Remove String stage 1.

28 files changed, 178 insertions, 187 deletions

diff --git a/src/ui/Helper.h b/src/ui/Helper.h
index 8bee72a6..625ba6e3 100644
--- a/src/ui/Helper.h
+++ b/src/ui/Helper.h
@@ -1,14 +1,5 @@
 #pragma once
-#include "cru/ui/Base.h"
-
-namespace cru::platform {
-namespace graphics {
-struct IGraphicsFactory;
-}
-namespace native {
-struct IUiApplication;
-}  // namespace native
-}  // namespace cru::platform
+#include <cru/platform/gui/UiApplication.h>
 
 namespace cru::ui {
 cru::platform::graphics::IGraphicsFactory* GetGraphicsFactory();
diff --git a/src/ui/ThemeManager.cpp b/src/ui/ThemeManager.cpp
index a95900b4..0f4daeb7 100644
--- a/src/ui/ThemeManager.cpp
+++ b/src/ui/ThemeManager.cpp
@@ -1,14 +1,9 @@
 #include "cru/ui/ThemeManager.h"
 
-#include "Helper.h"
-#include "cru/base/StringUtil.h"
 #include "cru/base/io/Resource.h"
 #include "cru/platform/graphics/Brush.h"
-#include "cru/platform/graphics/Factory.h"
-#include "cru/platform/gui/UiApplication.h"
 #include "cru/ui/ThemeResourceDictionary.h"
 #include "cru/ui/style/StyleRuleSet.h"
-#include "cru/xml/XmlParser.h"
 
 namespace cru::ui {
 ThemeManager* ThemeManager::GetInstance() {
@@ -48,22 +43,22 @@ void ThemeManager::PrependThemeResourceDictionary(
   theme_resource_change_event_.Raise(nullptr);
 }
 
-String ThemeManager::GetResourceString(const String& key) {
-  return GetResource<String>(key);
+std::string ThemeManager::GetResourceString(std::string_view key) {
+  return GetResource<String>(key).ToUtf8();
 }
 
 std::shared_ptr<platform::graphics::IBrush> ThemeManager::GetResourceBrush(
-    const String& key) {
+    std::string_view key) {
   return GetResource<std::shared_ptr<platform::graphics::IBrush>>(key);
 }
 
 std::shared_ptr<platform::graphics::IFont> ThemeManager::GetResourceFont(
-    const String& key) {
+    std::string_view key) {
   return GetResource<std::shared_ptr<platform::graphics::IFont>>(key);
 }
 
 std::shared_ptr<style::StyleRuleSet> ThemeManager::GetResourceStyleRuleSet(
-    const String& key) {
+    std::string_view key) {
   return GetResource<std::shared_ptr<style::StyleRuleSet>>(key);
 }
 }  // namespace cru::ui
diff --git a/src/ui/ThemeResourceDictionary.cpp b/src/ui/ThemeResourceDictionary.cpp
index d6f2d3e3..f76bdde8 100644
--- a/src/ui/ThemeResourceDictionary.cpp
+++ b/src/ui/ThemeResourceDictionary.cpp
@@ -43,7 +43,7 @@ void ThemeResourceDictionary::UpdateResourceMap(xml::XmlElementNode* xml_root) {
 
         ResourceEntry entry;
 
-        entry.name = String::FromUtf8(*key_attr);
+        entry.name = *key_attr;
         entry.xml_node = c->GetFirstChildElement();
 
         resource_map_[entry.name] = std::move(entry);
diff --git a/src/ui/components/Input.cpp b/src/ui/components/Input.cpp
index 6a53b938..e75eccc5 100644
--- a/src/ui/components/Input.cpp
+++ b/src/ui/components/Input.cpp
@@ -1,13 +1,13 @@
 #include "cru/ui/components/Input.h"
-#include "cru/base/Format.h"
 #include "cru/base/StringToNumberConverter.h"
 #include "cru/ui/controls/Control.h"
 
 #include <cmath>
 #include <optional>
+#include <string>
 
 namespace cru::ui::components {
-Input::Input() : last_validate_result_{true, u"Good value"} {
+Input::Input() : last_validate_result_{true, "Good value"} {
   text_box_.TextChangeEvent()->AddSpyOnlyHandler([this] {
     auto text = text_box_.GetText();
     auto validate_result = Validate();
@@ -20,9 +20,9 @@ Input::~Input() {}
 
 controls::Control* Input::GetRootControl() { return &text_box_; }
 
-String Input::GetText() const { return text_box_.GetText(); }
+std::string Input::GetText() const { return text_box_.GetText(); }
 
-void Input::SetText(String text) { text_box_.SetText(std::move(text)); }
+void Input::SetText(std::string text) { text_box_.SetText(std::move(text)); }
 
 IInputValidator* Input::GetValidator() const { return validator_; }
 
@@ -35,7 +35,7 @@ InputValidateResult Input::Validate() {
   if (validator_)
     last_validate_result_ = validator_->Validate(text_box_.GetTextView());
   else
-    last_validate_result_ = {true, u"Good value"};
+    last_validate_result_ = {true, "Good value"};
   return last_validate_result_;
 }
 
@@ -43,23 +43,23 @@ InputValidateResult Input::GetLastValidateResult() const {
   return last_validate_result_;
 }
 
-InputValidateResult FloatInputValidator::Validate(StringView text) const {
-  auto result =
-      text.ParseToFloat(nullptr, StringToNumberFlags::kAllowLeadingSpaces &
-                                     StringToNumberFlags::kAllowTrailingSpaces);
+InputValidateResult FloatInputValidator::Validate(std::string_view text) const {
+  auto result = String::FromUtf8(text).ParseToFloat(
+      nullptr, StringToNumberFlags::kAllowLeadingSpaces &
+                   StringToNumberFlags::kAllowTrailingSpaces);
   if (std::isnan(result)) {
-    return InputValidateResult{false, u"Invalid number."};
+    return InputValidateResult{false, "Invalid number."};
   }
 
   if (min && result < *min) {
-    return InputValidateResult{false, u"Value is less than minimum."};
+    return InputValidateResult{false, "Value is less than minimum."};
   }
 
   if (max && result > *max) {
-    return InputValidateResult{false, u"Value is greater than maximum."};
+    return InputValidateResult{false, "Value is greater than maximum."};
   }
 
-  return InputValidateResult{true, u"Good number"};
+  return InputValidateResult{true, "Good number"};
 }
 
