2 files changed, 107 insertions, 0 deletions
diff --git a/CruUI/ui/controls/margin_container.cpp b/CruUI/ui/controls/margin_container.cpp
new file mode 100644
index 00000000..8f9101b2
--- /dev/null
+++ b/CruUI/ui/controls/margin_container.cpp
@@ -0,0 +1,63 @@
+#include "margin_container.h"
+
+namespace cru::ui::controls
+{
+    inline float AtLeast0(const float value)
+    {
+        return value < 0 ? 0 : value;
+    }
+
+    inline Size AtLeast0(const Size& size)
+    {
+        return Size(AtLeast0(size.width), AtLeast0(size.height));
+    }
+
+    MarginContainer::MarginContainer(const Thickness& margin)
+        : Control(true), margin_(margin)
+    {
+    }
+
+    void MarginContainer::SetMargin(const Thickness& margin)
+    {
+        margin_ = margin;
+        Relayout();
+    }
+
+    Size MarginContainer::OnMeasure(const Size& available_size)
+    {
+        const auto margin_size = Size(margin_.left + margin_.right, margin_.top + margin_.bottom);
+        const auto coerced_available_size = AtLeast0(available_size - margin_size);
+        return Control::OnMeasure(coerced_available_size) + margin_size;
+    }
+
+    void MarginContainer::OnLayout(const Rect& rect)
+    {
+        const auto anchor = Point(margin_.left, margin_.top);
+        const auto margin_size = Size(margin_.left + margin_.right, margin_.top + margin_.bottom);
+        ForeachChild([anchor, margin_size, rect](Control* control)
+        {
+            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(anchor.x, layout_params->width.alignment, rect.width - margin_size.width, size.width),
+                calculate_anchor(anchor.y, layout_params->height.alignment, rect.height - margin_size.height, size.height)
+            ), size));
+        });
+    }
+}
diff --git a/CruUI/ui/controls/margin_container.h b/CruUI/ui/controls/margin_container.h
new file mode 100644
index 00000000..0eafc40e
--- /dev/null
+++ b/CruUI/ui/controls/margin_container.h
@@ -0,0 +1,44 @@
+#pragma once
+
+#include <initializer_list>
+
+#include "ui/control.h"
+
+namespace cru::ui::controls
+{
+    class MarginContainer : public Control
+    {
+    public:
+        static MarginContainer* Create(const Thickness& margin = Thickness::Zero(), const std::initializer_list<Control*>& children = std::initializer_list<Control*>())
+        {
+            const auto margin_container = new MarginContainer(margin);
+            for (const auto control : children)
+                margin_container->AddChild(control);
+            return margin_container;
+        }
+
+    protected:
+        explicit MarginContainer(const Thickness& margin);
+
+    public:
+        MarginContainer(const MarginContainer& other) = delete;
+        MarginContainer(MarginContainer&& other) = delete;
+        MarginContainer& operator=(const MarginContainer& other) = delete;
+        MarginContainer& operator=(MarginContainer&& other) = delete;
+        ~MarginContainer() override = default;
+
+        Thickness GetMargin() const
+        {
+            return margin_;
+        }
+
+        void SetMargin(const Thickness& margin);
+
+    protected:
+        Size OnMeasure(const Size& available_size) override;
+        void OnLayout(const Rect& rect) override;
+
+    private:
+        Thickness margin_;
+    };
+}