from indigo import Indigo
from indigo.renderer import IndigoRenderer

_indigo = Indigo()
renderer = IndigoRenderer(_indigo)
_indigo.setOption('render-output-format', 'png')
_indigo.setOption('render-margins', '5, 5')
_indigo.setOption('render-stereo-style', 'none')
_indigo.setOption('render-superatom-mode', 'collapse')
_indigo.setOption('ignore-stereochemistry-errors', True)
_indigo.setOption('render-label-mode', 'terminal-hetero')
_indigo.setOption('render-image-width', 1400)
_indigo.setOption('render-image-height', 900)

def trim(im, margin=5):
    bg = Image.new(im.mode, im.size, im.getpixel((0, 0)))
    diff = ImageChops.difference(im, bg)
    diff = ImageChops.add(diff, diff, 2.0, -100)
    bbox = diff.getbbox()
    if not bbox:
        return
    im = im.crop(bbox)
    w, h = im.size
    ret = Image.new(im.mode, (w + 2 * margin, h + 2 * margin), bg.getpixel((0, 0)))
    ret.paste(im, (margin, margin))
    return ret

def generate_image(renderer: IndigoRenderer, m: IndigoObject):
    buffer = renderer.renderToBuffer(m)
    b = BytesIO()
    b.write(buffer)
    im = Image.open(b)
    im = trim(im)
    ret = BytesIO()
    if not im:
        return None
    im.save(ret, 'png')
    return ret.getvalue()


m = _indigo.loadMolecule('CCC')  # both smiles or moltext is ok
b = generate_image(m)