trezor-firmware/core/tools/codegen/gen_font.py

#!/usr/bin/env python3

# script used to generate /embed/lib/fonts/font_*_*.c

from __future__ import annotations

import unicodedata
from dataclasses import dataclass
from pathlib import Path
from typing import TextIO
import json
import sys

# pip install freetype-py
import freetype

from foreign_chars import all_languages


def _normalize(s: str) -> str:
    return unicodedata.normalize("NFKC", s)


HERE = Path(__file__).parent
CORE_ROOT = HERE.parent.parent
FONTS_DIR = HERE / "fonts"
OUT_DIR = HERE / ".." / ".." / "embed" / "lib" / "fonts"
C_FONTS_DEST = CORE_ROOT / "embed" / "lib" / "fonts"
JSON_FONTS_DEST = CORE_ROOT / "translations" / "fonts"

MIN_GLYPH = ord(" ")
MAX_GLYPH = ord("~")

WRITE_WIDTHS = False

# characters for which bearingX is negative, but we choose to make it zero and modify
# advance instead
MODIFY_BEARING_X = [
    _normalize(c)
    for c in (
        "Ä",
        "À",
        "Â",
        "Æ",
        "Î",
        "Ï",
        "î",
        "ï",
        "ÿ",
        "Ý",
        "Ÿ",
        "Á",
        "ý",
        "A",
        "X",
        "Y",
        "j",
        "x",
        "y",
        "}",
        ")",
        ",",
        "/",
        "_",
    )
]

# metrics explanation: https://www.freetype.org/freetype2/docs/glyphs/metrics.png


def process_bitmap_buffer(
    buf: list[int], bpp: int, width: int, height: int
) -> list[int]:
    res = buf[:]
    if bpp == 1:
        for _ in range(8 - len(res) % 8):
            res.append(0)
        res = [
            (
                (a & 0x80)
                | ((b & 0x80) >> 1)
                | ((c & 0x80) >> 2)
                | ((d & 0x80) >> 3)
                | ((e & 0x80) >> 4)
                | ((f & 0x80) >> 5)
                | ((g & 0x80) >> 6)
                | ((h & 0x80) >> 7)
            )
            for a, b, c, d, e, f, g, h in [
                res[i : i + 8] for i in range(0, len(res), 8)
            ]
        ]
    elif bpp == 2:
        for _ in range(4 - len(res) % 4):
            res.append(0)
        res = [
            ((a & 0xC0) | ((b & 0xC0) >> 2) | ((c & 0xC0) >> 4) | ((d & 0xC0) >> 6))
            for a, b, c, d in [res[i : i + 4] for i in range(0, len(res), 4)]
        ]
    elif bpp == 4:
        res: list[int] = []
        for y in range(0, height):
            row = buf[y * width : (y + 1) * width]
            for a, b in zip(row[::2], row[1::2]):
                res.append(((b & 0xF0) | (a >> 4)))
            if width & 1 != 0:
                res.append(row[-1] >> 4)
    elif bpp == 8:
        pass
    else:
        raise ValueError
    return res


def drop_left_columns(buf: list[int], width: int, drop: int) -> list[int]:
    res: list[int] = []
    for i in range(len(buf)):
        if i % width >= drop:
            res.append(buf[i])
    return res


@dataclass
class Glyph:
    char: str
    width: int
    rows: int
    advance: int
    bearingX: int
    bearingY: int
    buf: list[int]
    num_grays: int
    inverse_colors: bool = False

    @classmethod
    def from_face(
        cls, face: freetype.Face, c: str, shaveX: int, inverse_colors: bool = False
    ) -> Glyph:
        assert len(c) == 1
        bitmap = face.glyph.bitmap
        metrics = face.glyph.metrics
        assert metrics.width // 64 == bitmap.width
        assert metrics.height // 64 == bitmap.rows
        assert metrics.width % 64 == 0
        assert metrics.height % 64 == 0
        assert metrics.horiAdvance % 64 == 0
        assert metrics.horiBearingX % 64 == 0
        assert metrics.horiBearingY % 64 == 0
        assert bitmap.width == bitmap.pitch
        assert len(bitmap.buffer) == bitmap.pitch * bitmap.rows
        width = bitmap.width
        rows = bitmap.rows
        advance = metrics.horiAdvance // 64
        bearingX = metrics.horiBearingX // 64

