...

13 files changed, 560 insertions, 1068 deletions

diff --git a/CruUI.vcxproj b/CruUI.vcxproj
index bd321715..f4fada4d 100644
--- a/CruUI.vcxproj
+++ b/CruUI.vcxproj
@@ -127,7 +127,6 @@
     <ClCompile Include="src\timer.cpp" />
     <ClCompile Include="src\ui\animations\animation.cpp" />
     <ClCompile Include="src\ui\control.cpp" />
-    <ClCompile Include="src\ui\border_property.cpp" />
     <ClCompile Include="src\ui\controls\button.cpp" />
     <ClCompile Include="src\ui\controls\frame_layout.cpp" />
     <ClCompile Include="src\ui\controls\linear_layout.cpp" />
@@ -141,7 +140,6 @@
     <ClInclude Include="src\util\any_map.hpp" />
     <ClInclude Include="src\util\format.hpp" />
     <ClInclude Include="src\util\math_util.hpp" />
-    <ClInclude Include="src\ui\border_property.hpp" />
     <ClInclude Include="src\ui\controls\frame_layout.hpp" />
     <ClInclude Include="src\ui\controls\list_item.hpp" />
     <ClInclude Include="src\ui\controls\popup_menu.hpp" />
@@ -151,7 +149,6 @@
     <ClCompile Include="src\ui\cursor.cpp" />
     <ClCompile Include="src\ui\events\ui_event.cpp" />
     <ClCompile Include="src\ui\input_util.cpp" />
-    <ClCompile Include="src\ui\layout_base.cpp" />
     <ClCompile Include="src\ui\render\flex_layout_render_object.cpp" />
     <ClCompile Include="src\ui\render\render_object.cpp" />
     <ClCompile Include="src\ui\ui_manager.cpp" />
@@ -180,7 +177,6 @@
     <ClInclude Include="src\ui\cursor.hpp" />
     <ClInclude Include="src\ui\events\ui_event.hpp" />
     <ClInclude Include="src\ui\input_util.hpp" />
-    <ClInclude Include="src\ui\layout_base.hpp" />
     <ClInclude Include="src\ui\render\flex_layout_render_object.hpp" />
     <ClInclude Include="src\ui\render\render_object.hpp" />
     <ClInclude Include="src\ui\ui_manager.hpp" />
diff --git a/CruUI.vcxproj.filters b/CruUI.vcxproj.filters
index 25923c76..1b7038d2 100644
--- a/CruUI.vcxproj.filters
+++ b/CruUI.vcxproj.filters
@@ -33,9 +33,6 @@
     <ClCompile Include="src\ui\control.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="src\ui\layout_base.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="src\ui\window.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -60,9 +57,6 @@
     <ClCompile Include="src\ui\events\ui_event.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="src\ui\border_property.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="src\ui\cursor.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -131,18 +125,12 @@
     <ClInclude Include="src\ui\events\ui_event.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="src\ui\border_property.hpp">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="src\ui\control.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
     <ClInclude Include="src\ui\cursor.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="src\ui\layout_base.hpp">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="src\ui\ui_base.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
diff --git a/src/ui/border_property.cpp b/src/ui/border_property.cpp
deleted file mode 100644
index b79bb482..00000000
--- a/src/ui/border_property.cpp
+++ /dev/null
@@ -1,23 +0,0 @@
-#include "border_property.hpp"
-
-#include "ui_manager.hpp"
-
-namespace cru::ui
-{
-    BorderProperty::BorderProperty(): BorderProperty(UiManager::GetInstance()->GetPredefineResources()->border_property_brush)
-    {
-
-    }
-
-    BorderProperty::BorderProperty(Microsoft::WRL::ComPtr<ID2D1Brush> brush): brush_(std::move(brush))
-    {
-
-    }
-
-    BorderProperty::BorderProperty(Microsoft::WRL::ComPtr<ID2D1Brush> brush, const float width, const float radius_x,
-        const float radius_y, Microsoft::WRL::ComPtr<ID2D1StrokeStyle> stroke_style) :
-        brush_(std::move(brush)), stroke_width_(width), radius_x_(radius_x), radius_y_(radius_y), stroke_style_(std::move(stroke_style))
-    {
-
-    }
-}
diff --git a/src/ui/border_property.hpp b/src/ui/border_property.hpp
deleted file mode 100644
index 4dee0e0f..00000000
--- a/src/ui/border_property.hpp
+++ /dev/null
@@ -1,87 +0,0 @@
-#pragma once
-
-// ReSharper disable once CppUnusedIncludeDirective
-#include "pre.hpp"
-
-#include "system_headers.hpp"
-
-#include "base.hpp"
-
-
-namespace cru::ui
-{
-    class BorderProperty final
-    {
-    public:
-        BorderProperty();
-        explicit BorderProperty(Microsoft::WRL::ComPtr<ID2D1Brush> brush);
-        BorderProperty(Microsoft::WRL::ComPtr<ID2D1Brush> brush, float width, float radius_x, float radius_y, Microsoft::WRL::ComPtr<ID2D1StrokeStyle> stroke_style = nullptr);
-        BorderProperty(const BorderProperty& other) = default;
-        BorderProperty(BorderProperty&& other) = default;
-        BorderProperty& operator=(const BorderProperty& other) = default;
-        BorderProperty& operator=(BorderProperty&& other) = default;
-        ~BorderProperty() = default;
-
-
-        Microsoft::WRL::ComPtr<ID2D1Brush> GetBrush() const
-        {
-            return brush_;
-        }
-
-        float GetStrokeWidth() const
-        {
-            return stroke_width_;
-        }
-
-        Microsoft::WRL::ComPtr<ID2D1StrokeStyle> GetStrokeStyle() const
-        {
-            return stroke_style_;
-        }
-
-        float GetRadiusX() const
-        {
-            return radius_x_;
-        }
-
-        float GetRadiusY() const
-        {
-            return radius_y_;
-        }
-
-        void SetBrush(Microsoft::WRL::ComPtr<ID2D1Brush> brush)
-        {
-            Require(brush == nullptr, "Brush of BorderProperty mustn't be null.");
-            brush_ = std::move(brush);
-        }
-
-        void SetStrokeWidth(const float stroke_width)
-        {
-            Require(stroke_width >= 0.0f, "Stroke width must be no less than 0.");
-            stroke_width_ = stroke_width;
-        }
-
-        void SetStrokeStyle(Microsoft::WRL::ComPtr<ID2D1StrokeStyle> stroke_style)
-        {
-            stroke_style_ = std::move(stroke_style);
-        }
-
-        void SetRadiusX(const float radius_x)
-        {
-            Require(radius_x >= 0.0f, "Radius-x must be no less than 0.");
-            radius_x_ = radius_x;
-        }
-
-        void SetRadiusY(const float radius_y)
-        {
-            Require(radius_y >= 0.0f, "Radius-y must be no less than 0.");
-            radius_y_ = radius_y;
-        }
-
-    private:
-        Microsoft::WRL::ComPtr<ID2D1Brush> brush_;
-        float stroke_width_ = 1.0f;
-        float radius_x_ = 0.0f;
-        float radius_y_ = 0.0f;
-        Microsoft::WRL::ComPtr<ID2D1StrokeStyle> stroke_style_ = nullptr;
-    };
-}
diff --git a/src/ui/control.cpp b/src/ui/control.cpp
index 617c50c7..ee2abad0 100644
--- a/src/ui/control.cpp
+++ b/src/ui/control.cpp
@@ -3,292 +3,192 @@
 #include <algorithm>
 #include <cassert>
 
-#include "window.hpp"
 #include "application.hpp"
-#include "graph/graph.hpp"
-#include "exception.hpp"
 #include "cru_debug.hpp"
 #include "d2d_util.hpp"
+#include "exception.hpp"
+#include "graph/graph.hpp"
 #include "math_util.hpp"
+#include "window.hpp"
 