 FloatInput::FloatInput() {
@@ -67,7 +67,7 @@ FloatInput::FloatInput() {
 
   ChangeEvent()->AddHandler([this](const InputChangeEventArgs& args) {
     if (args.valid) {
-      value_ = args.text.ParseToFloat(
+      value_ = String::FromUtf8(args.text).ParseToFloat(
           nullptr, StringToNumberFlags::kAllowLeadingSpaces &
                        StringToNumberFlags::kAllowTrailingSpaces);
     }
@@ -78,7 +78,7 @@ FloatInput::~FloatInput() {}
 
 float FloatInput::GetValue() const { return value_; }
 
-void FloatInput::SetValue(float value) { SetText(ToString(value)); }
+void FloatInput::SetValue(float value) { SetText(std::to_string(value)); }
 
 std::optional<float> FloatInput::GetMin() const { return validator_.min; }
 
diff --git a/src/ui/components/Menu.cpp b/src/ui/components/Menu.cpp
index 2da38990..59bcf8ec 100644
--- a/src/ui/components/Menu.cpp
+++ b/src/ui/components/Menu.cpp
@@ -14,17 +14,17 @@ namespace cru::ui::components {
 MenuItem::MenuItem() {
   container_.SetChild(&text_);
   container_.GetStyleRuleSet()->SetParent(
-      ThemeManager::GetInstance()->GetResourceStyleRuleSet(u"menuitem.style"));
+      ThemeManager::GetInstance()->GetResourceStyleRuleSet("menuitem.style"));
   container_.ClickEvent()->AddHandler([this](const helper::ClickEventArgs&) {
     if (this->on_click_) this->on_click_();
   });
 }
 
-MenuItem::MenuItem(String text) : MenuItem() { SetText(std::move(text)); }
+MenuItem::MenuItem(std::string text) : MenuItem() { SetText(std::move(text)); }
 
 MenuItem::~MenuItem() {}
 
-void MenuItem::SetText(String text) { text_.SetText(std::move(text)); }
+void MenuItem::SetText(std::string text) { text_.SetText(std::move(text)); }
 
 Menu::Menu() {
   container_.SetFlexDirection(controls::FlexDirection::Vertical);
@@ -65,7 +65,7 @@ void Menu::ClearItems() {
   container_.ClearChildren();
 }
 
-void Menu::AddTextItemAt(String text, Index index,
+void Menu::AddTextItemAt(std::string text, Index index,
                          std::function<void()> on_click) {
   MenuItem* item = new MenuItem(std::move(text));
   item->SetOnClick([this, index, on_click = std::move(on_click)] {
diff --git a/src/ui/components/PopupButton.cpp b/src/ui/components/PopupButton.cpp
index 41e0ad6c..5ea41d78 100644
--- a/src/ui/components/PopupButton.cpp
+++ b/src/ui/components/PopupButton.cpp
@@ -14,7 +14,7 @@ PopupMenuTextButton::PopupMenuTextButton() : popup_menu_(&button_) {
 
 PopupMenuTextButton::~PopupMenuTextButton() {}
 
-void PopupMenuTextButton::SetMenuItems(std::vector<String> items) {
+void PopupMenuTextButton::SetMenuItems(std::vector<std::string> items) {
   popup_menu_.GetMenu()->ClearItems();
   for (Index i = 0; i < items.size(); i++) {
     popup_menu_.GetMenu()->AddTextItem(
@@ -31,7 +31,7 @@ PopupMenuIconButton::PopupMenuIconButton() : popup_menu_(&button_) {
 
 PopupMenuIconButton::~PopupMenuIconButton() {}
 
-void PopupMenuIconButton::SetMenuItems(std::vector<String> items) {
+void PopupMenuIconButton::SetMenuItems(std::vector<std::string> items) {
   popup_menu_.GetMenu()->ClearItems();
   for (Index i = 0; i < items.size(); i++) {
     popup_menu_.GetMenu()->AddTextItem(
diff --git a/src/ui/components/Select.cpp b/src/ui/components/Select.cpp
index 90b49d30..5dbb727c 100644
--- a/src/ui/components/Select.cpp
+++ b/src/ui/components/Select.cpp
@@ -15,7 +15,7 @@ Select::Select() {
 
 Select::~Select() {}
 
-void Select::SetItems(std::vector<String> items) {
+void Select::SetItems(std::vector<std::string> items) {
   items_ = items;
   popup_menu_.GetMenu()->ClearItems();
   for (Index i = 0; i < items.size(); i++) {
diff --git a/src/ui/controls/Button.cpp b/src/ui/controls/Button.cpp
index d7d157c5..a44a7074 100644
--- a/src/ui/controls/Button.cpp
+++ b/src/ui/controls/Button.cpp
@@ -1,9 +1,5 @@
 #include "cru/ui/controls/Button.h"
 
-#include "../Helper.h"
-#include "cru/platform/graphics/Brush.h"
-#include "cru/platform/gui/Cursor.h"
-#include "cru/platform/gui/UiApplication.h"
 #include "cru/ui/ThemeManager.h"
 #include "cru/ui/helper/ClickDetector.h"
 #include "cru/ui/render/BorderRenderObject.h"
@@ -12,7 +8,7 @@ namespace cru::ui::controls {
 Button::Button() : click_detector_(this) {
   GetContainerRenderObject()->SetBorderEnabled(true);
   auto default_button_style =
-      ThemeManager::GetInstance()->GetResourceStyleRuleSet(u"button.style");
+      ThemeManager::GetInstance()->GetResourceStyleRuleSet("button.style");
   GetStyleRuleSet()->SetParent(std::move(default_button_style));
 }
 
diff --git a/src/ui/controls/CheckBox.cpp b/src/ui/controls/CheckBox.cpp
index a28c4633..778a7b4f 100644
--- a/src/ui/controls/CheckBox.cpp
+++ b/src/ui/controls/CheckBox.cpp
@@ -11,7 +11,7 @@ CheckBox::CheckBox()
 
   container_render_object_->SetBorderEnabled(true);
   auto default_checkbox_style =
-      ThemeManager::GetInstance()->GetResourceStyleRuleSet(u"checkbox.style");
+      ThemeManager::GetInstance()->GetResourceStyleRuleSet("checkbox.style");
   GetStyleRuleSet()->SetParent(std::move(default_checkbox_style));
 
   click_detector_.ClickEvent()->AddHandler(
diff --git a/src/ui/controls/IconButton.cpp b/src/ui/controls/IconButton.cpp
index 01ecabdd..059a7784 100644
--- a/src/ui/controls/IconButton.cpp
+++ b/src/ui/controls/IconButton.cpp
@@ -17,10 +17,10 @@ IconButton::IconButton()
   container_render_object_->SetBorderEnabled(true);
   GetStyleRuleSet()->SetParent(
       ThemeManager::GetInstance()->GetResourceStyleRuleSet(
-          u"icon-button.style"));
+          "icon-button.style"));
 }
 
