From dc0a27764fe37c56935d80fb26bab3931fdc8e02 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Fri, 6 Sep 2019 01:25:37 +0800
Subject: [PATCH 1/9] Improve input method and Unicode character
 display(#30661)

---
 shell/platform/common/cpp/text_input_model.cc | 16 ++++++++++++----
 shell/platform/common/cpp/text_input_model.h  | 10 ++++++----
 shell/platform/glfw/text_input_plugin.cc      |  2 +-
 shell/platform/windows/text_input_plugin.cc   |  2 +-
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index 41231a6d611d4..79d602dbe8274 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -26,10 +26,16 @@ static constexpr char kTextInputAction[] = "inputAction";
 static constexpr char kTextInputType[] = "inputType";
 static constexpr char kTextInputTypeName[] = "name";
 
+#if defined(_MSC_VER)
+// TODO(naifu): This temporary code is to solve link error.(VS2015/2017)
+// https://social.msdn.microsoft.com/Forums/vstudio/en-US/8f40dcd8-c67f-4eba-9134-a19b9178e481/vs-2015-rc-linker-stdcodecvt-error
+std::locale::id std::codecvt<char16_t, char, _Mbstatet>::id;
+#endif  // defined(_MSC_VER)
+
 namespace flutter {
 
 TextInputModel::TextInputModel(int client_id, const rapidjson::Value& config)
-    : text_(""),
+    : text_(std::u16string()),
       client_id_(client_id),
       selection_base_(text_.begin()),
       selection_extent_(text_.begin()) {
@@ -64,7 +70,8 @@ bool TextInputModel::SetEditingState(size_t selection_base,
   if (selection_extent > text.size()) {
     return false;
   }
-  text_ = std::string(text);
+  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf16conv;
+  text_ = utf16conv.from_bytes(text);
   selection_base_ = text_.begin() + selection_base;
   selection_extent_ = text_.begin() + selection_extent;
   return true;
@@ -76,7 +83,7 @@ void TextInputModel::DeleteSelected() {
   selection_extent_ = selection_base_;
 }
 
-void TextInputModel::AddCharacter(char c) {
+void TextInputModel::AddCharacter(unsigned int c) {
   if (selection_base_ != selection_extent_) {
     DeleteSelected();
   }
@@ -172,7 +179,8 @@ std::unique_ptr<rapidjson::Document> TextInputModel::GetState() const {
                           static_cast<int>(selection_extent_ - text_.begin()),
                           allocator);
   editing_state.AddMember(kSelectionIsDirectionalKey, false, allocator);
-  editing_state.AddMember(kTextKey, rapidjson::Value(text_, allocator).Move(),
+  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf8conv;
+  editing_state.AddMember(kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
                           allocator);
   args->PushBack(editing_state, allocator);
   return args;
diff --git a/shell/platform/common/cpp/text_input_model.h b/shell/platform/common/cpp/text_input_model.h
index e3ea19bae9010..03dfc089b305e 100644
--- a/shell/platform/common/cpp/text_input_model.h
+++ b/shell/platform/common/cpp/text_input_model.h
@@ -7,6 +7,8 @@
 
 #include <memory>
 #include <string>
+#include <codecvt>
+#include <locale>
 
 #include "rapidjson/document.h"
 
@@ -32,7 +34,7 @@ class TextInputModel {
   // Either appends after the cursor (when selection base and extent are the
   // same), or deletes the selected characters, replacing the text with the
   // character specified.
-  void AddCharacter(char c);
+  void AddCharacter(unsigned int c);
 
   // Deletes either the selection, or one character ahead of the cursor.
   //
@@ -89,12 +91,12 @@ class TextInputModel {
  private:
   void DeleteSelected();
 
-  std::string text_;
+  std::u16string text_;
   int client_id_;
   std::string input_type_;
   std::string input_action_;
-  std::string::iterator selection_base_;
-  std::string::iterator selection_extent_;
+  std::u16string::iterator selection_base_;
+  std::u16string::iterator selection_extent_;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/glfw/text_input_plugin.cc b/shell/platform/glfw/text_input_plugin.cc
index 3779510e301ac..66112a3a51661 100644
--- a/shell/platform/glfw/text_input_plugin.cc
+++ b/shell/platform/glfw/text_input_plugin.cc
@@ -42,7 +42,7 @@ void TextInputPlugin::CharHook(GLFWwindow* window, unsigned int code_point) {
   }
   // TODO(awdavies): Actually handle potential unicode characters. Probably
   // requires some ICU data or something.
-  active_model_->AddCharacter(static_cast<char>(code_point));
+  active_model_->AddCharacter(code_point);
   SendStateUpdate(*active_model_);
 }
 
