fix

com.unity.uiwidgets/Runtime/engine2/UIWidgetsPanel.cs

 using System.Collections;
 using System.Collections.Generic;
 using Unity.UIWidgets.engine2;
-using engine2;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.ui;
 using UnityEngine;
         }
 
 #if !UNITY_EDITOR && UNITY_ANDROID
-        bool InitAnroidGLFlag = true;
+        bool AndroidInitialized = true;
-        IEnumerator InitAnroidGL() {
+        IEnumerator DoInitAndroid() {
-            AndroidGLInit.Init();
+            AndroidPlatformUtil.Init();
+        bool IsAndroidInitialized() {
+            if (AndroidInitialized) {
+                enabled = false;
+                AndroidInitialized = false;
+                startCoroutine(DoInitAndroid());
+                return false;
+            }
+            return true;
+        }
-            if (InitAnroidGLFlag) {
-                enabled = false;
-                InitAnroidGLFlag = false;
-                startCoroutine(InitAnroidGL());
-                return;
-            }
+            if (!IsAndroidInitialized()) {return ;}
 #endif
             
             base.OnEnable();

com.unity.uiwidgets/Runtime/engine2/UIWidgetsPanelWrapper.cs

 
         public void Initiate(IUIWidgetsWindow host, int width, int height, float dpr, Configurations _configurations) {
             D.assert(renderTexture == null);
-#if !UNITY_EDITOR && UNITY_ANDROID
-            AndroidUnpackStreamingAssets.OnEnable();
-#endif
             _recreateRenderTexture(width: width, height: height, devicePixelRatio: dpr);
 
             _handle = GCHandle.Alloc(this);

engine/Build.bee.cs

     //bee.exe mac
     static void DeployAndroid()
     {
-
-        Backend.Current.AddAliasDependency("android", new NPath("libUIWidgetsMac.xcodeproj/project.pbxproj"));
         foreach (var dep in dependencies)
         {
             Backend.Current.AddAliasDependency("android", dep);
     static void DeployMac()
     {
-
         var libUIWidgets = SetupLibUIWidgets(UIWidgetsBuildTargetPlatform.mac, out var dependencies);
 
         var nativePrograms = new List<NativeProgram>();
         {
             Backend.Current.AddAliasDependency("mac", dep);
         }
-
     }
 
     static void Main()
                 "src/shell/platform/unity/gfx_worker_task_runner.h",
                 "src/shell/platform/unity/uiwidgets_system.h",
 
-                "src/shell/platform/unity/android_unpack_streaming_asset.cc",
-                "src/shell/platform/unity/android_unpack_streaming_asset.h",
+              
                 "src/shell/platform/unity/unity_console.cc",
                 "src/shell/platform/unity/unity_console.h",
 
 
         var androidSource = new NPath[]
         {
-
+            "src/shell/platform/unity/android_unpack_streaming_asset.cc",
+            "src/shell/platform/unity/android_unpack_streaming_asset.h",
-            "src/shell/platform/unity/android/cocoa_task_runner.cc",
+            "src/shell/platform/unity/android/android_task_runner.cc",
             "src/shell/platform/unity/android/uiwidgets_panel.cc",
         };
 
             "-Wl,-z,now",
             "-Wl,-z,relro",
             "-Wl,-z,defs",
-            "--gcc-toolchain="+ Build.flutterRoot +
+            "--gcc-toolchain="+ flutterRoot +
             "/third_party/android_tools/ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64",
             "-Wl,--no-undefined",
             "-Wl,--exclude-libs,ALL",
             "-nostdlib++",
             "-Wl,--warn-shared-textrel",
             "-nostdlib",
-            "--sysroot="+ Build.flutterRoot+"/third_party/android_tools/ndk/platforms/android-16/arch-arm",
-            "-L"+ Build.flutterRoot +            "/third_party/android_tools/ndk/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a",
+            "--sysroot="+ flutterRoot+"/third_party/android_tools/ndk/platforms/android-16/arch-arm",
+            "-L"+ flutterRoot + "/third_party/android_tools/ndk/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a",
             "-Wl,--build-id=sha1",
             "-g",
             "-Wl,-soname=libUIWidgets_d.so",
                 var buildNP = np.SetupSpecificConfiguration(config, androidToolchain.DynamicLibraryFormat).DeployTo("build");
 