-IconButton::IconButton(StringView icon_svg_path_data_string,
+IconButton::IconButton(std::string_view icon_svg_path_data_string,
                        const Rect& view_port)
     : IconButton() {
   SetIconWithSvgPathDataString(icon_svg_path_data_string, view_port);
@@ -33,18 +33,18 @@ void IconButton::SetIconFillColor(const Color& color) {
 }
 
 void IconButton::SetIconWithSvgPathDataString(
-    StringView icon_svg_path_data_string, const Rect& view_port) {
+    std::string_view icon_svg_path_data_string, const Rect& view_port) {
   SetIconGeometry(platform::graphics::CreateGeometryFromSvgPathData(
                       GetGraphicsFactory(), icon_svg_path_data_string),
                   view_port);
 }
 
 void IconButton::SetIconWithSvgPathDataStringResourceKey(
-    StringView icon_svg_path_data_string_resource_key, const Rect& view_port) {
-  SetIconWithSvgPathDataString(
-      ThemeManager::GetInstance()->GetResourceString(
-          icon_svg_path_data_string_resource_key.ToString()),
-      view_port);
+    std::string_view icon_svg_path_data_string_resource_key,
+    const Rect& view_port) {
+  SetIconWithSvgPathDataString(ThemeManager::GetInstance()->GetResourceString(
+                                   icon_svg_path_data_string_resource_key),
+                               view_port);
 }
 
 }  // namespace cru::ui::controls
diff --git a/src/ui/controls/TextBlock.cpp b/src/ui/controls/TextBlock.cpp
index 0dad4f5d..790c534b 100644
--- a/src/ui/controls/TextBlock.cpp
+++ b/src/ui/controls/TextBlock.cpp
@@ -15,10 +15,10 @@ TextBlock::TextBlock() {
   const auto theme_manager = ThemeManager::GetInstance();
 
   text_render_object_ = std::make_unique<TextRenderObject>(
-      theme_manager->GetResourceBrush(u"text.brush"),
-      theme_manager->GetResourceFont(u"text.font"),
-      theme_manager->GetResourceBrush(u"text.selection.brush"),
-      theme_manager->GetResourceBrush(u"text.caret.brush"));
+      theme_manager->GetResourceBrush("text.brush"),
+      theme_manager->GetResourceFont("text.font"),
+      theme_manager->GetResourceBrush("text.selection.brush"),
+      theme_manager->GetResourceBrush("text.caret.brush"));
 
   text_render_object_->SetAttachedControl(this);
 
@@ -34,9 +34,11 @@ render::RenderObject* TextBlock::GetRenderObject() const {
   return text_render_object_.get();
 }
 
-String TextBlock::GetText() const { return service_->GetText(); }
+std::string TextBlock::GetText() const { return service_->GetText(); }
 
-void TextBlock::SetText(String text) { service_->SetText(std::move(text)); }
+void TextBlock::SetText(std::string text) {
+  service_->SetText(std::move(text));
+}
 
 bool TextBlock::IsSelectable() const { return service_->IsEnabled(); }
 
diff --git a/src/ui/controls/TextBox.cpp b/src/ui/controls/TextBox.cpp
index 87672b4f..70695a01 100644
--- a/src/ui/controls/TextBox.cpp
+++ b/src/ui/controls/TextBox.cpp
@@ -18,10 +18,10 @@ TextBox::TextBox()
   auto theme_manager = ThemeManager::GetInstance();
 
   text_render_object_ = std::make_unique<TextRenderObject>(
-      theme_manager->GetResourceBrush(u"text.brush"),
-      theme_manager->GetResourceFont(u"text.font"),
-      theme_manager->GetResourceBrush(u"text.selection.brush"),
-      theme_manager->GetResourceBrush(u"text.caret.brush"));
+      theme_manager->GetResourceBrush("text.brush"),
+      theme_manager->GetResourceFont("text.font"),
+      theme_manager->GetResourceBrush("text.selection.brush"),
+      theme_manager->GetResourceBrush("text.caret.brush"));
   text_render_object_->SetEditMode(true);
 
   border_render_object_->SetChild(scroll_render_object_.get());
@@ -40,7 +40,7 @@ TextBox::TextBox()
   border_render_object_->SetBorderEnabled(true);
 
   GetStyleRuleSet()->SetParent(
-      theme_manager->GetResourceStyleRuleSet(u"textbox.style"));
+      theme_manager->GetResourceStyleRuleSet("textbox.style"));
 }
 
 TextBox::~TextBox() {}
diff --git a/src/ui/controls/TextHostControlService.cpp b/src/ui/controls/TextHostControlService.cpp
index 690aa95d..bb723e3f 100644
--- a/src/ui/controls/TextHostControlService.cpp
+++ b/src/ui/controls/TextHostControlService.cpp
@@ -1,8 +1,8 @@
 #include "cru/ui/controls/TextHostControlService.h"
 
+#include <cru/platform/gui/Input.h>
 #include "../Helper.h"
 #include "cru/base/Base.h"
-#include "cru/base/String.h"
 #include "cru/base/StringUtil.h"
 #include "cru/base/log/Logger.h"
 #include "cru/platform/graphics/Font.h"
@@ -10,7 +10,6 @@
 #include "cru/platform/gui/Clipboard.h"
 #include "cru/platform/gui/Cursor.h"
 #include "cru/platform/gui/InputMethod.h"
-#include "cru/platform/gui/Keyboard.h"
 #include "cru/platform/gui/UiApplication.h"
 #include "cru/platform/gui/Window.h"
 #include "cru/ui/Base.h"
@@ -27,42 +26,42 @@
 
