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feat: first font implementation

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pull/1/head
flop 4 weeks ago
parent 5af50fcd29
commit b9fa8ba3ac
7 changed files with 454 additions and 239 deletions
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  1. 216
      ts/src/font.ts
  2. 0
      ts/src/font/fonts/5x7.ts
  3. 0
      ts/src/font/fonts/test.ts
  4. 5
      ts/src/font/index.ts
  5. 11
      ts/src/font/types.ts
  6. 411
      ts/src/font/u8g2.ts
  7. 16
      ts/src/renderer.ts

216
ts/src/font.ts
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// =============================================================================
// font.ts — built-in 5×7 bitmap font + text rasteriser
//
// Font encoding: column-major, 5 bytes per glyph (one byte per column).
// Each byte: bit 0 = topmost pixel, bit 6 = bottom pixel (7 rows used).
// Covers ASCII 0x20 (space) … 0x7E (~). Unknown codepoints → replacement glyph.
//
// Custom fonts (U8G2 binary format) accepted but glyph lookup not yet
// implemented — falls back to built-in automatically.
// =============================================================================
export const GLYPH_W = 5; // pixel columns per glyph
export const GLYPH_H = 7; // pixel rows per glyph
export const GLYPH_ADVANCE = 6; // pixels advanced per character (glyph + 1px gap)
// ---------------------------------------------------------------------------
// Built-in 5×7 font data — classic Adafruit GFX / GNU unifont subset
// ---------------------------------------------------------------------------
// prettier-ignore
const FONT_5x7 = new Uint8Array([
0x00, 0x00, 0x00, 0x00, 0x00, // 0x20 ' '
0x00, 0x00, 0x5F, 0x00, 0x00, // 0x21 '!'
0x00, 0x07, 0x00, 0x07, 0x00, // 0x22 '"'
0x14, 0x7F, 0x14, 0x7F, 0x14, // 0x23 '#'
0x24, 0x2A, 0x7F, 0x2A, 0x12, // 0x24 '$'
0x23, 0x13, 0x08, 0x64, 0x62, // 0x25 '%'
0x36, 0x49, 0x55, 0x22, 0x50, // 0x26 '&'
0x00, 0x05, 0x03, 0x00, 0x00, // 0x27 "'"
0x00, 0x1C, 0x22, 0x41, 0x00, // 0x28 '('
0x00, 0x41, 0x22, 0x1C, 0x00, // 0x29 ')'
0x14, 0x08, 0x3E, 0x08, 0x14, // 0x2A '*'
0x08, 0x08, 0x3E, 0x08, 0x08, // 0x2B '+'
0x00, 0x50, 0x30, 0x00, 0x00, // 0x2C ','
0x08, 0x08, 0x08, 0x08, 0x08, // 0x2D '-'
0x00, 0x60, 0x60, 0x00, 0x00, // 0x2E '.'
0x20, 0x10, 0x08, 0x04, 0x02, // 0x2F '/'
0x3E, 0x51, 0x49, 0x45, 0x3E, // 0x30 '0'
0x00, 0x42, 0x7F, 0x40, 0x00, // 0x31 '1'
0x42, 0x61, 0x51, 0x49, 0x46, // 0x32 '2'
0x21, 0x41, 0x45, 0x4B, 0x31, // 0x33 '3'
0x18, 0x14, 0x12, 0x7F, 0x10, // 0x34 '4'
0x27, 0x45, 0x45, 0x45, 0x39, // 0x35 '5'
0x3C, 0x4A, 0x49, 0x49, 0x30, // 0x36 '6'
0x01, 0x71, 0x09, 0x05, 0x03, // 0x37 '7'
0x36, 0x49, 0x49, 0x49, 0x36, // 0x38 '8'
0x06, 0x49, 0x49, 0x29, 0x1E, // 0x39 '9'
0x00, 0x36, 0x36, 0x00, 0x00, // 0x3A ':'
0x00, 0x56, 0x36, 0x00, 0x00, // 0x3B ';'
0x08, 0x14, 0x22, 0x41, 0x00, // 0x3C '<'
0x14, 0x14, 0x14, 0x14, 0x14, // 0x3D '='
0x00, 0x41, 0x22, 0x14, 0x08, // 0x3E '>'
0x02, 0x01, 0x51, 0x09, 0x06, // 0x3F '?'
