  A ring $R$ is called strongly clean if every element of $R$ is the sum of a
unit and an idempotent that commute.
  By {\rm SRC} factorization, Borooah, Diesl, and Dorsey
  \cite{BDD051} completely determined when ${\mathbb M}_n(R)$ over a
commutative local ring $R$ is strongly clean.
  We generalize the notion of {\rm SRC} factorization to commutative rings,
prove that commutative $n$-{\rm SRC} rings $(n\ge 2)$ are precisely the
commutative local rings over which ${\mathbb M}_n(R)$ is strongly clean, and
characterize strong cleanness of matrices over commutative projective-free
rings having {\rm ULP}. The strongly $\pi$-regular property (hence, strongly
clean property) of ${\mathbb M}_n(C(X,{\mathbb C}))$ with $X$ a {\rm P}-space
relative to ${\mathbb C}$ is also obtained where $C(X,{\mathbb C})$ is the ring
of complex valued continuous functions.
