fonttools/Snippets/compact_gpos.py

import argparse
from collections import defaultdict
import csv
import time
import sys
from pathlib import Path
from typing import Any, Iterable, List, Optional, Sequence, Tuple

from fontTools.ttLib import TTFont
from fontTools.otlLib.optimize import compact

MODES = [str(c) for c in range(1, 10)]


def main(args: Optional[List[str]] = None):
    parser = argparse.ArgumentParser()
    parser.add_argument("fonts", type=Path, nargs="+", help="Path to TTFs.")
    parsed_args = parser.parse_args(args)

    runtimes = defaultdict(list)
    rows = []
    font_path: Path
    for font_path in parsed_args.fonts:
        font = TTFont(font_path)
        if "GPOS" not in font:
            print(f"No GPOS in {font_path.name}, skipping.", file=sys.stderr)
            continue
        size_orig = len(font.getTableData("GPOS")) / 1024
        print(f"Measuring {font_path.name}...", file=sys.stderr)

        fonts = {}
        font_paths = {}
        sizes = {}
        for mode in MODES:
            print(f"    Running mode={mode}", file=sys.stderr)
            fonts[mode] = TTFont(font_path)
            before = time.perf_counter()
            compact(fonts[mode], mode=str(mode))
            runtimes[mode].append(time.perf_counter() - before)
            font_paths[mode] = (
                font_path.parent
                / "compact"
                / (font_path.stem + f"_{mode}" + font_path.suffix)
            )
            font_paths[mode].parent.mkdir(parents=True, exist_ok=True)
            fonts[mode].save(font_paths[mode])
            fonts[mode] = TTFont(font_paths[mode])
            sizes[mode] = len(fonts[mode].getTableData("GPOS")) / 1024

        print(f"    Runtimes:", file=sys.stderr)
        for mode, times in runtimes.items():
            print(
                f"        {mode:10} {' '.join(f'{t:5.2f}' for t in times)}",
                file=sys.stderr,
            )

        # Bonus: measure WOFF2 file sizes.
        print(f"    Measuring WOFF2 sizes", file=sys.stderr)
        size_woff_orig = woff_size(font, font_path) / 1024
        sizes_woff = {
            mode: woff_size(fonts[mode], font_paths[mode]) / 1024 for mode in MODES
        }

        rows.append(
            (
                font_path.name,
                size_orig,
                size_woff_orig,
                *flatten(
                    (
                        sizes[mode],
                        pct(sizes[mode], size_orig),
                        sizes_woff[mode],
                        pct(sizes_woff[mode], size_woff_orig),
                    )
                    for mode in MODES
                ),
            )
        )

    write_csv(rows)


def woff_size(font: TTFont, path: Path) -> int:
    font.flavor = "woff2"
    woff_path = path.with_suffix(".woff2")
    font.save(woff_path)
    return woff_path.stat().st_size


def write_csv(rows: List[Tuple[Any]]) -> None:
    sys.stdout.reconfigure(encoding="utf-8")
    sys.stdout.write("\uFEFF")
    writer = csv.writer(sys.stdout, lineterminator="\n")
    writer.writerow(
        [
            "File",
            "Original GPOS Size",
            "Original WOFF2 Size",
            *flatten(
                (
                    f"mode={mode}",
                    f"Change {mode}",
                    f"mode={mode} WOFF2 Size",
                    f"Change {mode} WOFF2 Size",
                )
                for mode in MODES
            ),
        ]
    )
    for row in rows:
        writer.writerow(row)


def pct(new: float, old: float) -> float:
    return -(1 - (new / old))


def flatten(seq_seq: Iterable[Iterable[Any]]) -> List[Any]:
    return [thing for seq in seq_seq for thing in seq]


if __name__ == "__main__":
    main()