oxide-gui-core 0.1.0

Portable no_std GUI framework: Backend trait, Canvas, GNOME-style widgets, embedded 8x16 bitmap font. Zero dependencies; runs in OS kernels, embedded systems, and bare metal.
Documentation 
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//! Embedded 8×16 bitmap font covering printable ASCII (0x20–0x7E).
//!
//! Each glyph is 16 bytes (one per row), 8 pixels wide.  MSB of each byte
//! is the leftmost pixel.  The font is stored as a `const` so it lands in
//! read-only data and costs zero heap.
//!
//! `render_char` paints one glyph into any `Backend` using `fill_rect(1×1)`
//! for each lit pixel — simple and correct on every platform.  Backends that
//! have direct pixel access can bypass this and write the glyph data directly
//! for better performance.

use crate::backend::Backend;
use crate::color::Color;

pub const CHAR_W:  u32 = 8;
pub const CHAR_H:  u32 = 16;
pub const FIRST:   u8  = 0x20; // ' '
pub const LAST:    u8  = 0x7E; // '~'
pub const N_CHARS: usize = (LAST - FIRST + 1) as usize; // 95

/// Render glyph `ch` at pixel `(x, y)` into `backend`.
pub fn render_char<B: Backend + ?Sized>(backend: &mut B, x: u32, y: u32, ch: char, color: Color) {
    let byte = ch as u32;
    if byte < FIRST as u32 || byte > LAST as u32 { return; }
    let idx = (byte - FIRST as u32) as usize;
    let glyph = &FONT_DATA[idx * CHAR_H as usize .. (idx + 1) * CHAR_H as usize];
    for (row, &bits) in glyph.iter().enumerate() {
        let py = y + row as u32;
        if py >= backend.height() { break; }
        for col in 0..CHAR_W {
            if bits & (0x80 >> col) != 0 {
                let px = x + col;
                if px < backend.width() {
                    backend.fill_rect(px, py, 1, 1, color);
                }
            }
        }
    }
}

/// Measure the pixel width of `text` using the embedded font.
pub fn text_width(text: &str) -> u32 {
    text.chars().count() as u32 * CHAR_W
}

// ── Bitmap data ───────────────────────────────────────────────────────────────
// 95 glyphs × 16 rows = 1 520 bytes.
// Each byte encodes one row of 8 pixels; MSB = leftmost pixel.