 #ifdef CRU_DEBUG_LAYOUT
 #include "ui_manager.hpp"
 #endif
 
-namespace cru::ui
-{
-
-    void Control::SetParent(Control* parent)
-    {
-        const auto old_parent = GetParent();
-        parent_ = parent;
-        const auto new_parent = GetParent();
-        if (old_parent != new_parent)
-            OnParentChanged(old_parent, new_parent);
-    }
-
-    void Control::SetDescendantWindow(Window* window)
-    {
-        if (window == nullptr && window_ == nullptr)
-            return;
-
-        //You can only attach or detach window.
-        assert((window != nullptr && window_ == nullptr) || (window == nullptr && window_ != nullptr));
-
-        if (window == nullptr)
-        {
-            const auto old = window_;
-            TraverseDescendants([old](Control* control)
-            {
-                control->window_ = nullptr;
-                control->OnDetachToWindow(old);
-            });
-        }
-        else
-            TraverseDescendants([window](Control* control)
-            {
-                control->window_ = window;
-                control->OnAttachToWindow(window);
-            });            
-    }
-
-    void Control::TraverseDescendants(const std::function<void(Control*)>& predicate)
-    {
-        TraverseDescendantsInternal(this, predicate);
-    }
-
-    void Control::TraverseDescendantsInternal(Control * control, const std::function<void(Control*)>& predicate)
-    {
-        predicate(control);
-        for (auto c: control->GetInternalChildren())
-            TraverseDescendantsInternal(c, predicate);
-    }
-
-
-    Point Control::ControlToWindow(const Point& point) const
-    {
-        const auto position = GetPositionInWindow();
-        return Point(point.x + position.x, point.y + position.y);
-    }
-
-    Point Control::WindowToControl(const Point & point) const
-    {
-        const auto position = GetPositionInWindow();
-        return Point(point.x - position.x, point.y - position.y);
-    }
-
-    bool Control::RequestFocus()
-    {
-        auto window = GetWindow();
-        if (window == nullptr)
-            return false;
-
-        return window->RequestFocusFor(this);
-    }
-
-    bool Control::HasFocus()
-    {
-        auto window = GetWindow();
-        if (window == nullptr)
-            return false;
-
-        return window->GetFocusControl() == this;
-    }
-
-    void Control::SetCursor(const Cursor::Ptr& cursor)
-    {
-        if (cursor != cursor_)
-        {
-            cursor_ = cursor;
-            const auto window = GetWindow();
-            if (window && window->GetMouseHoverControl() == this)
-                window->UpdateCursor();
-        }
-    }
-
-    void Control::OnParentChanged(Control* old_parent, Control* new_parent)
-    {
-
-    }
-
-    void Control::OnAttachToWindow(Window* window)
-    {
-
-    }
-
-    void Control::OnDetachToWindow(Window * window)
-    {
-
-    }
-
-    void Control::OnMouseClickBegin(MouseButton button)
-    {
-
-    }
-
-    void Control::OnMouseClickEnd(MouseButton button)
-    {
-
-    }
-
-
-    const std::vector<Control*> NoChildControl::empty_control_vector{};
+namespace cru::ui {
 
+void Control::_SetParent(Control* parent) {
+  const auto old_parent = GetParent();
+  parent_ = parent;
+  const auto new_parent = GetParent();
+  if (old_parent != new_parent) OnParentChanged(old_parent, new_parent);
+}
 
-    ContentControl::ContentControl() : child_vector_{nullptr}, child_(child_vector_[0])
-    {
+void Control::_SetDescendantWindow(Window* window) {
+  if (window == nullptr && window_ == nullptr) return;
+
+  // You can only attach or detach window.
+  assert((window != nullptr && window_ == nullptr) ||
+         (window == nullptr && window_ != nullptr));
+
+  if (window == nullptr) {
+    const auto old = window_;
+    TraverseDescendants([old](Control* control) {
+      control->window_ = nullptr;
+      control->OnDetachToWindow(old);
+    });
+  } else
+    TraverseDescendants([window](Control* control) {
+      control->window_ = window;
+      control->OnAttachToWindow(window);
+    });
+}
 
-    }
+void Control::TraverseDescendants(
+    const std::function<void(Control*)>& predicate) {
+  TraverseDescendantsInternal(this, predicate);
+}
 
-    ContentControl::~ContentControl()
-    {
-        delete child_;
-    }
+void Control::TraverseDescendantsInternal(
+    Control* control, const std::function<void(Control*)>& predicate) {
+  predicate(control);
+  for (auto c : control->GetChildren())
+    TraverseDescendantsInternal(c, predicate);
+}
+bool Control::RequestFocus() {
+  auto window = GetWindow();
+  if (window == nullptr) return false;
 
-    void ContentControl::SetChild(Control* child)
-    {
-        if (child == child_)
-            return;
+  return window->RequestFocusFor(this);
+}
 
-        const auto window = GetWindow();
-        const auto old_child = child_;
-        child_ = child;
-        if (old_child)
-        {
-            old_child->SetParent(nullptr);
-            old_child->SetDescendantWindow(nullptr);
-        }
-        if (child)
-        {
-            child->SetParent(this);
-            child->SetDescendantWindow(window);
-        }
-        OnChildChanged(old_child, child);
-    }
+bool Control::HasFocus() {
+  auto window = GetWindow();
+  if (window == nullptr) return false;
 
-    void ContentControl::OnChildChanged(Control* old_child, Control* new_child)
-    {
+  return window->GetFocusControl() == this;
+}
 
-    }
+void Control::SetCursor(const Cursor::Ptr& cursor) {
+  if (cursor != cursor_) {
+    cursor_ = cursor;
+    const auto window = GetWindow();
+    if (window && window->GetMouseHoverControl() == this)
+      window->UpdateCursor();
+  }
+}
 
-    void ControlAddChildCheck(Control* control)
-    {
-        if (control->GetParent() != nullptr)
-            throw std::invalid_argument("The control already has a parent.");
+void Control::OnParentChanged(Control* old_parent, Control* new_parent) {}
 
-        if (dynamic_cast<Window*>(control))
-            throw std::invalid_argument("Can't add a window as child.");
-    }
+void Control::OnAttachToWindow(Window* window) {}
 
-    MultiChildControl::~MultiChildControl()
-    {
-        for (const auto child : children_)
-            delete child;
-    }
+void Control::OnDetachToWindow(Window* window) {}
 
-    void MultiChildControl::AddChild(Control* control)
-    {
-        ControlAddChildCheck(control);
+void Control::OnMouseClickBegin(MouseButton button) {}
 
-        children_.push_back(control);
+void Control::OnMouseClickEnd(MouseButton button) {}
 
-        control->SetParent(this);
-        control->SetDescendantWindow(GetWindow());
+const std::vector<Control*> NoChildControl::empty_control_vector{};
 
-        OnAddChild(control);
-    }
+ContentControl::ContentControl()
+    : child_vector_{nullptr}, child_(child_vector_[0]) {}
 
-    void MultiChildControl::AddChild(Control* control, const int position)
-    {
-        ControlAddChildCheck(control);
+ContentControl::~ContentControl() { delete child_; }
 
-        if (position < 0 || static_cast<decltype(children_.size())>(position) > this->children_.size())
-            throw std::invalid_argument("The position is out of range.");
+void ContentControl::SetChild(Control* child) {
+  if (child == child_) return;
 
-        children_.insert(this->children_.cbegin() + position, control);
+  const auto window = GetWindow();
+  const auto old_child = child_;
+  child_ = child;
+  if (old_child) {
+    old_child->_SetParent(nullptr);
+    old_child->_SetDescendantWindow(nullptr);
+  }
+  if (child) {
+    child->_SetParent(this);
+    child->_SetDescendantWindow(window);
+  }
+  OnChildChanged(old_child, child);
+}
 
-        control->SetParent(this);
-        control->SetDescendantWindow(GetWindow());
+void ContentControl::OnChildChanged(Control* old_child, Control* new_child) {}
 
-        OnAddChild(control);
-    }
+void ControlAddChildCheck(Control* control) {
+  if (control->GetParent() != nullptr)
+    throw std::invalid_argument("The control already has a parent.");
 
