foliator/foliator.py
2026-05-29 18:42:41 +02:00

90 lines
3.8 KiB
Python
Executable file

#!/usr/bin/env python3
import argparse
from pypdf import PaperSize, PdfReader, PdfWriter, Transformation
from pypdf.annotations import Line
from pypdf.generic import ArrayObject, FloatObject, NameObject
import math
# Interprets input_pdf as a list of A6 pages, and appends to append_to with
# A5 pages using the following rules:
# a. Odd/even page pairs correspond to front/back pages of a single sheet, printed
# with "mirror around **short** edge"
# b. when grouped as consecutive sequences of max_folio_size or less, the printed
# sheets can be folded in the middle and assembled as a folio
# FIXME: currently max_folio_size is ignored, and the output is one large folio.
def foliate_A6(input_pdf, max_folio_size=-1, append_to=PdfWriter()):
num_A5 = math.ceil(len(input_pdf.pages)/4.0) * 2
writer = append_to
for i in range(num_A5):
dpage = writer.add_blank_page(width=PaperSize.A5.height,
height=PaperSize.A5.width)
ipage = input_pdf.pages[i]
ipage.mediabox = dpage.mediabox
if i % 2 == 0: # Even pages are filled right to left
ipage.add_transformation(Transformation().translate(PaperSize.A6.width,
0))
dpage.merge_page(ipage)
# Now for the fun part: work backwards to fill the remaining pages
for j in range(len(input_pdf.pages) - num_A5):
dpage = writer.pages[num_A5 - 1 - j]
ipage = input_pdf.pages[num_A5+j]
ipage.mediabox = dpage.mediabox
if (num_A5 - 1 - j) % 2 == 1:
ipage.add_transformation(Transformation().translate(PaperSize.A6.width,
0))
dpage.merge_page(ipage)
return writer
# Take an A5 printing plan, with odd/even pages being understood
# as front/back pairs of sheets, short edge mirroring. Produces an A4 printing plan
# containing two A5 panels per sheet, long edge mirroring.
def blit_to_A4(input_pdf, append_to=PdfWriter()):
L = len(input_pdf.pages)
writer = append_to
for k in range(0, L, 2):
if(k%4 == 0): # Open up a new sheet
front_page = writer.add_blank_page(width=PaperSize.A4.width,
height=PaperSize.A4.height)
back_page = writer.add_blank_page(width=PaperSize.A4.width,
height=PaperSize.A4.height)
midline = Line(rect = (0, PaperSize.A4.height/2, PaperSize.A4.width, PaperSize.A4.height/2),
p1=(10, PaperSize.A4.height/2),
p2=(PaperSize.A4.width-10, PaperSize.A4.height/2))
midline.flags = 4 # print the midline
midline[NameObject("/C")] = ArrayObject([FloatObject(0.5)])
writer.add_annotation(front_page, midline)
front = input_pdf.pages[k]
back = input_pdf.pages[k+1] if (k+1<L) else create_blank_page(None, PaperSize.A5.width, PaperSize.A5.height)
front.mediabox = front_page.mediabox
back.mediabox = back_page.mediabox
if(k%4 == 0): # Translate to bottom half of page
front.add_transformation(Transformation().translate(0, PaperSize.A5.width))
back.add_transformation(Transformation().translate(0, PaperSize.A5.width))
front_page.merge_page(front)
back_page.merge_page(back)
return writer
parser = argparse.ArgumentParser()
parser.add_argument("infile", help="input document, A6 pages")
parser.add_argument("outfile", help="output document")
parser.add_argument("-a5", help="output as a5, reverse on short edge",
action="store_true")
args = parser.parse_args()
input_pdf = PdfReader(args.infile)
a5 = foliate_A6(input_pdf)
if (args.a5):
a5.write(args.outfile)
else:
a4 = blit_to_A4(a5)
a4.write(args.outfile)