keleusma 0.2.2

//! Minimal bitmap-font text renderer. Each glyph is a five-
//! column by seven-row pixel pattern stored as seven bytes; the
//! low five bits of each byte are the row's pixels with the
//! high bit at the left. The renderer draws each pixel as a
//! square through SDL3 `fill_rect`, which scales to any integer
//! size without bilinear blur.
//!
//! The character set covers digits, uppercase letters, space,
//! period, colon, slash, dash, plus, and exclamation. The HUD
//! and the game-over screen need no more.

use sdl3::pixels::Color;
use sdl3::rect::Rect;
use sdl3::render::Canvas;
use sdl3::video::Window;

/// Glyph dimensions in pixels at scale one.
pub const GLYPH_W: i32 = 5;
pub const GLYPH_H: i32 = 7;
pub const GLYPH_GAP: i32 = 1;

/// Width in pixels of a single character at the given integer
/// scale, including the inter-character gap.
pub fn char_width(scale: i32) -> i32 {
    (GLYPH_W + GLYPH_GAP) * scale
}

/// Width in pixels of an entire string at the given integer
/// scale. Trailing gap is included to make right-aligned layout
/// straightforward.
pub fn text_width(text: &str, scale: i32) -> i32 {
    text.chars().count() as i32 * char_width(scale)
}

/// Draw a left-aligned string at `(x, y)` in the given colour.
/// Unknown characters render as blank space.
pub fn draw_text(
    canvas: &mut Canvas<Window>,
    x: i32,
    y: i32,
    text: &str,
    color: Color,
    scale: i32,
) {
    canvas.set_draw_color(color);
    let mut cx = x;
    for ch in text.chars() {
        let bitmap = glyph_for(ch);
        for row in 0..GLYPH_H {
            let bits = bitmap[row as usize];
            for col in 0..GLYPH_W {
                let bit = (bits >> (GLYPH_W - 1 - col)) & 1;
                if bit != 0 {
                    let px = cx + col * scale;
                    let py = y + row * scale;
                    let _ = canvas.fill_rect(Rect::new(px, py, scale as u32, scale as u32));
                }
            }
        }
        cx += char_width(scale);
    }
}