-    void MultiChildControl::RemoveChild(Control* child)
-    {
-        const auto i = std::find(this->children_.cbegin(), this->children_.cend(), child);
-        if (i == this->children_.cend())
-            throw std::invalid_argument("The argument child is not a child of this control.");
+  if (dynamic_cast<Window*>(control))
+    throw std::invalid_argument("Can't add a window as child.");
+}
+
+MultiChildControl::~MultiChildControl() {
+  for (const auto child : children_) delete child;
+}
+
+void MultiChildControl::AddChild(Control* control, const int position) {
+  ControlAddChildCheck(control);
 
-        children_.erase(i);
+  if (position < 0 || static_cast<decltype(children_.size())>(position) >
+                          this->children_.size())
+    throw std::invalid_argument("The position is out of range.");
 
-        child->SetParent(nullptr);
-        child->SetDescendantWindow(nullptr);
+  children_.insert(this->children_.cbegin() + position, control);
+
+  control->_SetParent(this);
+  control->_SetDescendantWindow(GetWindow());
+
+  OnAddChild(control);
+}
 
-        OnRemoveChild(child);
-    }
+void MultiChildControl::RemoveChild(const int position) {
+  if (position < 0 || static_cast<decltype(this->children_.size())>(position) >=
+                          this->children_.size())
+    throw std::invalid_argument("The position is out of range.");
 
-    void MultiChildControl::RemoveChild(const int position)
-    {
-        if (position < 0 || static_cast<decltype(this->children_.size())>(position) >= this->children_.size())
-            throw std::invalid_argument("The position is out of range.");
-
-        const auto i = children_.cbegin() + position;
-        const auto child = *i;
-
-        children_.erase(i);
-
-        child->SetParent(nullptr);
-        child->SetDescendantWindow(nullptr);
-
-        OnRemoveChild(child);
-    }
-
-    void MultiChildControl::OnAddChild(Control* child)
-    {
-
-    }
-
-    void MultiChildControl::OnRemoveChild(Control* child)
-    {
-
-    }
-
-    std::list<Control*> GetAncestorList(Control* control)
-    {
-        std::list<Control*> l;
-        while (control != nullptr)
-        {
-            l.push_front(control);
-            control = control->GetParent();
-        }
-        return l;
-    }
+  const auto i = children_.cbegin() + position;
+  const auto child = *i;
 
-    Control* FindLowestCommonAncestor(Control * left, Control * right)
-    {
-        if (left == nullptr || right == nullptr)
-            return nullptr;
+  children_.erase(i);
 
-        auto&& left_list = GetAncestorList(left);
-        auto&& right_list = GetAncestorList(right);
-
-        // the root is different
-        if (left_list.front() != right_list.front())
-            return nullptr;
+  child->_SetParent(nullptr);
+  child->_SetDescendantWindow(nullptr);
+
+  OnRemoveChild(child);
+}
+
+void MultiChildControl::OnAddChild(Control* child) {}
+
+void MultiChildControl::OnRemoveChild(Control* child) {}
+
+std::list<Control*> GetAncestorList(Control* control) {
+  std::list<Control*> l;
+  while (control != nullptr) {
+    l.push_front(control);
+    control = control->GetParent();
+  }
+  return l;
+}
 
-        // find the last same control or the last control (one is ancestor of the other)
-        auto left_i = left_list.cbegin();
-        auto right_i = right_list.cbegin();
-        while (true)
-        {
-            if (left_i == left_list.cend())
-                return *(--left_i);
-            if (right_i == right_list.cend())
-                return *(--right_i);
-            if (*left_i != *right_i)
-                return *(--left_i);
-            ++left_i;
-            ++right_i;
-        }
-    }
+Control* FindLowestCommonAncestor(Control* left, Control* right) {
+  if (left == nullptr || right == nullptr) return nullptr;
+
+  auto&& left_list = GetAncestorList(left);
+  auto&& right_list = GetAncestorList(right);
+
+  // the root is different
+  if (left_list.front() != right_list.front()) return nullptr;
+
+  // find the last same control or the last control (one is ancestor of the
+  // other)
+  auto left_i = left_list.cbegin();
+  auto right_i = right_list.cbegin();
+  while (true) {
+    if (left_i == left_list.cend()) return *(--left_i);
+    if (right_i == right_list.cend()) return *(--right_i);
+    if (*left_i != *right_i) return *(--left_i);
+    ++left_i;
+    ++right_i;
+  }
 }
+}  // namespace cru::ui
diff --git a/src/ui/control.hpp b/src/ui/control.hpp
index 8e69fb07..e85d0e6d 100644
--- a/src/ui/control.hpp
+++ b/src/ui/control.hpp
@@ -1,357 +1,243 @@
 #pragma once
-
-// ReSharper disable once CppUnusedIncludeDirective
 #include "pre.hpp"
 
-#include "system_headers.hpp"
-#include <unordered_map>
 #include <any>
+#include <unordered_map>
 #include <utility>
+#include "system_headers.hpp"
 
 #include "base.hpp"
-#include "ui_base.hpp"
-#include "layout_base.hpp"
-#include "events/ui_event.hpp"
 #include "cursor.hpp"
-#include "any_map.hpp"
+#include "events/ui_event.hpp"
 #include "input_util.hpp"
+#include "ui_base.hpp"
 
-namespace cru::ui
-{
-    class Window;
-
-
-    class Control : public Object
-    {
-        friend class Window;
-
-    protected:
-        Control() = default;
-    public:
-        Control(const Control& other) = delete;
-        Control(Control&& other) = delete;
-        Control& operator=(const Control& other) = delete;
-        Control& operator=(Control&& other) = delete;
-        ~Control() override = default;
-
-    public:
-        virtual StringView GetControlType() const = 0;
-
-
-        //*************** region: tree ***************
-    public:
-        //Get the window if attached, otherwise, return nullptr.
-        Window* GetWindow() const
-        {
-            return window_;
-        }
-
-        Control* GetParent() const
-        {
-            return parent_;
-        }
-
-        void SetParent(Control* parent);
-
-        void SetDescendantWindow(Window* window);
-
-        //Traverse the tree rooted the control including itself.
-        void TraverseDescendants(const std::function<void(Control*)>& predicate);
-
-    private:
-        static void TraverseDescendantsInternal(Control* control, const std::function<void(Control*)>& predicate);
-
-        //*************** region: position ***************
-    public:
-        virtual Point GetPositionInWindow() const = 0;
-
-        //Local point to absolute point.
-        Point ControlToWindow(const Point& point) const;
-
-        //Absolute point to local point.
-        Point WindowToControl(const Point& point) const;
-
-
-
-        //*************** region: focus ***************
-    public:
-        bool RequestFocus();
-
-        bool HasFocus();
-
-        
-        //*************** region: cursor ***************
-        // If cursor is set to null, then it uses parent's cursor.
-        // Window's cursor can't be null.
-    public:
-        Cursor::Ptr GetCursor() const
-        {
-            return cursor_;
-        }
-
-        void SetCursor(const Cursor::Ptr& cursor);
-
-
-        //*************** region: additional properties ***************
-    public:
-        AnyMap* GetAdditionalPropertyMap()
-        {
-            return &additional_property_map_;
-        }
-
-
-        //*************** region: events ***************
-    public:
-        //Raised when mouse enter the control.
-        events::RoutedEvent<events::MouseEventArgs> mouse_enter_event;
-        //Raised when mouse is leave the control.
-        events::RoutedEvent<events::MouseEventArgs> mouse_leave_event;
-        //Raised when mouse is move in the control.
-        events::RoutedEvent<events::MouseEventArgs> mouse_move_event;
-        //Raised when a mouse button is pressed in the control.
-        events::RoutedEvent<events::MouseButtonEventArgs> mouse_down_event;
-        //Raised when a mouse button is released in the control.
-        events::RoutedEvent<events::MouseButtonEventArgs> mouse_up_event;
-        //Raised when a mouse button is pressed in the control and released in the control with mouse not leaving it between two operations.
-        events::RoutedEvent<events::MouseButtonEventArgs> mouse_click_event;
-
-        events::RoutedEvent<events::MouseWheelEventArgs> mouse_wheel_event;
-
-        events::RoutedEvent<events::KeyEventArgs> key_down_event;
-        events::RoutedEvent<events::KeyEventArgs> key_up_event;
-        events::RoutedEvent<events::CharEventArgs> char_event;
-
-        events::RoutedEvent<events::FocusChangeEventArgs> get_focus_event;
-        events::RoutedEvent<events::FocusChangeEventArgs> lose_focus_event;
-
-
-        //*************** region: tree ***************
-    protected:
-        virtual const std::vector<Control*>& GetInternalChildren() const = 0;
-
-        virtual void OnParentChanged(Control* old_parent, Control* new_parent);
-        virtual void OnAttachToWindow(Window* window);
-        virtual void OnDetachToWindow(Window* window);
-
-
-        //*************** region: additional mouse event ***************
-    protected:
-        virtual void OnMouseClickBegin(MouseButton button);
-        virtual void OnMouseClickEnd(MouseButton button);
-
-
-    private:
-        Window * window_ = nullptr;
-        Control* parent_ = nullptr;
-
-        Cursor::Ptr cursor_{};
-
-        AnyMap additional_property_map_{};
-    };
+namespace cru::ui {
+class Window;
 
