Paint filling algorithm implemented in OO style!

CPaintFiller.h

#pragma once

#include <glm/glm.hpp>


namespace Relic
{

	class CPaintFiller
	{
    
        public:
		
		// Implement these two pure virtuals in a subclass!
    
		// Return true if the pixel is part of the group you are trying to "fill"
		// In the paint example, this would be true if the pixel is the same color as the pixel you clicked
		virtual bool IsPixelInGroup(int x, int y) = 0;
		
		// This function is called by this class when it finds a pixel that is "in the group"
		// In the paint example, this would be where you change the color of the pixel to the "fill" color
		// NOTE: My code expects that you make this change here!
		// Otherwise it would keep looping around the same area in an infinite loop
		// You need to modify the pixel so that IsPixelInGroup(...) is no longer true
		virtual void SuccessCallback(int x, int y) = 0;
		
		// Change this as appropriate
		glm::ivec2 MapSize = glm::ivec2(640, 480);

		int Run(int const StartX, int const StartY)
		{
			int NumberFilled = 0;

			if (Check(StartX, StartY))
			{
				NumberFilled = 1;

				while (! Queue.empty())
				{
					glm::ivec2 const Current = Queue.back();
					Queue.pop_back();

					int const u = Current.x;
					int const v = Current.y;

					NumberFilled += Check(u + 1, v);
					NumberFilled += Check(u - 1, v);
					NumberFilled += Check(u, v + 1);
					NumberFilled += Check(u, v - 1);
				}
			}

			return NumberFilled;
		}

	protected:

		int Check(int const u, int const v)
		{
			if (u >= 0 && v >= 0 && u < MapSize.x && v < MapSize.y)
			{
				if (IsPixelInGroup(u, v))
				{
					SuccessCallback(u, v);
					Queue.push_back(glm::ivec2(u, v));

					return 1;
				}
			}

			return 0;
		}

		vector<glm::ivec2> Queue;
	};
}