1 files changed, 188 insertions, 0 deletions
diff --git a/src/ui/layout_base.hpp b/src/ui/layout_base.hpp
new file mode 100644
index 00000000..1c35f0b7
--- /dev/null
+++ b/src/ui/layout_base.hpp
@@ -0,0 +1,188 @@
+#pragma once
+
+#include <unordered_set>
+
+#include "base.hpp"
+#include "ui_base.hpp"
+
+namespace cru::ui
+{
+    class Control;
+    class Window;
+
+    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 Thickness
+    {
+        constexpr static Thickness Zero()
+        {
+            return Thickness(0);
+        }
+
+        constexpr Thickness() : Thickness(0) { }
+
+        constexpr explicit Thickness(const float width)
+            : left(width), top(width), right(width), bottom(width) { }
+
+        constexpr explicit Thickness(const float horizontal, const float vertical)
+            : left(horizontal), top(vertical), right(horizontal), bottom(vertical) { }
+
+        constexpr Thickness(const float left, const float top, const float right, const float bottom)
+            : left(left), top(top), right(right), bottom(bottom) { }
+
+        float GetHorizontalTotal() const
+        {
+            return left + right;
+        }
+
+        float GetVerticalTotal() const
+        {
+            return top + bottom;
+        }
+
+        float Validate() const
+        {
+            return left >= 0.0 && top >= 0.0 && right >= 0.0 && bottom >= 0.0;
+        }
+
+        float left;
+        float top;
+        float right;
+        float bottom;
+    };
+
+    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;
+    };
+
+
+    class LayoutManager : public Object
+    {
+    public:
+        static LayoutManager* GetInstance();
+
+    public:
+        LayoutManager() = default;
+        LayoutManager(const LayoutManager& other) = delete;
+        LayoutManager(LayoutManager&& other) = delete;
+        LayoutManager& operator=(const LayoutManager& other) = delete;
+        LayoutManager& operator=(LayoutManager&& other) = delete;
+        ~LayoutManager() override = default;
+
+
+        //*************** region: position cache ***************
+
+        //Mark position cache of the control and its descendants invalid,
+        //(which is saved as an auto-managed list internal)
+        //and send a message to refresh them.
+        void InvalidateControlPositionCache(Control* control);
+
+        //Refresh position cache of the control and its descendants whose cache
+        //has been marked as invalid.
+        void RefreshInvalidControlPositionCache();
+
+        //Refresh position cache of the control and its descendants immediately.
+        static void RefreshControlPositionCache(Control* control);
+
+
+        //*************** region: layout ***************
+
+        void InvalidateWindowLayout(Window* window);
+
+        void RefreshInvalidWindowLayout();
+
+    private:
+        static void RefreshControlPositionCacheInternal(Control* control, const Point& parent_lefttop_absolute);
+
+    private:
+        std::unordered_set<Control*> cache_invalid_controls_;
+        std::unordered_set<Window*> layout_invalid_windows_;
+    };
+}