+class Control : public Object {
+  friend class Window;
 
-    
-    class NoChildControl : public Control
-    {
-    private:
-        // used in GetInternalChildren.
-        static const std::vector<Control*> empty_control_vector;
+ protected:
+  Control() = default;
 
-    protected:
-        NoChildControl() = default;
-    public:
-        NoChildControl(const NoChildControl& other) = delete;
-        NoChildControl(NoChildControl&& other) = delete;
-        NoChildControl& operator=(const NoChildControl& other) = delete;
-        NoChildControl& operator=(NoChildControl&& other) = delete;
-        ~NoChildControl() override = default;
-
-    protected:
-        const std::vector<Control*>& GetInternalChildren() const override final
-        {
-            return empty_control_vector;
-        }
-    };
-
-
-    class ContentControl : public Control
-    {
-    protected:
-        ContentControl();
-    public:
-        ContentControl(const ContentControl& other) = delete;
-        ContentControl(ContentControl&& other) = delete;
-        ContentControl& operator=(const ContentControl& other) = delete;
-        ContentControl& operator=(ContentControl&& other) = delete;
-        ~ContentControl() override;
-
-        Control* GetChild() const
-        {
-            return child_;
-        }
-
-        void SetChild(Control* child);
-
-    protected:
-        const std::vector<Control*>& GetInternalChildren() const override final
-        {
-            return child_vector_;
-        }
-
-        // Override should call base.
-        virtual void OnChildChanged(Control* old_child, Control* new_child);
-
-    private:
-        std::vector<Control*> child_vector_;
-        Control*& child_;
-    };
-
-
-    class MultiChildControl : public Control
-    {
-    protected:
-        MultiChildControl() = default;
-    public:
-        MultiChildControl(const MultiChildControl& other) = delete;
-        MultiChildControl(MultiChildControl&& other) = delete;
-        MultiChildControl& operator=(const MultiChildControl& other) = delete;
-        MultiChildControl& operator=(MultiChildControl&& other) = delete;
-        ~MultiChildControl() override;
-
-        const std::vector<Control*>& GetInternalChildren() const override final
-        {
-            return children_;
-        }
-
-        const std::vector<Control*>& GetChildren() const
-        {
-            return children_;
-        }
-
-        //Add a child at tail.
-        void AddChild(Control* control);
-
-        //Add a child before the position.
-        void AddChild(Control* control, int position);
-
-        //Remove a child.
-        void RemoveChild(Control* child);
-
-        //Remove a child at specified position.
-        void RemoveChild(int position);
-
-    protected:
-        virtual void OnAddChild(Control* child);
-        virtual void OnRemoveChild(Control* child);
-
-    private:
-        std::vector<Control*> children_;
-    };
-
-
-
-    //*************** region: event dispatcher helper ***************
-
-    // Dispatch the event.
-    // 
-    // This will raise routed event of the control and its parent and parent's
-    // parent ... (until "last_receiver" if it's not nullptr) with appropriate args.
-    // 
-    // First tunnel from top to bottom possibly stopped by "handled" flag in EventArgs.
-    // Second bubble from bottom to top possibly stopped by "handled" flag in EventArgs.
-    // Last direct to each control.
-    // 
-    // Args is of type "EventArgs". The first init argument is "sender", which is
-    // automatically bound to each receiving control. The second init argument is
-    // "original_sender", which is unchanged. And "args" will be perfectly forwarded
-    // as the rest arguments.
-    template<typename EventArgs, typename... Args>
-    void DispatchEvent(Control* const original_sender, events::RoutedEvent<EventArgs> Control::* event_ptr, Control* const last_receiver, Args&&... args)
-    {
-        std::list<Control*> receive_list;
-
-        auto parent = original_sender;
-        while (parent != last_receiver)
-        {
-            receive_list.push_back(parent);
-            parent = parent->GetInternalParent();
-        }
-
-        auto handled = false;
-
-        //tunnel
-        for (auto i = receive_list.crbegin(); i != receive_list.crend(); ++i)
-        {
-            EventArgs event_args(*i, original_sender, std::forward<Args>(args)...);
-            (*i->*event_ptr).tunnel.Raise(event_args);
-            if (event_args.IsHandled())
-            {
-                handled = true;
-                break;
-            }
-        }
-
-        //bubble
-        if (!handled)
-        {
-            for (auto i : receive_list)
-            {
-                EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
-                (i->*event_ptr).bubble.Raise(event_args);
-                if (event_args.IsHandled())
-                    break;
-            }
-        }
-
-        //direct
-        for (auto i : receive_list)
-        {
-            EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
-            (i->*event_ptr).direct.Raise(event_args);
-        }
+ public:
+  Control(const Control& other) = delete;
+  Control(Control&& other) = delete;
+  Control& operator=(const Control& other) = delete;
+  Control& operator=(Control&& other) = delete;
+  ~Control() override = default;
+
+ public:
+  virtual StringView GetControlType() const = 0;
+
+  //*************** region: tree ***************
+ public:
+  // Get the window if attached, otherwise, return nullptr.
+  Window* GetWindow() const { return window_; }
+
+  Control* GetParent() const { return parent_; }
+
+  virtual const std::vector<Control*>& GetChildren() const = 0;
+
+  // Traverse the tree rooted the control including itself.
+  void TraverseDescendants(const std::function<void(Control*)>& predicate);
+
+  void _SetParent(Control* parent);
+  void _SetDescendantWindow(Window* window);
+
+ private:
+  static void TraverseDescendantsInternal(
+      Control* control, const std::function<void(Control*)>& predicate);
+
+  //*************** region: focus ***************
+ public:
+  bool RequestFocus();
+
+  bool HasFocus();
+
+  //*************** region: cursor ***************
+  // If cursor is set to null, then it uses parent's cursor.
+  // Window's cursor can't be null.
+ public:
+  Cursor::Ptr GetCursor() const { return cursor_; }
+
+  void SetCursor(const Cursor::Ptr& cursor);
+
+  //*************** region: events ***************
+ public:
+  // Raised when mouse enter the control.
+  events::RoutedEvent<events::MouseEventArgs> mouse_enter_event;
+  // Raised when mouse is leave the control.
+  events::RoutedEvent<events::MouseEventArgs> mouse_leave_event;
+  // Raised when mouse is move in the control.
+  events::RoutedEvent<events::MouseEventArgs> mouse_move_event;
+  // Raised when a mouse button is pressed in the control.
+  events::RoutedEvent<events::MouseButtonEventArgs> mouse_down_event;
+  // Raised when a mouse button is released in the control.
+  events::RoutedEvent<events::MouseButtonEventArgs> mouse_up_event;
+  // Raised when a mouse button is pressed in the control and released in the
+  // control with mouse not leaving it between two operations.
+  events::RoutedEvent<events::MouseButtonEventArgs> mouse_click_event;
+
+  events::RoutedEvent<events::MouseWheelEventArgs> mouse_wheel_event;
+
+  events::RoutedEvent<events::KeyEventArgs> key_down_event;
+  events::RoutedEvent<events::KeyEventArgs> key_up_event;
+  events::RoutedEvent<events::CharEventArgs> char_event;
+
+  events::RoutedEvent<events::FocusChangeEventArgs> get_focus_event;
+  events::RoutedEvent<events::FocusChangeEventArgs> lose_focus_event;
+
+  //*************** region: tree ***************
+ protected:
+  virtual void OnParentChanged(Control* old_parent, Control* new_parent);
+  virtual void OnAttachToWindow(Window* window);
+  virtual void OnDetachToWindow(Window* window);
+
+  //*************** region: additional mouse event ***************
+ protected:
+  virtual void OnMouseClickBegin(MouseButton button);
+  virtual void OnMouseClickEnd(MouseButton button);
+
+ private:
+  Window* window_ = nullptr;
+  Control* parent_ = nullptr;
+
+  Cursor::Ptr cursor_{};
+};
+
+class NoChildControl : public Control {
+ private:
+  static const std::vector<Control*> empty_control_vector;
+
+ protected:
+  NoChildControl() = default;
+
+ public:
+  NoChildControl(const NoChildControl& other) = delete;
+  NoChildControl(NoChildControl&& other) = delete;
+  NoChildControl& operator=(const NoChildControl& other) = delete;
+  NoChildControl& operator=(NoChildControl&& other) = delete;
+  ~NoChildControl() override = default;
+
+ protected:
+  const std::vector<Control*>& GetChildren() const override final {
+    return empty_control_vector;
+  }
+};
+
+class ContentControl : public Control {
+ protected:
+  ContentControl();
+
+ public:
+  ContentControl(const ContentControl& other) = delete;
+  ContentControl(ContentControl&& other) = delete;
+  ContentControl& operator=(const ContentControl& other) = delete;
+  ContentControl& operator=(ContentControl&& other) = delete;
+  ~ContentControl() override;
+
+  const std::vector<Control*>& GetChildren() const override final {
+    return child_vector_;
+  }
+  Control* GetChild() const { return child_; }
+  void SetChild(Control* child);
+
+ protected:
+  virtual void OnChildChanged(Control* old_child, Control* new_child);
+
+ private:
+  std::vector<Control*> child_vector_;
+  Control*& child_;
+};
+
+class MultiChildControl : public Control {
+ protected:
+  MultiChildControl() = default;
+
+ public:
+  MultiChildControl(const MultiChildControl& other) = delete;
+  MultiChildControl(MultiChildControl&& other) = delete;
+  MultiChildControl& operator=(const MultiChildControl& other) = delete;
+  MultiChildControl& operator=(MultiChildControl&& other) = delete;
+  ~MultiChildControl() override;
+
+  const std::vector<Control*>& GetChildren() const override final {
+    return children_;
+  }
+
+  void AddChild(Control* control, int position);
+
+  void RemoveChild(int position);
+
+ protected:
+  virtual void OnAddChild(Control* child);
+  virtual void OnRemoveChild(Control* child);
+
+ private:
+  std::vector<Control*> children_;
+};
+
+//*************** region: event dispatcher helper ***************
+
+// Dispatch the event.
+//
+// This will raise routed event of the control and its parent and parent's
+// parent ... (until "last_receiver" if it's not nullptr) with appropriate args.
+//
+// First tunnel from top to bottom possibly stopped by "handled" flag in
+// EventArgs. Second bubble from bottom to top possibly stopped by "handled"
+// flag in EventArgs. Last direct to each control.
+//
+// Args is of type "EventArgs". The first init argument is "sender", which is
+// automatically bound to each receiving control. The second init argument is
+// "original_sender", which is unchanged. And "args" will be perfectly forwarded
+// as the rest arguments.
+template <typename EventArgs, typename... Args>
+void DispatchEvent(Control* const original_sender,
+                   events::RoutedEvent<EventArgs> Control::*event_ptr,
+                   Control* const last_receiver, Args&&... args) {
+  std::list<Control*> receive_list;
+
+  auto parent = original_sender;
+  while (parent != last_receiver) {
+    receive_list.push_back(parent);
+    parent = parent->GetInternalParent();
+  }
+
+  auto handled = false;
+
+  // tunnel
+  for (auto i = receive_list.crbegin(); i != receive_list.crend(); ++i) {
+    EventArgs event_args(*i, original_sender, std::forward<Args>(args)...);
+    (*i->*event_ptr).tunnel.Raise(event_args);
+    if (event_args.IsHandled()) {
+      handled = true;
+      break;
     }
-
-
-    //*************** region: tree helper ***************
-
-    // Find the lowest common ancestor.
-    // Return nullptr if "left" and "right" are not in the same tree.
-    Control* FindLowestCommonAncestor(Control* left, Control* right);
-
-
-    //*************** region: create helper ***************
-
-    template <typename TControl, typename... Args>
-    TControl* CreateWithLayout(const LayoutSideParams& width, const LayoutSideParams& height, Args&&... args)
-    {
-        static_assert(std::is_base_of_v<Control, TControl>, "TControl is not a control class.");
-        TControl* control = TControl::Create(std::forward<Args>(args)...);
-        control->GetLayoutParams()->width = width;
-        control->GetLayoutParams()->height = height;
-        return control;
+  }
+
+  // bubble
+  if (!handled) {
+    for (auto i : receive_list) {
+      EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
+      (i->*event_ptr).bubble.Raise(event_args);
+      if (event_args.IsHandled()) break;
     }
+  }
 