0x32, 0x49, 0x79, 0x41, 0x3E, // 0x40 '@'
0x7E, 0x11, 0x11, 0x11, 0x7E, // 0x41 'A'
0x7F, 0x49, 0x49, 0x49, 0x36, // 0x42 'B'
0x3E, 0x41, 0x41, 0x41, 0x22, // 0x43 'C'
0x7F, 0x41, 0x41, 0x22, 0x1C, // 0x44 'D'
0x7F, 0x49, 0x49, 0x49, 0x41, // 0x45 'E'
0x7F, 0x09, 0x09, 0x09, 0x01, // 0x46 'F'
0x3E, 0x41, 0x49, 0x49, 0x7A, // 0x47 'G'
0x7F, 0x08, 0x08, 0x08, 0x7F, // 0x48 'H'
0x00, 0x41, 0x7F, 0x41, 0x00, // 0x49 'I'
0x20, 0x40, 0x41, 0x3F, 0x01, // 0x4A 'J'
0x7F, 0x08, 0x14, 0x22, 0x41, // 0x4B 'K'
0x7F, 0x40, 0x40, 0x40, 0x40, // 0x4C 'L'
0x7F, 0x02, 0x0C, 0x02, 0x7F, // 0x4D 'M'
0x7F, 0x04, 0x08, 0x10, 0x7F, // 0x4E 'N'
0x3E, 0x41, 0x41, 0x41, 0x3E, // 0x4F 'O'
0x7F, 0x09, 0x09, 0x09, 0x06, // 0x50 'P'
0x3E, 0x41, 0x51, 0x21, 0x5E, // 0x51 'Q'
0x7F, 0x09, 0x19, 0x29, 0x46, // 0x52 'R'
0x46, 0x49, 0x49, 0x49, 0x31, // 0x53 'S'
0x01, 0x01, 0x7F, 0x01, 0x01, // 0x54 'T'
0x3F, 0x40, 0x40, 0x40, 0x3F, // 0x55 'U'
0x1F, 0x20, 0x40, 0x20, 0x1F, // 0x56 'V'
0x3F, 0x40, 0x38, 0x40, 0x3F, // 0x57 'W'
0x63, 0x14, 0x08, 0x14, 0x63, // 0x58 'X'
0x07, 0x08, 0x70, 0x08, 0x07, // 0x59 'Y'
0x61, 0x51, 0x49, 0x45, 0x43, // 0x5A 'Z'
0x00, 0x7F, 0x41, 0x41, 0x00, // 0x5B '['
0x02, 0x04, 0x08, 0x10, 0x20, // 0x5C '\'
0x00, 0x41, 0x41, 0x7F, 0x00, // 0x5D ']'
0x04, 0x02, 0x01, 0x02, 0x04, // 0x5E '^'
0x40, 0x40, 0x40, 0x40, 0x40, // 0x5F '_'
0x00, 0x01, 0x02, 0x04, 0x00, // 0x60 '`'
0x20, 0x54, 0x54, 0x54, 0x78, // 0x61 'a'
0x7F, 0x48, 0x44, 0x44, 0x38, // 0x62 'b'
0x38, 0x44, 0x44, 0x44, 0x20, // 0x63 'c'
0x38, 0x44, 0x44, 0x48, 0x7F, // 0x64 'd'
0x38, 0x54, 0x54, 0x54, 0x18, // 0x65 'e'
0x08, 0x7E, 0x09, 0x01, 0x02, // 0x66 'f'
0x0C, 0x52, 0x52, 0x52, 0x3E, // 0x67 'g'
0x7F, 0x08, 0x04, 0x04, 0x78, // 0x68 'h'
0x00, 0x44, 0x7D, 0x40, 0x00, // 0x69 'i'
0x20, 0x40, 0x44, 0x3D, 0x00, // 0x6A 'j'
0x7F, 0x10, 0x28, 0x44, 0x00, // 0x6B 'k'
0x00, 0x41, 0x7F, 0x40, 0x00, // 0x6C 'l'
0x7C, 0x04, 0x18, 0x04, 0x78, // 0x6D 'm'
0x7C, 0x08, 0x04, 0x04, 0x78, // 0x6E 'n'
0x38, 0x44, 0x44, 0x44, 0x38, // 0x6F 'o'
0x7C, 0x14, 0x14, 0x14, 0x08, // 0x70 'p'
0x08, 0x14, 0x14, 0x18, 0x7C, // 0x71 'q'
0x7C, 0x08, 0x04, 0x04, 0x08, // 0x72 'r'
0x48, 0x54, 0x54, 0x54, 0x20, // 0x73 's'
0x04, 0x3F, 0x44, 0x40, 0x20, // 0x74 't'
0x3C, 0x40, 0x40, 0x20, 0x7C, // 0x75 'u'
0x1C, 0x20, 0x40, 0x20, 0x1C, // 0x76 'v'
0x3C, 0x40, 0x30, 0x40, 0x3C, // 0x77 'w'
0x44, 0x28, 0x10, 0x28, 0x44, // 0x78 'x'
0x0C, 0x50, 0x50, 0x50, 0x3C, // 0x79 'y'
0x44, 0x64, 0x54, 0x4C, 0x44, // 0x7A 'z'
0x00, 0x08, 0x36, 0x41, 0x00, // 0x7B '{'
0x00, 0x00, 0x7F, 0x00, 0x00, // 0x7C '|'
0x00, 0x41, 0x36, 0x08, 0x00, // 0x7D '}'
0x10, 0x08, 0x08, 0x10, 0x08, // 0x7E '~'
]);
// Replacement glyph for codepoints outside built-in coverage: filled 5×7 box
// prettier-ignore
const REPLACEMENT_GLYPH = new Uint8Array([0x7F, 0x41, 0x41, 0x41, 0x7F]);
/**
* Return the 5 column-bytes for a codepoint from the built-in font.
