5 files changed, 76 insertions, 4 deletions
diff --git a/src/theme_builder/components/MainWindow.cpp b/src/theme_builder/components/MainWindow.cpp
index 3d521d44..d52193f1 100644
--- a/src/theme_builder/components/MainWindow.cpp
+++ b/src/theme_builder/components/MainWindow.cpp
@@ -1,4 +1,7 @@
 #include "MainWindow.hpp"
+#include "cru/ui/Base.hpp"
+#include "cru/ui/controls/StackLayout.hpp"
+#include "cru/ui/controls/TextBlock.hpp"
 
 namespace cru::theme_builder {
 using namespace cru::ui;
@@ -8,6 +11,19 @@ using namespace cru::platform::gui;
 MainWindow::MainWindow() {
   window_ = Window::Create();
   window_->GetNativeWindow()->SetTitle(u"CruUI Theme Builder");
+
+  main_layout_ = FlexLayout::Create();
+  main_layout_->SetFlexDirection(FlexDirection::Horizontal);
+  window_->AddChild(main_layout_, 0);
+
+  preview_layout_ = StackLayout::Create();
+  main_layout_->AddChild(preview_layout_, 0);
+
+  preview_button_ = Button::Create();
+  preview_button_->SetChild(TextBlock::Create(u"Preview"));
+  preview_layout_->AddChild(preview_button_, 0);
+  preview_layout_->SetChildLayoutData(
+      0, StackChildLayoutData{Alignment::Center, Alignment::Center});
 }
 
 MainWindow::~MainWindow() { delete window_; }
diff --git a/src/theme_builder/components/MainWindow.hpp b/src/theme_builder/components/MainWindow.hpp
index fd7f7996..ef37b7a2 100644
--- a/src/theme_builder/components/MainWindow.hpp
+++ b/src/theme_builder/components/MainWindow.hpp
@@ -1,5 +1,8 @@
 #pragma once
 #include "cru/ui/components/Component.hpp"
+#include "cru/ui/controls/Button.hpp"
+#include "cru/ui/controls/FlexLayout.hpp"
+#include "cru/ui/controls/StackLayout.hpp"
 #include "cru/ui/controls/Window.hpp"
 
 namespace cru::theme_builder {
@@ -18,5 +21,8 @@ class MainWindow : public ui::components::Component {
 
  private:
   ui::controls::Window* window_;
+  ui::controls::FlexLayout* main_layout_;
+  ui::controls::StackLayout* preview_layout_;
+  ui::controls::Button* preview_button_;
 };
 }  // namespace cru::theme_builder
diff --git a/src/ui/controls/RootControl.cpp b/src/ui/controls/RootControl.cpp
index 7edf4a1d..a7366155 100644
--- a/src/ui/controls/RootControl.cpp
+++ b/src/ui/controls/RootControl.cpp
@@ -3,6 +3,7 @@
 #include "cru/common/Base.hpp"
 #include "cru/platform/gui/Base.hpp"
 #include "cru/platform/gui/Window.hpp"
+#include "cru/ui/Base.hpp"
 #include "cru/ui/host/WindowHost.hpp"
 #include "cru/ui/render/Base.hpp"
 #include "cru/ui/render/StackLayoutRenderObject.hpp"
@@ -15,6 +16,8 @@ RootControl::RootControl(Control* attached_control)
     : attached_control_(attached_control) {
   render_object_ = std::make_unique<render::StackLayoutRenderObject>();
   render_object_->SetAttachedControl(this);
+  render_object_->SetDefaultHorizontalAlignment(Alignment::Stretch);
+  render_object_->SetDefaultVertialAlignment(Alignment::Stretch);
   SetContainerRenderObject(render_object_.get());
   window_host_ = std::make_unique<host::WindowHost>(this);
 }
diff --git a/src/ui/controls/StackLayout.cpp b/src/ui/controls/StackLayout.cpp
index 89968571..667e6755 100644
--- a/src/ui/controls/StackLayout.cpp
+++ b/src/ui/controls/StackLayout.cpp
@@ -17,4 +17,13 @@ StackLayout::~StackLayout() = default;
 render::RenderObject* StackLayout::GetRenderObject() const {
   return render_object_.get();
 }
+
+const StackChildLayoutData& StackLayout::GetChildLayoutData(Index position) {
+  return render_object_->GetChildLayoutData(position);
+}
+
+void StackLayout::SetChildLayoutData(Index position,
+                                     StackChildLayoutData data) {
+  render_object_->SetChildLayoutData(position, std::move(data));
+}
 }  // namespace cru::ui::controls
diff --git a/src/ui/render/StackLayoutRenderObject.cpp b/src/ui/render/StackLayoutRenderObject.cpp
index 753612af..1b6cc9fc 100644
--- a/src/ui/render/StackLayoutRenderObject.cpp
+++ b/src/ui/render/StackLayoutRenderObject.cpp
@@ -7,6 +7,17 @@
 #include <algorithm>
 
