libcamera: matrix: Add a Span based constructor

When one wants to create a Matrix from existing data, currently the only
way is via std::array. Add a Span based constructor to allow creation
from vectors and alike.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

include/libcamera/internal/matrix.h

@@ -34,6 +34,11 @@ public:
 		std::copy(data.begin(), data.end(), data_.begin());
 	}
 
+	Matrix(const Span<const T, Rows * Cols> data)
+	{
+		std::copy(data.begin(), data.end(), data_.begin());
+	}
+
 	static constexpr Matrix identity()
 	{
 		Matrix ret;

src/libcamera/matrix.cpp

@@ -41,6 +41,16 @@ LOG_DEFINE_CATEGORY(Matrix)
  * number of rows and columns of the matrix (Rows x Cols).
  */
 
+/**
+ * \fn Matrix::Matrix(const Span<const T, Rows * Cols> data)
+ * \brief Construct a matrix from supplied data
+ * \param[in] data Data from which to construct a matrix
+ *
+ * \a data is a one-dimensional Span and will be turned into a matrix in
+ * row-major order. The size of \a data must be equal to the product of the
+ * number of rows and columns of the matrix (Rows x Cols).
+ */
+
 /**
  * \fn Matrix::identity()
  * \brief Construct an identity matrix