1 files changed, 39 insertions, 0 deletions
diff --git a/include/cru/ui/render/CanvasRenderObject.hpp b/include/cru/ui/render/CanvasRenderObject.hpp
new file mode 100644
index 00000000..ba50a985
--- /dev/null
+++ b/include/cru/ui/render/CanvasRenderObject.hpp
@@ -0,0 +1,39 @@
+#pragma once
+#include "RenderObject.hpp"
+
+namespace cru::ui::render {
+// The measure logic for `CanvasRenderObject` is that you set a desired size by
+// `SetDesiredSize` (not `SetPreferredSize`) and it will compare desired size
+// and available size and use the smaller one (by `Min`).
+class CanvasRenderObject : public RenderObject {
+ public:
+  CanvasRenderObject();
+
+  CRU_DELETE_COPY(CanvasRenderObject)
+  CRU_DELETE_MOVE(CanvasRenderObject)
+
+  ~CanvasRenderObject();
+
+ public:
+  void Draw(platform::graph::IPainter* painter) override;
+
+  RenderObject* HitTest(const Point& point) override;
+
+  Size GetDesiredSize() const { return desired_size_; }
+
+  // Set the desired size. This is the content size excluding padding and
+  // margin.
+  void SetDesiredSize(const Size& new_size) { desired_size_ = new_size; }
+
+  IEvent<CanvasPaintEventArgs>* PaintEvent() { return &paint_event_; }
+
+ protected:
+  Size OnMeasureContent(const Size& available_size) override;
+  void OnLayoutContent(const Rect& content_rect) override;
+
+ private:
+  Size desired_size_{};
+
+  Event<CanvasPaintEventArgs> paint_event_;
+};
+}  // namespace cru::ui::render