#[rustfmt::skip]
const FONT_DATA: &[u8] = &[
// 0x20 ' '
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x21 '!'
0x00,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x00,0x18,0x18,0x00,0x00,0x00,0x00,0x00,
// 0x22 '"'
0x00,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x23 '#'
0x00,0x36,0x36,0x7F,0x36,0x36,0x36,0x7F,0x36,0x36,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x24 '$'
0x00,0x0C,0x3E,0x6B,0x68,0x3E,0x0B,0x6B,0x3E,0x0C,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x25 '%'
0x00,0x60,0x66,0x0C,0x18,0x18,0x30,0x66,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x26 '&'
0x00,0x38,0x6C,0x6C,0x38,0x76,0xDC,0xCC,0x76,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x27 "'"
0x00,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x28 '('
0x00,0x0C,0x18,0x30,0x30,0x30,0x30,0x30,0x18,0x0C,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x29 ')'
0x00,0x30,0x18,0x0C,0x0C,0x0C,0x0C,0x0C,0x18,0x30,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2A '*'
0x00,0x00,0x00,0x66,0x3C,0xFF,0x3C,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2B '+'
0x00,0x00,0x00,0x18,0x18,0x7E,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2C ','
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x30,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2D '-'
0x00,0x00,0x00,0x00,0x00,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2E '.'
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x2F '/'
0x00,0x06,0x06,0x0C,0x0C,0x18,0x18,0x30,0x30,0x60,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x30 '0'
0x00,0x3C,0x66,0x6E,0x76,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x31 '1'
0x00,0x18,0x38,0x18,0x18,0x18,0x18,0x18,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x32 '2'
0x00,0x3C,0x66,0x06,0x0C,0x18,0x30,0x60,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x33 '3'
0x00,0x3C,0x66,0x06,0x1C,0x06,0x06,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x34 '4'
0x00,0x0C,0x1C,0x3C,0x6C,0x7E,0x0C,0x0C,0x0C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x35 '5'
0x00,0x7E,0x60,0x60,0x7C,0x06,0x06,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x36 '6'
0x00,0x1C,0x30,0x60,0x7C,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x37 '7'
0x00,0x7E,0x06,0x0C,0x18,0x18,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x38 '8'
0x00,0x3C,0x66,0x66,0x3C,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x39 '9'
0x00,0x3C,0x66,0x66,0x66,0x3E,0x06,0x0C,0x38,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3A ':'
0x00,0x00,0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3B ';'
0x00,0x00,0x00,0x18,0x18,0x00,0x00,0x18,0x18,0x30,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3C '<'
0x00,0x00,0x06,0x0C,0x18,0x30,0x18,0x0C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3D '='
0x00,0x00,0x00,0x00,0x7E,0x00,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3E '>'
0x00,0x00,0x60,0x30,0x18,0x0C,0x18,0x30,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x3F '?'
0x00,0x3C,0x66,0x06,0x0C,0x18,0x00,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x40 '@'
0x00,0x3C,0x66,0x6E,0x6A,0x6E,0x60,0x62,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x41 'A'
0x00,0x18,0x3C,0x66,0x66,0x7E,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x42 'B'
0x00,0x7C,0x66,0x66,0x7C,0x66,0x66,0x66,0x7C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x43 'C'
0x00,0x3C,0x66,0x60,0x60,0x60,0x60,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x44 'D'
0x00,0x78,0x6C,0x66,0x66,0x66,0x66,0x6C,0x78,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x45 'E'
0x00,0x7E,0x60,0x60,0x7C,0x60,0x60,0x60,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x46 'F'
0x00,0x7E,0x60,0x60,0x7C,0x60,0x60,0x60,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x47 'G'
0x00,0x3C,0x66,0x60,0x60,0x6E,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x48 'H'
0x00,0x66,0x66,0x66,0x7E,0x66,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x49 'I'
0x00,0x3C,0x18,0x18,0x18,0x18,0x18,0x18,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4A 'J'
0x00,0x1E,0x0C,0x0C,0x0C,0x0C,0x6C,0x6C,0x38,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4B 'K'
0x00,0x66,0x6C,0x78,0x70,0x78,0x6C,0x66,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4C 'L'
0x00,0x60,0x60,0x60,0x60,0x60,0x60,0x60,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4D 'M'
0x00,0x63,0x77,0x7F,0x6B,0x63,0x63,0x63,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4E 'N'
0x00,0x66,0x76,0x7E,0x7E,0x6E,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x4F 'O'
0x00,0x3C,0x66,0x66,0x66,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x50 'P'