        remove_left = shaveX
        # discard space on the left side
        if shaveX > 0:
            diff = min(advance, bearingX, shaveX)
            advance -= diff
            bearingX -= diff
            remove_left -= diff
        # the following code is here just for some letters (listed at start)
        # not using negative bearingX makes life so much easier; add it to advance instead
        if bearingX < 0:
            if c in MODIFY_BEARING_X:
                advance += -bearingX
                bearingX = 0
            else:
                raise ValueError("Negative bearingX for character '%s'" % c)
        bearingY = metrics.horiBearingY // 64
        assert advance >= 0 and advance <= 255
        assert bearingX >= 0 and bearingX <= 255
        if bearingY < 0:  # HACK
            print("normalizing bearingY %d for '%s'" % (bearingY, c))
            bearingY = 0
        assert bearingY >= 0 and bearingY <= 255
        buf = list(bitmap.buffer)
        # discard non-space pixels on the left side
        if remove_left > 0 and width > 0:
            assert bearingX == 0
            buf = drop_left_columns(buf, width, remove_left)
            assert width > remove_left
            width -= remove_left
            assert advance > remove_left
            advance -= remove_left
            print(
                'Glyph "%c": removed %d pixel columns from the left' % (c, remove_left)
            )

        return Glyph(
            char=c,
            width=width,
            rows=rows,
            advance=advance,
            bearingX=bearingX,
            bearingY=bearingY,
            buf=buf,
            num_grays=bitmap.num_grays,
            inverse_colors=inverse_colors,
        )

    def print_metrics(self) -> None:
        print(
            'Loaded glyph "%c" ... %d x %d @ %d grays (%d bytes, metrics: %d, %d, %d)'
            % (
                self.char,
                self.width,
                self.rows,
                self.num_grays,
                len(self.buf),
                self.advance,
                self.bearingX,
                self.bearingY,
            )
        )

    def process_byte(self, b: int) -> int:
        if self.inverse_colors:
            return b ^ 0xFF
        else:
            return b

    def get_definition_line(
        self, name_style_size: str, bpp: int, i: int | str, static: bool = True
    ) -> str:
        numbers = ", ".join(str(n) for n in self.to_bytes(bpp))
        comment = f"/* {self.char} */"
        const_name = f"Font_{name_style_size}_glyph_{i}"
        if static:
            modifier = "static const"
        else:
            modifier = "const"
        return f"{comment} {modifier} uint8_t {const_name}[] = {{ {numbers} }};\n"

    def to_bytes(self, bpp: int) -> bytes:
        infos = [
            self.width,
            self.rows,
            self.advance,
            self.bearingX,
            self.bearingY,
        ]
        if self.buf:
            data = [
                self.process_byte(x)
                for x in process_bitmap_buffer(self.buf, bpp, self.width, self.rows)
            ]
            return bytes(infos + data)
        else:
            return bytes(infos)


class FaceProcessor:
    def __init__(
        self,
        name: str,
        style: str,
        size: int,
        bpp: int = 4,
        shaveX: int = 0,
        ext: str = "ttf",
    ):
        print("Processing ... %s %s %s" % (name, style, size))
        self.name = name
        self.style = style
        self.size = size
        self.bpp = bpp
        self.shaveX = shaveX
        self.ext = ext
        self.face = freetype.Face(str(FONTS_DIR / f"{name}-{style}.{ext}"))
        self.face.set_pixel_sizes(0, size)  # type: ignore
        self.fontname = "%s_%s_%d" % (name.lower(), style.lower(), size)
        self.font_ymin = 0
        self.font_ymax = 0

    @property
    def _name_style_size(self) -> str:
        return f"{self.name}_{self.style}_{self.size}"

    @property
    def _c_file_name(self) -> Path:
        return C_FONTS_DEST / f"font_{self.fontname}.c"

    @property
    def _h_file_name(self) -> Path:
        return C_FONTS_DEST / f"font_{self.fontname}.h"

    def write_files(self) -> None:
        self.write_c_files()
        self.write_foreign_json()
        if WRITE_WIDTHS:
            self.write_char_widths_files()

    def write_c_files(self) -> None:
        self._write_c_file()
        self._write_h_file()

    def write_foreign_json(self) -> None:
        for lang, language_chars in all_languages.items():
            fontdata = {}
            for item in language_chars:
                c = _normalize(item)
                assert len(c) == 1
                self._load_char(c)
                glyph = Glyph.from_face(self.face, c, self.shaveX)
                glyph.print_metrics()
                fontdata[c] = glyph.to_bytes(self.bpp).hex()
            file = JSON_FONTS_DEST / f"font_{self.fontname}_{lang}.json"
            json_content = json.dumps(fontdata, indent=2, ensure_ascii=False)
            file.write_text(json_content + "\n")

    def write_char_widths_files(self) -> None:
        chars: set[str] = set()
        widths: dict[str, int] = {}

        # "normal" ASCII characters
        for i in range(MIN_GLYPH, MAX_GLYPH + 1):
            c = chr(i)
            chars.add(c)
        # foreign language data
        for _lang, lang_chars in all_languages.items():
            for c in lang_chars:
                chars.add(c)

        for c in sorted(chars):
            self._load_char(c)
            glyph = Glyph.from_face(self.face, c, self.shaveX)
            widths[c] = glyph.advance

        filename = f"font_widths_{self.fontname}.json"
        with open(filename, "w", encoding="utf-8") as f:
            json_content = json.dumps(widths, indent=2, ensure_ascii=False)
            f.write(json_content + "\n")

    def _write_c_file(self) -> None:
        with open(OUT_DIR / self._c_file_name, "wt") as f:
            self._write_c_file_header(f)
            self._write_c_file_content(f)

    def _write_c_file_content(self, f: TextIO) -> None:
        # Write "normal" ASCII characters
        for i in range(MIN_GLYPH, MAX_GLYPH + 1):
            c = chr(i)
            self._write_char_definition(f, c, i)

