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"""Image utility functions for Sphinx."""
import base64
import imghdr
from collections import OrderedDict
from os import path
from typing import IO, BinaryIO, NamedTuple, Optional, Tuple
import imagesize
try:
from PIL import Image
except ImportError:
Image = None
mime_suffixes = OrderedDict([
('.gif', 'image/gif'),
('.jpg', 'image/jpeg'),
('.png', 'image/png'),
('.pdf', 'application/pdf'),
('.svg', 'image/svg+xml'),
('.svgz', 'image/svg+xml'),
('.ai', 'application/illustrator'),
])
class DataURI(NamedTuple):
mimetype: str
charset: str
data: bytes
def get_image_size(filename: str) -> Optional[Tuple[int, int]]:
try:
size = imagesize.get(filename)
if size[0] == -1:
size = None
elif isinstance(size[0], float) or isinstance(size[1], float):
size = (int(size[0]), int(size[1]))
if size is None and Image: # fallback to Pillow
with Image.open(filename) as im:
size = im.size
return size
except Exception:
return None
def guess_mimetype_for_stream(stream: IO, default: Optional[str] = None) -> Optional[str]:
imgtype = imghdr.what(stream)
if imgtype:
return 'image/' + imgtype
else:
return default
def guess_mimetype(filename: str = '', default: Optional[str] = None) -> Optional[str]:
_, ext = path.splitext(filename.lower())
if ext in mime_suffixes:
return mime_suffixes[ext]
elif path.exists(filename):
with open(filename, 'rb') as f:
return guess_mimetype_for_stream(f, default=default)
return default
def get_image_extension(mimetype: str) -> Optional[str]:
for ext, _mimetype in mime_suffixes.items():
if mimetype == _mimetype:
return ext
return None
def parse_data_uri(uri: str) -> Optional[DataURI]:
if not uri.startswith('data:'):
return None
# data:[<MIME-type>][;charset=<encoding>][;base64],<data>
mimetype = 'text/plain'
charset = 'US-ASCII'
properties, data = uri[5:].split(',', 1)
for prop in properties.split(';'):
if prop == 'base64':
pass # skip
elif prop.startswith('charset='):
charset = prop[8:]
elif prop:
mimetype = prop
image_data = base64.b64decode(data)
return DataURI(mimetype, charset, image_data)
def test_svg(h: bytes, f: Optional[BinaryIO]) -> Optional[str]:
"""An additional imghdr library helper; test the header is SVG's or not."""
try:
if '<svg' in h.decode().lower():
return 'svg+xml'
except UnicodeDecodeError:
pass
return None
# install test_svg() to imghdr
# refs: https://docs.python.org/3.6/library/imghdr.html#imghdr.tests
imghdr.tests.append(test_svg)
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