* Returns REPLACEMENT_GLYPH for anything outside ASCII 0x20–0x7E.
*/
export function builtinGlyph(cp: number): Uint8Array {
if (cp >= 0x20 && cp <= 0x7E) {
const off = (cp - 0x20) * GLYPH_W;
return FONT_5x7.subarray(off, off + GLYPH_W);
}
return REPLACEMENT_GLYPH;
}
// ---------------------------------------------------------------------------
// Custom font (U8G2 binary format)
// ---------------------------------------------------------------------------
/**
* Look up a glyph in a U8G2 font blob.
* Returns null if the codepoint is not found or the format is unsupported,
* in which case the caller should fall back to builtinGlyph().
*
* U8G2 font parsing is not yet fully implemented — this is a hook for future
* integration with the u8g2-fonts Rust crate output.
*/
export function u8g2Glyph(
_cp: number,
_fontData: Uint8Array,
): { cols: Uint8Array; w: number; h: number; xOff: number; yOff: number } | null {
// TODO: implement U8G2 binary glyph lookup
return null;
}
// ---------------------------------------------------------------------------
// Text → pixel-image rasteriser
// ---------------------------------------------------------------------------
/**
* Rasterise `text` into a 1bpp pixel image.
* Iterates over actual Unicode codepoints (handles surrogate pairs / emoji).
*
* - `cellHeight`: height of the destination cell in pixels; glyphs are
* centred vertically within it.
* - `customFont`: optional raw U8G2 font data; if provided and the glyph is
* found, it is used instead of the built-in font.
*
* Returns a pixel image sized (textWidth × cellHeight) where each byte is 0
* (off) or 1 (on).
*/
export function rasterizeText(
text: string,
cellHeight: number,
customFont?: Uint8Array,
): { pixels: Uint8Array; width: number; height: number } {
// Collect glyph column data for each codepoint
const glyphs: Array<{ cols: Uint8Array; w: number; h: number; yOff: number }> = [];
for (const char of text) { // ← real codepoint iteration
const cp = char.codePointAt(0) ?? 0x3F; // '?' fallback
// Try custom font first, fall back to built-in
const custom = customFont ? u8g2Glyph(cp, customFont) : null;
if (custom) {
glyphs.push({ cols: custom.cols, w: custom.w, h: custom.h, yOff: custom.yOff });
} else {
glyphs.push({ cols: builtinGlyph(cp), w: GLYPH_W, h: GLYPH_H, yOff: 0 });
}
}
// Total pixel width = sum of advances (GLYPH_ADVANCE per glyph, no trailing gap)
const totalW = Math.max(1, glyphs.length * GLYPH_ADVANCE - 1); // remove last gap
const pixels = new Uint8Array(totalW * cellHeight);
// Vertical centre of glyph within cell
const yBase = Math.max(0, Math.floor((cellHeight - GLYPH_H) / 2));
let x = 0;
for (const g of glyphs) {
const top = yBase + g.yOff;
for (let col = 0; col < g.w; col++) {
const colByte = g.cols[col] ?? 0;
for (let row = 0; row < g.h; row++) {
if ((colByte >> row) & 1) {
const py = top + row;
if (py >= 0 && py < cellHeight) {
pixels[py * totalW + x + col] = 1;
}
}
}
}
x += GLYPH_ADVANCE;
}
return { pixels, width: totalW, height: cellHeight };
}

0
ts/src/font/fonts/5x7.ts