-    template <typename TControl, typename... Args>
-    TControl* CreateWithLayout(const Thickness& padding, const Thickness& margin, Args&&... args)
-    {
-        static_assert(std::is_base_of_v<Control, TControl>, "TControl is not a control class.");
-        TControl* control = TControl::Create(std::forward<Args>(args)...);
-        control->GetLayoutParams()->padding = padding;
-        control->GetLayoutParams()->margin = margin;
-        return control;
-    }
+  // direct
+  for (auto i : receive_list) {
+    EventArgs event_args(i, original_sender, std::forward<Args>(args)...);
+    (i->*event_ptr).direct.Raise(event_args);
+  }
+}
 
-    template <typename TControl, typename... Args>
-    TControl* CreateWithLayout(const LayoutSideParams& width, const LayoutSideParams& height, const Thickness& padding, const Thickness& margin, Args&&... args)
-    {
-        static_assert(std::is_base_of_v<Control, TControl>, "TControl is not a control class.");
-        TControl* control = TControl::Create(std::forward<Args>(args)...);
-        control->GetLayoutParams()->width = width;
-        control->GetLayoutParams()->height = height;
-        control->GetLayoutParams()->padding = padding;
-        control->GetLayoutParams()->margin = margin;
-        return control;
-    }
+//*************** region: tree helper ***************
 
-    using ControlList = std::initializer_list<Control*>;
-}
+// Find the lowest common ancestor.
+// Return nullptr if "left" and "right" are not in the same tree.
+Control* FindLowestCommonAncestor(Control* left, Control* right);
+
+}  // namespace cru::ui
diff --git a/src/ui/controls/linear_layout.cpp b/src/ui/controls/linear_layout.cpp
index d3fdc9b5..c3de7ca3 100644
--- a/src/ui/controls/linear_layout.cpp
+++ b/src/ui/controls/linear_layout.cpp
@@ -27,7 +27,7 @@ namespace cru::ui::controls
 
