Done.

14 files changed, 118 insertions, 64 deletions

diff --git a/src/ui/controls/button.cpp b/src/ui/controls/button.cpp
index a9f101f8..d4537f54 100644
--- a/src/ui/controls/button.cpp
+++ b/src/ui/controls/button.cpp
@@ -5,7 +5,7 @@
 
 namespace cru::ui::controls
 {
-    Button::Button() : Control(true),
+    Button::Button() :
         normal_border_{UiManager::GetInstance()->GetPredefineResources()->button_normal_border},
         pressed_border_{UiManager::GetInstance()->GetPredefineResources()->button_press_border}
     {
diff --git a/src/ui/controls/button.hpp b/src/ui/controls/button.hpp
index c53f7ed9..82694fe8 100644
--- a/src/ui/controls/button.hpp
+++ b/src/ui/controls/button.hpp
@@ -9,16 +9,15 @@
 
 namespace cru::ui::controls
 {
-    class Button : public Control
+    class Button : public SingleChildControl
     {
     public:
         static constexpr auto control_type = L"Button";
 
-        static Button* Create(const std::initializer_list<Control*>& children = std::initializer_list<Control*>())
+        static Button* Create(Control* child = nullptr)
         {
             const auto button = new Button();
-            for (const auto control : children)
-                button->AddChild(control);
+            button->SetChild(child);
             return button;
         }
 
diff --git a/src/ui/controls/frame_layout.cpp b/src/ui/controls/frame_layout.cpp
index 32d25edc..d68bc338 100644
--- a/src/ui/controls/frame_layout.cpp
+++ b/src/ui/controls/frame_layout.cpp
@@ -2,10 +2,7 @@
 
 namespace cru::ui::controls
 {
-    FrameLayout::FrameLayout() : Control(true)
-    {
-
-    }
+    FrameLayout::FrameLayout() = default;
 
     FrameLayout::~FrameLayout() = default;
 
@@ -13,4 +10,61 @@ namespace cru::ui::controls
     {
         return control_type;
     }
+
+    Size FrameLayout::OnMeasureContent(const Size& available_size, const AdditionalMeasureInfo& additional_info)
+    {
+        auto max_child_size = Size::Zero();
+        for (auto control: GetChildren())
+        {
+            control->Measure(available_size, additional_info);
+            const auto&& size = control->GetDesiredSize();
+            if (max_child_size.width < size.width)
+                max_child_size.width = size.width;
+            if (max_child_size.height < size.height)
+                max_child_size.height = size.height;
+        }
+
+        // coerce size fro stretch.
+        for (auto control: GetChildren())
+        {
+            auto size = control->GetDesiredSize();
+            const auto layout_params = control->GetLayoutParams();
+            if (layout_params->width.mode == MeasureMode::Stretch)
+                size.width = max_child_size.width;
+            if (layout_params->height.mode == MeasureMode::Stretch)
+                size.height = max_child_size.height;
+            control->SetDesiredSize(size);
+        }
+
+        return max_child_size;
+    }
+
+    void FrameLayout::OnLayoutContent(const Rect& rect, const AdditionalLayoutInfo& additional_info)
+    {
+        for (auto control: GetChildren())
+        {
+            const auto layout_params = control->GetLayoutParams();
+            const auto size = control->GetDesiredSize();
+
+            auto&& calculate_anchor = [](const float anchor, const Alignment alignment, const float layout_length, const float control_length) -> float
+            {
+                switch (alignment)
+                {
+                case Alignment::Center:
+                    return anchor + (layout_length - control_length) / 2;
+                case Alignment::Start:
+                    return anchor;
+                case Alignment::End:
+                    return anchor + layout_length - control_length;
+                default:
+                    UnreachableCode();
+                }
+            };
+
+            control->Layout(Rect(Point(
+                calculate_anchor(rect.left, layout_params->width.alignment, rect.width, size.width),
+                calculate_anchor(rect.top, layout_params->height.alignment, rect.height, size.height)
+            ), size), additional_info);
+        }
+    }
 }
diff --git a/src/ui/controls/frame_layout.hpp b/src/ui/controls/frame_layout.hpp
index 45971584..c2d6f0d6 100644
--- a/src/ui/controls/frame_layout.hpp
+++ b/src/ui/controls/frame_layout.hpp
@@ -9,7 +9,7 @@
 
 namespace cru::ui::controls
 {
-    class FrameLayout : public Control
+    class FrameLayout : public MultiChildControl
     {
     public:
         static constexpr auto control_type = L"FrameLayout";
@@ -32,5 +32,9 @@ namespace cru::ui::controls
         ~FrameLayout() override;
 