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export * from "./types";
export * as _5x7 from "./5x7";
export * from "./u8g2";

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export class MonoDisplayFont {
public static FONT_DATA: Uint8Array;
}
export type RasterizedText = { pixels: Uint8Array; width: number; height: number };
export type RasterizeTextFunction = (
text: string,
cellHeight: number,
font?: MonoDisplayFont,
) => RasterizedText;

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ts/src/font/u8g2.ts
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// ---------------------------------------------------------------------------
// U8G2 font binary format constants (header offsets)
// ---------------------------------------------------------------------------
// The U8G2 font blob layout (all offsets are byte positions):
// [0] glyph_cnt – number of glyphs
// [1] bbx_mode – bounding-box mode
// [2] bits_per_0 – RLE bits for "off" run
// [3] bits_per_1 – RLE bits for "on" run
// [4] bits_per_char_width
// [5] bits_per_char_height
// [6] bits_per_char_x
// [7] bits_per_char_y
// [8] bits_per_delta_x
// [9] max_char_width
// [10] max_char_height
// [11] x_offset (signed)
// [12] y_offset (signed)
// [13] ascent_A
// [14] descent_g (negative)
// [15] ascent_para
// [16] descent_para
// [17..18] start_pos_upper (uint16 BE) – offset of uppercase glyph block
// [19..20] start_pos_lower (uint16 BE) – offset of lowercase glyph block
// [21..22] start_pos_unicode (uint16 BE) – offset of Unicode glyph block
// Glyph records follow the three jump-table blocks.
// Each glyph record:
// • A variable-length RLE bitstream (width × height bits) – MSB first
// • Followed by a fixed-width metadata section:
// dwidth (bits_per_delta_x bits) – horizontal advance
// width (bits_per_char_width)
// height (bits_per_char_height)
// x (bits_per_char_x, signed)
// y (bits_per_char_y, signed)
// The very first two bytes of each record encode the encoding (codepoint)
// as a uint16 LE, then a uint16 LE jump offset to the next record.
import type { MonoDisplayFont } from "./types";
// ---------------------------------------------------------------------------
// Built-in 5×7 font (printable ASCII 0x20–0x7E)
// Each entry is 5 column bytes, bit 0 = top row.
// ---------------------------------------------------------------------------
// prettier-ignore
const BUILTIN_FONT_DATA: Record<number, number[]> = {
0x20: [0x00, 0x00, 0x00, 0x00, 0x00], // space
0x21: [0x00, 0x00, 0x5F, 0x00, 0x00], // !
0x22: [0x00, 0x07, 0x00, 0x07, 0x00], // "
0x23: [0x14, 0x7F, 0x14, 0x7F, 0x14], // #
0x24: [0x24, 0x2A, 0x7F, 0x2A, 0x12], // $
0x25: [0x23, 0x13, 0x08, 0x64, 0x62], // %
0x26: [0x36, 0x49, 0x55, 0x22, 0x50], // &
0x27: [0x00, 0x05, 0x03, 0x00, 0x00], // '
0x28: [0x00, 0x1C, 0x22, 0x41, 0x00], // (
0x29: [0x00, 0x41, 0x22, 0x1C, 0x00], // )
0x2A: [0x14, 0x08, 0x3E, 0x08, 0x14], // *
0x2B: [0x08, 0x08, 0x3E, 0x08, 0x08], // +
0x2C: [0x00, 0x50, 0x30, 0x00, 0x00], // ,
0x2D: [0x08, 0x08, 0x08, 0x08, 0x08], // -
0x2E: [0x00, 0x60, 0x60, 0x00, 0x00], // .