 namespace cru::ui::controls {
 TextControlMovePattern TextControlMovePattern::kLeft(
-    u"Left", helper::ShortcutKeyBind(platform::gui::KeyCode::Left),
-    [](TextHostControlService* service, StringView text,
+    "Left", helper::ShortcutKeyBind(platform::gui::KeyCode::Left),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      Utf16PreviousCodePoint(text, current_position, &current_position);
+      Utf8PreviousCodePoint(text, current_position, &current_position);
       return current_position;
     });
 TextControlMovePattern TextControlMovePattern::kRight(
-    u"Right", helper::ShortcutKeyBind(platform::gui::KeyCode::Right),
-    [](TextHostControlService* service, StringView text,
+    "Right", helper::ShortcutKeyBind(platform::gui::KeyCode::Right),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      Utf16NextCodePoint(text, current_position, &current_position);
+      Utf8NextCodePoint(text, current_position, &current_position);
       return current_position;
     });
 TextControlMovePattern TextControlMovePattern::kCtrlLeft(
-    u"Ctrl+Left(Previous Word)",
+    "Ctrl+Left(Previous Word)",
     helper::ShortcutKeyBind(platform::gui::KeyCode::Left,
-                            platform::gui::KeyModifiers::ctrl),
-    [](TextHostControlService* service, StringView text,
+                            platform::gui::KeyModifiers::Ctrl),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      return Utf16PreviousWord(text, current_position);
+      return Utf8PreviousWord(text, current_position);
     });
 TextControlMovePattern TextControlMovePattern::kCtrlRight(
-    u"Ctrl+Right(Next Word)",
+    "Ctrl+Right(Next Word)",
     helper::ShortcutKeyBind(platform::gui::KeyCode::Right,
-                            platform::gui::KeyModifiers::ctrl),
-    [](TextHostControlService* service, StringView text,
+                            platform::gui::KeyModifiers::Ctrl),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      return Utf16NextWord(text, current_position);
+      return Utf8NextWord(text, current_position);
     });
 TextControlMovePattern TextControlMovePattern::kUp(
-    u"Up", helper::ShortcutKeyBind(platform::gui::KeyCode::Up),
-    [](TextHostControlService* service, StringView text,
+    "Up", helper::ShortcutKeyBind(platform::gui::KeyCode::Up),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(text)
       auto text_render_object = service->GetTextRenderObject();
@@ -72,8 +71,8 @@ TextControlMovePattern TextControlMovePattern::kUp(
       return result.trailing ? result.position + 1 : result.position;
     });
 TextControlMovePattern TextControlMovePattern::kDown(
-    u"Down", helper::ShortcutKeyBind(platform::gui::KeyCode::Down),
-    [](TextHostControlService* service, StringView text,
+    "Down", helper::ShortcutKeyBind(platform::gui::KeyCode::Down),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(text)
       auto text_render_object = service->GetTextRenderObject();
@@ -83,26 +82,26 @@ TextControlMovePattern TextControlMovePattern::kDown(
       return result.trailing ? result.position + 1 : result.position;
     });
 TextControlMovePattern TextControlMovePattern::kHome(
-    u"Home(Line Begin)", helper::ShortcutKeyBind(platform::gui::KeyCode::Home),
-    [](TextHostControlService* service, StringView text,
+    "Home(Line Begin)", helper::ShortcutKeyBind(platform::gui::KeyCode::Home),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      return Utf16BackwardUntil(text, current_position,
-                                [](CodePoint c) { return c == u'\n'; });
+      return Utf8BackwardUntil(text, current_position,
+                               [](CodePoint c) { return c == u'\n'; });
     });
 TextControlMovePattern TextControlMovePattern::kEnd(
-    u"End(Line End)", helper::ShortcutKeyBind(platform::gui::KeyCode::End),
-    [](TextHostControlService* service, StringView text,
+    "End(Line End)", helper::ShortcutKeyBind(platform::gui::KeyCode::End),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
-      return Utf16ForwardUntil(text, current_position,
-                               [](CodePoint c) { return c == u'\n'; });
+      return Utf8ForwardUntil(text, current_position,
+                              [](CodePoint c) { return c == u'\n'; });
     });
 TextControlMovePattern TextControlMovePattern::kCtrlHome(
-    u"Ctrl+Home(Document Begin)",
+    "Ctrl+Home(Document Begin)",
     helper::ShortcutKeyBind(platform::gui::KeyCode::Home,
-                            platform::gui::KeyModifiers::ctrl),
-    [](TextHostControlService* service, StringView text,
+                            platform::gui::KeyModifiers::Ctrl),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
       CRU_UNUSED(text)
@@ -110,10 +109,10 @@ TextControlMovePattern TextControlMovePattern::kCtrlHome(
       return 0;
     });
 TextControlMovePattern TextControlMovePattern::kCtrlEnd(
-    u"Ctrl+End(Document End)",
+    "Ctrl+End(Document End)",
     helper::ShortcutKeyBind(platform::gui::KeyCode::End,
-                            platform::gui::KeyModifiers::ctrl),
-    [](TextHostControlService* service, StringView text,
+                            platform::gui::KeyModifiers::Ctrl),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
       CRU_UNUSED(text)
@@ -121,8 +120,8 @@ TextControlMovePattern TextControlMovePattern::kCtrlEnd(
       return text.size();
     });
 TextControlMovePattern TextControlMovePattern::kPageUp(
-    u"PageUp", helper::ShortcutKeyBind(platform::gui::KeyCode::PageUp),
-    [](TextHostControlService* service, StringView text,
+    "PageUp", helper::ShortcutKeyBind(platform::gui::KeyCode::PageUp),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
       CRU_UNUSED(text)
@@ -130,8 +129,8 @@ TextControlMovePattern TextControlMovePattern::kPageUp(
       return current_position;
     });
 TextControlMovePattern TextControlMovePattern::kPageDown(
-    u"PageDown", helper::ShortcutKeyBind(platform::gui::KeyCode::PageDown),
-    [](TextHostControlService* service, StringView text,
+    "PageDown", helper::ShortcutKeyBind(platform::gui::KeyCode::PageDown),
+    [](TextHostControlService* service, std::string_view text,
        Index current_position) {
       CRU_UNUSED(service)
       CRU_UNUSED(text)
@@ -214,7 +213,7 @@ void TextHostControlService::SetMultiLine(bool multi_line) {
   }
 }
 
-void TextHostControlService::SetText(String text, bool stop_composition) {
+void TextHostControlService::SetText(std::string text, bool stop_composition) {
   this->text_ = std::move(text);
   CoerceSelection();
   if (stop_composition) {
@@ -224,13 +223,14 @@ void TextHostControlService::SetText(String text, bool stop_composition) {
   text_change_event_.Raise(nullptr);
 }
 
-void TextHostControlService::InsertText(Index position, StringView text,
+void TextHostControlService::InsertText(Index position, std::string_view text,
                                         bool stop_composition) {
-  if (!Utf16IsValidInsertPosition(this->text_, position)) {
+  if (!Utf8IsValidInsertPosition(this->text_, position)) {
     CRU_LOG_TAG_ERROR("Invalid text insert position.");
     return;
   }
-  this->text_.insert(this->text_.cbegin() + position, text);
+  this->text_.insert(this->text_.cbegin() + position, text.cbegin(),
+                     text.cend());
   if (stop_composition) {
     CancelComposition();
   }
@@ -239,26 +239,26 @@ void TextHostControlService::InsertText(Index position, StringView text,
 }
 
 void TextHostControlService::DeleteChar(Index position, bool stop_composition) {
-  if (!Utf16IsValidInsertPosition(this->text_, position)) {
+  if (!Utf8IsValidInsertPosition(this->text_, position)) {
     CRU_LOG_TAG_ERROR("Invalid text delete position.");
     return;
   }
   if (position == static_cast<Index>(this->text_.size())) return;
   Index next;
-  Utf16NextCodePoint(this->text_, position, &next);
+  Utf8NextCodePoint(this->text_, position, &next);
   this->DeleteText(TextRange::FromTwoSides(position, next), stop_composition);
 }
 
