9 files changed, 38 insertions, 47 deletions
diff --git a/include/cru/ui/controls/ControlHost.h b/include/cru/ui/controls/ControlHost.h
index 5d0b7947..e6eb472d 100644
--- a/include/cru/ui/controls/ControlHost.h
+++ b/include/cru/ui/controls/ControlHost.h
@@ -23,6 +23,9 @@ class CRU_UI_API ControlHost : public Object {
   void ScheduleRepaint();
   void ScheduleRelayout();
 
+  Rect GetPaintInvalidArea();
+  void AddPaintInvalidArea(const Rect& area);
+
   void Repaint();
   void Relayout();
   void RelayoutWithSize(const Size& available_size = Size::Infinite(),
@@ -56,7 +59,7 @@ class CRU_UI_API ControlHost : public Object {
   std::unique_ptr<platform::gui::INativeWindow> CreateNativeWindow();
 
   void OnNativeDestroy(std::nullptr_t);
-  void OnNativePaint(std::nullptr_t);
+  void OnNativePaint1(const cru::platform::gui::NativePaintEventArgs& args);
   void OnNativeResize(const Size& size);
   void OnNativeFocus(cru::platform::gui::FocusChangeType focus);
   void OnNativeMouseEnterLeave(cru::platform::gui::MouseEnterLeaveType enter);
@@ -190,6 +193,8 @@ class CRU_UI_API ControlHost : public Object {
 
   bool layout_prefer_to_fill_window_;
 
+  Rect paint_invalid_area_;
+
   platform::gui::TimerAutoCanceler relayout_schedule_canceler_;
 };
 }  // namespace cru::ui::controls
diff --git a/include/cru/ui/render/BorderRenderObject.h b/include/cru/ui/render/BorderRenderObject.h
index 73fc85c1..c011cda0 100644
--- a/include/cru/ui/render/BorderRenderObject.h
+++ b/include/cru/ui/render/BorderRenderObject.h
@@ -43,7 +43,6 @@ class CRU_UI_API BorderRenderObject : public SingleChildRenderObject {
   void ApplyBorderStyle(const style::ApplyBorderStyleInfo& style);
 
   RenderObject* HitTest(const Point& point) override;
-  void Draw(platform::graphics::IPainter* painter) override;
 
   Thickness GetTotalSpaceThickness() override;
   Thickness GetInnerSpaceThickness() override;
@@ -53,6 +52,7 @@ class CRU_UI_API BorderRenderObject : public SingleChildRenderObject {
  protected:
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 
   void OnResize(const Size& new_size) override;
 
diff --git a/include/cru/ui/render/CanvasRenderObject.h b/include/cru/ui/render/CanvasRenderObject.h
index 2e44fcc2..b2da3207 100644
--- a/include/cru/ui/render/CanvasRenderObject.h
+++ b/include/cru/ui/render/CanvasRenderObject.h
@@ -33,12 +33,11 @@ class CRU_UI_API CanvasRenderObject : public RenderObject {
  public:
   RenderObject* HitTest(const Point& point) override;
 
-  void Draw(platform::graphics::IPainter* painter) override;
-
   CRU_DEFINE_EVENT(Paint, const CanvasPaintEventArgs&)
 
  protected:
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 };
 }  // namespace cru::ui::render
diff --git a/include/cru/ui/render/GeometryRenderObject.h b/include/cru/ui/render/GeometryRenderObject.h
index 1994daf3..455af6b8 100644
--- a/include/cru/ui/render/GeometryRenderObject.h
+++ b/include/cru/ui/render/GeometryRenderObject.h
@@ -15,7 +15,6 @@ class GeometryRenderObject : public RenderObject {
   GeometryRenderObject();
 
  public:
-  void Draw(platform::graphics::IPainter* painter) override;
   RenderObject* HitTest(const Point& point) override;
 
   std::shared_ptr<platform::graphics::IGeometry> GetGeometry();
@@ -37,6 +36,7 @@ class GeometryRenderObject : public RenderObject {
  protected:
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 
  private:
   std::shared_ptr<platform::graphics::IGeometry> geometry_ = nullptr;
diff --git a/include/cru/ui/render/LayoutRenderObject.h b/include/cru/ui/render/LayoutRenderObject.h
index 5cb70680..99dd8057 100644
--- a/include/cru/ui/render/LayoutRenderObject.h
+++ b/include/cru/ui/render/LayoutRenderObject.h
@@ -1,8 +1,6 @@
 #pragma once
 #include "RenderObject.h"
 
-#include "cru/platform/graphics/Painter.h"
-
 namespace cru::ui::render {
 template <typename TChildLayoutData>
 class LayoutRenderObject : public RenderObject {
@@ -81,16 +79,6 @@ class LayoutRenderObject : public RenderObject {
     InvalidateLayout();
   }
 
-  void Draw(platform::graphics::IPainter* painter) override {
-    for (const auto& child : children_) {
-      painter->PushState();
-      painter->ConcatTransform(
-          Matrix::Translation(child.render_object->GetOffset()));
-      child.render_object->Draw(painter);
-      painter->PopState();
-    }
-  }
-
   RenderObject* HitTest(const Point& point) override {
     const auto child_count = GetChildCount();
     for (auto i = child_count - 1; i >= 0; --i) {
@@ -104,6 +92,14 @@ class LayoutRenderObject : public RenderObject {
     return GetPaddingRect().IsPointInside(point) ? this : nullptr;
   }
 