                 var deoployNp = buildNP.DeployTo("../Samples/UIWidgetsSamples_2019_4/Assets/Plugins/Android");
-                buildNP.DeployTo("/Users/siyao/Documents/GitHub/untitled folder/unityLibrary/src/main/jniLibs/armeabi-v7a");
                 dependencies.Add(buildNP.Path);
                 dependencies.Add(deoployNp.Path);
             }
         {
-
             var toolchain = ToolChain.Store.Host();
             var validConfigurations = new List<NativeProgramConfiguration>();
             foreach (var codegen in codegens)

engine/README.md

 
 Follow https://github.com/flutter/flutter/wiki/Setting-up-the-Engine-development-environment
 
-2. Checkout flutter-1.18-candidate.5
+2. Checkout flutter-1.17-candidate.5
-git checkout flutter-1.18-candidate.5
+git checkout flutter-1.17-candidate.5
 gclient sync -D
 ```
 

engine/src/assets/directory_asset_bundle.cc

 
 #include "flutter/fml/file.h"
 #include "flutter/fml/mapping.h"
-
+#if __ANDROID__
-
+#endif
 namespace uiwidgets {
 
 DirectoryAssetBundle::DirectoryAssetBundle(fml::UniqueFD descriptor)
   }
 
 #if __ANDROID__
-    const char* file = AndroidUnpackStreamingAsset::Unpack(asset_name.c_str());
+  AndroidUnpackStreamingAsset::Unpack(asset_name.c_str());
 #endif
 
   auto mapping = std::make_unique<fml::FileMapping>(fml::OpenFile(

engine/src/flow/raster_cache.cc

                                      const SkRect& logical_rect)
     : image_(std::move(image)), logical_rect_(logical_rect) {}
 #if __ANDROID__
-#define ABS(x) abs(x)
+#define Math_abs(x) abs(x)
 template<typename T>
 T abs(T x) {
   if (x < 0) {
 }
 #else 
-#define ABS(x) std::abs(x)
+#define Math_abs(x) std::abs(x)
 #endif
 
 void RasterCacheResult::draw(SkCanvas& canvas, const SkPaint* paint) const {
       RasterCache::GetDeviceBounds(logical_rect_, canvas.getTotalMatrix());
-      auto a = bounds.size().width() - image_->dimensions().width();
-        ABS(bounds.size().width() - image_->dimensions().width()) <= 1 &&
-        ABS(bounds.size().height() - image_->dimensions().height()) <= 1);
+        Math_abs(bounds.size().width() - image_->dimensions().width()) <= 1 &&
+        Math_abs(bounds.size().height() - image_->dimensions().height()) <= 1);
   canvas.resetMatrix();
   canvas.drawImage(image_, bounds.fLeft, bounds.fTop, paint);
 }

engine/src/lib/ui/painting/skottie.cc

 #include "skottie.h"
 
 #include "lib/ui/ui_mono_state.h"
+#if __ANDROID__
-
+#endif
 namespace uiwidgets {
 fml::RefPtr<Skottie> Skottie::Create(char* path) {
 #if __ANDROID__

engine/src/runtime/mono_api.cc

   pthread_threadid_np(NULL, &tid);
   return tid;
 }
-#endif
-
-#ifdef __ANDROID__
+#elif __ANDROID__
 uint64_t GetCurrentThreadId() { 
   return gettid();
 }

engine/src/shell/platform/unity/android/uiwidgets_panel.h

 #include "shell/platform/unity/gfx_worker_task_runner.h"
 #include "runtime/mono_api.h"
 #include "unity_surface_manager.h"
-#include "cocoa_task_runner.h"
+#include "android_task_runner.h"
 
 namespace uiwidgets {
 

engine/src/shell/platform/unity/android/android_task_runner.cc

-#include "cocoa_task_runner.h"
+#include "android_task_runner.h"
 
 #include <flutter/fml/time/time_point.h>
 

com.unity.uiwidgets/Runtime/engine2/AndroidPlatformUtil.cs

+#if !UNITY_EDITOR && UNITY_ANDROID
+using UnityEngine;
+using AOT;
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using NativeBindings = Unity.UIWidgets.ui.NativeBindings;
+namespace Unity.UIWidgets.engine2 {
+    public static class AndroidPlatformUtil {