0x2F: [0x20, 0x10, 0x08, 0x04, 0x02], // /
0x30: [0x3E, 0x51, 0x49, 0x45, 0x3E], // 0
0x31: [0x00, 0x42, 0x7F, 0x40, 0x00], // 1
0x32: [0x42, 0x61, 0x51, 0x49, 0x46], // 2
0x33: [0x21, 0x41, 0x45, 0x4B, 0x31], // 3
0x34: [0x18, 0x14, 0x12, 0x7F, 0x10], // 4
0x35: [0x27, 0x45, 0x45, 0x45, 0x39], // 5
0x36: [0x3C, 0x4A, 0x49, 0x49, 0x30], // 6
0x37: [0x01, 0x71, 0x09, 0x05, 0x03], // 7
0x38: [0x36, 0x49, 0x49, 0x49, 0x36], // 8
0x39: [0x06, 0x49, 0x49, 0x29, 0x1E], // 9
0x3A: [0x00, 0x36, 0x36, 0x00, 0x00], // :
0x3B: [0x00, 0x56, 0x36, 0x00, 0x00], // ;
0x3C: [0x08, 0x14, 0x22, 0x41, 0x00], // <
0x3D: [0x14, 0x14, 0x14, 0x14, 0x14], // =
0x3E: [0x00, 0x41, 0x22, 0x14, 0x08], // >
0x3F: [0x02, 0x01, 0x51, 0x09, 0x06], // ?
0x40: [0x32, 0x49, 0x79, 0x41, 0x3E], // @
0x41: [0x7E, 0x11, 0x11, 0x11, 0x7E], // A
0x42: [0x7F, 0x49, 0x49, 0x49, 0x36], // B
0x43: [0x3E, 0x41, 0x41, 0x41, 0x22], // C
0x44: [0x7F, 0x41, 0x41, 0x22, 0x1C], // D
0x45: [0x7F, 0x49, 0x49, 0x49, 0x41], // E
0x46: [0x7F, 0x09, 0x09, 0x09, 0x01], // F
0x47: [0x3E, 0x41, 0x49, 0x49, 0x7A], // G
0x48: [0x7F, 0x08, 0x08, 0x08, 0x7F], // H
0x49: [0x00, 0x41, 0x7F, 0x41, 0x00], // I
0x4A: [0x20, 0x40, 0x41, 0x3F, 0x01], // J
0x4B: [0x7F, 0x08, 0x14, 0x22, 0x41], // K
0x4C: [0x7F, 0x40, 0x40, 0x40, 0x40], // L
0x4D: [0x7F, 0x02, 0x0C, 0x02, 0x7F], // M
0x4E: [0x7F, 0x04, 0x08, 0x10, 0x7F], // N
0x4F: [0x3E, 0x41, 0x41, 0x41, 0x3E], // O
0x50: [0x7F, 0x09, 0x09, 0x09, 0x06], // P
0x51: [0x3E, 0x41, 0x51, 0x21, 0x5E], // Q
0x52: [0x7F, 0x09, 0x19, 0x29, 0x46], // R
0x53: [0x46, 0x49, 0x49, 0x49, 0x31], // S
0x54: [0x01, 0x01, 0x7F, 0x01, 0x01], // T
0x55: [0x3F, 0x40, 0x40, 0x40, 0x3F], // U
0x56: [0x1F, 0x20, 0x40, 0x20, 0x1F], // V
0x57: [0x3F, 0x40, 0x38, 0x40, 0x3F], // W
0x58: [0x63, 0x14, 0x08, 0x14, 0x63], // X
0x59: [0x07, 0x08, 0x70, 0x08, 0x07], // Y
0x5A: [0x61, 0x51, 0x49, 0x45, 0x43], // Z
0x5B: [0x00, 0x7F, 0x41, 0x41, 0x00], // [
0x5C: [0x02, 0x04, 0x08, 0x10, 0x20], // backslash
0x5D: [0x00, 0x41, 0x41, 0x7F, 0x00], // ]
0x5E: [0x04, 0x02, 0x01, 0x02, 0x04], // ^
0x5F: [0x40, 0x40, 0x40, 0x40, 0x40], // _
0x60: [0x00, 0x01, 0x02, 0x04, 0x00], // `
0x61: [0x20, 0x54, 0x54, 0x54, 0x78], // a
0x62: [0x7F, 0x48, 0x44, 0x44, 0x38], // b
0x63: [0x38, 0x44, 0x44, 0x44, 0x20], // c
0x64: [0x38, 0x44, 0x44, 0x48, 0x7F], // d
0x65: [0x38, 0x54, 0x54, 0x54, 0x18], // e
0x66: [0x08, 0x7E, 0x09, 0x01, 0x02], // f
0x67: [0x0C, 0x52, 0x52, 0x52, 0x3E], // g
0x68: [0x7F, 0x08, 0x04, 0x04, 0x78], // h
0x69: [0x00, 0x44, 0x7D, 0x40, 0x00], // i
0x6A: [0x20, 0x40, 0x44, 0x3D, 0x00], // j
0x6B: [0x7F, 0x10, 0x28, 0x44, 0x00], // k
0x6C: [0x00, 0x41, 0x7F, 0x40, 0x00], // l
0x6D: [0x7C, 0x04, 0x18, 0x04, 0x78], // m
0x6E: [0x7C, 0x08, 0x04, 0x04, 0x78], // n
0x6F: [0x38, 0x44, 0x44, 0x44, 0x38], // o
0x70: [0x7C, 0x14, 0x14, 0x14, 0x08], // p
0x71: [0x08, 0x14, 0x14, 0x18, 0x7C], // q