 // Return the position of deleted character.
 Index TextHostControlService::DeleteCharPrevious(Index position,
                                                  bool stop_composition) {
-  if (!Utf16IsValidInsertPosition(this->text_, position)) {
+  if (!Utf8IsValidInsertPosition(this->text_, position)) {
     CRU_LOG_TAG_ERROR("Invalid text delete position.");
     return 0;
   }
   if (position == 0) return 0;
   Index previous;
-  Utf16PreviousCodePoint(this->text_, position, &previous);
+  Utf8PreviousCodePoint(this->text_, position, &previous);
   this->DeleteText(TextRange::FromTwoSides(previous, position),
                    stop_composition);
   return previous;
@@ -268,11 +268,11 @@ void TextHostControlService::DeleteText(TextRange range,
                                         bool stop_composition) {
   if (range.count == 0) return;
   range = range.Normalize();
-  if (!Utf16IsValidInsertPosition(this->text_, range.GetStart())) {
+  if (!Utf8IsValidInsertPosition(this->text_, range.GetStart())) {
     CRU_LOG_TAG_ERROR("Invalid text delete start position.");
     return;
   }
-  if (!Utf16IsValidInsertPosition(this->text_, range.GetStart())) {
+  if (!Utf8IsValidInsertPosition(this->text_, range.GetStart())) {
     CRU_LOG_TAG_ERROR("Invalid text delete end position.");
     return;
   }
@@ -352,7 +352,7 @@ render::ScrollRenderObject* TextHostControlService::GetScrollRenderObject() {
   return this->text_host_control_->GetScrollRenderObject();
 }
 
-StringView TextHostControlService::GetSelectedText() {
+std::string_view TextHostControlService::GetSelectedText() {
   auto selection = this->GetSelection().Normalize();
   return GetTextView().substr(selection.position, selection.count);
 }
@@ -372,7 +372,7 @@ void TextHostControlService::SetSelection(TextRange selection,
 }
 
 void TextHostControlService::SelectAll() {
-  this->SetSelection(TextRange{0, this->text_.size()});
+  this->SetSelection(TextRange{0, static_cast<Index>(this->text_.size())});
 }
 
 void TextHostControlService::ChangeSelectionEnd(Index new_end) {
@@ -389,7 +389,7 @@ void TextHostControlService::AbortSelection() {
   SetSelection(GetCaretPosition());
 }
 
-void TextHostControlService::ReplaceSelectedText(StringView text) {
+void TextHostControlService::ReplaceSelectedText(std::string_view text) {
   DeleteSelectedText();
   InsertText(GetSelection().GetStart(), text);
   SetSelection(GetSelection().GetStart() + text.size());
@@ -402,14 +402,14 @@ void TextHostControlService::DeleteSelectedText() {
 
 void TextHostControlService::Cut() {
   Copy();
-  ReplaceSelectedText(StringView{});
+  ReplaceSelectedText(std::string_view{});
 }
 
 void TextHostControlService::Copy() {
   auto selected_text = GetSelectedText();
   if (selected_text.size() == 0) return;
   auto clipboard = GetUiApplication()->GetClipboard();
-  clipboard->SetText(selected_text.ToString());
+  clipboard->SetText(std::string(selected_text));
 }
 
 void TextHostControlService::Paste() {
@@ -442,7 +442,8 @@ void TextHostControlService::SyncTextRenderObject() {
   if (composition_info) {
     const auto caret_position = GetCaretPosition();
     auto text = this->text_;
-    text.insert(text.cbegin() + caret_position, composition_info->text);
+    text.insert(text.cbegin() + caret_position, composition_info->text.cbegin(),
+                composition_info->text.cend());
     text_render_object->SetText(text);
     text_render_object->SetCaretPosition(caret_position +
                                          composition_info->selection.GetEnd());
@@ -477,7 +478,7 @@ void TextHostControlService::MouseDownHandler(
     events::MouseButtonEventArgs& args) {
   if (IsEnabled()) {
     this->control_->SetFocus();
-    if (args.GetButton() == mouse_buttons::left &&
+    if (args.GetButton() == MouseButtons::Left &&
         !this->mouse_move_selecting_) {
       if (!this->control_->CaptureMouse()) return;
       this->mouse_move_selecting_ = true;
@@ -487,7 +488,7 @@ void TextHostControlService::MouseDownHandler(
       const auto position = result.position + (result.trailing ? 1 : 0);
       SetSelection(position);
       args.SetHandled(true);
-    } else if (args.GetButton() == mouse_buttons::right) {
+    } else if (args.GetButton() == MouseButtons::Right) {
       // TODO: Finish context menu logic here.
 
       const Point p = args.GetPointToContent(GetTextRenderObject());
@@ -536,7 +537,7 @@ void TextHostControlService::MouseDownHandler(
 
 void TextHostControlService::MouseUpHandler(
     events::MouseButtonEventArgs& args) {
-  if (args.GetButton() == mouse_buttons::left && mouse_move_selecting_) {
+  if (args.GetButton() == MouseButtons::Left && mouse_move_selecting_) {
     this->control_->ReleaseMouse();
     this->mouse_move_selecting_ = false;
     args.SetHandled();
@@ -573,12 +574,13 @@ void TextHostControlService::GainFocusHandler(
     input_method_context_event_guard_ +=
         input_method_context->CompositionEndEvent()->AddHandler(sync);
     input_method_context_event_guard_ +=
-        input_method_context->TextEvent()->AddHandler([this](StringView text) {
-          if (!multi_line_ && text == u"\n") {
-            return;
-          }
-          this->ReplaceSelectedText(text);
-        });
+        input_method_context->TextEvent()->AddHandler(
+            [this](std::string_view text) {
+              if (!multi_line_ && text == "\n") {
+                return;
+              }
+              this->ReplaceSelectedText(text);
+            });
 
     host::WindowHost* window_host = control_->GetWindowHost();
     if (window_host)
@@ -606,7 +608,7 @@ void TextHostControlService::SetUpShortcuts() {
   using platform::gui::KeyModifiers;
   using platform::gui::kKeyModifierCommand;
 
-  shortcut_hub_.RegisterShortcut(u"Select All",
+  shortcut_hub_.RegisterShortcut("Select All",
                                  {KeyCode::A, kKeyModifierCommand}, [this] {
                                    if (IsEnabled()) {
                                      this->SelectAll();
@@ -615,7 +617,7 @@ void TextHostControlService::SetUpShortcuts() {
                                    return false;
                                  });
 
-  shortcut_hub_.RegisterShortcut(u"Cut", {KeyCode::X, kKeyModifierCommand},
+  shortcut_hub_.RegisterShortcut("Cut", {KeyCode::X, kKeyModifierCommand},
                                  [this] {
                                    if (IsEnabled() && IsEditable()) {
                                      this->Cut();
@@ -624,7 +626,7 @@ void TextHostControlService::SetUpShortcuts() {
                                    return false;
                                  });
 
-  shortcut_hub_.RegisterShortcut(u"Copy", {KeyCode::C, kKeyModifierCommand},
+  shortcut_hub_.RegisterShortcut("Copy", {KeyCode::C, kKeyModifierCommand},
                                  [this] {
                                    if (IsEnabled()) {
                                      this->Copy();
@@ -633,7 +635,7 @@ void TextHostControlService::SetUpShortcuts() {
                                    return false;
                                  });
 
