Module font 

Bitmap glyph fonts and CP437 mapping, shared by retroglyph’s graphical backends.

A BitmapFont holds a static 1-bit-per-pixel glyph table. Each glyph is stored as glyph_height bytes, one byte per row, MSB = leftmost pixel. For the standard 8-pixel-wide VGA format one byte covers all 8 pixels of a row; wider fonts would need two bytes per row, but that is not yet supported.

This module is the dependency-free glyph-source layer both retroglyph-software (CPU rasterizer) and retroglyph-gl (GPU atlas) build on, so their text output stays pixel-identical. It lives here (rather than in a standalone crate) because both consumers already depend on retroglyph-window for Presenter, and it needs none of winit: it is available with default-features = false. Enable the default-font feature for the embedded Unscii 16 font (unscii16::FONT); leave it off to supply your own via BitmapFont::new.

Future work

• Expanded glyph cache: For wider fonts (>8px), consider pre-computing expanded scanlines to avoid per-frame bit extraction. Currently the bit extraction loop is not a bottleneck for 8px-wide fonts at typical grid sizes, but wider fonts (10px, 16px) would benefit from caching.

• Wider glyphs: To support glyphs wider than 8px, change BitmapFont::rows to return ceil(glyph_width / 8) bytes per row and update the consumers’ bit extraction to index across bytes. Tracked in retroglyph issue #164; deferred until a second, non-8px-wide font is actually needed.

Modules

legacy_computing

Generated fallback BitmapFonts, embedded when the legacy-computing feature is enabled.

unscii16

The Unscii 16 font, embedded when the default-font feature is enabled.

Structs

BitmapFont

A 1-bit-per-pixel bitmap glyph font.

FontChain

The glyph source a backend draws from: a primary BitmapFont plus an ordered list of fallback fonts.

ResolvedGlyph

A glyph resolved from a FontChain: the glyph index plus the specific BitmapFont it came from, since each font in a chain owns its own bitmap data.