diff --git a/shell/platform/windows/text_input_plugin.cc b/shell/platform/windows/text_input_plugin.cc
index 3324e8ee0f685..2105c8a3979cc 100644
--- a/shell/platform/windows/text_input_plugin.cc
+++ b/shell/platform/windows/text_input_plugin.cc
@@ -44,7 +44,7 @@ void TextInputPlugin::CharHook(Win32FlutterWindow* window,
     return;
   }
   // TODO bug 30661
-  active_model_->AddCharacter(static_cast<char>(code_point));
+  active_model_->AddCharacter(code_point);
   SendStateUpdate(*active_model_);
 }
 

From 79f4a570db157f61d538f0094eabf60301b3b357 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Fri, 6 Sep 2019 01:56:50 +0800
Subject: [PATCH 2/9] clang-format

---
 shell/platform/common/cpp/text_input_model.cc | 5 +++--
 shell/platform/common/cpp/text_input_model.h  | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index 79d602dbe8274..abe00417684cb 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -180,8 +180,9 @@ std::unique_ptr<rapidjson::Document> TextInputModel::GetState() const {
                           allocator);
   editing_state.AddMember(kSelectionIsDirectionalKey, false, allocator);
   std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf8conv;
-  editing_state.AddMember(kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
-                          allocator);
+  editing_state.AddMember(
+      kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
+      allocator);
   args->PushBack(editing_state, allocator);
   return args;
 }
diff --git a/shell/platform/common/cpp/text_input_model.h b/shell/platform/common/cpp/text_input_model.h
index 03dfc089b305e..f52aec204a689 100644
--- a/shell/platform/common/cpp/text_input_model.h
+++ b/shell/platform/common/cpp/text_input_model.h
@@ -5,10 +5,10 @@
 #ifndef FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
 #define FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
 
-#include <memory>
-#include <string>
 #include <codecvt>
 #include <locale>
+#include <memory>
+#include <string>
 
 #include "rapidjson/document.h"
 

From 60ba55c13188b4319e962c2d32335f8dfd6a846b Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Fri, 6 Sep 2019 08:42:47 +0800
Subject: [PATCH 3/9] patch set-1

---
 shell/platform/common/cpp/text_input_model.cc | 20 +++++++++----------
 shell/platform/common/cpp/text_input_model.h  | 10 ++++------
 shell/platform/glfw/text_input_plugin.cc      |  4 +---
 shell/platform/glfw/text_input_plugin.h       |  2 +-
 shell/platform/windows/text_input_plugin.cc   |  3 +--
 shell/platform/windows/text_input_plugin.h    |  2 +-
 6 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index abe00417684cb..01d25b8123e06 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -4,7 +4,9 @@
 
 #include "flutter/shell/platform/common/cpp/text_input_model.h"
 
+#include <codecvt>
 #include <iostream>
+#include <locale>
 
 // TODO(awdavies): Need to fix this regarding issue #47.
 static constexpr char kComposingBaseKey[] = "composingBase";
@@ -29,14 +31,13 @@ static constexpr char kTextInputTypeName[] = "name";
 #if defined(_MSC_VER)
 // TODO(naifu): This temporary code is to solve link error.(VS2015/2017)
 // https://social.msdn.microsoft.com/Forums/vstudio/en-US/8f40dcd8-c67f-4eba-9134-a19b9178e481/vs-2015-rc-linker-stdcodecvt-error
-std::locale::id std::codecvt<char16_t, char, _Mbstatet>::id;
+std::locale::id std::codecvt<char32_t, char, _Mbstatet>::id;
 #endif  // defined(_MSC_VER)
 
 namespace flutter {
 
 TextInputModel::TextInputModel(int client_id, const rapidjson::Value& config)
-    : text_(std::u16string()),
-      client_id_(client_id),
+    : client_id_(client_id),
       selection_base_(text_.begin()),
       selection_extent_(text_.begin()) {
   // TODO: Improve error handling during refactoring; this is just minimal
@@ -70,8 +71,8 @@ bool TextInputModel::SetEditingState(size_t selection_base,
   if (selection_extent > text.size()) {
     return false;
   }
-  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf16conv;
-  text_ = utf16conv.from_bytes(text);
+  std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utf32conv;
+  text_ = utf32conv.from_bytes(text);
   selection_base_ = text_.begin() + selection_base;
   selection_extent_ = text_.begin() + selection_extent;
   return true;
@@ -83,7 +84,7 @@ void TextInputModel::DeleteSelected() {
   selection_extent_ = selection_base_;
 }
 
