Fully decompose u to its Unicode compatibility decomposition. The codepoints of the decomposition will be written to decomposed. The complete length of the decomposition will be returned.
If u has no compatibility decomposition, zero should be returned.
The Unicode standard guarantees that a buffer of length %HB_UNICODE_MAX_DECOMPOSITION_LEN codepoints will always be sufficient for any compatibility decomposition plus an terminating value of 0. Consequently, decompose must be allocated by the caller to be at least this length. Implementations of this function type must ensure that they do not write past the provided array.
HarfBuzz::UnicodeFuncsT, UInt32, Pointer(UInt32) -> UInt32