embed icudtl.dat into dll

engine/Build.bee.cs

                 "src/shell/common/shell_io_manager.h",
                 "src/shell/common/surface.cc",
                 "src/shell/common/surface.h",
+                "src/shell/common/switches.cc",
+                "src/shell/common/switches.h",
                 "src/shell/common/thread_host.cc",
                 "src/shell/common/thread_host.h",
                 "src/shell/common/vsync_waiter.cc",
             },
             OutputName = {c => $"libUIWidgets{(c.CodeGen == CodeGen.Debug ? "_d" : "")}"},
         };
+        np.Libraries.Add(new BagOfObjectFilesLibrary(
+            new NPath[]{
+                skiaRoot+"out/Debug/icudtl.o"
+        }));
         np.CompilerSettings().Add(c => c.WithCppLanguageVersion(CppLanguageVersion.Cpp17));
         
         np.IncludeDirectories.Add("third_party");
 
             builtNP.DeployTo("../Samples/UIWidgetsSamples_2019_4/Assets/Plugins/x86_64");
         }
-        CopyTool.Instance().Setup(new NPath("../Samples/UIWidgetsSamples_2019_4/Assets/StreamingAssets/").Combine("icudtl.dat"), new NPath("").Combine(skiaRoot, "out/Debug/icudtl.dat"));
-
         return np;
     }
 

engine/README.md

 ```
 Ignore this error: "lld-link: error: could not open 'EGL': no such file or directory"
 
+convert icudtl.dat to object file
+```
+cd out/Debug
+ld -r -b binary -o .\icudtl.o .\icudtl.dat
+```
 ### Build flutter fml
 
 1. Setting up the Engine development environment

engine/src/shell/common/shell.cc

     if (settings.icu_initialization_required) {
       if (settings.icu_data_path.length() > 0) {
         uiwidgets::icu::InitializeICU(settings.icu_data_path);
+      } else {
+        uiwidgets::icu::InitializeICUFromMapping(settings.icu_mapper());
       }
     }
   });

engine/src/shell/platform/embedder/embedder.cc

   Settings settings;  // = SettingsFromCommandLine(command_line);
 
   settings.icu_data_path = icu_data_path;
+  settings.icu_mapper = args->icu_mapper;
   settings.assets_path = args->assets_path;
 
   settings.task_observer_add = [task_observer_add = args->task_observer_add,

engine/src/shell/platform/embedder/embedder.h

 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include "src/common/settings.h"
 
 #if defined(__cplusplus)
 extern "C" {
   size_t struct_size;
   const char* assets_path;
   const char* icu_data_path;
+  uiwidgets::MappingCallback icu_mapper;
   int command_line_argc;
   const char* const* command_line_argv;
   UIWidgetsPlatformMessageCallback platform_message_callback;

engine/src/shell/platform/unity/uiwidgets_panel.cc

 #include "lib/ui/window/viewport_metrics.h"
 #include "runtime/mono_api.h"
 #include "shell/platform/embedder/embedder_engine.h"
+#include "src/shell/common/switches.h"
 #include "uiwidgets_system.h"
 
 namespace uiwidgets {
   args.struct_size = sizeof(UIWidgetsProjectArgs);
 
   args.assets_path = streaming_assets_path;
-  std::string icu_path = std::string(streaming_assets_path) + "/icudtl.dat";
-  args.icu_data_path = icu_path.c_str();
+  // std::string icu_path = std::string(streaming_assets_path) + "/icudtl.dat";
+  // args.icu_data_path = icu_path.c_str();
+  args.icu_mapper = GetICUStaticMapping;
+  // std::string icu_symbol_prefix = "_binary_icudtl_dat_start";
+  // std::string native_lib_path =
+  // "pathtodll/Plugins/x86_64/libUIWidgets_d.dll"; args.icu_mapper =
+  // [icu_symbol_prefix, native_lib_path] {
+  //  return GetSymbolMapping(icu_symbol_prefix, native_lib_path);
+  // };
   args.command_line_argc = 0;
   args.command_line_argv = nullptr;
 

engine/src/shell/common/switches.cc

+#include "switches.h"
+
+#include <cstdint>
+
+namespace uiwidgets {
+extern "C" uint8_t _binary_icudtl_dat_start[];
+extern "C" uint8_t _binary_icudtl_dat_end[];
+
+std::unique_ptr<fml::Mapping> GetICUStaticMapping() {
+  return std::make_unique<fml::NonOwnedMapping>(
+      _binary_icudtl_dat_start,
+      _binary_icudtl_dat_end - _binary_icudtl_dat_start);
+}
+
+std::unique_ptr<fml::Mapping> GetSymbolMapping(std::string symbol_prefix,
+                                               std::string native_lib_path) {
+  const uint8_t* mapping;
+  intptr_t size;
+
+  auto lookup_symbol = [&mapping, &size, symbol_prefix](
+                           const fml::RefPtr<fml::NativeLibrary>& library) {
+    mapping = library->ResolveSymbol((symbol_prefix + "_start").c_str());
+    size = reinterpret_cast<intptr_t>(
+        library->ResolveSymbol((symbol_prefix + "_size").c_str()));
+  };
+
+  fml::RefPtr<fml::NativeLibrary> library =
+      fml::NativeLibrary::CreateForCurrentProcess();
+  lookup_symbol(library);
+
+  if (!(mapping && size)) {
+    // Symbol lookup for the current process fails on some devices.  As a
+    // fallback, try doing the lookup based on the path to the Flutter library.
+    library = fml::NativeLibrary::Create(native_lib_path.c_str());
+    lookup_symbol(library);
+  }
+
+  FML_CHECK(mapping && size) << "Unable to resolve symbols: " << symbol_prefix;
+  return std::make_unique<fml::NonOwnedMapping>(mapping, size);
+}
+
+}  // namespace uiwidgets

engine/src/shell/common/switches.h

+#pragma once
+#include <flutter/fml/memory/ref_counted.h>
+
+#include "flutter/fml/mapping.h"
+
+namespace uiwidgets {
+std::unique_ptr<fml::Mapping> GetICUStaticMapping();
+std::unique_ptr<fml::Mapping> GetSymbolMapping(std::string symbol_prefix,
+                                               std::string native_lib_path);
+}  // namespace uiwidgets