-  shortcut_hub_.RegisterShortcut(u"Paste", {KeyCode::V, kKeyModifierCommand},
+  shortcut_hub_.RegisterShortcut("Paste", {KeyCode::V, kKeyModifierCommand},
                                  [this] {
                                    if (IsEnabled() && IsEditable()) {
                                      this->Paste();
@@ -642,7 +644,7 @@ void TextHostControlService::SetUpShortcuts() {
                                    return false;
                                  });
 
-  shortcut_hub_.RegisterShortcut(u"Backspace", KeyCode::Backspace, [this] {
+  shortcut_hub_.RegisterShortcut("Backspace", KeyCode::Backspace, [this] {
     if (!IsEnabled()) return false;
     if (!IsEditable()) return false;
     const auto selection = GetSelection();
@@ -654,7 +656,7 @@ void TextHostControlService::SetUpShortcuts() {
     return true;
   });
 
-  shortcut_hub_.RegisterShortcut(u"Delete", KeyCode::Delete, [this] {
+  shortcut_hub_.RegisterShortcut("Delete", KeyCode::Delete, [this] {
     if (!IsEnabled()) return false;
     if (!IsEditable()) return false;
     const auto selection = GetSelection();
@@ -669,7 +671,7 @@ void TextHostControlService::SetUpShortcuts() {
   for (const auto& pattern : TextControlMovePattern::kDefaultPatterns) {
     auto name = pattern.GetName();
     shortcut_hub_.RegisterShortcut(
-        u"Move " + name, pattern.GetKeyBind(), [this, &pattern] {
+        "Move " + name, pattern.GetKeyBind(), [this, &pattern] {
           auto text = this->GetTextView();
           auto caret = this->GetCaretPosition();
           auto new_position = pattern.Move(this, text, caret);
@@ -678,8 +680,8 @@ void TextHostControlService::SetUpShortcuts() {
         });
 
     shortcut_hub_.RegisterShortcut(
-        u"Move And Select " + name,
-        pattern.GetKeyBind().AddModifier(platform::gui::KeyModifiers::shift),
+        "Move And Select " + name,
+        pattern.GetKeyBind().AddModifier(platform::gui::KeyModifiers::Shift),
         [this, &pattern] {
           auto text = this->GetTextView();
           auto caret = this->GetCaretPosition();
@@ -695,16 +697,16 @@ void TextHostControlService::OpenContextMenu(const Point& position,
   context_menu_ = MakeDeleteLaterPtr<components::PopupMenu>();
   auto menu = context_menu_->GetMenu();
   if (items & ContextMenuItem::kSelectAll) {
-    menu->AddTextItem(u"Select All", [this] { this->SelectAll(); });
+    menu->AddTextItem("Select All", [this] { this->SelectAll(); });
   }
   if (items & ContextMenuItem::kCopy) {
-    menu->AddTextItem(u"Copy", [this] { this->Copy(); });
+    menu->AddTextItem("Copy", [this] { this->Copy(); });
   }
   if (items & ContextMenuItem::kCut) {
-    menu->AddTextItem(u"Cut", [this] { this->Cut(); });
+    menu->AddTextItem("Cut", [this] { this->Cut(); });
   }
   if (items & ContextMenuItem::kPaste) {
-    menu->AddTextItem(u"Paste", [this] { this->Paste(); });
+    menu->AddTextItem("Paste", [this] { this->Paste(); });
   }
   context_menu_->SetPosition(position);
   context_menu_->Show();
diff --git a/src/ui/helper/ShortcutHub.cpp b/src/ui/helper/ShortcutHub.cpp
index 80e70fe1..fd23802e 100644
--- a/src/ui/helper/ShortcutHub.cpp
+++ b/src/ui/helper/ShortcutHub.cpp
@@ -89,18 +89,17 @@ void ShortcutHub::OnKeyDown(events::KeyEventArgs& event) {
 
   if constexpr (debug_flags::shortcut) {
     if (shortcut_list.empty()) {
-      CRU_LOG_TAG_DEBUG("No shortcut for key bind {}.",
-                        key_bind.ToString().ToUtf8());
+      CRU_LOG_TAG_DEBUG("No shortcut for key bind {}.", key_bind.ToString());
     }
     CRU_LOG_TAG_DEBUG("Begin to handle shortcut for key bind {}.",
-                      key_bind.ToString().ToUtf8());
+                      key_bind.ToString());
   }
 
   for (const auto& shortcut : shortcut_list) {
     auto is_handled = shortcut.handler();
     if (is_handled) {
       if constexpr (debug_flags::shortcut) {
-        CRU_LOG_TAG_DEBUG("Handle {} handled it.", shortcut.name.ToUtf8());
+        CRU_LOG_TAG_DEBUG("Handle {} handled it.", shortcut.name);
       }
 
       handled = true;
@@ -109,8 +108,7 @@ void ShortcutHub::OnKeyDown(events::KeyEventArgs& event) {
       break;
     } else {
       if constexpr (debug_flags::shortcut) {
-        CRU_LOG_TAG_DEBUG("Handle {} didn't handle it.",
-                          shortcut.name.ToUtf8());
+        CRU_LOG_TAG_DEBUG("Handle {} didn't handle it.", shortcut.name);
       }
     }
   }
@@ -118,7 +116,7 @@ void ShortcutHub::OnKeyDown(events::KeyEventArgs& event) {
   if constexpr (debug_flags::shortcut) {
     if (!shortcut_list.empty()) {
       CRU_LOG_TAG_DEBUG("End handling shortcut for key bind {}.",
-                        key_bind.ToString().ToUtf8());
+                        key_bind.ToString());
     }
   }
 
@@ -126,7 +124,7 @@ void ShortcutHub::OnKeyDown(events::KeyEventArgs& event) {
     if constexpr (debug_flags::shortcut) {
       CRU_LOG_TAG_DEBUG(
           "Raise fallback event for unhandled shortcut of key bind {}.",
-          key_bind.ToString().ToUtf8());
+          key_bind.ToString());
     }
     fallback_event_.Raise(event);
   }
diff --git a/src/ui/mapper/ColorMapper.cpp b/src/ui/mapper/ColorMapper.cpp
index dcf3a522..82e9dfbc 100644
--- a/src/ui/mapper/ColorMapper.cpp
+++ b/src/ui/mapper/ColorMapper.cpp
@@ -1,5 +1,7 @@
 #include "cru/ui/mapper/ColorMapper.h"
 