-void TextInputModel::AddCharacter(unsigned int c) {
+void TextInputModel::AddCharacter(uint32_t c) {
   if (selection_base_ != selection_extent_) {
     DeleteSelected();
   }
@@ -179,10 +180,9 @@ std::unique_ptr<rapidjson::Document> TextInputModel::GetState() const {
                           static_cast<int>(selection_extent_ - text_.begin()),
                           allocator);
   editing_state.AddMember(kSelectionIsDirectionalKey, false, allocator);
-  std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t> utf8conv;
-  editing_state.AddMember(
-      kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
-      allocator);
+  std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utf8conv;
+  editing_state.AddMember(kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
+                          allocator);
   args->PushBack(editing_state, allocator);
   return args;
 }
diff --git a/shell/platform/common/cpp/text_input_model.h b/shell/platform/common/cpp/text_input_model.h
index f52aec204a689..f32b58a97ec49 100644
--- a/shell/platform/common/cpp/text_input_model.h
+++ b/shell/platform/common/cpp/text_input_model.h
@@ -5,8 +5,6 @@
 #ifndef FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
 #define FLUTTER_SHELL_PLATFORM_CPP_TEXT_INPUT_MODEL_H_
 
-#include <codecvt>
-#include <locale>
 #include <memory>
 #include <string>
 
@@ -34,7 +32,7 @@ class TextInputModel {
   // Either appends after the cursor (when selection base and extent are the
   // same), or deletes the selected characters, replacing the text with the
   // character specified.
-  void AddCharacter(unsigned int c);
+  void AddCharacter(uint32_t c);
 
   // Deletes either the selection, or one character ahead of the cursor.
   //
@@ -91,12 +89,12 @@ class TextInputModel {
  private:
   void DeleteSelected();
 
-  std::u16string text_;
+  std::u32string text_;
   int client_id_;
   std::string input_type_;
   std::string input_action_;
-  std::u16string::iterator selection_base_;
-  std::u16string::iterator selection_extent_;
+  std::u32string::iterator selection_base_;
+  std::u32string::iterator selection_extent_;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/glfw/text_input_plugin.cc b/shell/platform/glfw/text_input_plugin.cc
index 66112a3a51661..756b037dfcb82 100644
--- a/shell/platform/glfw/text_input_plugin.cc
+++ b/shell/platform/glfw/text_input_plugin.cc
@@ -36,12 +36,10 @@ static constexpr uint32_t kInputModelLimit = 256;
 
 namespace flutter {
 
-void TextInputPlugin::CharHook(GLFWwindow* window, unsigned int code_point) {
+void TextInputPlugin::CharHook(GLFWwindow* window, uint32_t code_point) {
   if (active_model_ == nullptr) {
     return;
   }
-  // TODO(awdavies): Actually handle potential unicode characters. Probably
-  // requires some ICU data or something.
   active_model_->AddCharacter(code_point);
   SendStateUpdate(*active_model_);
 }
diff --git a/shell/platform/glfw/text_input_plugin.h b/shell/platform/glfw/text_input_plugin.h
index daf2fa7d22f05..8d31a8bbbdbf8 100644
--- a/shell/platform/glfw/text_input_plugin.h
+++ b/shell/platform/glfw/text_input_plugin.h
@@ -33,7 +33,7 @@ class TextInputPlugin : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(GLFWwindow* window, unsigned int code_point) override;
+  void CharHook(GLFWwindow* window, uint32_t code_point) override;
 
  private:
   // Sends the current state of the given model to the Flutter engine.
diff --git a/shell/platform/windows/text_input_plugin.cc b/shell/platform/windows/text_input_plugin.cc
index 2105c8a3979cc..266ae49e9e059 100644
--- a/shell/platform/windows/text_input_plugin.cc
+++ b/shell/platform/windows/text_input_plugin.cc
@@ -39,11 +39,10 @@ static constexpr uint32_t kInputModelLimit = 256;
 namespace flutter {
 
 void TextInputPlugin::CharHook(Win32FlutterWindow* window,
-                               unsigned int code_point) {
+                               uint32_t code_point) {
   if (active_model_ == nullptr) {
     return;
   }
-  // TODO bug 30661
   active_model_->AddCharacter(code_point);
   SendStateUpdate(*active_model_);
 }
diff --git a/shell/platform/windows/text_input_plugin.h b/shell/platform/windows/text_input_plugin.h
index 1cc57642e8af0..722d0e7dc58d2 100644
--- a/shell/platform/windows/text_input_plugin.h
+++ b/shell/platform/windows/text_input_plugin.h
@@ -35,7 +35,7 @@ class TextInputPlugin : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(Win32FlutterWindow* window, unsigned int code_point) override;
+  void CharHook(Win32FlutterWindow* window, uint32_t code_point) override;
 
  private:
   // Sends the current state of the given model to the Flutter engine.

