"""
PDF processor using pypdf (metadata) and pdf2image (rasterization).
The optional ``pdf`` dependency group must be installed::
uv sync --extra pdf
"""
from __future__ import annotations
import io
from collections.abc import Mapping
from typing import IO, Any
from madam.core import Asset, OperatorError, Processor, operator
_MIME_TYPE_TO_PIL_FORMAT: dict[str, str] = {
'image/jpeg': 'JPEG',
'image/png': 'PNG',
}
[docs]
class PDFProcessor(Processor):
"""
Represents a processor that handles *Portable Document Format* (PDF) files.
Reading requires `pypdf <https://pypdf.readthedocs.io/>`_. Rasterization
additionally requires `pdf2image <https://github.com/Belval/pdf2image>`_
and a system-wide installation of *poppler*.
"""
[docs]
def __init__(self, config: Mapping[str, Any] | None = None) -> None:
"""
Initializes a new ``PDFProcessor``.
:param config: Mapping with settings.
"""
super().__init__(config)
[docs]
def can_read(self, file: IO) -> bool:
header = file.read(4)
file.seek(0)
return header == b'%PDF'
[docs]
def read(self, file: IO) -> Asset:
"""
Reads a PDF file and returns an :class:`~madam.core.Asset`.
The returned asset carries a ``page_count`` metadata attribute with the
number of pages in the document.
:param file: Readable binary file-like object containing PDF data
:type file: IO
:return: Asset with ``mime_type='application/pdf'`` and ``page_count``
:rtype: Asset
"""
try:
import pypdf
except ImportError as e:
raise OperatorError('pypdf is required for reading PDFs; install the pdf extra') from e
pdf_bytes = file.read()
reader = pypdf.PdfReader(io.BytesIO(pdf_bytes))
page_count = len(reader.pages)
return Asset._from_bytes(pdf_bytes, mime_type='application/pdf', page_count=page_count)
[docs]
@operator
def rasterize(self, asset: Asset, page: int = 0, dpi: int = 72, mime_type: str = 'image/jpeg') -> Asset:
"""
Converts one page of a PDF asset into a raster image.
Requires the ``pdf2image`` package and a system *poppler* installation.
:param asset: PDF asset to rasterize
:type asset: Asset
:param page: Zero-based page index
:type page: int
:param dpi: Output resolution in dots per inch
:type dpi: int
:param mime_type: MIME type of the output image (``'image/jpeg'`` or ``'image/png'``)
:type mime_type: str
:return: Raster image asset
:rtype: Asset
:raises OperatorError: if *page* is out of range or rasterization fails
"""
try:
import pdf2image
except ImportError as e:
raise OperatorError('pdf2image is required for rasterization; install the pdf extra') from e
page_count = asset.page_count
if page < 0 or page >= page_count:
raise OperatorError(f'Page index {page} is out of range for a PDF with {page_count} pages')
pil_format = _MIME_TYPE_TO_PIL_FORMAT.get(mime_type)
if pil_format is None:
raise OperatorError(f'Unsupported MIME type for rasterization: {mime_type!r}')
# pdf2image uses 1-based page numbers
images = pdf2image.convert_from_bytes(
asset.essence.read(),
dpi=dpi,
first_page=page + 1,
last_page=page + 1,
)
if not images:
raise OperatorError(f'Rasterization produced no output for page {page}')
pil_image = images[0]
width, height = pil_image.size
buf = io.BytesIO()
pil_image.save(buf, format=pil_format)
buf.seek(0)
return Asset(essence=buf, mime_type=mime_type, width=width, height=height)