         // First measure Content and Exactly and count Stretch.
         if (orientation_ == Orientation::Horizontal)
-            for(auto control: GetInternalChildren())
+            for(auto control: GetChildren())
             {
                 const auto mode = control->GetLayoutParams()->width.mode;
                 if (mode == MeasureMode::Content || mode == MeasureMode::Exactly)
@@ -42,7 +42,7 @@ namespace cru::ui::controls
                     stretch_control_list.push_back(control);
             }
         else
-            for(auto control: GetInternalChildren())
+            for(auto control: GetChildren())
             {
                 const auto mode = control->GetLayoutParams()->height.mode;
                 if (mode == MeasureMode::Content || mode == MeasureMode::Exactly)
@@ -82,7 +82,7 @@ namespace cru::ui::controls
 
         if (orientation_ == Orientation::Horizontal)
         {
-            for (auto control : GetInternalChildren())
+            for (auto control : GetChildren())
             {
                 if (control->GetLayoutParams()->height.mode == MeasureMode::Stretch)
                 {
@@ -93,7 +93,7 @@ namespace cru::ui::controls
         }
         else
         {
-            for (auto control : GetInternalChildren())
+            for (auto control : GetChildren())
             {
                 if (control->GetLayoutParams()->width.mode == MeasureMode::Stretch)
                 {
@@ -110,7 +110,7 @@ namespace cru::ui::controls
     void LinearLayout::OnLayoutContent(const Rect& rect, const AdditionalLayoutInfo& additional_info)
     {
         float current_main_side_anchor = 0;
-        for(auto control: GetInternalChildren())
+        for(auto control: GetChildren())
         {
             const auto layout_params = control->GetLayoutParams();
             const auto size = control->GetDesiredSize();
diff --git a/src/ui/d2d_util.hpp b/src/ui/d2d_util.hpp
index 5f2e10b2..94ef6223 100644
--- a/src/ui/d2d_util.hpp
+++ b/src/ui/d2d_util.hpp
@@ -1,6 +1,4 @@
 #pragma once
-
-// ReSharper disable once CppUnusedIncludeDirective
 #include "pre.hpp"
 
 #include "system_headers.hpp"
diff --git a/src/ui/layout_base.cpp b/src/ui/layout_base.cpp
deleted file mode 100644
index 5898a623..00000000
--- a/src/ui/layout_base.cpp
+++ /dev/null
@@ -1,6 +0,0 @@
-#include "layout_base.hpp"
-
-namespace cru::ui
-{
-
-}
diff --git a/src/ui/layout_base.hpp b/src/ui/layout_base.hpp
deleted file mode 100644
index 527d9f98..00000000
--- a/src/ui/layout_base.hpp
+++ /dev/null
@@ -1,102 +0,0 @@
-#pragma once
-
-// ReSharper disable once CppUnusedIncludeDirective
-#include "pre.hpp"
-
-#include "ui_base.hpp"
-
-namespace cru::ui
-{
-    enum class Alignment
-    {
-        Center,
-        Start,
-        End
-    };
-
-    enum class MeasureMode
-    {
-        Exactly,
-        Content,
-        Stretch
-    };
-
-    enum class RectRange
-    {
-        Content, // content excluding padding, border and margin
-        Padding, // only including content and padding
-        HalfBorder, // including content, padding and half border
-        FullBorder, // including content, padding and full border
-        Margin // including content, padding, border and margin
-    };
-
-    struct LayoutSideParams final
-    {
-        constexpr static LayoutSideParams Exactly(const float length, const Alignment alignment = Alignment::Center)
-        {
-            return LayoutSideParams(MeasureMode::Exactly, length, alignment);
-        }
-
-        constexpr static LayoutSideParams Content(const Alignment alignment = Alignment::Center)
-        {
-            return LayoutSideParams(MeasureMode::Content, 0, alignment);
-        }
-
-        constexpr static LayoutSideParams Stretch(const Alignment alignment = Alignment::Center)
-        {
-            return LayoutSideParams(MeasureMode::Stretch, 0, alignment);
-        }
-
-        constexpr LayoutSideParams() = default;
-
-        constexpr explicit LayoutSideParams(const MeasureMode mode, const float length, const Alignment alignment)
-            : length(length), mode(mode), alignment(alignment)
-        {
-
-        }
-
-        constexpr bool Validate() const
-        {
-            if (length < 0.0)
-                return false;
-            if (min.has_value() && min.value() < 0.0)
-                return false;
-            if (max.has_value() && max.value() < 0.0)
-                return false;
-            if (min.has_value() && max.has_value() && min.value() > max.value())
-                return false;
-            return true;
-        }
-
-        // only used in exactly mode, specify the exactly side length of content.
-        float length = 0.0;
-        MeasureMode mode = MeasureMode::Content;
-        Alignment alignment = Alignment::Center;
-
-        // min and max specify the min/max side length of content.
-        // they are used as hint and respect the actual size that content needs.
-        // when mode is exactly, length is coerced into the min-max range.
-        std::optional<float> min = std::nullopt;
-        std::optional<float> max = std::nullopt;
-    };
-
-    struct BasicLayoutParams final
-    {
-        BasicLayoutParams() = default;
-        BasicLayoutParams(const BasicLayoutParams&) = default;
-        BasicLayoutParams(BasicLayoutParams&&) = default;
-        BasicLayoutParams& operator = (const BasicLayoutParams&) = default;
-        BasicLayoutParams& operator = (BasicLayoutParams&&) = default;
-        ~BasicLayoutParams() = default;
-
-        bool Validate() const
-        {
-            return width.Validate() && height.Validate() && margin.Validate() && padding.Validate();
-        }
-
-        LayoutSideParams width;
-        LayoutSideParams height;
-        Thickness padding;
-        Thickness margin;
-    };
-}
diff --git a/src/ui/render/render_object.cpp b/src/ui/render/render_object.cpp
index 0035d1be..0a0e693c 100644
--- a/src/ui/render/render_object.cpp
+++ b/src/ui/render/render_object.cpp
@@ -3,14 +3,6 @@
 #include "cru_debug.hpp"
 
 namespace cru::ui::render {
-void RenderObject::SetRenderHost(IRenderHost* new_render_host) {
-  if (new_render_host == render_host_) return;
-
-  const auto old = render_host_;
-  render_host_ = new_render_host;
-  OnRenderHostChanged(old, new_render_host);
-}
-
 void RenderObject::AddChild(RenderObject* render_object, const int position) {
   if (render_object->GetParent() != nullptr)
     throw std::invalid_argument("Render object already has a parent.");
@@ -52,17 +44,6 @@ void RenderObject::Layout(const Rect& rect) {
   OnLayoutCore(Rect{Point::Zero(), rect.GetSize()});
 }
 
-void RenderObject::OnRenderHostChanged(IRenderHost* old_render_host,
-                                       IRenderHost* new_render_host) {}
-
-void RenderObject::InvalidateRenderHostPaint() const {
-  if (render_host_ != nullptr) render_host_->InvalidatePaint();
-}
-
-void RenderObject::InvalidateRenderHostLayout() const {
-  if (render_host_ != nullptr) render_host_->InvalidateLayout();
-}
-
 void RenderObject::OnParentChanged(RenderObject* old_parent,
                                    RenderObject* new_parent) {}
 
diff --git a/src/ui/render/render_object.hpp b/src/ui/render/render_object.hpp
index aeba1457..34f5dcee 100644
--- a/src/ui/render/render_object.hpp
+++ b/src/ui/render/render_object.hpp
@@ -8,11 +8,11 @@
 #include "base.hpp"
 #include "ui/ui_base.hpp"
 
+namespace cru::ui {
+class Control;
+}
+
 namespace cru::ui::render {
-struct IRenderHost : Interface {
-  virtual void InvalidatePaint() = 0;
-  virtual void InvalidateLayout() = 0;
-};
 
 class RenderObject : public Object {
  protected:
@@ -25,8 +25,8 @@ class RenderObject : public Object {
   RenderObject& operator=(RenderObject&& other) = delete;
   ~RenderObject() override = default;
 
-  IRenderHost* GetRenderHost() const { return render_host_; }
-  void SetRenderHost(IRenderHost* new_render_host);
+  Control* GetAttachedControl() const { return control_; }
+  void SetAttachedControl(Control* new_control) { control_ = new_control; }
 