From 1a6cbcc7023615c3cf142ebad849c072cc95c6c9 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Fri, 6 Sep 2019 09:09:51 +0800
Subject: [PATCH 4/9] clang-format

---
 shell/platform/common/cpp/text_input_model.cc | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index 01d25b8123e06..206e1d7c2bd39 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -181,8 +181,9 @@ std::unique_ptr<rapidjson::Document> TextInputModel::GetState() const {
                           allocator);
   editing_state.AddMember(kSelectionIsDirectionalKey, false, allocator);
   std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utf8conv;
-  editing_state.AddMember(kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
-                          allocator);
+  editing_state.AddMember(
+      kTextKey, rapidjson::Value(utf8conv.to_bytes(text_), allocator).Move(),
+      allocator);
   args->PushBack(editing_state, allocator);
   return args;
 }

From 9b080e15caf4a23243330d74436c5c9873de3677 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Sat, 7 Sep 2019 12:17:39 +0800
Subject: [PATCH 5/9] utf-16 convert logic

---
 shell/platform/common/cpp/text_input_model.cc | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index 206e1d7c2bd39..82044adf4c55e 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -88,7 +88,30 @@ void TextInputModel::AddCharacter(uint32_t c) {
   if (selection_base_ != selection_extent_) {
     DeleteSelected();
   }
-  selection_extent_ = text_.insert(selection_extent_, c);
+  char32_t ch = c;
+  {
+    // I put this code (compatible processing logic for UTF-16) here for
+    // several reasons:
+    // 1. If I put it in win32/glfw 's message processing logic, there would
+    // be two sets of duplicate code.
+    // 2. Putting it here can still be guaranteed to be platform-independent
+    // and can handle more scenarios.
+    // Specific logic:
+    // What we expect to pass in is a Unicode, if it's UTF-32, it doesn't need
+    // any processing, and if it's UTF-16, it's converted to Unicode.
+    static char32_t lead_ch = 0;
+    // If ch is Lead Surrogate.
+    if ((ch & 0xFFFFFC00) == 0xD800) {
+      lead_ch = ch;
+      return;
+    }
+    // If ch is Trail Surrogate and pre-ch is Lead Surrogate.
+    if (lead_ch != 0 && (ch & 0xFFFFFC00) == 0xDC00) {
+      ch = 0x10000 + ((lead_ch & 0x000003FF) << 10) + (ch & 0x3FF);
+    }
+    lead_ch = 0;
+  }
+  selection_extent_ = text_.insert(selection_extent_, ch);
   selection_extent_++;
   selection_base_ = selection_extent_;
 }

From ad7984b4e0b21aea8330e398b12838a9e1d2c6a3 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Sat, 7 Sep 2019 22:51:36 +0800
Subject: [PATCH 6/9] move logic to MessageHandler

---
 shell/platform/common/cpp/text_input_model.cc | 27 ++---------------
 shell/platform/common/cpp/text_input_model.h  |  2 +-
 shell/platform/windows/text_input_plugin.cc   |  2 +-
 shell/platform/windows/text_input_plugin.h    |  2 +-
 shell/platform/windows/win32_window.cc        | 29 +++++++++++++++++--
 5 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/shell/platform/common/cpp/text_input_model.cc b/shell/platform/common/cpp/text_input_model.cc
index 82044adf4c55e..35bc07592f0a2 100644
--- a/shell/platform/common/cpp/text_input_model.cc
+++ b/shell/platform/common/cpp/text_input_model.cc
@@ -84,34 +84,11 @@ void TextInputModel::DeleteSelected() {
   selection_extent_ = selection_base_;
 }
 
