From 80f21e78a664cfae518a7b4e5d59cd8ff15b9e58 Mon Sep 17 00:00:00 2001 From: Stefan Klug Date: Tue, 19 Nov 2024 09:45:53 +0100 Subject: libcamera: internal: matrix: Replace vector with array in constructor The Matrix constructor that takes a std::vector is meant and only used to initialize a Matrix from an initializer list. Using a std::vector is problematic for two reasons. First, it requires constructing a vector, copying the data from the initializer list, which is an expensive operation. Then, the vector size can't be verified at compile time, making the constructor unsafe. The first issue could be solved by replacing the vector with a std::initializer_list or a Span. The second issue would require checking the initializer list size with a static assertion, or restricting usage of the constructor to fixed-extent spans. Unfortunately, even if the size of initializer lists is always known at compile time, the std::initializer_list::size() function is a compile-time constant only for constant initializer lists. Using a span would work better, but construction of a fixed extent span from an initializer list must be explicit, making the API cumbersome. We can solve all those issues by passing an std::array to the constructor. Construction of an array from an initializer list can be implicit and doesn't involve a copy, and the array size is a template parameter and therefore guaranteed to be a compile-time constant. Signed-off-by: Stefan Klug Reviewed-by: Laurent Pinchart --- src/libcamera/matrix.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src') diff --git a/src/libcamera/matrix.cpp b/src/libcamera/matrix.cpp index 55359aa2..4d95a19b 100644 --- a/src/libcamera/matrix.cpp +++ b/src/libcamera/matrix.cpp @@ -32,7 +32,7 @@ LOG_DEFINE_CATEGORY(Matrix) */ /** - * \fn Matrix::Matrix(const std::vector &data) + * \fn Matrix::Matrix(const std::array &data) * \brief Construct a matrix from supplied data * \param[in] data Data from which to construct a matrix * -- cgit v1.2.1