   RenderObject* GetParent() const { return parent_; }
 
@@ -58,12 +58,6 @@ class RenderObject : public Object {
   virtual RenderObject* HitTest(const Point& point) = 0;
 
  protected:
-  virtual void OnRenderHostChanged(IRenderHost* old_render_host,
-                                   IRenderHost* new_render_host);
-
-  void InvalidateRenderHostPaint() const;
-  void InvalidateRenderHostLayout() const;
-
   virtual void OnParentChanged(RenderObject* old_parent,
                                RenderObject* new_parent);
 
@@ -80,7 +74,7 @@ class RenderObject : public Object {
   void OnLayoutCore(const Rect& rect);
 
  private:
-  IRenderHost* render_host_ = nullptr;
+  Control* control_ = nullptr;
 
   RenderObject* parent_ = nullptr;
   std::vector<RenderObject*> children_{};
diff --git a/src/ui/window.hpp b/src/ui/window.hpp
index d3374684..ac26de22 100644
--- a/src/ui/window.hpp
+++ b/src/ui/window.hpp
@@ -3,276 +3,243 @@
 // ReSharper disable once CppUnusedIncludeDirective
 #include "pre.hpp"
 
-#include "system_headers.hpp"
 #include <map>
 #include <memory>
+#include "system_headers.hpp"
 
 #include "control.hpp"
 #include "events/ui_event.hpp"
 
-namespace cru::graph
-{
-    class WindowRenderTarget;
+namespace cru::graph {
+class WindowRenderTarget;
 }
 
-namespace cru::ui
-{
-    class WindowManager : public Object
-    {
-    public:
-        static WindowManager* GetInstance();
-    private:
-        WindowManager();
-    public:
-        WindowManager(const WindowManager& other) = delete;
-        WindowManager(WindowManager&& other) = delete;
-        WindowManager& operator=(const WindowManager& other) = delete;
-        WindowManager& operator=(WindowManager&& other) = delete;
-        ~WindowManager() override = default;
+namespace cru::ui {
+class WindowManager : public Object {
+ public:
+  static WindowManager* GetInstance();
 
+ private:
+  WindowManager();
 
-        //Get the general window class for creating ordinary window.
-        WindowClass* GetGeneralWindowClass() const
-        {
-            return general_window_class_.get();
-        }
+ public:
+  WindowManager(const WindowManager& other) = delete;
+  WindowManager(WindowManager&& other) = delete;
+  WindowManager& operator=(const WindowManager& other) = delete;
+  WindowManager& operator=(WindowManager&& other) = delete;
+  ~WindowManager() override = default;
 
-        //Register a window newly created.
-        //This function adds the hwnd to hwnd-window map.
-        //It should be called immediately after a window was created.
-        void RegisterWindow(HWND hwnd, Window* window);
+  // Get the general window class for creating ordinary window.
+  WindowClass* GetGeneralWindowClass() const {
+    return general_window_class_.get();
+  }
 
-        //Unregister a window that is going to be destroyed.
-        //This function removes the hwnd from the hwnd-window map.
-        //It should be called immediately before a window is going to be destroyed,
-        void UnregisterWindow(HWND hwnd);
+  // Register a window newly created.
+  // This function adds the hwnd to hwnd-window map.
+  // It should be called immediately after a window was created.
+  void RegisterWindow(HWND hwnd, Window* window);
 
-        //Return a pointer to the Window object related to the HWND or nullptr if the hwnd is not in the map.
-        Window* FromHandle(HWND hwnd);
+  // Unregister a window that is going to be destroyed.
+  // This function removes the hwnd from the hwnd-window map.
+  // It should be called immediately before a window is going to be destroyed,
+  void UnregisterWindow(HWND hwnd);
 
-        std::vector<Window*> GetAllWindows() const;
+  // Return a pointer to the Window object related to the HWND or nullptr if the
+  // hwnd is not in the map.
+  Window* FromHandle(HWND hwnd);
 
-    private:
-        std::unique_ptr<WindowClass> general_window_class_;
-        std::map<HWND, Window*> window_map_;
-    };
+  std::vector<Window*> GetAllWindows() const;
 
+ private:
+  std::unique_ptr<WindowClass> general_window_class_;
+  std::map<HWND, Window*> window_map_;
+};
 
+class Window final : public ContentControl {
+  friend class WindowManager;
 
-    class Window final : public ContentControl
-    {
-        friend class WindowManager;
-    public:
-        static constexpr auto control_type = L"Window";
+ public:
+  static constexpr auto control_type = L"Window";
 
-    public:
-        static Window* CreateOverlapped();
-        static Window* CreatePopup(Window* parent, bool caption = false);
+ public:
+  static Window* CreateOverlapped();
+  static Window* CreatePopup(Window* parent, bool caption = false);
 
-    private:
-        struct tag_overlapped_constructor {};
-        struct tag_popup_constructor {};
+ private:
+  struct tag_overlapped_constructor {};
+  struct tag_popup_constructor {};
 
-        explicit Window(tag_overlapped_constructor);
-        Window(tag_popup_constructor, Window* parent, bool caption);
+  explicit Window(tag_overlapped_constructor);
+  Window(tag_popup_constructor, Window* parent, bool caption);
 
-        void BeforeCreateHwnd();
-        void AfterCreateHwnd(WindowManager* window_manager);
+  void BeforeCreateHwnd();
+  void AfterCreateHwnd(WindowManager* window_manager);
 
-    public:
-        Window(const Window& other) = delete;
-        Window(Window&& other) = delete;
-        Window& operator=(const Window& other) = delete;
-        Window& operator=(Window&& other) = delete;
-        ~Window() override;
+ public:
+  Window(const Window& other) = delete;
+  Window(Window&& other) = delete;
+  Window& operator=(const Window& other) = delete;
+  Window& operator=(Window&& other) = delete;
+  ~Window() override;
 
-    public:
-        StringView GetControlType() const override final;
+ public:
+  StringView GetControlType() const override final;
 
-        void SetDeleteThisOnDestroy(bool value);
+  void SetDeleteThisOnDestroy(bool value);
 
-        //*************** region: handle ***************
+  //*************** region: handle ***************
 
-        //Get the handle of the window. Return null if window is invalid.
-        HWND GetWindowHandle() const
-        {
-            return hwnd_;
-        }
+  // Get the handle of the window. Return null if window is invalid.
+  HWND GetWindowHandle() const { return hwnd_; }
 
-        //Return if the window is still valid, that is, hasn't been closed or destroyed.
-        bool IsWindowValid() const
-        {
-            return hwnd_ != nullptr;
-        }
+  // Return if the window is still valid, that is, hasn't been closed or
+  // destroyed.
+  bool IsWindowValid() const { return hwnd_ != nullptr; }
 
+  //*************** region: window operations ***************
 
-        //*************** region: window operations ***************
+  Window* GetParentWindow() const { return parent_window_; }
 
-        Window* GetParentWindow() const
-        {
-            return parent_window_;
-        }
+  // Close and destroy the window if the window is valid.
+  void Close();
 
-        //Close and destroy the window if the window is valid.
-        void Close();
+  // Send a repaint message to the window's message queue which may make the
+  // window repaint.
+  void InvalidateDraw() override final;
 
-        //Send a repaint message to the window's message queue which may make the window repaint.
-        void InvalidateDraw() override final;
+  // Show the window.
+  void Show();
 
-        //Show the window.
-        void Show();
+  // Hide thw window.
+  void Hide();
 
-        //Hide thw window.
-        void Hide();
+  // Get the client size.
+  Size GetClientSize();
 
-        //Get the client size.
-        Size GetClientSize();
+  // Set the client size and repaint.
+  void SetClientSize(const Size& size);
 
-        //Set the client size and repaint.
-        void SetClientSize(const Size& size);
+  // Get the rect of the window containing frame.
+  // The lefttop of the rect is relative to screen lefttop.
+  Rect GetWindowRect();
 