 namespace cru::ui::render {
+void StackLayoutRenderObject::SetDefaultHorizontalAlignment(
+    Alignment alignment) {
+  default_horizontal_alignment_ = alignment;
+  InvalidateLayout();
+}
+
+void StackLayoutRenderObject::SetDefaultVertialAlignment(Alignment alignment) {
+  default_vertical_alignment_ = alignment;
+  InvalidateLayout();
+}
+
 Size StackLayoutRenderObject::OnMeasureContent(
     const MeasureRequirement& requirement, const MeasureSize& preferred_size) {
   Size child_max_size;
@@ -22,6 +33,31 @@ Size StackLayoutRenderObject::OnMeasureContent(
   child_max_size = Max(preferred_size.GetSizeOr0(), child_max_size);
   child_max_size = Max(requirement.min.GetSizeOr0(), child_max_size);
 
+  for (Index i = 0; i < GetChildren().size(); ++i) {
+    auto child_layout_data = GetChildLayoutData(i);
+    auto horizontal_stretch =
+        child_layout_data.horizontal.value_or(default_horizontal_alignment_) ==
+        Alignment::Stretch;
+    auto vertical_stretch =
+        child_layout_data.vertical.value_or(default_vertical_alignment_) ==
+        Alignment::Stretch;
+    if (horizontal_stretch || vertical_stretch) {
+      auto child = GetChildren()[i];
+      auto child_size = child->GetSize();
+      MeasureRequirement child_requirement(child_size, child_size);
+      if (horizontal_stretch) {
+        child_requirement.min.width = child_requirement.max.width =
+            child_max_size.width;
+      }
+
+      if (vertical_stretch) {
+        child_requirement.min.height = child_requirement.max.height =
+            child_max_size.height;
+      }
+      child->Measure(child_requirement, MeasureSize::NotSpecified());
+    }
+  }
+
   return child_max_size;
 }
 
@@ -34,10 +70,12 @@ void StackLayoutRenderObject::OnLayoutContent(const Rect& content_rect) {
     const auto& layout_data = GetChildLayoutData(i);
     const auto& size = child->GetSize();
     child->Layout(Point{
-        CalculateAnchorByAlignment(layout_data.horizontal, content_rect.left,
-                                   content_rect.width, size.width),
-        CalculateAnchorByAlignment(layout_data.vertical, content_rect.top,
-                                   content_rect.height, size.height)});
+        CalculateAnchorByAlignment(
+            layout_data.horizontal.value_or(default_horizontal_alignment_),
+            content_rect.left, content_rect.width, size.width),
+        CalculateAnchorByAlignment(
+            layout_data.vertical.value_or(default_vertical_alignment_),
+            content_rect.top, content_rect.height, size.height)});
   }
 }
 }  // namespace cru::ui::render