-void TextInputModel::AddCharacter(uint32_t c) {
+void TextInputModel::AddCharacter(char32_t c) {
   if (selection_base_ != selection_extent_) {
     DeleteSelected();
   }
-  char32_t ch = c;
-  {
-    // I put this code (compatible processing logic for UTF-16) here for
-    // several reasons:
-    // 1. If I put it in win32/glfw 's message processing logic, there would
-    // be two sets of duplicate code.
-    // 2. Putting it here can still be guaranteed to be platform-independent
-    // and can handle more scenarios.
-    // Specific logic:
-    // What we expect to pass in is a Unicode, if it's UTF-32, it doesn't need
-    // any processing, and if it's UTF-16, it's converted to Unicode.
-    static char32_t lead_ch = 0;
-    // If ch is Lead Surrogate.
-    if ((ch & 0xFFFFFC00) == 0xD800) {
-      lead_ch = ch;
-      return;
-    }
-    // If ch is Trail Surrogate and pre-ch is Lead Surrogate.
-    if (lead_ch != 0 && (ch & 0xFFFFFC00) == 0xDC00) {
-      ch = 0x10000 + ((lead_ch & 0x000003FF) << 10) + (ch & 0x3FF);
-    }
-    lead_ch = 0;
-  }
-  selection_extent_ = text_.insert(selection_extent_, ch);
+  selection_extent_ = text_.insert(selection_extent_, c);
   selection_extent_++;
   selection_base_ = selection_extent_;
 }
diff --git a/shell/platform/common/cpp/text_input_model.h b/shell/platform/common/cpp/text_input_model.h
index f32b58a97ec49..0688512aedbd8 100644
--- a/shell/platform/common/cpp/text_input_model.h
+++ b/shell/platform/common/cpp/text_input_model.h
@@ -32,7 +32,7 @@ class TextInputModel {
   // Either appends after the cursor (when selection base and extent are the
   // same), or deletes the selected characters, replacing the text with the
   // character specified.
-  void AddCharacter(uint32_t c);
+  void AddCharacter(char32_t c);
 
   // Deletes either the selection, or one character ahead of the cursor.
   //
diff --git a/shell/platform/windows/text_input_plugin.cc b/shell/platform/windows/text_input_plugin.cc
index 266ae49e9e059..d1a35e3a071ce 100644
--- a/shell/platform/windows/text_input_plugin.cc
+++ b/shell/platform/windows/text_input_plugin.cc
@@ -39,7 +39,7 @@ static constexpr uint32_t kInputModelLimit = 256;
 namespace flutter {
 
 void TextInputPlugin::CharHook(Win32FlutterWindow* window,
-                               uint32_t code_point) {
+                               unsigned int code_point) {
   if (active_model_ == nullptr) {
     return;
   }
diff --git a/shell/platform/windows/text_input_plugin.h b/shell/platform/windows/text_input_plugin.h
index 722d0e7dc58d2..1cc57642e8af0 100644
--- a/shell/platform/windows/text_input_plugin.h
+++ b/shell/platform/windows/text_input_plugin.h
@@ -35,7 +35,7 @@ class TextInputPlugin : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(Win32FlutterWindow* window, uint32_t code_point) override;
+  void CharHook(Win32FlutterWindow* window, unsigned int code_point) override;
 
  private:
   // Sends the current state of the given model to the Flutter engine.
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index fce8ae73e1450..d929a9ffe70de 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -153,13 +153,36 @@ Win32Window::MessageHandler(HWND hwnd,
         window->OnScroll(
             0.0, -(static_cast<short>(HIWORD(wparam)) / (double)WHEEL_DELTA));
         break;
+      case WM_UNICHAR:
+      {
+        // Tell thiary-pary app, we can support Unicode.
+        if (wparam == UNICODE_NOCHAR)
+          return TRUE;
+        // DefWindowProc will send WM_CHAR for this WM_UNICHAR.
+        break;
+      }
       case WM_CHAR:
       case WM_SYSCHAR:
-      case WM_UNICHAR:
-        if (wparam != VK_BACK) {
-          window->OnChar(static_cast<unsigned int>(wparam));
+      {
+        if (wparam == VK_BACK)
+          break;
+        char32_t ch = static_cast<char32_t>(wparam);
+        // What we expect to pass in is a Unicode, if it's UTF-32, it doesn't
+        // need any processing, and if it's UTF-16, it's converted to Unicode.
+        static char32_t lead_ch = 0;
+        // If ch is Lead Surrogate.
+        if ((ch & 0xFFFFFC00) == 0xD800) {
+          lead_ch = ch;
+          return TRUE;
+        }
+        // If ch is Trail Surrogate and pre-ch is Lead Surrogate.
+        if (lead_ch != 0 && (ch & 0xFFFFFC00) == 0xDC00) {
+          ch = 0x10000 + ((lead_ch & 0x000003FF) << 10) + (ch & 0x3FF);
         }
+        lead_ch = 0;
+        window->OnChar(ch);
         break;
+      }
       case WM_KEYDOWN:
       case WM_SYSKEYDOWN:
       case WM_KEYUP:

