1 files changed, 36 insertions, 12 deletions

diff --git a/include/cru/ui/render/RenderObject.hpp b/include/cru/ui/render/RenderObject.hpp
index 7cfa3883..9de2cc27 100644
--- a/include/cru/ui/render/RenderObject.hpp
+++ b/include/cru/ui/render/RenderObject.hpp
@@ -1,12 +1,22 @@
 #pragma once
 #include "Base.hpp"
 
+#include "MeasureRequirement.hpp"
 #include "cru/common/Event.hpp"
 
 namespace cru::ui::render {
+
 // Render object will not destroy its children when destroyed. Control must
 // manage lifecycle of its render objects. Since control will destroy its
 // children when destroyed, render objects will be destroyed along with it.
+//
+// To write a custom RenderObject, override following methods:
+// public:
+//  void Draw(platform::graph::IPainter* painter) override;
+//  RenderObject* HitTest(const Point& point) override;
+// protected:
+//  Size OnMeasureContent(const MeasureRequirement& requirement) override;
+//  void OnLayoutContent(const Rect& content_rect) override;
 class RenderObject : public Object {
   friend WindowRenderObject;
 
@@ -41,12 +51,12 @@ class RenderObject : public Object {
   void AddChild(RenderObject* render_object, Index position);
   void RemoveChild(Index position);
 
+  // Offset from parent's lefttop to lefttop of this render object. Margin is
+  // accounted for.
   Point GetOffset() const { return offset_; }
-  void SetOffset(const Point& offset) { offset_ = offset; }
+  Size GetSize() const { return size_; }
   Point GetTotalOffset() const;
   Point FromRootToContent(const Point& point) const;
-  Size GetSize() const { return size_; }
-  void SetSize(const Size& size) { size_ = size; }
 
   Thickness GetMargin() const { return margin_; }
   void SetMargin(const Thickness& margin) { margin_ = margin; }
@@ -54,16 +64,16 @@ class RenderObject : public Object {
   Thickness GetPadding() const { return padding_; }
   void SetPadding(const Thickness& padding) { padding_ = padding; }
 
-  Size GetPreferredSize() const { return preferred_size_; }
-  void SetPreferredSize(const Size& preferred_size) {
-    preferred_size_ = preferred_size;
-  }
+  Size GetMeasuredSize() const { return measured_size_; }
 
-  void Measure(const Size& available_size);
+  void Measure(const MeasureRequirement& requirement);
+  // Size of rect must not be negative.
   void Layout(const Rect& rect);
 
   virtual void Draw(platform::graph::IPainter* painter) = 0;
 
+  // Param point must be relative the lefttop of render object including margin.
+  // Add offset before pass point to children.
   virtual RenderObject* HitTest(const Point& point) = 0;
 
  public:
@@ -82,9 +92,23 @@ class RenderObject : public Object {
   // default is to invalidate both layout and paint
   virtual void OnRemoveChild(RenderObject* removed_child, Index position);
 
-  virtual void OnMeasureCore(const Size& available_size);
-  virtual void OnLayoutCore(const Rect& rect);
-  virtual Size OnMeasureContent(const Size& available_size) = 0;
+  // Size measure including margin and padding. Please reduce margin and padding
+  // or other custom things and pass the result content measure requirement to
+  // OnMeasureContent.
+  // Return value must not be negative and not bigger than requirement.
+  virtual Size OnMeasureCore(const MeasureRequirement& requirement);
+
+  // Size including margin and padding. Please reduce margin and padding or
+  // other custom things and pass the result content rect to OnLayoutContent.
+  // Parameter size are never negative.
+  virtual void OnLayoutCore(const Size& size);
+
+  // Do not consider margin or padding in this method because they are already
+  // considered in OnMeasureCore. Returned size should never be bigger than
+  // requirement.
+  virtual Size OnMeasureContent(const MeasureRequirement& requirement) = 0;
+
+  // Lefttop of content_rect should be added when calculated children's offset.
   virtual void OnLayoutContent(const Rect& content_rect) = 0;
 
   virtual void OnAfterLayout();
@@ -113,6 +137,6 @@ class RenderObject : public Object {
   Thickness margin_{};
   Thickness padding_{};
 
-  Size preferred_size_{};
+  Size measured_size_{};
 };
 }  // namespace cru::ui::render