93 lines
3.7 KiB
Python
93 lines
3.7 KiB
Python
import zlib
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from concurrent.futures import ThreadPoolExecutor
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from pathlib import Path
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from PIL import Image
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from .settings import BuildConfig, PAGES_DIR, PDF_COMPRESSION_LEVEL, PRINT_DIR, worker_count
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def write_pdf(config: BuildConfig) -> Path | None:
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pages = sorted(PAGES_DIR.glob("page_*.png"))
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if not pages:
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return None
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out_name = config.output_pdf_name.strip() or "blockminers_printable.pdf"
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if not out_name.lower().endswith(".pdf"):
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out_name += ".pdf"
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PRINT_DIR.mkdir(parents=True, exist_ok=True)
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out = PRINT_DIR / Path(out_name).name
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write_lossless_image_pdf(pages, out, config.dpi)
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return out
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def write_lossless_image_pdf(page_paths: list[Path], out_path: Path, dpi: int) -> None:
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max_obj = 2 + len(page_paths) * 3
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offsets = [0] * (max_obj + 1)
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page_objects: list[int] = []
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def pdf_num(value: float) -> str:
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return f"{value:.4f}".rstrip("0").rstrip(".")
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def write_obj(f, obj_id: int, body: bytes) -> None:
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offsets[obj_id] = f.tell()
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f.write(f"{obj_id} 0 obj\n".encode("ascii"))
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f.write(body)
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f.write(b"\nendobj\n")
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def write_stream_obj(f, obj_id: int, dictionary: str, stream: bytes) -> None:
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header = f"<< {dictionary} /Length {len(stream)} >>\nstream\n".encode("ascii")
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write_obj(f, obj_id, header + stream + b"\nendstream")
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def compress_page(path: Path) -> tuple[int, int, float, float, bytes]:
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with Image.open(path).convert("RGB") as img:
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width_px, height_px = img.size
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width_pt = width_px / dpi * 72.0
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height_pt = height_px / dpi * 72.0
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compressed = zlib.compress(img.tobytes(), level=PDF_COMPRESSION_LEVEL)
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return width_px, height_px, width_pt, height_pt, compressed
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with ThreadPoolExecutor(max_workers=worker_count(len(page_paths))) as executor:
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compressed_pages = list(executor.map(compress_page, page_paths))
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with out_path.open("wb") as f:
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f.write(b"%PDF-1.4\n%\xe2\xe3\xcf\xd3\n")
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for index, (width_px, height_px, width_pt, height_pt, compressed) in enumerate(compressed_pages):
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page_obj = 3 + index * 3
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image_obj = page_obj + 1
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content_obj = page_obj + 2
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page_objects.append(page_obj)
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image_dict = (
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f"/Type /XObject /Subtype /Image /Width {width_px} /Height {height_px} "
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"/ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /FlateDecode"
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)
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write_stream_obj(f, image_obj, image_dict, compressed)
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content = (
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f"q\n{pdf_num(width_pt)} 0 0 {pdf_num(height_pt)} 0 0 cm\n/Im0 Do\nQ\n"
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).encode("ascii")
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write_stream_obj(f, content_obj, "", content)
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page_body = (
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f"<< /Type /Page /Parent 2 0 R /MediaBox [0 0 {pdf_num(width_pt)} {pdf_num(height_pt)}] "
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f"/Resources << /XObject << /Im0 {image_obj} 0 R >> >> "
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f"/Contents {content_obj} 0 R >>"
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).encode("ascii")
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write_obj(f, page_obj, page_body)
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kids = " ".join(f"{obj_id} 0 R" for obj_id in page_objects)
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write_obj(f, 2, f"<< /Type /Pages /Kids [{kids}] /Count {len(page_objects)} >>".encode("ascii"))
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write_obj(f, 1, b"<< /Type /Catalog /Pages 2 0 R >>")
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xref_offset = f.tell()
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f.write(f"xref\n0 {max_obj + 1}\n".encode("ascii"))
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f.write(b"0000000000 65535 f \n")
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for obj_id in range(1, max_obj + 1):
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f.write(f"{offsets[obj_id]:010d} 00000 n \n".encode("ascii"))
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f.write(
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f"trailer\n<< /Size {max_obj + 1} /Root 1 0 R >>\nstartxref\n{xref_offset}\n%%EOF\n".encode(
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"ascii"
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)
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)
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