From 59ce05affd94e5578631cd2a8b21eeaa7e59a0db Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Sat, 7 Sep 2019 23:00:39 +0800
Subject: [PATCH 7/9] format

---
 shell/platform/glfw/text_input_plugin.cc | 2 +-
 shell/platform/glfw/text_input_plugin.h  | 2 +-
 shell/platform/windows/win32_window.cc   | 8 +++-----
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/shell/platform/glfw/text_input_plugin.cc b/shell/platform/glfw/text_input_plugin.cc
index 756b037dfcb82..ebf7cc62bb121 100644
--- a/shell/platform/glfw/text_input_plugin.cc
+++ b/shell/platform/glfw/text_input_plugin.cc
@@ -36,7 +36,7 @@ static constexpr uint32_t kInputModelLimit = 256;
 
 namespace flutter {
 
-void TextInputPlugin::CharHook(GLFWwindow* window, uint32_t code_point) {
+void TextInputPlugin::CharHook(GLFWwindow* window, unsigned int code_point) {
   if (active_model_ == nullptr) {
     return;
   }
diff --git a/shell/platform/glfw/text_input_plugin.h b/shell/platform/glfw/text_input_plugin.h
index 8d31a8bbbdbf8..daf2fa7d22f05 100644
--- a/shell/platform/glfw/text_input_plugin.h
+++ b/shell/platform/glfw/text_input_plugin.h
@@ -33,7 +33,7 @@ class TextInputPlugin : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(GLFWwindow* window, uint32_t code_point) override;
+  void CharHook(GLFWwindow* window, unsigned int code_point) override;
 
  private:
   // Sends the current state of the given model to the Flutter engine.
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index d929a9ffe70de..450d1ca933545 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -153,17 +153,15 @@ Win32Window::MessageHandler(HWND hwnd,
         window->OnScroll(
             0.0, -(static_cast<short>(HIWORD(wparam)) / (double)WHEEL_DELTA));
         break;
-      case WM_UNICHAR:
-      {
-        // Tell thiary-pary app, we can support Unicode.
+      case WM_UNICHAR: {
+        // Tell third-pary app, we can support Unicode.
         if (wparam == UNICODE_NOCHAR)
           return TRUE;
         // DefWindowProc will send WM_CHAR for this WM_UNICHAR.
         break;
       }
       case WM_CHAR:
-      case WM_SYSCHAR:
-      {
+      case WM_SYSCHAR: {
         if (wparam == VK_BACK)
           break;
         char32_t ch = static_cast<char32_t>(wparam);

From c65c5a78fb37226ee26999186dc359c47458f23a Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Sun, 8 Sep 2019 05:40:54 +0800
Subject: [PATCH 8/9] style changes

---
 shell/platform/windows/key_event_handler.cc   |  2 +-
 shell/platform/windows/key_event_handler.h    |  2 +-
 .../platform/windows/keyboard_hook_handler.h  |  2 +-
 shell/platform/windows/text_input_plugin.cc   |  2 +-
 shell/platform/windows/text_input_plugin.h    |  2 +-
 .../platform/windows/win32_flutter_window.cc  |  4 +--
 shell/platform/windows/win32_flutter_window.h |  4 +--
 shell/platform/windows/win32_window.cc        | 25 ++++++++++---------
 shell/platform/windows/win32_window.h         |  2 +-
 9 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/shell/platform/windows/key_event_handler.cc b/shell/platform/windows/key_event_handler.cc
index e2e94d6398748..63af2446b889b 100644
--- a/shell/platform/windows/key_event_handler.cc
+++ b/shell/platform/windows/key_event_handler.cc
@@ -32,7 +32,7 @@ KeyEventHandler::KeyEventHandler(flutter::BinaryMessenger* messenger)
 KeyEventHandler::~KeyEventHandler() = default;
 
 void KeyEventHandler::CharHook(Win32FlutterWindow* window,
-                               unsigned int code_point) {}
+                               char32_t code_point) {}
 
