def _transcode_png(pike: Pdf, filename: Path, xref: Xref) -> bool:
output = filename.with_suffix('.png.pdf')
with output.open('wb') as f:
img2pdf.convert(fspath(filename), outputstream=f)
with pikepdf.open(output) as pdf_image:
foreign_image = next(pdf_image.pages[0].images.values())
local_image = pike.copy_foreign(foreign_image)
im_obj = pike.get_object(xref, 0)
im_obj.write(
local_image.read_raw_bytes(),
filter=local_image.Filter,
decode_parms=local_image.DecodeParms,
)
# Don't copy keys from the new image...
del_keys = set(im_obj.keys()) - set(local_image.keys())
# ...except for the keep_fields, which are essential to displaying
# the image correctly and preserving its metadata. (/Decode arrays
# and /SMaskInData are implicitly discarded prior to this point.)
keep_fields = {
'/ID',
'/Intent',
'/Interpolate',
'/Mask',
'/Metadata',
'/OC',
'/OPI',
'/SMask',
'/StructParent',
}
del_keys -= keep_fields
for key in local_image.keys():
if key != Name.Length and str(key) not in keep_fields:
im_obj[key] = local_image[key]
for key in del_keys:
del im_obj[key]
return True
def _transcode_png(pike: Pdf, filename: Path, xref: Xref) -> bool:
output = filename.with_suffix('.png.pdf')
with output.open('wb') as f:
img2pdf.convert(fspath(filename), outputstream=f)
with pikepdf.open(output) as pdf_image:
foreign_image = next(pdf_image.pages[0].images.values())
local_image = pike.copy_foreign(foreign_image)
im_obj = pike.get_object(xref, 0)
im_obj.write(
local_image.read_raw_bytes(),
filter=local_image.Filter,
decode_parms=local_image.DecodeParms,
)
del_keys = set(im_obj.keys()) - set(local_image.keys())
for key in local_image.keys():
if key != Name.Length:
im_obj[key] = local_image[key]
for key in del_keys:
del im_obj[key]