+#include <cru/base/String.h>
+
 namespace cru::ui::mapper {
 bool ColorMapper::XmlElementIsOfThisType(xml::XmlElementNode* node) {
   return cru::string::CaseInsensitiveCompare(node->GetTag(), "Color") == 0;
diff --git a/src/ui/mapper/FontMapper.cpp b/src/ui/mapper/FontMapper.cpp
index bb3550ea..1f749513 100644
--- a/src/ui/mapper/FontMapper.cpp
+++ b/src/ui/mapper/FontMapper.cpp
@@ -1,5 +1,6 @@
 #include "cru/ui/mapper/FontMapper.h"
 #include "../Helper.h"
+#include "cru/base/String.h"
 #include "cru/platform/graphics/Factory.h"
 
 namespace cru::ui::mapper {
@@ -16,7 +17,6 @@ std::shared_ptr<platform::graphics::IFont> FontMapper::DoMapFromXml(
   auto font_size =
       font_size_attr ? String::FromUtf8(*font_size_attr).ParseToFloat() : 24.0f;
 
-  return GetGraphicsFactory()->CreateFont(String::FromUtf8(font_family),
-                                          font_size);
+  return GetGraphicsFactory()->CreateFont(font_family, font_size);
 }
 }  // namespace cru::ui::mapper
diff --git a/src/ui/mapper/Mapper.cpp b/src/ui/mapper/Mapper.cpp
index ca6cf0b3..47e783c9 100644
--- a/src/ui/mapper/Mapper.cpp
+++ b/src/ui/mapper/Mapper.cpp
@@ -9,8 +9,7 @@ MapperBase::MapperBase(std::type_index type_index)
 
 bool MapperBase::XmlElementIsOfThisType(xml::XmlElementNode* node) {
   for (const auto& tag : allowed_tags_) {
-    if (cru::string::CaseInsensitiveCompare(node->GetTag(), tag.ToUtf8()) ==
-        0) {
+    if (cru::string::CaseInsensitiveCompare(node->GetTag(), tag) == 0) {
       return true;
     }
   }
diff --git a/src/ui/mapper/PointMapper.cpp b/src/ui/mapper/PointMapper.cpp
index 16731544..12f000ef 100644
--- a/src/ui/mapper/PointMapper.cpp
+++ b/src/ui/mapper/PointMapper.cpp
@@ -1,5 +1,7 @@
 #include "cru/ui/mapper/PointMapper.h"
 
+#include <cru/base/String.h>
+
 namespace cru::ui::mapper {
 bool PointMapper::XmlElementIsOfThisType(xml::XmlElementNode* node) {
   return cru::string::CaseInsensitiveCompare(node->GetTag(), "Point") == 0;
diff --git a/src/ui/mapper/SizeMapper.cpp b/src/ui/mapper/SizeMapper.cpp
index f976bfe4..de8a0ded 100644
--- a/src/ui/mapper/SizeMapper.cpp
+++ b/src/ui/mapper/SizeMapper.cpp
@@ -1,5 +1,7 @@
 #include "cru/ui/mapper/SizeMapper.h"
 
+#include <cru/base/String.h>
+
 namespace cru::ui::mapper {
 bool SizeMapper::XmlElementIsOfThisType(xml::XmlElementNode* node) {
   return cru::string::CaseInsensitiveCompare(node->GetTag(), "Size") == 0;
diff --git a/src/ui/mapper/StringMapper.cpp b/src/ui/mapper/StringMapper.cpp
index 6e224d3f..5914da17 100644
--- a/src/ui/mapper/StringMapper.cpp
+++ b/src/ui/mapper/StringMapper.cpp
@@ -1,8 +1,9 @@
 #include "cru/ui/mapper/StringMapper.h"
 #include "cru/xml/XmlNode.h"
+#include "cru/base/String.h"
 
 namespace cru::ui::mapper {
-StringMapper::StringMapper() { SetAllowedTags({u"String"}); }
+StringMapper::StringMapper() { SetAllowedTags({"String"}); }
 
 StringMapper::~StringMapper() {}
 
diff --git a/src/ui/mapper/ThicknessMapper.cpp b/src/ui/mapper/ThicknessMapper.cpp
index 61c3641c..96f016a7 100644
--- a/src/ui/mapper/ThicknessMapper.cpp
+++ b/src/ui/mapper/ThicknessMapper.cpp
@@ -1,5 +1,6 @@
 #include "cru/ui/mapper/ThicknessMapper.h"
 #include "cru/xml/XmlNode.h"
+#include "cru/base/String.h"
 
 namespace cru::ui::mapper {
 bool ThicknessMapper::XmlElementIsOfThisType(xml::XmlElementNode* node) {
diff --git a/src/ui/mapper/style/ContentBrushStylerMapper.cpp b/src/ui/mapper/style/ContentBrushStylerMapper.cpp
index b3571374..027622fe 100644
--- a/src/ui/mapper/style/ContentBrushStylerMapper.cpp
+++ b/src/ui/mapper/style/ContentBrushStylerMapper.cpp
@@ -7,7 +7,7 @@
 
 namespace cru::ui::mapper::style {
 ContentBrushStylerMapper::ContentBrushStylerMapper() {
-  SetAllowedTags({u"ContentBrushStyler"});
+  SetAllowedTags({"ContentBrushStyler"});
 }
 
 ContentBrushStylerMapper::~ContentBrushStylerMapper() {}
diff --git a/src/ui/mapper/style/FontStylerMapper.cpp b/src/ui/mapper/style/FontStylerMapper.cpp
index 3b1817ac..1555c071 100644
--- a/src/ui/mapper/style/FontStylerMapper.cpp
+++ b/src/ui/mapper/style/FontStylerMapper.cpp
@@ -3,7 +3,7 @@
 #include "cru/ui/mapper/MapperRegistry.h"
 
 namespace cru::ui::mapper::style {
-FontStylerMapper::FontStylerMapper() { SetAllowedTags({u"FontStyler"}); }
+FontStylerMapper::FontStylerMapper() { SetAllowedTags({"FontStyler"}); }
 
 FontStylerMapper::~FontStylerMapper() {}
 
diff --git a/src/ui/mapper/style/MarginStylerMapper.cpp b/src/ui/mapper/style/MarginStylerMapper.cpp
index 0968b53e..ffbdcd75 100644
--- a/src/ui/mapper/style/MarginStylerMapper.cpp
+++ b/src/ui/mapper/style/MarginStylerMapper.cpp
@@ -4,7 +4,7 @@
 #include "cru/ui/style/Styler.h"
 
 namespace cru::ui::mapper::style {
-MarginStylerMapper::MarginStylerMapper() { SetAllowedTags({u"MarginStyler"}); }
+MarginStylerMapper::MarginStylerMapper() { SetAllowedTags({"MarginStyler"}); }
 
 MarginStylerMapper::~MarginStylerMapper() {}
 
diff --git a/src/ui/mapper/style/PaddingStylerMapper.cpp b/src/ui/mapper/style/PaddingStylerMapper.cpp
index 0f0f87d7..faa86082 100644
--- a/src/ui/mapper/style/PaddingStylerMapper.cpp
+++ b/src/ui/mapper/style/PaddingStylerMapper.cpp
@@ -5,7 +5,7 @@
 
 namespace cru::ui::mapper::style {
 PaddingStylerMapper::PaddingStylerMapper() {
-  SetAllowedTags({u"PaddingStyler"});
+  SetAllowedTags({"PaddingStyler"});
 }
 