0x00,0x7C,0x66,0x66,0x66,0x7C,0x60,0x60,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x51 'Q'
0x00,0x3C,0x66,0x66,0x66,0x66,0x6E,0x3C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x52 'R'
0x00,0x7C,0x66,0x66,0x7C,0x6C,0x66,0x66,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x53 'S'
0x00,0x3C,0x66,0x60,0x3C,0x06,0x06,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x54 'T'
0x00,0x7E,0x18,0x18,0x18,0x18,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x55 'U'
0x00,0x66,0x66,0x66,0x66,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x56 'V'
0x00,0x66,0x66,0x66,0x66,0x66,0x3C,0x3C,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x57 'W'
0x00,0x63,0x63,0x63,0x6B,0x7F,0x77,0x63,0x41,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x58 'X'
0x00,0x66,0x66,0x3C,0x18,0x3C,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x59 'Y'
0x00,0x66,0x66,0x66,0x3C,0x18,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5A 'Z'
0x00,0x7E,0x06,0x0C,0x18,0x30,0x60,0x60,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5B '['
0x00,0x3C,0x30,0x30,0x30,0x30,0x30,0x30,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5C '\'
0x00,0x60,0x60,0x30,0x30,0x18,0x18,0x0C,0x0C,0x06,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5D ']'
0x00,0x3C,0x0C,0x0C,0x0C,0x0C,0x0C,0x0C,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5E '^'
0x00,0x18,0x3C,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x5F '_'
0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x60 '`'
0x00,0x30,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x61 'a'
0x00,0x00,0x00,0x3C,0x06,0x3E,0x66,0x66,0x3B,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x62 'b'
0x00,0x60,0x60,0x7C,0x66,0x66,0x66,0x66,0x7C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x63 'c'
0x00,0x00,0x00,0x3C,0x66,0x60,0x60,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x64 'd'
0x00,0x06,0x06,0x3E,0x66,0x66,0x66,0x66,0x3B,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x65 'e'
0x00,0x00,0x00,0x3C,0x66,0x7E,0x60,0x60,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x66 'f'
0x00,0x0E,0x18,0x18,0x3E,0x18,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x67 'g'
0x00,0x00,0x00,0x3B,0x66,0x66,0x66,0x3E,0x06,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,
// 0x68 'h'
0x00,0x60,0x60,0x7C,0x66,0x66,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x69 'i'
0x00,0x18,0x00,0x38,0x18,0x18,0x18,0x18,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6A 'j'
0x00,0x06,0x00,0x0E,0x06,0x06,0x06,0x06,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6B 'k'
0x00,0x60,0x60,0x66,0x6C,0x78,0x78,0x6C,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6C 'l'
0x00,0x38,0x18,0x18,0x18,0x18,0x18,0x18,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6D 'm'
0x00,0x00,0x00,0x76,0x7F,0x6B,0x6B,0x6B,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6E 'n'
0x00,0x00,0x00,0x7C,0x66,0x66,0x66,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x6F 'o'
0x00,0x00,0x00,0x3C,0x66,0x66,0x66,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x70 'p'
0x00,0x00,0x00,0x7C,0x66,0x66,0x66,0x7C,0x60,0x60,0x60,0x00,0x00,0x00,0x00,0x00,
// 0x71 'q'
0x00,0x00,0x00,0x3B,0x66,0x66,0x66,0x3E,0x06,0x06,0x06,0x00,0x00,0x00,0x00,0x00,
// 0x72 'r'
0x00,0x00,0x00,0x6C,0x76,0x60,0x60,0x60,0x60,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x73 's'
0x00,0x00,0x00,0x3C,0x66,0x38,0x0C,0x66,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x74 't'
0x00,0x18,0x18,0x7E,0x18,0x18,0x18,0x18,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x75 'u'
0x00,0x00,0x00,0x66,0x66,0x66,0x66,0x66,0x3B,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x76 'v'
0x00,0x00,0x00,0x66,0x66,0x66,0x3C,0x3C,0x18,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x77 'w'
0x00,0x00,0x00,0x63,0x63,0x6B,0x7F,0x77,0x63,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x78 'x'
0x00,0x00,0x00,0x66,0x66,0x3C,0x3C,0x66,0x66,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x79 'y'
0x00,0x00,0x00,0x66,0x66,0x66,0x3E,0x06,0x3C,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x7A 'z'
0x00,0x00,0x00,0x7E,0x0C,0x18,0x30,0x60,0x7E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x7B '{'
0x00,0x0E,0x18,0x18,0x70,0x18,0x18,0x18,0x0E,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x7C '|'
0x00,0x18,0x18,0x18,0x18,0x00,0x18,0x18,0x18,0x18,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x7D '}'
0x00,0x70,0x18,0x18,0x0E,0x18,0x18,0x18,0x70,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
// 0x7E '~'
0x00,0x76,0xDC,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,
];