0x72: [0x7C, 0x08, 0x04, 0x04, 0x08], // r
0x73: [0x48, 0x54, 0x54, 0x54, 0x20], // s
0x74: [0x04, 0x3F, 0x44, 0x40, 0x20], // t
0x75: [0x3C, 0x40, 0x40, 0x20, 0x7C], // u
0x76: [0x1C, 0x20, 0x40, 0x20, 0x1C], // v
0x77: [0x3C, 0x40, 0x30, 0x40, 0x3C], // w
0x78: [0x44, 0x28, 0x10, 0x28, 0x44], // x
0x79: [0x0C, 0x50, 0x50, 0x50, 0x3C], // y
0x7A: [0x44, 0x64, 0x54, 0x4C, 0x44], // z
0x7B: [0x00, 0x08, 0x36, 0x41, 0x00], // {
0x7C: [0x00, 0x00, 0x7F, 0x00, 0x00], // |
0x7D: [0x00, 0x41, 0x36, 0x08, 0x00], // }
0x7E: [0x10, 0x08, 0x08, 0x10, 0x08], // ~
};
// Built-in font metrics (5×7, 1px column gap → advance = 6)
export const GLYPH_W = 5;
export const GLYPH_H = 7;
export const GLYPH_ADVANCE = 6; // width + 1px gap
/**
* Return column bytes for a codepoint from the built-in 5×7 font.
* Falls back to '?' (0x3F) for unknown codepoints.
*/
export function builtinGlyph(cp: number): Uint8Array {
const cols = BUILTIN_FONT_DATA[cp] ?? BUILTIN_FONT_DATA[0x3F]!;
return new Uint8Array(cols);
}
// ---------------------------------------------------------------------------
// U8G2 binary font parser
// ---------------------------------------------------------------------------
/** Bit-level reader over a Uint8Array, MSB-first within each byte. */
class BitReader {
private pos = 0; // bit position
constructor(private data: Uint8Array, startBit = 0) {
this.pos = startBit;
}
read(n: number): number {
let v = 0;
for (let i = 0; i < n; i++) {
const byteIdx = (this.pos) >> 3;
const bitIdx = 7 - ((this.pos) & 7); // MSB first
v = (v << 1) | ((this.data[byteIdx]! >> bitIdx) & 1);
this.pos++;
}
return v;
}
/** Read a signed value stored in `n` bits (two's complement). */
readSigned(n: number): number {
const v = this.read(n);
const sign = 1 << (n - 1);
return v & sign ? v - (sign << 1) : v;
}
get bitPos(): number { return this.pos; }
}
/** Read a big-endian uint16 from a byte array at `offset`. */
function readU16BE(data: Uint8Array, offset: number): number {
return ((data[offset]! << 8) | data[offset + 1]!) >>> 0;
}
/**
* Glyph result from a U8G2 font blob.
* `cols` – column bytes (bit 0 = top row), length = w.
*/
export interface U8G2GlyphData {
cols: Uint8Array;
w: number;
h: number;
yOff: number; // positive = shift down
}
/**
* Parse header fields from a U8G2 font blob and return the key metrics
* needed to decode glyphs.
*/
function parseHeader(font: Uint8Array) {
return {
glyphCnt: font[0]!,
bbxMode: font[1]!,
bitsPerRle0: font[2]!,
bitsPerRle1: font[3]!,
bitsPerW: font[4]!,
bitsPerH: font[5]!,
bitsPerX: font[6]!,
bitsPerY: font[7]!,
bitsPerDx: font[8]!,
maxCharW: font[9]!,
maxCharH: font[10]!,
xOff: font[11]! as number, // signed but treated as-is
yOff: font[12]! as number,
ascentA: font[13]!,
descentG: font[14]!,
startUpper: readU16BE(font, 17),
startLower: readU16BE(font, 19),
startUnicode: readU16BE(font, 21),
};
}
/**
* Decode one glyph from the U8G2 font RLE bitstream at `byteOffset`.
