Add geometry handling.

src/graphics/DrawingContext.cpp

@@ -1,6 +1,7 @@
 #include "DrawingContext.h"
 
 #include "INativeDrawingContext.h"
+#include "AbstractGeometricItem.h"
 
 std::unique_ptr<DrawingContext> DrawingContext::Create()
 {
@@ -16,3 +17,18 @@ INativeDrawingContext* DrawingContext::GetNativeContext()
 {
     return mNativeDrawingContext.get();
 }
+
+void DrawingContext::AddDrawable(AbstractGeometricItemPtr item)
+{
+    mItems.push_back(std::move(item));
+}
+
+unsigned DrawingContext::GetNumItems() const
+{
+    return mItems.size();
+}
+
+AbstractGeometricItem* DrawingContext::GetDrawable(unsigned idx) const
+{
+    return mItems[idx].get();
+}