CJK Font for Rust embedded-graphics

font.py

from PIL import Image, ImageDraw, ImageFont
import PIL.features

# ! brew install libraqm
print('libraqm:', PIL.features.check('raqm'))

size = (320, 16)

"""
FORMAT = "RGB"
BG = (255, 255, 255)
FG = (0, 0, 0)
"""

FORMAT = '1'
BG = 0
FG = 1

YOFF = 0  # or -1

CHARS = "气温湿度照压卧槽艹牛逼数据设备"

im = Image.new(FORMAT, size, BG)

# font = ImageFont.truetype("sarasa-mono-sc-nerd-light.ttf", size=16, index=0)
# font = ImageFont.truetype("sarasa-mono-sc-nerd-regular.ttf", size=16, index=0)
font = ImageFont.truetype("Unibit.ttf", size=16, index=0)
# font = ImageFont.truetype("zpix.ttf", size=12, index=0)


draw = ImageDraw.Draw(im)

# code snippet to show the rendering resuble
draw.text((0, YOFF), CHARS, font=font, fill=FG, language='zh-CN')
im.save('font.png')
im.show()

draw.rectangle([(0, 0), size], fill=BG)

# NOTE: char 127 is replaced with '°'
# all control ascii chars can be used for half width symbols.
ASCII = '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f !"#$%&\'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~°'

charmap = []

for i, c in enumerate(ASCII):
    if c.isprintable():
        draw.text((0, YOFF), c, font=font, fill=FG)
    else:
        draw.text((0, YOFF), "  ", font=font, fill=FG)

    for y in range(16):
        v = 0
        for x in range(0, 8):
            b = im.getpixel((x, y))
            v = (v << 1) + b

        charmap.append(v)

    draw.rectangle([(0, 0), size], fill=BG)

for i, c in enumerate(CHARS):
    draw.text((0, YOFF), c, font=font, fill=FG)

    for y in range(16):
        v = 0
        for x in range(0, 16):
            b = im.getpixel((x, y))
            v = (v << 1) + b

        charmap.append(v >> 8)
        charmap.append(v & 0xFF)

    draw.rectangle([(0, 0), size], fill=BG)


with open('font.raw', 'wb') as fp:
    fp.write(bytes(charmap))

font.rs

use embedded_graphics::fonts::Font;
use embedded_graphics::geometry::Size;

#[derive(Clone, Copy)]
pub struct FontCn;

impl Font for FontCn {
    const FONT_IMAGE: &'static [u8] = include_bytes!("../font.raw");
    // add 1pixel row spacing
    const CHARACTER_SIZE: Size = Size::new(16, 16 + 1);
    const VARIABLE_WIDTH: bool = true;
    const FONT_IMAGE_WIDTH: u32 = 16;
    const CHARACTER_SPACING: u32 = 1;

    fn char_offset(_c: char) -> u32 {
        unreachable!()
    }

    fn char_width(c: char) -> u32 {
        match c {
            _ if (c as u16) < 128 => 8,
            '°' => 8,
            _ => 16,
        }
    }

    fn character_pixel(c: char, x: u32, y: u32) -> bool {
        if x >= 16 || y >= 16 {
            return false;
        }
        if c.is_ascii_graphic() {
            let map = &Self::FONT_IMAGE[16 * (c as usize)..16 + (c as usize) * 16];
            return (map[y as usize] & (1 << (7 - x))) != 0;
        }

        // chars that are remaped to 0-127 chontrol chars
        if c == '°' {
            let map = &Self::FONT_IMAGE[16 * 127..16 + 16 * 128];
            return (map[y as usize] & (1 << (7 - x))) != 0;
        }

        const start: usize = 128 * 16;
        const step: usize = 2 * 16;

        if let Some(index) = "气温湿度照压卧槽艹牛逼数据设备"
            .chars()
            .position(|ch| ch == c)
        {
            let bitmap = &Self::FONT_IMAGE[start + index * step..start + (index + 1) * step];

            if x >= 8 {
                (bitmap[y as usize * 2 + 1] & (1 << (15 - x))) != 0
            } else {
                (bitmap[y as usize * 2] & (1 << (7 - x))) != 0
            }
        } else {
            false
        }
    }
}