* Returns decoded data or null if the stream is malformed.
*
* U8G2 glyph encoding (bitstream, MSB-first):
* [bitsPerW] w glyph bitmap width
* [bitsPerH] h glyph bitmap height
* [bitsPerX] x signed x bearing
* [bitsPerY] y signed y bearing (positive = up from baseline)
* [bitsPerDx] dwidth horizontal advance
* Then w×h bits of RLE-encoded bitmap:
* repeat:
* 1-bit type (0 = off-run, 1 = on-run)
* bitsPerRleN count bits
*/
function decodeGlyphAt(
font: Uint8Array,
byteOffset: number,
hdr: ReturnType<typeof parseHeader>,
): U8G2GlyphData | null {
try {
const br = new BitReader(font, byteOffset * 8);
const w = br.read(hdr.bitsPerW);
const h = br.read(hdr.bitsPerH);
const xBrg = br.readSigned(hdr.bitsPerX);
const yBrg = br.readSigned(hdr.bitsPerY); // positive = up
br.read(hdr.bitsPerDx); // advance – not needed here
if (w === 0 || h === 0) {
// Blank glyph (e.g. space)
return { cols: new Uint8Array(GLYPH_W), w: GLYPH_W, h: GLYPH_H, yOff: 0 };
}
// Decode RLE bitmap into a flat bit array [row-major, top-to-bottom]
const totalBits = w * h;
const bits = new Uint8Array(totalBits);
let filled = 0;
while (filled < totalBits) {
const type = br.read(1); // 0=off, 1=on
const bitsN = type === 0 ? hdr.bitsPerRle0 : hdr.bitsPerRle1;
const count = br.read(bitsN) + 1; // stored as count-1
const val = type & 1;
for (let i = 0; i < count && filled < totalBits; i++) {
bits[filled++] = val;
}
}
// Convert row-major bitmap → column bytes (bit 0 = top row) to match
// the builtin font layout consumed by rasterizeText.
const cols = new Uint8Array(w);
for (let row = 0; row < h; row++) {
for (let col = 0; col < w; col++) {
if (bits[row * w + col]) {
// ts-ignore
cols[col] |= 1 << row;
}
}
}
// yBrg is measured upward from baseline in U8G2 conventions.
// Convert to a downward pixel offset relative to the top of GLYPH_H.
// ascentA = pixels above baseline for capital 'A'
// yOff = (ascentA - yBrg - h): rows to push down from the top of
// the glyph box so the baseline lands in the right place.
const yOff = Math.max(0, hdr.ascentA - yBrg - h);
return { cols, w, h, yOff };
} catch {
return null;
}
}
/**
* Scan the correct block of a U8G2 font for `cp` and return decoded glyph
* data, or null if not found.
*
* Each glyph record in the jump table starts with:
* [1 byte] encoding (codepoint, 0x00–0xFF in ASCII blocks)
* [1 byte] jump offset to next record (0 = end of block)
* then the bitstream described in decodeGlyphAt.
*
* For the Unicode block the encoding is 2 bytes (uint16 LE) and the jump
* offset is also 2 bytes (uint16 LE).