 void KeyEventHandler::KeyboardHook(Win32FlutterWindow* window,
                                    int key,
diff --git a/shell/platform/windows/key_event_handler.h b/shell/platform/windows/key_event_handler.h
index 4fc569ffce9f4..47ec63f6d1755 100644
--- a/shell/platform/windows/key_event_handler.h
+++ b/shell/platform/windows/key_event_handler.h
@@ -34,7 +34,7 @@ class KeyEventHandler : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(Win32FlutterWindow* window, unsigned int code_point) override;
+  void CharHook(Win32FlutterWindow* window, char32_t code_point) override;
 
  private:
   // The Flutter system channel for key event messages.
diff --git a/shell/platform/windows/keyboard_hook_handler.h b/shell/platform/windows/keyboard_hook_handler.h
index 761dbd655d222..2c3f6f21768b4 100644
--- a/shell/platform/windows/keyboard_hook_handler.h
+++ b/shell/platform/windows/keyboard_hook_handler.h
@@ -25,7 +25,7 @@ class KeyboardHookHandler {
 
   // A function for hooking into unicode code point input.
   virtual void CharHook(Win32FlutterWindow* window,
-                        unsigned int code_point) = 0;
+                        char32_t code_point) = 0;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/text_input_plugin.cc b/shell/platform/windows/text_input_plugin.cc
index d1a35e3a071ce..128f1f8d5b9a3 100644
--- a/shell/platform/windows/text_input_plugin.cc
+++ b/shell/platform/windows/text_input_plugin.cc
@@ -39,7 +39,7 @@ static constexpr uint32_t kInputModelLimit = 256;
 namespace flutter {
 
 void TextInputPlugin::CharHook(Win32FlutterWindow* window,
-                               unsigned int code_point) {
+                               char32_t code_point) {
   if (active_model_ == nullptr) {
     return;
   }
diff --git a/shell/platform/windows/text_input_plugin.h b/shell/platform/windows/text_input_plugin.h
index 1cc57642e8af0..c367dbcc427b6 100644
--- a/shell/platform/windows/text_input_plugin.h
+++ b/shell/platform/windows/text_input_plugin.h
@@ -35,7 +35,7 @@ class TextInputPlugin : public KeyboardHookHandler {
                     int mods) override;
 
   // |KeyboardHookHandler|
-  void CharHook(Win32FlutterWindow* window, unsigned int code_point) override;
+  void CharHook(Win32FlutterWindow* window, char32_t code_point) override;
 
  private:
   // Sends the current state of the given model to the Flutter engine.
diff --git a/shell/platform/windows/win32_flutter_window.cc b/shell/platform/windows/win32_flutter_window.cc
index edd40d989309c..5b2f20c153576 100644
--- a/shell/platform/windows/win32_flutter_window.cc
+++ b/shell/platform/windows/win32_flutter_window.cc
@@ -125,7 +125,7 @@ void Win32FlutterWindow::OnPointerUp(double x, double y) {
   }
 }
 
-void Win32FlutterWindow::OnChar(unsigned int code_point) {
+void Win32FlutterWindow::OnChar(char32_t code_point) {
   if (process_events_) {
     SendChar(code_point);
   }
@@ -207,7 +207,7 @@ void Win32FlutterWindow::SendPointerUp(double x, double y) {
   SendPointerEventWithData(event);
 }
 
-void Win32FlutterWindow::SendChar(unsigned int code_point) {
+void Win32FlutterWindow::SendChar(char32_t code_point) {
   for (const auto& handler : keyboard_hook_handlers_) {
     handler->CharHook(this, code_point);
   }
diff --git a/shell/platform/windows/win32_flutter_window.h b/shell/platform/windows/win32_flutter_window.h
index bd5f40c9b94ad..c2316a88e0add 100644
--- a/shell/platform/windows/win32_flutter_window.h
+++ b/shell/platform/windows/win32_flutter_window.h
@@ -54,7 +54,7 @@ class Win32FlutterWindow : public Win32Window {
   void OnPointerUp(double x, double y) override;
 
   // |Win32Window|
-  void OnChar(unsigned int code_point) override;
+  void OnChar(char32_t code_point) override;
 
   // |Win32Window|
   void OnKey(int key, int scancode, int action, int mods) override;
@@ -103,7 +103,7 @@ class Win32FlutterWindow : public Win32Window {
   void SendPointerUp(double x, double y);
 
   // Reports a keyboard character to Flutter engine.
-  void SendChar(unsigned int code_point);
+  void SendChar(char32_t code_point);
 