         StringView GetControlType() const override final;
+
+    protected:
+        Size OnMeasureContent(const Size& available_size, const AdditionalMeasureInfo& additional_info) override;
+        void OnLayoutContent(const Rect& rect, const AdditionalLayoutInfo& additional_info) override;
     };
 }
diff --git a/src/ui/controls/linear_layout.cpp b/src/ui/controls/linear_layout.cpp
index 2b8f3e43..d3fdc9b5 100644
--- a/src/ui/controls/linear_layout.cpp
+++ b/src/ui/controls/linear_layout.cpp
@@ -7,7 +7,7 @@
 namespace cru::ui::controls
 {
     LinearLayout::LinearLayout(const Orientation orientation)
-        : Control(true), orientation_(orientation)
+        : orientation_(orientation)
     {
 
     }
@@ -27,7 +27,7 @@ namespace cru::ui::controls
 
         // First measure Content and Exactly and count Stretch.
         if (orientation_ == Orientation::Horizontal)
-            for(auto control: GetChildren())
+            for(auto control: GetInternalChildren())
             {
                 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: GetChildren())
+            for(auto control: GetInternalChildren())
             {
                 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 : GetChildren())
+            for (auto control : GetInternalChildren())
             {
                 if (control->GetLayoutParams()->height.mode == MeasureMode::Stretch)
                 {
@@ -93,7 +93,7 @@ namespace cru::ui::controls
         }
         else
         {
-            for (auto control : GetChildren())
+            for (auto control : GetInternalChildren())
             {
                 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: GetChildren())
+        for(auto control: GetInternalChildren())
         {
             const auto layout_params = control->GetLayoutParams();
             const auto size = control->GetDesiredSize();
diff --git a/src/ui/controls/linear_layout.hpp b/src/ui/controls/linear_layout.hpp
index 96becc6f..ceb1c4e6 100644
--- a/src/ui/controls/linear_layout.hpp
+++ b/src/ui/controls/linear_layout.hpp
@@ -9,7 +9,7 @@ namespace cru::ui::controls
 {
     // Min length of main side in layout params is of no meaning.
     // All children will layout from start and redundant length is blank.
-    class LinearLayout : public Control
+    class LinearLayout : public MultiChildControl
     {
     public:
         static constexpr auto control_type = L"LinearLayout";
diff --git a/src/ui/controls/list_item.cpp b/src/ui/controls/list_item.cpp
index 8234da30..e0ca28a9 100644
--- a/src/ui/controls/list_item.cpp
+++ b/src/ui/controls/list_item.cpp
@@ -5,7 +5,7 @@
 
 namespace cru::ui::controls
 {
-    ListItem::ListItem() : Control(true)
+    ListItem::ListItem()
     {
         const auto predefine_resources = UiManager::GetInstance()->GetPredefineResources();
 
diff --git a/src/ui/controls/list_item.hpp b/src/ui/controls/list_item.hpp
index e150efbb..a50b2496 100644
--- a/src/ui/controls/list_item.hpp
+++ b/src/ui/controls/list_item.hpp
@@ -10,7 +10,7 @@
 
 namespace cru::ui::controls
 {
-    class ListItem : public Control
+    class ListItem : public SingleChildControl
     {
     public:
         static constexpr auto control_type = L"ListItem";
@@ -30,11 +30,10 @@ namespace cru::ui::controls
         };
 
     public:
-        static ListItem* Create(const std::initializer_list<Control*>& children)
+        static ListItem* Create(Control* child = nullptr)
         {
             const auto list_item = new ListItem();
-            for (auto control : children)
-                list_item->AddChild(control);
+            list_item->SetChild(child);
             return list_item;
         }
 
