Method GetFreeSpots

Xaml/Controls/UniformGrid.cpp:318–354

	}

	std::experimental::generator<std::tuple<int, int>> UniformGrid::GetFreeSpots(int firstColumn, bool topDown)
	{
		// Provides the next spot in the boolean array with a 'false' value.
		if (topDown)
		{
			// Layout spots from Top-Bottom, Left-Right (right-left handled automatically by Grid with Flow-Direction).
			// Effectively transpose the Grid Layout.
			for (int c = 0; c < m_SpotsWidth; c++)
			{
				int start = (c == 0 && firstColumn > 0 && firstColumn < m_SpotsHeight) ? firstColumn : 0;
				for (int r = start; r < m_SpotsHeight; r++)
				{
					if (!GetSpot(r, c))
					{
						co_yield { r, c };
					}
				}
			}
		}
		else
		{
			// Layout spots as normal from Left-Right.
			// (right-left handled automatically by Grid with Flow-Direction
			// during its layout, internal model is always left-right).
			for (int r = 0; r < m_SpotsHeight; r++)
			{
				int start = (r == 0 && firstColumn > 0 && firstColumn < m_SpotsWidth) ? firstColumn : 0;
				for (int c = start; c < m_SpotsWidth; c++)
				{
					if (!GetSpot(r, c))
					{
						co_yield { r, c };
					}
				}
			}
		}
	}
}