Add ellipse plotter and oval drawing

PortabilityLayer/EllipsePlotter.h

@@ -0,0 +1,62 @@
+#pragma once
+
+#include "IPlotter.h"
+#include "PlotDirection.h"
+#include "Vec2i.h"
+
+#define PL_DEBUG_ELLIPSE_PLOTTER 1
+
+namespace PortabilityLayer
+{
+	struct Rect2i;
+
+	class EllipsePlotter final : public IPlotter
+	{
+	public:
+		EllipsePlotter();
+		PlotDirection PlotNext() override;
+		const Vec2i &GetPoint() const override;
+
+		void Reset(const Rect2i &bounds);
+
+	private:
+		enum Quadrant
+		{
+			Quadrant_NxNy,
+			Quadrant_NxPy,
+			Quadrant_PxNy,
+			Quadrant_PxPy,
+
+			Quadrant_Finished
+		};
+
+		void IncrementX();
+		bool ConditionalIncrementX();
+
+		void IncrementY();
+		bool ConditionalIncrementY();
+
+		void DecrementX();
+		bool ConditionalDecrementX();
+
+		void DecrementY();
+		bool ConditionalDecrementY();
+
+		Vec2i m_2center;
+		Vec2i m_point;
+		Vec2i m_diameters;
+		int32_t m_sqDistFromEdge;
+		Quadrant m_quadrant;
+
+		int32_t m_xChangeCostDynamicFactor;
+		int32_t m_yChangeCostDynamicFactor;
+		int32_t m_xChangeCostDynamicFactorStep;
+		int32_t m_yChangeCostDynamicFactorStep;
+		int32_t m_xChangeCostStaticFactor;
+		int32_t m_yChangeCostStaticFactor;
+
+#if PL_DEBUG_ELLIPSE_PLOTTER 1
+		Vec2i m_2offsetFromCenter;
+#endif
+	};
+}