PDF Thumbnail utils

[skip ci]

Author: khemarato

scripts/pdfutils.py

@@ -1,6 +1,8 @@
 #!/bin/python
 from strutils import (
   whitespace,
+  thumbnail_path_for_file,
+  THUMBNAIL_SIZES,
 )
 import subprocess
 from pathlib import Path
@@ -20,6 +22,35 @@ def get_page_count(pdf_path) -> int | None:
     except:
         return None
 
+def render_pdf_thumbnail(path, min_d_size=256, max_d_size=512, type='png') -> bytes:
+  try:
+    import fitz
+  except:
+    print("pip install pymupdf")
+    exit(1)
+  doc = fitz.open(path)
+  page = doc[0]
+  maxzoom = max_d_size / max(page.rect.width, page.rect.height, max_d_size)
+  minzoom = min_d_size / min(page.rect.width, page.rect.height)
+  zoom = minzoom if minzoom < maxzoom else maxzoom
+  pix = page.get_pixmap(matrix=fitz.Matrix(zoom, zoom))
+  return pix.tobytes(type)
+
+def get_shared_cached_pdf_thumbnail(pdf_path: Path, size='large') -> bytes:
+  thumbnail_path = thumbnail_path_for_file(pdf_path, shared=True, size=size)
+  if thumbnail_path.is_file():
+    return thumbnail_path.read_bytes()
+  tsize = THUMBNAIL_SIZES[size]
+  thebytes = render_pdf_thumbnail(
+    pdf_path,
+    min_d_size=tsize,
+    max_d_size=2*tsize,
+    type='png',
+  )
+  thumbnail_path.parent.mkdir(exist_ok=True, parents=True)
+  thumbnail_path.write_bytes(thebytes)
+  return thebytes
+
 def readpdf(pdf_file: str | Path, max_len=None, normalize=1) -> str:
   """Returns a pdf's text.
   

scripts/strutils.py

@@ -89,6 +89,25 @@ def md5(text: bytes | str | Path):
     raise ValueError(f"Expected bytes or str or Path, got {type(text)}")
   return hashlib.md5(bts).hexdigest()
 
+THUMBNAIL_SIZES = {
+  'normal': 128,
+  'large': 256,
+  'x-large': 512,
+  'xx-large': 1024,
+  'fail': 0,
+}
+
+def thumbnail_path_for_file(filepath: Path | str, shared=False, size='large'):
+  # Following the spec at https://specifications.freedesktop.org/thumbnail/latest/thumbsave.html
+  filepath = Path(filepath).expanduser().resolve()
+  if shared:
+    cachdir = filepath.parent.joinpath('.sh_thumbnails').joinpath(size)
+  else:
+    cachdir = Path('~/.cache/thumbnails/').expanduser().joinpath(size)
+  return cachdir.joinpath(
+    f"{md5("file://"+str(filepath))}.png"
+  )
+
 def cumsum(vec):
     return reduce(lambda a,x: a+[a[-1]+x] if a else [x], vec, [])