+ protected:
+  void OnDraw(RenderObjectDrawContext& context) override {
+    auto painter = context.painter;
+    for (const auto& child : children_) {
+      context.DrawChild(child.render_object);
+    }
+  }
+
  private:
   std::vector<ChildData> children_;
 };
diff --git a/include/cru/ui/render/RenderObject.h b/include/cru/ui/render/RenderObject.h
index e696aefe..85cb7990 100644
--- a/include/cru/ui/render/RenderObject.h
+++ b/include/cru/ui/render/RenderObject.h
@@ -1,33 +1,24 @@
 #pragma once
 #include "../Base.h"
-
 #include "MeasureRequirement.h"
 
 #include <cru/base/Event.h>
 #include <cru/platform/graphics/Painter.h>
+
 #include <string>
 
 namespace cru::ui::render {
-struct BoxConstraint {
-  static const BoxConstraint kNotLimit;
-
-  Size max;
-  Size min;
+class RenderObject;
 
-  constexpr bool Validate() const {
-    return max.width >= min.width && max.height >= min.height &&
-           min.width >= 0 && min.height >= 0;
-  }
-
-  constexpr bool Satisfy(const Size& size) const {
-    return size.width <= max.width && size.height <= max.height &&
-           size.width >= min.width && size.height >= min.height;
-  }
+struct CRU_UI_API RenderObjectDrawContext {
+  /**
+   * Coordinates are related to the render object to be painted. So parent
+   * render object should adjust this before passing to children.
+   */
+  Rect paint_invalid_area;
+  platform::graphics::IPainter* painter;
 
-  constexpr Size Coerce(const Size& size) const {
-    return Size{std::min(std::max(size.width, min.width), max.width),
-                std::min(std::max(size.height, min.height), max.height)};
-  }
+  void DrawChild(RenderObject* render_object);
 };
 
 /**
@@ -37,11 +28,11 @@ struct BoxConstraint {
  * To write a custom RenderObject, override following methods:
  *
  * public:
- *  void Draw(platform::graphics::IPainter* painter) override;
  *  RenderObject* HitTest(const Point& point) override;
  * protected:
  *  Size OnMeasureContent(const MeasureRequirement& requirement) override;
  *  void OnLayoutContent(const Rect& content_rect) override;
+ *  void OnDraw(RenderObjectDrawContext& context) override;
  */
 class CRU_UI_API RenderObject : public Object {
  private:
@@ -124,10 +115,12 @@ class CRU_UI_API RenderObject : public Object {
   virtual Rect GetPaddingRect();
   virtual Rect GetContentRect();
 
-  virtual void Draw(platform::graphics::IPainter* painter) = 0;
+  virtual Rect GetRenderRect();
 
-  // Param point must be relative the lefttop of render object including margin.
-  // Add offset before pass point to children.
+  void Draw(RenderObjectDrawContext& context);
+
+  // 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:
@@ -160,13 +153,14 @@ class CRU_UI_API RenderObject : public Object {
   // Override this function to measure content and children(Call Measure on
   // them). Do not consider margin or padding in this method because they are
   // already considered in OnMeasureCore. Returned size must obey requirement.
-  // Caller should guarantee preferred_size is corerced into required range.
   virtual Size OnMeasureContent(const MeasureRequirement& requirement) = 0;
 
   // Layout all content and children(Call Layout on them).
   // Lefttop of content_rect should be added when calculated children's offset.
   virtual void OnLayoutContent(const Rect& content_rect) = 0;
 
+  virtual void OnDraw(RenderObjectDrawContext& context) = 0;
+
   virtual void OnAttachedControlChanged(controls::Control* old_control,
                                         controls::Control* new_control) {}
 
diff --git a/include/cru/ui/render/ScrollRenderObject.h b/include/cru/ui/render/ScrollRenderObject.h
index ae11f361..ed67331d 100644
--- a/include/cru/ui/render/ScrollRenderObject.h
+++ b/include/cru/ui/render/ScrollRenderObject.h
@@ -62,8 +62,6 @@ class CRU_UI_API ScrollRenderObject : public SingleChildRenderObject {
   bool VerticalCanScrollUp();
   bool VerticalCanScrollDown();
 
-  void Draw(platform::graphics::IPainter* painter) override;
-
  protected:
   // Logic:
   // If available size is bigger than child's preferred size, then child's
@@ -71,6 +69,7 @@ class CRU_UI_API ScrollRenderObject : public SingleChildRenderObject {
   // If not, all available size is taken while forming a scroll area.
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 
   void OnAttachedControlChanged(controls::Control* old_control,
                                 controls::Control* new_control) override;
diff --git a/include/cru/ui/render/TextRenderObject.h b/include/cru/ui/render/TextRenderObject.h
index 0d17853b..eefb3264 100644
--- a/include/cru/ui/render/TextRenderObject.h
+++ b/include/cru/ui/render/TextRenderObject.h
@@ -88,12 +88,11 @@ class CRU_UI_API TextRenderObject : public RenderObject {
 
   RenderObject* HitTest(const Point& point) override;
 
-  void Draw(platform::graphics::IPainter* painter) override;
-
  protected:
   // See remarks of this class.
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 
  private:
   std::shared_ptr<platform::graphics::IBrush> brush_;
diff --git a/include/cru/ui/render/TreeRenderObject.h b/include/cru/ui/render/TreeRenderObject.h
index 599e0f65..425eee23 100644
--- a/include/cru/ui/render/TreeRenderObject.h
+++ b/include/cru/ui/render/TreeRenderObject.h
@@ -62,11 +62,10 @@ class CRU_UI_API TreeRenderObject : public RenderObject {
 
   RenderObject* HitTest(const Point& point) override;
 
-  void Draw(platform::graphics::IPainter* painter) override;
-
  protected:
   Size OnMeasureContent(const MeasureRequirement& requirement) override;
   void OnLayoutContent(const Rect& content_rect) override;
+  void OnDraw(RenderObjectDrawContext& context) override;
 
  private:
   float tab_width_ = 12.f;