TypeError: initializer for ctype 'unsigned int *' must be a cdata pointer, not bytes

I try to convert PIL image to leptonica PIX. Here is my code python 3.6:

import os, cffi
from PIL import Image

# initialize leptonica
ffi = cffi.FFI()
ffi.cdef("""
    typedef int           l_int32;
    typedef unsigned int  l_uint32;
    struct                Pix;
    typedef struct Pix    PIX;
    PIX * pixCreate       (int width, int height, int depth);
    l_int32 pixSetData    (PIX *pix, l_uint32 *data);
""")
leptonica = ffi.dlopen(os.path.join(os.getcwd(), "leptonica-1.78.0.dll"))

# convert PIL to PIX
im = Image.open("test.png").convert("RGBA")
depth = 32
width, height = im.size
data = im.tobytes("raw", "RGBA")
pixs = leptonica.pixCreate(width, height, depth)
leptonica.pixSetData(pixs, data)

pixSetData failes with message: TypeError: initializer for ctype 'unsigned int *' must be a cdata pointer, not bytes. How to convert bytes object (data) to cdata pointer?

PIL and Leptonica seem not to share exactly the same raw format. At last RGBA vs. ABGR. What worked for me was to use uncompressed TIFF as a fast and dependable data exchange format.

# Add these to ffi.cdef():
# 
# typedef unsigned char l_uint8;
# PIX * pixReadMem(const l_uint8 *data, size_t size);
# l_ok pixWriteMem(l_uint8 **pdata, size_t *psize, PIX *pix, l_int32 format);

from io import BytesIO
import PIL.Image

IFF_TIFF = 4


def img_pil_to_lepto(pilimage):
    with BytesIO() as bytesio:
        pilimage.save(bytesio, 'TIFF')
        tiff_bytes = bytesio.getvalue()

    cdata = ffi.from_buffer('l_uint8[]', tiff_bytes)
    pix = leptonica.pixReadMem(cdata, len(tiff_bytes))
    return pix


def img_lepto_to_pil(pix):
    cdata_ptr = ffi.new('l_uint8**')
    size_ptr = ffi.new('size_t*')
    leptonica.pixWriteMem(cdata_ptr, size_ptr, pix, IFF_TIFF)
    cdata = cdata_ptr[0]
    size = size_ptr[0]

    tiff_bytes = bytes(ffi.buffer(cdata, size))
    with BytesIO(tiff_bytes) as bytesio:
        pilimage = PIL.Image.open(bytesio).copy()
        return pilimage