-        //Get the rect of the window containing frame.
-        //The lefttop of the rect is relative to screen lefttop.
-        Rect GetWindowRect();
+  // Set the rect of the window containing frame.
+  // The lefttop of the rect is relative to screen lefttop.
+  void SetWindowRect(const Rect& rect);
 
-        //Set the rect of the window containing frame.
-        //The lefttop of the rect is relative to screen lefttop.
-        void SetWindowRect(const Rect& rect);
+  // Set the lefttop of the window relative to screen.
+  void SetWindowPosition(const Point& position);
 
-        //Set the lefttop of the window relative to screen.
-        void SetWindowPosition(const Point& position);
+  Point PointToScreen(const Point& point);
 
-        Point PointToScreen(const Point& point);
+  Point PointFromScreen(const Point& point);
 
-        Point PointFromScreen(const Point& point);
+  // Handle the raw window message.
+  // Return true if the message is handled and get the result through "result"
+  // argument. Return false if the message is not handled.
+  bool HandleWindowMessage(HWND hwnd, int msg, WPARAM w_param, LPARAM l_param,
+                           LRESULT& result);
 
-        //Handle the raw window message.
-        //Return true if the message is handled and get the result through "result" argument.
-        //Return false if the message is not handled.
-        bool HandleWindowMessage(HWND hwnd, int msg, WPARAM w_param, LPARAM l_param, LRESULT& result);
+  //*************** region: mouse ***************
 
-        //*************** region: mouse ***************
+  Point GetMousePosition();
 
-        Point GetMousePosition();
+  Control* GetMouseHoverControl() const { return mouse_hover_control_; }
 
-        Control* GetMouseHoverControl() const
-        {
-            return mouse_hover_control_;
-        }
+  //*************** region: layout ***************
 
-        //*************** region: position and size ***************
+  void WindowInvalidateLayout();
 
-        //Always return (0, 0) for a window.
-        Point GetOffset() override final;
+  void Relayout();
 
-        //Get the size of client area for a window.
-        Size GetSize() override final;
+  void SetSizeFitContent(const Size& max_size = Size(1000, 1000));
 
-        //This method has no effect for a window. Use SetClientSize instead.
-        void SetRect(const Rect& size) override final;
+  //*************** region: focus ***************
 
-        //Override. If point is in client area, it is in window.
-        bool IsPointInside(const Point& point) override final;
+  // Request focus for specified control.
+  bool RequestFocusFor(Control* control);
 
-        //*************** region: layout ***************
+  // Get the control that has focus.
+  Control* GetFocusControl();
 
-        void WindowInvalidateLayout();
+  //*************** region: mouse capture ***************
 
-        void Relayout();
+  Control* CaptureMouseFor(Control* control);
+  Control* ReleaseCurrentMouseCapture();
 
-        void SetSizeFitContent(const Size& max_size = Size(1000, 1000));
+  //*************** region: cursor ***************
+  void UpdateCursor();
 
+  //*************** region: debug ***************
+#ifdef CRU_DEBUG_LAYOUT
+  bool IsDebugLayout() const { return debug_layout_; }
 
-        //*************** region: focus ***************
+  void SetDebugLayout(bool value);
+#endif
 
-        //Request focus for specified control.
-        bool RequestFocusFor(Control* control);
+ public:
+  //*************** region: events ***************
+  Event<events::UiEventArgs> activated_event;
+  Event<events::UiEventArgs> deactivated_event;
 
-        //Get the control that has focus.
-        Control* GetFocusControl();
+  Event<events::WindowNativeMessageEventArgs> native_message_event;
 
+ private:
+  //*************** region: native operations ***************
 
-        //*************** region: mouse capture ***************
+  // Get the client rect in pixel.
+  RECT GetClientRectPixel();
 
-        Control* CaptureMouseFor(Control* control);
-        Control* ReleaseCurrentMouseCapture();
+  bool IsMessageInQueue(UINT message);
 
-        
-        //*************** region: cursor ***************
-        void UpdateCursor();
+  void SetCursorInternal(HCURSOR cursor);
 
-        //*************** region: debug ***************
-#ifdef CRU_DEBUG_LAYOUT
-        bool IsDebugLayout() const
-        {
-            return debug_layout_;
-        }
+  //*************** region: native messages ***************
 
-        void SetDebugLayout(bool value);
-#endif
- 
-    public:
-        //*************** region: events ***************
-        Event<events::UiEventArgs> activated_event;
-        Event<events::UiEventArgs> deactivated_event;
-
-        Event<events::WindowNativeMessageEventArgs> native_message_event;
- 
-    private:
-        //*************** region: native operations ***************
- 
-        //Get the client rect in pixel.
-        RECT GetClientRectPixel();
- 
-        bool IsMessageInQueue(UINT message);
- 
-        void SetCursorInternal(HCURSOR cursor);
- 
- 
-        //*************** region: native messages ***************
- 
-        void OnDestroyInternal();
-        void OnPaintInternal();
-        void OnResizeInternal(int new_width, int new_height);
- 
-        void OnSetFocusInternal();
-        void OnKillFocusInternal();
- 
-        void OnMouseMoveInternal(POINT point);
-        void OnMouseLeaveInternal();
-        void OnMouseDownInternal(MouseButton button, POINT point);
-        void OnMouseUpInternal(MouseButton button, POINT point);
-
-        void OnMouseWheelInternal(short delta, POINT point);
-        void OnKeyDownInternal(int virtual_code);
-        void OnKeyUpInternal(int virtual_code);
-        void OnCharInternal(wchar_t c);
- 
-        void OnActivatedInternal();
-        void OnDeactivatedInternal();
- 
-        //*************** region: event dispatcher helper ***************
- 
-        void DispatchMouseHoverControlChangeEvent(Control* old_control, Control * new_control, const Point& point);
-
-    private:
-        bool delete_this_on_destroy_ = true;
-
-        HWND hwnd_ = nullptr;
-        Window* parent_window_ = nullptr;
-        std::shared_ptr<graph::WindowRenderTarget> render_target_{};
- 
-        Control* mouse_hover_control_ = nullptr;
- 
-        bool window_focus_ = false;
-        Control* focus_control_ = this; // "focus_control_" can't be nullptr
- 
-        Control* mouse_capture_control_ = nullptr;
-
-        bool is_layout_invalid_ = false;
+  void OnDestroyInternal();
+  void OnPaintInternal();
+  void OnResizeInternal(int new_width, int new_height);
+
+  void OnSetFocusInternal();
+  void OnKillFocusInternal();
+
+  void OnMouseMoveInternal(POINT point);
+  void OnMouseLeaveInternal();
+  void OnMouseDownInternal(MouseButton button, POINT point);
+  void OnMouseUpInternal(MouseButton button, POINT point);
+
+  void OnMouseWheelInternal(short delta, POINT point);
+  void OnKeyDownInternal(int virtual_code);
+  void OnKeyUpInternal(int virtual_code);
+  void OnCharInternal(wchar_t c);
+
+  void OnActivatedInternal();
+  void OnDeactivatedInternal();
+
+  //*************** region: event dispatcher helper ***************
+
+  void DispatchMouseHoverControlChangeEvent(Control* old_control,
+                                            Control* new_control,
+                                            const Point& point);
+
+ private:
+  bool delete_this_on_destroy_ = true;
+
+  HWND hwnd_ = nullptr;
+  Window* parent_window_ = nullptr;
+  std::shared_ptr<graph::WindowRenderTarget> render_target_{};
+
+  Control* mouse_hover_control_ = nullptr;
+
+  bool window_focus_ = false;
+  Control* focus_control_ = this;  // "focus_control_" can't be nullptr
+
+  Control* mouse_capture_control_ = nullptr;
+
+  bool is_layout_invalid_ = false;
 
 #ifdef CRU_DEBUG_LAYOUT
-        bool debug_layout_ = false;
+  bool debug_layout_ = false;
 #endif
-    };
-}
+};
+}  // namespace cru::ui