Function JxlSignatureCheck 

pub unsafe extern "C-unwind" fn JxlSignatureCheck(
    buf: *const u8,
    len: usize,
) -> JxlSignature

JPEG XL signature identification.

Checks if the passed buffer contains a valid JPEG XL signature. The passed buf of size size doesn’t need to be a full image, only the beginning of the file.

Returns

A flag indicating if a JPEG XL signature was found and what type.

• JxlSignature::NotEnoughBytes if not enough bytes were passed to determine if a valid signature is there.
• JxlSignature::Invalid if no valid signature found for JPEG XL decoding.
• JxlSignature::Codestream if a valid JPEG XL codestream signature was found.
• JxlSignature::Container if a valid JPEG XL container signature was found.