+        [DllImport(NativeBindings.dllName)]
+        internal static extern void InitUnpackFile(UnpackFileCallback unpack);
+
+        internal delegate string UnpackFileCallback(string file);
+
+        [MonoPInvokeCallback(typeof(UnpackFileCallback))]
+        internal static string unpackFile(string file) {
+            var dir = Application.temporaryCachePath + "/";
+            if (!File.Exists(dir + file)) {
+                WWW unpackerWWW = new WWW("jar:file://" + Application.dataPath + "!/assets/" + file);
+                while (!unpackerWWW.isDone) {
+                } // This will block in the webplayer.
+
+                if (!string.IsNullOrEmpty(unpackerWWW.error)) {
+                    Debug.Log("Error unpacking 'jar:file://" + Application.dataPath + "!/assets/" + file +
+                              "'");
+                    dir = "";
+                    return dir + file;
+                }
+
+                File.WriteAllBytes(dir + file, unpackerWWW.bytes); // 64MB limit on File.WriteAllBytes.
+            }
+
+            return dir + file;
+
+            return "";
+        }
+        
+        [DllImport(NativeBindings.dllName)]
+        static extern System.IntPtr GetUnityContextEventFunc();
+
+        public static void Init() {
+            if (Application.platform == RuntimePlatform.Android) {
+                InitUnpackFile(unpackFile);
+                GL.IssuePluginEvent(GetUnityContextEventFunc(), 1);
+            }
+        }
+    }
+}
+#endif

com.unity.uiwidgets/Runtime/engine2/AndroidGLInit.cs

-using System.Runtime.InteropServices;
-using Unity.UIWidgets.ui;
-using UnityEngine;
-
-namespace engine2 {
-    public class AndroidGLInit {
-        [DllImport(NativeBindings.dllName)]
-        static extern System.IntPtr GetUnityContextEventFunc();
-
-        public static void Init() {
-            GL.IssuePluginEvent(GetUnityContextEventFunc(), 1);
-        }
-    }
-}

com.unity.uiwidgets/Runtime/engine2/AndroidUnpackStreamingAsset.cs

-using UnityEngine;
-using AOT;
-using System;
-using System.IO;
-using System.Runtime.InteropServices;
-using NativeBindings = Unity.UIWidgets.ui.NativeBindings;
-
-public static class AndroidUnpackStreamingAssets {
-
-    [DllImport(NativeBindings.dllName)]
-    internal static extern void InitUnpackFile(UnpackFileCallback unpack);
-    
-    internal delegate string UnpackFileCallback(string file);
-    
-    [MonoPInvokeCallback(typeof(UnpackFileCallback))]
-    internal static string unpackFile(string file) {
-        if (Application.platform == RuntimePlatform.Android) {
-            var dir = Application.temporaryCachePath + "/";
-            if (!File.Exists(dir + file)) {
-                WWW unpackerWWW = new WWW("jar:file://" + Application.dataPath + "!/assets/" + file);
-                while (!unpackerWWW.isDone) {
-                } // This will block in the webplayer.
-
-                if (!string.IsNullOrEmpty(unpackerWWW.error)) {
-                    Debug.Log("Error unpacking 'jar:file://" + Application.dataPath + "!/assets/" + file +
-                              "'");
-                    dir = "";
-                    return dir + file;
-                }
-                File.WriteAllBytes(dir + file, unpackerWWW.bytes); // 64MB limit on File.WriteAllBytes.
-            }
-            return dir + file;
-        }
-
-        return "";
-    }
-    
-    public static void OnEnable()
-    {
-        InitUnpackFile(unpackFile);
-    }
-}