*/
export function u8g2Glyph(cp: number, font: Uint8Array): U8G2GlyphData | null {
if (font.length < 23) return null;
const hdr = parseHeader(font);
let blockStart: number;
let wide: boolean; // true for the Unicode block (2-byte encoding + 2-byte jump)
if (cp >= 0x20 && cp <= 0x5F) {
blockStart = hdr.startUpper;
wide = false;
} else if (cp >= 0x60 && cp <= 0x9F) {
blockStart = hdr.startLower;
wide = false;
} else {
blockStart = hdr.startUnicode;
wide = true;
}
if (blockStart === 0 || blockStart >= font.length) return null;
let pos = blockStart;
while (pos < font.length) {
let encoding: number;
let jump: number;
if (wide) {
if (pos + 4 > font.length) break;
encoding = (font[pos]! | (font[pos + 1]! << 8)) >>> 0; // LE uint16
jump = (font[pos + 2]! | (font[pos + 3]! << 8)) >>> 0;
pos += 4;
} else {
if (pos + 2 > font.length) break;
encoding = font[pos]!;
jump = font[pos + 1]!;
pos += 2;
}
if (jump === 0) break; // end-of-block sentinel
if (encoding === cp) {
return decodeGlyphAt(font, pos, hdr);
}
pos += jump; // skip to next record
}
return null; // codepoint not in font
}
// ---------------------------------------------------------------------------
// Text → pixel-image rasteriser (as specified)
// ---------------------------------------------------------------------------
export function rasterizeText(
text: string,
cellHeight: number,
font?: MonoDisplayFont,
): { pixels: Uint8Array; width: number; height: number } {
const glyphs: Array<{ cols: Uint8Array; w: number; h: number; yOff: number }> = [];
for (const char of text) {
const cp = char.codePointAt(0) ?? 0x3F;
const custom = font ? u8g2Glyph(cp, font.FONT_DATA) : null;
if (custom) {
glyphs.push({ cols: custom.cols, w: custom.w, h: custom.h, yOff: custom.yOff });
} else {
glyphs.push({ cols: builtinGlyph(cp), w: GLYPH_W, h: GLYPH_H, yOff: 0 });
}
}
const totalW = Math.max(1, glyphs.length * GLYPH_ADVANCE - 1);
const pixels = new Uint8Array(totalW * cellHeight);
const yBase = Math.max(0, Math.floor((cellHeight - GLYPH_H) / 2));
let x = 0;
for (const g of glyphs) {
const top = yBase + g.yOff;
for (let col = 0; col < g.w; col++) {
const colByte = g.cols[col] ?? 0;
for (let row = 0; row < g.h; row++) {
if ((colByte >> row) & 1) {
const py = top + row;
if (py >= 0 && py < cellHeight) {
pixels[py * totalW + x + col] = 1;
}
}
}
}
x += GLYPH_ADVANCE;
}
return { pixels, width: totalW, height: cellHeight };
}

16
ts/src/renderer.ts
Unescape View File

@ -16,7 +16,7 @@ import {
type MonoFormatVScroll
} from "./types.js";
import { type MonoDisplayDriverOptions } from "./driver";
import { rasterizeText } from "./font";
import { rasterizeText, MonoDisplayFont } from "./font";
/**
* Renders a MonoFormatFile onto an HTMLCanvasElement.
* Uses setInterval at 1000/fps ms per tick. All element state (animation
@ -36,14 +36,18 @@ export class MonoDisplayRenderer {
private animState: Map<number, { frame: number; counter: number }> = new Map();
private hScrollPos: Map<number, number> = new Map(); // pixel offset (may be fractional)
private vScrollPos: Map<number, number> = new Map();
private customFonts: Uint8Array[] = [];
private customFonts: MonoDisplayFont[] = [];
private textCache: Map<string, MonoFormatPixelImage> = new Map();
private builtinFonts: MonoDisplayFont[];
constructor(canvas: HTMLCanvasElement, opts: Required<MonoDisplayDriverOptions>) {
const ctx = canvas.getContext("2d");
if (!ctx) throw new Error("Cannot get 2D canvas context");
this.ctx = ctx;
this.opts = opts;
this.builtinFonts = [
];
}
stop(): void {
@ -211,11 +215,11 @@ export class MonoDisplayRenderer {
const { ctx, opts: { onColor, offColor, scale: s } } = this;
ctx.fillStyle = el.invertPixels ? offColor : onColor;
let [x0, y0, x1, y1] = [el.xOrigin, el.yOrigin, el.xTarget, el.yTarget];
const dx = Math.abs(x1-x0), sx = x0 < x1 ? 1 : -1;
const dy = -Math.abs(y1-y0), sy = y0 < y1 ? 1 : -1;
const dx = Math.abs(x1 - x0), sx = x0 < x1 ? 1 : -1;
const dy = -Math.abs(y1 - y0), sy = y0 < y1 ? 1 : -1;
let err = dx + dy;
while (true) {
ctx.fillRect(x0*s, y0*s, s, s);
ctx.fillRect(x0 * s, y0 * s, s, s);
if (x0 === x1 && y0 === y1) break;
const e2 = 2 * err;
if (e2 >= dy) { err += dy; x0 += sx; }
@ -227,7 +231,7 @@ export class MonoDisplayRenderer {
const key = `${text}|${fontIndex}|${height}`;
const cached = this.textCache.get(key);
if (cached) return cached;
const customFont = fontIndex >= 0x8000 ? this.customFonts[fontIndex - 0x8000] : undefined;
const customFont = fontIndex >= 0x8000 ? this.customFonts[fontIndex - 0x8000] : this.builtinFonts[fontIndex];
const img = rasterizeText(text, height, customFont);
this.textCache.set(key, img);
return img;

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