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perf: Bypass img2pdf python slow bottleneck #20

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Merged
ThomasParistech merged 1 commit into from
Mar 26, 2026
Merged

perf: Bypass img2pdf python slow bottleneck #20

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16 changes: 8 additions & 8 deletions dobble/steps/pdf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,10 @@
"""Merge Dobble cards into a scaled PDF ready to print."""
import math
import os
import subprocess
from typing import cast

import cv2
import img2pdf
import numpy as np
from tqdm import tqdm

Expand Down Expand Up @@ -61,7 +61,7 @@ def save_batch_image(out_batches_folder: str,
nb_patch_in_w: int,
k: int) -> str:
"""Save a batch of cards into a single image."""
batch_path = os.path.join(out_batches_folder, f"batch_cards_{k}.png")
batch_path = os.path.join(out_batches_folder, f"batch_cards_{k}.jpg")
batch_images = [load_image(os.path.join(cards_folder, name))
if name is not None else 255*np.ones_like(first_img)
for name in names[nb_patch_per_batch*k:nb_patch_per_batch*k+nb_patch_per_batch]]
Expand All @@ -86,7 +86,7 @@ def _save_back_page(out_batches_folder: str,
nb_patch_in_h: int,
nb_patch_in_w: int) -> str:
"""Generate a single back page with the back image at each card position, flipped for recto-verso."""
back_path = os.path.join(out_batches_folder, "batch_back.png")
back_path = os.path.join(out_batches_folder, "batch_back.jpg")
back_resized = cast(NpIntArrayType, cv2.resize(back_img, (card_size_pix, card_size_pix)))
back_flipped = cast(NpIntArrayType, cv2.flip(back_resized, 1))
images: list[NpIntArrayType] = [back_flipped] * nb_patch_per_batch
Expand Down Expand Up @@ -178,10 +178,10 @@ def main(cards_folder: str,
interleaved.append(back_path)
batches_paths = interleaved

a4inpt = (img2pdf.mm_to_pt(210), img2pdf.mm_to_pt(297))
layout_fun = img2pdf.get_layout_fun(a4inpt)

with open(pdf_path, "wb") as f:
f.write(img2pdf.convert(batches_paths, layout_fun=layout_fun))
subprocess.run(
["img2pdf", "--pagesize", "A4", "--fit", "into", "-o", pdf_path,
*batches_paths],
check=True,
)

logger.info(f"Congratulations! Your Dobble has been saved at {os.path.abspath(pdf_path)}")
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