fn glyph_for(ch: char) -> [u8; 7] {
    match ch {
        '0' => [
            0b01110, 0b10001, 0b10011, 0b10101, 0b11001, 0b10001, 0b01110,
        ],
        '1' => [
            0b00100, 0b01100, 0b00100, 0b00100, 0b00100, 0b00100, 0b01110,
        ],
        '2' => [
            0b01110, 0b10001, 0b00001, 0b00010, 0b00100, 0b01000, 0b11111,
        ],
        '3' => [
            0b11110, 0b00001, 0b00001, 0b01110, 0b00001, 0b00001, 0b11110,
        ],
        '4' => [
            0b00010, 0b00110, 0b01010, 0b10010, 0b11111, 0b00010, 0b00010,
        ],
        '5' => [
            0b11111, 0b10000, 0b11110, 0b00001, 0b00001, 0b10001, 0b01110,
        ],
        '6' => [
            0b00110, 0b01000, 0b10000, 0b11110, 0b10001, 0b10001, 0b01110,
        ],
        '7' => [
            0b11111, 0b00001, 0b00010, 0b00100, 0b01000, 0b01000, 0b01000,
        ],
        '8' => [
            0b01110, 0b10001, 0b10001, 0b01110, 0b10001, 0b10001, 0b01110,
        ],
        '9' => [
            0b01110, 0b10001, 0b10001, 0b01111, 0b00001, 0b00010, 0b01100,
        ],
        'A' => [
            0b01110, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001,
        ],
        'B' => [
            0b11110, 0b10001, 0b10001, 0b11110, 0b10001, 0b10001, 0b11110,
        ],
        'C' => [
            0b01110, 0b10001, 0b10000, 0b10000, 0b10000, 0b10001, 0b01110,
        ],
        'D' => [
            0b11110, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b11110,
        ],
        'E' => [
            0b11111, 0b10000, 0b10000, 0b11110, 0b10000, 0b10000, 0b11111,
        ],
        'F' => [
            0b11111, 0b10000, 0b10000, 0b11110, 0b10000, 0b10000, 0b10000,
        ],
        'G' => [
            0b01110, 0b10001, 0b10000, 0b10111, 0b10001, 0b10001, 0b01110,
        ],
        'H' => [
            0b10001, 0b10001, 0b10001, 0b11111, 0b10001, 0b10001, 0b10001,
        ],
        'I' => [
            0b01110, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b01110,
        ],
        'J' => [
            0b00111, 0b00010, 0b00010, 0b00010, 0b00010, 0b10010, 0b01100,
        ],
        'K' => [
            0b10001, 0b10010, 0b10100, 0b11000, 0b10100, 0b10010, 0b10001,
        ],
        'L' => [
            0b10000, 0b10000, 0b10000, 0b10000, 0b10000, 0b10000, 0b11111,
        ],
        'M' => [
            0b10001, 0b11011, 0b10101, 0b10101, 0b10001, 0b10001, 0b10001,
        ],
        'N' => [
            0b10001, 0b11001, 0b10101, 0b10101, 0b10011, 0b10001, 0b10001,
        ],
        'O' => [
            0b01110, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01110,
        ],
        'P' => [
            0b11110, 0b10001, 0b10001, 0b11110, 0b10000, 0b10000, 0b10000,
        ],
        'Q' => [
            0b01110, 0b10001, 0b10001, 0b10001, 0b10101, 0b10010, 0b01101,
        ],
        'R' => [
            0b11110, 0b10001, 0b10001, 0b11110, 0b10100, 0b10010, 0b10001,
        ],
        'S' => [
            0b01110, 0b10001, 0b10000, 0b01110, 0b00001, 0b10001, 0b01110,
        ],
        'T' => [
            0b11111, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0b00100,
        ],
        'U' => [
            0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01110,
        ],
        'V' => [
            0b10001, 0b10001, 0b10001, 0b10001, 0b10001, 0b01010, 0b00100,
        ],
        'W' => [
            0b10001, 0b10001, 0b10001, 0b10101, 0b10101, 0b11011, 0b10001,
        ],
        'X' => [
            0b10001, 0b10001, 0b01010, 0b00100, 0b01010, 0b10001, 0b10001,
        ],
        'Y' => [
            0b10001, 0b10001, 0b10001, 0b01010, 0b00100, 0b00100, 0b00100,
        ],
        'Z' => [
            0b11111, 0b00001, 0b00010, 0b00100, 0b01000, 0b10000, 0b11111,
        ],
        ' ' => [0; 7],
        '.' => [0, 0, 0, 0, 0, 0b00110, 0b00110],
        ',' => [0, 0, 0, 0, 0b00110, 0b00100, 0b01000],
        ':' => [0, 0b00110, 0b00110, 0, 0b00110, 0b00110, 0],
        '/' => [
            0b00001, 0b00001, 0b00010, 0b00100, 0b01000, 0b10000, 0b10000,
        ],
        '-' => [0, 0, 0, 0b11111, 0, 0, 0],
        '+' => [0, 0, 0b00100, 0b01110, 0b00100, 0, 0],
        '!' => [0b00100, 0b00100, 0b00100, 0b00100, 0b00100, 0, 0b00100],
        '?' => [0b01110, 0b10001, 0b00001, 0b00010, 0b00100, 0, 0b00100],
        '(' => [
            0b00010, 0b00100, 0b01000, 0b01000, 0b01000, 0b00100, 0b00010,
        ],
        ')' => [
            0b01000, 0b00100, 0b00010, 0b00010, 0b00010, 0b00100, 0b01000,
        ],
        _ => [0; 7],
    }
}