diff --git a/src/ui/controls/popup_menu.cpp b/src/ui/controls/popup_menu.cpp
index 7f4b9d08..fbe9039d 100644
--- a/src/ui/controls/popup_menu.cpp
+++ b/src/ui/controls/popup_menu.cpp
@@ -26,7 +26,7 @@ namespace cru::ui::controls
             auto list_item = CreateWithLayout<ListItem>(
                 LayoutSideParams::Stretch(Alignment::Center),
                 LayoutSideParams::Content(Alignment::Start),
-                ControlList{ text_block }
+                text_block
             );
 
             list_item->mouse_click_event.bubble.AddHandler([popup, action](events::MouseButtonEventArgs& args)
@@ -48,7 +48,7 @@ namespace cru::ui::controls
         for (const auto& item : items)
             menu->AddChild(create_menu_item(item.first, item.second));
 
-        popup->AddChild(menu);
+        popup->SetChild(menu);
 
         popup->SetSizeFitContent();
         popup->SetWindowPosition(anchor);
diff --git a/src/ui/controls/scroll_control.cpp b/src/ui/controls/scroll_control.cpp
index 8358abc5..ae99f414 100644
--- a/src/ui/controls/scroll_control.cpp
+++ b/src/ui/controls/scroll_control.cpp
@@ -3,7 +3,6 @@
 #include <limits>
 
 #include "cru_debug.hpp"
-#include "format.hpp"
 #include "ui/convert_util.hpp"
 #include "exception.hpp"
 #include "math_util.hpp"
@@ -14,7 +13,7 @@ namespace cru::ui::controls
 {
     constexpr auto scroll_bar_width = 15.0f;
 
-    ScrollControl::ScrollControl(const bool container) : Control(container)
+    ScrollControl::ScrollControl(const bool container)
     {
         SetClipContent(true);
 
@@ -245,38 +244,25 @@ namespace cru::ui::controls
             available_size_for_children.height = std::numeric_limits<float>::max();
         }
 
-        auto max_child_size = Size::Zero();
-        for (auto control: GetChildren())
-        {
-            control->Measure(available_size_for_children, AdditionalMeasureInfo{false, false});
-            const auto&& size = control->GetDesiredSize();
-            if (max_child_size.width < size.width)
-                max_child_size.width = size.width;
-            if (max_child_size.height < size.height)
-                max_child_size.height = size.height;
-        }
+        const auto child = GetChild();
 
-        // coerce size for stretch.
-        for (auto control: GetChildren())
+        auto size = Size::Zero();
+        if (child)
         {
-            auto size = control->GetDesiredSize();
-            const auto child_layout_params = control->GetLayoutParams();
-            if (child_layout_params->width.mode == MeasureMode::Stretch)
-                size.width = max_child_size.width;
-            if (child_layout_params->height.mode == MeasureMode::Stretch)
-                size.height = max_child_size.height;
-            control->SetDesiredSize(size);
+            child->Measure(available_size_for_children, AdditionalMeasureInfo{false, false});
+            size = child->GetDesiredSize();
         }
 
-        auto result = max_child_size;
+
+        auto result = size;
         if (IsHorizontalScrollEnabled())
         {
-            SetViewWidth(max_child_size.width);
+            SetViewWidth(size.width);
             result.width = available_size.width;
         }
         if (IsVerticalScrollEnabled())
         {
-            SetViewHeight(max_child_size.height);
+            SetViewHeight(size.height);
             result.height = available_size.height;
         }
 
@@ -292,18 +278,31 @@ namespace cru::ui::controls
         if (IsVerticalScrollEnabled())
             layout_rect.height = GetViewHeight();
 
