enableMipMap: 1
     wrapU: -1
     wrapV: -1
     wrapW: -1
-  nPOTScale: 1
+  nPOTScale: 0
   lightmap: 0
   compressionQuality: 50
   spriteMode: 0
   platformSettings:
   - serializedVersion: 2
     buildTarget: DefaultTexturePlatform
+    maxTextureSize: 2048
+    resizeAlgorithm: 0
+    textureFormat: -1
+    textureCompression: 1
+    compressionQuality: 50
+    crunchedCompression: 0
+    allowsAlphaSplitting: 0
+    overridden: 0
+    androidETC2FallbackOverride: 0
+  - serializedVersion: 2
+    buildTarget: Standalone
+    maxTextureSize: 2048
+    resizeAlgorithm: 0
+    textureFormat: -1
+    textureCompression: 1
+    compressionQuality: 50
+    crunchedCompression: 0
+    allowsAlphaSplitting: 0
+    overridden: 0
+    androidETC2FallbackOverride: 0
+  - serializedVersion: 2
+    buildTarget: iPhone
+    maxTextureSize: 2048
+    resizeAlgorithm: 0
+    textureFormat: -1
+    textureCompression: 1
+    compressionQuality: 50
+    crunchedCompression: 0
+    allowsAlphaSplitting: 0
+    overridden: 0
+    androidETC2FallbackOverride: 0
+  - serializedVersion: 2
+    buildTarget: WebGL
     maxTextureSize: 2048
     resizeAlgorithm: 0
     textureFormat: -1