gameframe-bitmap-font

An old game's bitmap font as a TrueType font, built in memory. Many games of the 1990s keep their fonts as fixed cells of palette indices, with an advance for each character. A launcher's theme, a page or a tool that wants to write in the game's own letters gives this crate the cells (Bitmap, one Glyph per character with its Unicode code point) and gets a .ttf back (build). font_face wraps it in a CSS @font-face rule with a data URL, ready for a web view such as the frame's (FrameSetup::with_theme).

Each set pixel becomes part of a square outline, 64 font units to the pixel. Runs of pixels in a row, merged with the same run in the rows below, make one rectangle each. The tables are the few a browser's font loader needs (head, hhea, maxp, OS/2, hmtx, cmap format 4, loca, glyf, name, post 3.0), with no hinting. Draw the font at a whole multiple of the cell's height in CSS pixels, and each pixel stays whole.

Nothing is written to disk, so a project can make the font from the player's own files each time it starts and commit none of the game. Hardwar's launcher does this with the game's HARDS.FNT and HARDL.FNT.

No dependencies and no unsafe code; builds for WebAssembly.

use gameframe_bitmap_font::{build, font_face, Bitmap, Glyph};

let i = [1u8, 1, 1, 1];
let font = Bitmap {
    family: "Tiny",
    width: 1,
    height: 4,
    baseline: 4,
    glyphs: vec![Glyph { code: 'i' as u16, advance: 2, pixels: &i }],
};
let css = font_face("Tiny", &build(&font));
assert!(css.starts_with("@font-face"));

Licence: Apache 2.0.