 PaddingStylerMapper::~PaddingStylerMapper() {}
diff --git a/src/ui/render/BorderRenderObject.cpp b/src/ui/render/BorderRenderObject.cpp
index 03fdff24..957cf9bb 100644
--- a/src/ui/render/BorderRenderObject.cpp
+++ b/src/ui/render/BorderRenderObject.cpp
@@ -83,12 +83,10 @@ void BorderRenderObject::Draw(platform::graphics::IPainter* painter) {
   if constexpr (debug_flags::draw) {
     CRU_LOG_TAG_DEBUG(
         "BorderRenderObject draw, background: {}, foreground: {}.",
-        background_brush_ == nullptr
-            ? "NONE"
-            : background_brush_->GetDebugString().ToUtf8(),
-        foreground_brush_ == nullptr
-            ? "NONE"
-            : foreground_brush_->GetDebugString().ToUtf8());
+        background_brush_ == nullptr ? "NONE"
+                                     : background_brush_->GetDebugString(),
+        foreground_brush_ == nullptr ? "NONE"
+                                     : foreground_brush_->GetDebugString());
   }
 
   if (background_brush_ != nullptr)
diff --git a/src/ui/render/ScrollBar.cpp b/src/ui/render/ScrollBar.cpp
index af2851cd..f4f9496e 100644
--- a/src/ui/render/ScrollBar.cpp
+++ b/src/ui/render/ScrollBar.cpp
@@ -9,6 +9,7 @@
 #include "cru/platform/graphics/util/Painter.h"
 #include "cru/platform/gui/Base.h"
 #include "cru/platform/gui/Cursor.h"
+#include "cru/platform/gui/Input.h"
 #include "cru/ui/Base.h"
 #include "cru/ui/ThemeManager.h"
 #include "cru/ui/events/UiEvents.h"
@@ -38,39 +39,39 @@ constexpr std::array<ScrollBarAreaKind, 5> kScrollBarAreaKindList{
     ScrollBarAreaKind::UpSlot, ScrollBarAreaKind::DownSlot,
     ScrollBarAreaKind::Thumb};
 
-String GenerateScrollBarThemeColorKey(ScrollBarBrushUsageKind usage,
+std::string GenerateScrollBarThemeColorKey(ScrollBarBrushUsageKind usage,
                                       ScrollBarBrushStateKind state) {
-  String result = u"scrollbar.";
+  std::string result = "scrollbar.";
   switch (usage) {
     case ScrollBarBrushUsageKind::Arrow:
-      result.append(u"arrow");
+      result.append("arrow");
       break;
     case ScrollBarBrushUsageKind::ArrowBackground:
-      result.append(u"arrow-background");
+      result.append("arrow-background");
       break;
     case ScrollBarBrushUsageKind::Slot:
-      result.append(u"slot");
+      result.append("slot");
       break;
     case ScrollBarBrushUsageKind::Thumb:
-      result.append(u"thumb");
+      result.append("thumb");
       break;
   }
-  result.push_back(u'.');
+  result.push_back('.');
   switch (state) {
     case ScrollBarBrushStateKind::Normal:
-      result.append(u"normal");
+      result.append("normal");
       break;
     case ScrollBarBrushStateKind::Hover:
-      result.append(u"hover");
+      result.append("hover");
       break;
     case ScrollBarBrushStateKind::Press:
-      result.append(u"press");
+      result.append("press");
       break;
     case ScrollBarBrushStateKind::Disable:
-      result.append(u"disable");
+      result.append("disable");
       break;
   }
-  result.append(u".color");
+  result.append(".color");
   return result;
 }
 
@@ -123,7 +124,7 @@ void ScrollBar::InstallHandlers(controls::Control* control) {
     event_guard_ +=
         control->MouseDownEvent()->Tunnel()->PrependShortCircuitHandler(
             [control, this](events::MouseButtonEventArgs& event) {
-              if (event.GetButton() == mouse_buttons::left && IsEnabled() &&
+              if (event.GetButton() == MouseButtons::Left && IsEnabled() &&
                   IsExpanded()) {
                 auto hit_test_result =
                     ExpandedHitTest(event.GetPoint(render_object_));
@@ -182,7 +183,7 @@ void ScrollBar::InstallHandlers(controls::Control* control) {
                 render_object_->InvalidatePaint();
               }
 
-              if (event.GetButton() == mouse_buttons::left &&
+              if (event.GetButton() == MouseButtons::Left &&
                   move_thumb_start_) {
                 move_thumb_start_ = std::nullopt;
 
@@ -264,7 +265,7 @@ std::shared_ptr<platform::graphics::IBrush>
 ScrollBar::GetCollapsedThumbBrush() {
   return collapsed_thumb_brush_ ? collapsed_thumb_brush_
                                 : ThemeManager::GetInstance()->GetResourceBrush(
-                                      u"scrollbar.collapse-thumb.color");
+                                      "scrollbar.collapse-thumb.color");
 }
 
 void ScrollBar::SetCollapsedThumbBrush(
diff --git a/src/ui/render/TextRenderObject.cpp b/src/ui/render/TextRenderObject.cpp
index 346b4957..18020032 100644
--- a/src/ui/render/TextRenderObject.cpp
+++ b/src/ui/render/TextRenderObject.cpp
@@ -28,14 +28,16 @@ TextRenderObject::TextRenderObject(
   caret_brush.swap(caret_brush_);
 
   const auto graph_factory = GetGraphicsFactory();
-  text_layout_ = graph_factory->CreateTextLayout(font_, u"");
+  text_layout_ = graph_factory->CreateTextLayout(font_, "");
 }
 
 TextRenderObject::~TextRenderObject() = default;
 
-String TextRenderObject::GetText() const { return text_layout_->GetText(); }
+std::string TextRenderObject::GetText() const {
+  return text_layout_->GetText();
+}
 
-void TextRenderObject::SetText(String new_text) {
+void TextRenderObject::SetText(std::string new_text) {
   text_layout_->SetText(std::move(new_text));
   InvalidateLayout();
 }
@@ -181,8 +183,7 @@ void TextRenderObject::Draw(platform::graphics::IPainter* painter) {
         "Begin to paint, total_offset: {}, size: {}, text_layout: "
         "{}, brush: {}.",
         this->GetTotalOffset(), this->GetDesiredSize(),
-        this->text_layout_->GetDebugString().ToUtf8(),
-        this->brush_->GetDebugString().ToUtf8());
+        this->text_layout_->GetDebugString(), this->brush_->GetDebugString());
   }
 
   if (this->selection_range_.has_value()) {