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146 lines
3.6 KiB
146 lines
3.6 KiB
"""Image utility functions for Sphinx."""
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from __future__ import annotations
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import base64
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from os import path
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from typing import TYPE_CHECKING, NamedTuple, overload
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import imagesize
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if TYPE_CHECKING:
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from os import PathLike
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try:
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from PIL import Image
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except ImportError:
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Image = None
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mime_suffixes = {
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'.gif': 'image/gif',
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'.jpg': 'image/jpeg',
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'.png': 'image/png',
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'.pdf': 'application/pdf',
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'.svg': 'image/svg+xml',
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'.svgz': 'image/svg+xml',
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'.ai': 'application/illustrator',
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}
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_suffix_from_mime = {v: k for k, v in reversed(mime_suffixes.items())}
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class DataURI(NamedTuple):
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mimetype: str
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charset: str
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data: bytes
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def get_image_size(filename: str) -> tuple[int, int] | None:
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try:
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size = imagesize.get(filename)
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if size[0] == -1:
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size = None
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elif isinstance(size[0], float) or isinstance(size[1], float):
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size = (int(size[0]), int(size[1]))
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if size is None and Image: # fallback to Pillow
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with Image.open(filename) as im:
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size = im.size
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return size
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except Exception:
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return None
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@overload
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def guess_mimetype(filename: PathLike[str] | str, default: str) -> str:
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...
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@overload
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def guess_mimetype(filename: PathLike[str] | str, default: None = None) -> str | None:
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...
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def guess_mimetype(
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filename: PathLike[str] | str = '',
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default: str | None = None,
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) -> str | None:
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ext = path.splitext(filename)[1].lower()
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if ext in mime_suffixes:
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return mime_suffixes[ext]
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if path.exists(filename):
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try:
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imgtype = _image_type_from_file(filename)
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except ValueError:
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pass
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else:
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return 'image/' + imgtype
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return default
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def get_image_extension(mimetype: str) -> str | None:
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return _suffix_from_mime.get(mimetype)
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def parse_data_uri(uri: str) -> DataURI | None:
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if not uri.startswith('data:'):
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return None
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# data:[<MIME-type>][;charset=<encoding>][;base64],<data>
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mimetype = 'text/plain'
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charset = 'US-ASCII'
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properties, data = uri[5:].split(',', 1)
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for prop in properties.split(';'):
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if prop == 'base64':
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pass # skip
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elif prop.startswith('charset='):
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charset = prop[8:]
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elif prop:
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mimetype = prop
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image_data = base64.b64decode(data)
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return DataURI(mimetype, charset, image_data)
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def _image_type_from_file(filename: PathLike[str] | str) -> str:
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with open(filename, 'rb') as f:
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header = f.read(32) # 32 bytes
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# Bitmap
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# https://en.wikipedia.org/wiki/BMP_file_format#Bitmap_file_header
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if header.startswith(b'BM'):
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return 'bmp'
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# GIF
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# https://en.wikipedia.org/wiki/GIF#File_format
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if header.startswith((b'GIF87a', b'GIF89a')):
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return 'gif'
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# JPEG data
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# https://en.wikipedia.org/wiki/JPEG_File_Interchange_Format#File_format_structure
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if header.startswith(b'\xFF\xD8'):
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return 'jpeg'
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# Portable Network Graphics
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# https://en.wikipedia.org/wiki/PNG#File_header
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if header.startswith(b'\x89PNG\r\n\x1A\n'):
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return 'png'
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# Scalable Vector Graphics
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# https://svgwg.org/svg2-draft/struct.html
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if b'<svg' in header.lower():
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return 'svg+xml'
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# TIFF
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# https://en.wikipedia.org/wiki/TIFF#Byte_order
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if header.startswith((b'MM', b'II')):
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return 'tiff'
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# WebP
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# https://en.wikipedia.org/wiki/WebP#Technology
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if header.startswith(b'RIFF') and header[8:12] == b'WEBP':
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return 'webp'
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msg = 'Could not detect image type!'
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raise ValueError(msg)
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