        # Write non-printable character
        f.write("\n")
        nonprintable = self._get_nonprintable_definition_line()
        f.write(nonprintable)

        # Write array of all glyphs
        f.write("\n")
        f.write(
            "const uint8_t * const Font_%s[%d + 1 - %d] = {\n"
            % (self._name_style_size, MAX_GLYPH, MIN_GLYPH)
        )
        for i in range(MIN_GLYPH, MAX_GLYPH + 1):
            f.write("    Font_%s_glyph_%d,\n" % (self._name_style_size, i))
        f.write("};\n")

    def _write_char_definition(self, f: TextIO, c: str, i: int) -> None:
        self._load_char(c)
        glyph = Glyph.from_face(self.face, c, self.shaveX)
        glyph.print_metrics()
        definition_line = glyph.get_definition_line(self._name_style_size, self.bpp, i)
        f.write(definition_line)

        # Update mix/max metrics
        yMin = glyph.bearingY - glyph.rows
        yMax = yMin + glyph.rows
        self.font_ymin = min(self.font_ymin, yMin)
        self.font_ymax = max(self.font_ymax, yMax)

    def _write_c_file_header(self, f: TextIO) -> None:
        f.write("#include <stdint.h>\n\n")
        f.write("// clang-format off\n\n")
        f.write("// - the first two bytes are width and height of the glyph\n")
        f.write(
            "// - the third, fourth and fifth bytes are advance, bearingX and bearingY of the horizontal metrics of the glyph\n"
        )
        f.write("// - the rest is packed %d-bit glyph data\n\n" % self.bpp)

    def _get_nonprintable_definition_line(self) -> str:
        c = "?"
        self._load_char(c)
        glyph = Glyph.from_face(self.face, c, self.shaveX, inverse_colors=True)
        return glyph.get_definition_line(
            self._name_style_size, self.bpp, "nonprintable", static=False
        )

    def _load_char(self, c: str) -> None:
        self.face.load_char(c, freetype.FT_LOAD_RENDER | freetype.FT_LOAD_TARGET_NORMAL)  # type: ignore

    def _write_h_file(self) -> None:
        with open(OUT_DIR / self._h_file_name, "wt") as f:
            f.write("#include <stdint.h>\n\n")
            f.write("#if TREZOR_FONT_BPP != %d\n" % self.bpp)
            f.write("#error Wrong TREZOR_FONT_BPP (expected %d)\n" % self.bpp)
            f.write("#endif\n")

            f.write("#define Font_%s_HEIGHT %d\n" % (self._name_style_size, self.size))
            f.write(
                "#define Font_%s_MAX_HEIGHT %d\n"
                % (self._name_style_size, self.font_ymax - self.font_ymin)
            )
            f.write(
                "#define Font_%s_BASELINE %d\n"
                % (self._name_style_size, -self.font_ymin)
            )
            f.write(
                "extern const uint8_t* const Font_%s[%d + 1 - %d];\n"
                % (self._name_style_size, MAX_GLYPH, MIN_GLYPH)
            )
            f.write(
                "extern const uint8_t Font_%s_glyph_nonprintable[];\n"
                % (self._name_style_size)
            )


if __name__ == "__main__":
    if len(sys.argv) > 1 and "width" in sys.argv[1]:
        WRITE_WIDTHS = True  # type: ignore

    FaceProcessor("Roboto", "Regular", 20).write_files()
    FaceProcessor("Roboto", "Bold", 20).write_files()

    FaceProcessor("TTHoves", "Regular", 21, ext="otf").write_files()
    FaceProcessor("TTHoves", "DemiBold", 21, ext="otf").write_files()
    FaceProcessor("TTHoves", "Bold", 17, ext="otf").write_files()
    FaceProcessor("RobotoMono", "Medium", 20).write_files()

    FaceProcessor("PixelOperator", "Regular", 8, bpp=1, shaveX=1).write_files()

    FaceProcessor("PixelOperator", "Bold", 8, bpp=1, shaveX=1).write_files()
    FaceProcessor("PixelOperatorMono", "Regular", 8, bpp=1, shaveX=1).write_files()

    # For model R
    FaceProcessor("Unifont", "Regular", 16, bpp=1, shaveX=1, ext="otf").write_files()
    # NOTE: Unifont Bold does not seem to have czech characters
    FaceProcessor("Unifont", "Bold", 16, bpp=1, shaveX=1, ext="otf").write_files()