-        for (auto control: GetChildren())
+        const auto child = GetChild();
+
+        if (child)
         {
-            const auto size = control->GetDesiredSize();
-            // Ignore alignment, always center aligned.
-            auto&& calculate_anchor = [](const float anchor, const float layout_length, const float control_length, const float offset) -> float
+            const auto layout_params = child->GetLayoutParams();
+            const auto size = child->GetDesiredSize();
+
+            auto&& calculate_anchor = [](const float anchor, const Alignment alignment, const float layout_length, const float control_length) -> float
             {
-                return anchor + (layout_length - control_length) / 2 - offset;
+                switch (alignment)
+                {
+                case Alignment::Center:
+                    return anchor + (layout_length - control_length) / 2;
+                case Alignment::Start:
+                    return anchor;
+                case Alignment::End:
+                    return anchor + layout_length - control_length;
+                default:
+                    UnreachableCode();
+                }
             };
 
-            control->Layout(Rect(Point(
-                calculate_anchor(rect.left, layout_rect.width, size.width, offset_x_),
-                calculate_anchor(rect.top, layout_rect.height, size.height, offset_y_)
+            child->Layout(Rect(Point(
+                IsHorizontalScrollEnabled() ? layout_rect.left + offset_x_ : calculate_anchor(layout_rect.left, layout_params->width.alignment, layout_rect.width, size.width),
+                IsVerticalScrollEnabled() ? layout_rect.top + offset_y_ : calculate_anchor(layout_rect.top, layout_params->height.alignment, layout_rect.height, size.height)
             ), size), additional_info);
         }
     }
@@ -327,7 +326,7 @@ namespace cru::ui::controls
 
         if (update_children)
         {
-            for (auto child : GetChildren())
+            if (const auto child = GetChild())
             {
                 const auto old_position = child->GetPositionRelative();
                 child->SetRect(Rect(Point(
diff --git a/src/ui/controls/scroll_control.hpp b/src/ui/controls/scroll_control.hpp
index db29b141..7138add6 100644
--- a/src/ui/controls/scroll_control.hpp
+++ b/src/ui/controls/scroll_control.hpp
@@ -17,7 +17,7 @@ namespace cru::ui::controls
     // Done: API
     // Done: ScrollBar
     // Done: MouseEvent
-    class ScrollControl : public Control
+    class ScrollControl : public SingleChildControl
     {
     private:
         struct ScrollBarInfo
@@ -40,11 +40,10 @@ namespace cru::ui::controls
             Always
         };
 
-        static ScrollControl* Create(const std::initializer_list<Control*>& children = std::initializer_list<Control*>{})
+        static ScrollControl* Create(Control* child = nullptr)
         {
             const auto control = new ScrollControl(true);
-            for (auto child : children)
-                control->AddChild(child);
+            control->SetChild(child);
             return control;
         }
 
diff --git a/src/ui/controls/text_control.cpp b/src/ui/controls/text_control.cpp
index 6412eec9..e53d3c69 100644
--- a/src/ui/controls/text_control.cpp
+++ b/src/ui/controls/text_control.cpp
@@ -44,7 +44,7 @@ namespace cru::ui::controls
     }
 
     TextControl::TextControl(const Microsoft::WRL::ComPtr<IDWriteTextFormat>& init_text_format,
-        const Microsoft::WRL::ComPtr<ID2D1Brush>& init_brush) : Control(false)
+        const Microsoft::WRL::ComPtr<ID2D1Brush>& init_brush)
     {
         text_format_ = init_text_format;
 
diff --git a/src/ui/controls/text_control.hpp b/src/ui/controls/text_control.hpp
index 9b83f4bb..58d48c13 100644
--- a/src/ui/controls/text_control.hpp
+++ b/src/ui/controls/text_control.hpp
@@ -7,7 +7,7 @@
 
 namespace cru::ui::controls
 {
-    class TextControl : public Control
+    class TextControl : public NoChildControl
     {
     protected:
         TextControl(
diff --git a/src/ui/controls/toggle_button.hpp b/src/ui/controls/toggle_button.hpp
index 091f908a..dee655d4 100644
--- a/src/ui/controls/toggle_button.hpp
+++ b/src/ui/controls/toggle_button.hpp
@@ -7,7 +7,7 @@
 
 namespace cru::ui::controls
 {
-    class ToggleButton : public Control
+    class ToggleButton : public NoChildControl
     {
     public:
         static constexpr auto control_type = L"ToggleButton";