Function get_padbuf

src/fl/gfx/blur.cpp.hpp:349–355

// Thread-local padded pixel buffer for zero-padding approach.
template <typename RGB_T>
static fl::span<RGB_T> get_padbuf(int minSize) {
    fl::vector<RGB_T> &buf = SingletonThreadLocal<fl::vector<RGB_T>>::instance();
    if (static_cast<int>(buf.size()) < minSize) {
        buf.resize(minSize);
    }
    return buf;
}

// Interior row pixel — fully-unrolled, no bounds checks.
// Also reused for vertical pass via linearized column data.