   // Reports a raw keyboard message to Flutter engine.
   void SendKey(int key, int scancode, int action, int mods);
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index 450d1ca933545..aa0e623ef09ed 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -164,21 +164,22 @@ Win32Window::MessageHandler(HWND hwnd,
       case WM_SYSCHAR: {
         if (wparam == VK_BACK)
           break;
-        char32_t ch = static_cast<char32_t>(wparam);
-        // What we expect to pass in is a Unicode, if it's UTF-32, it doesn't
-        // need any processing, and if it's UTF-16, it's converted to Unicode.
-        static char32_t lead_ch = 0;
-        // If ch is Lead Surrogate.
-        if ((ch & 0xFFFFFC00) == 0xD800) {
-          lead_ch = ch;
+        char32_t code_point = static_cast<char32_t>(wparam);
+        static char32_t lead_surrogate = 0;
+        // If code_point is LeadSurrogate, save and return.
+        if ((code_point & 0xFFFFFC00) == 0xD800) {
+          lead_surrogate = code_point;
           return TRUE;
         }
-        // If ch is Trail Surrogate and pre-ch is Lead Surrogate.
-        if (lead_ch != 0 && (ch & 0xFFFFFC00) == 0xDC00) {
-          ch = 0x10000 + ((lead_ch & 0x000003FF) << 10) + (ch & 0x3FF);
+        // Merge TrailSurrogate and LeadSurrogate.
+        if (lead_surrogate != 0 && (code_point & 0xFFFFFC00) == 0xDC00) {
+          code_point =
+            0x10000
+            + ((lead_surrogate & 0x000003FF) << 10)
+            + (code_point & 0x3FF);
         }
-        lead_ch = 0;
-        window->OnChar(ch);
+        lead_surrogate = 0;
+        window->OnChar(code_point);
         break;
       }
       case WM_KEYDOWN:
diff --git a/shell/platform/windows/win32_window.h b/shell/platform/windows/win32_window.h
index 99036802f01a4..45819b589ea61 100644
--- a/shell/platform/windows/win32_window.h
+++ b/shell/platform/windows/win32_window.h
@@ -89,7 +89,7 @@ class Win32Window {
   virtual void OnPointerUp(double x, double y) = 0;
 
   // Called when character input occurs.
-  virtual void OnChar(unsigned int code_point) = 0;
+  virtual void OnChar(char32_t code_point) = 0;
 
   // Called when raw keyboard input occurs.
   virtual void OnKey(int key, int scancode, int action, int mods) = 0;

From 80aabe982d967f9d0daf2f46e9a02b8b276e82b4 Mon Sep 17 00:00:00 2001
From: shoryukenn <naifu.guan@gmail.com>
Date: Sun, 8 Sep 2019 05:54:15 +0800
Subject: [PATCH 9/9] clang-format

---
 shell/platform/windows/keyboard_hook_handler.h | 3 +--
 shell/platform/windows/win32_window.cc         | 6 ++----
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/shell/platform/windows/keyboard_hook_handler.h b/shell/platform/windows/keyboard_hook_handler.h
index 2c3f6f21768b4..1b3304ddd50b0 100644
--- a/shell/platform/windows/keyboard_hook_handler.h
+++ b/shell/platform/windows/keyboard_hook_handler.h
@@ -24,8 +24,7 @@ class KeyboardHookHandler {
                             int mods) = 0;
 
   // A function for hooking into unicode code point input.
-  virtual void CharHook(Win32FlutterWindow* window,
-                        char32_t code_point) = 0;
+  virtual void CharHook(Win32FlutterWindow* window, char32_t code_point) = 0;
 };
 
 }  // namespace flutter
diff --git a/shell/platform/windows/win32_window.cc b/shell/platform/windows/win32_window.cc
index aa0e623ef09ed..ad6265109d805 100644
--- a/shell/platform/windows/win32_window.cc
+++ b/shell/platform/windows/win32_window.cc
@@ -173,10 +173,8 @@ Win32Window::MessageHandler(HWND hwnd,
         }
         // Merge TrailSurrogate and LeadSurrogate.
         if (lead_surrogate != 0 && (code_point & 0xFFFFFC00) == 0xDC00) {
-          code_point =
-            0x10000
-            + ((lead_surrogate & 0x000003FF) << 10)
-            + (code_point & 0x3FF);
+          code_point = 0x10000 + ((lead_surrogate & 0x000003FF) << 10) +
+                       (code_point & 0x3FF);
         }
         lead_surrogate = 0;
         window->OnChar(code_point);