glyph picker

kiln-core/src/cp437.rs

@@ -0,0 +1,91 @@
+//! CP437 → Unicode mapping for interpreting glyph tile indices as characters.
+//!
+//! kiln stores each cell's visual as a `tile: u32` index into a bitmap font.
+//! The default kiln font is IBM CP437, where the tile index equals the CP437
+//! code point. A terminal can't draw the bitmap font, so a front-end reinterprets
+//! the tile index as a character via this table and prints that character with
+//! the cell's foreground/background colors. This lives in kiln-core (not a
+//! front-end) because it is the *meaning* of a tile index under the default font,
+//! shared by every renderer and by the editor's glyph picker.
+
+/// CP437 code point → Unicode scalar value.
+///
+/// Index this array by a byte value (0–255) to get the displayable character.
+/// The low control range (0x00–0x1F) maps to CP437's graphic glyphs (hearts,
+/// arrows, musical notes, etc.) rather than ASCII control codes, matching how
+/// these byte values render in a DOS/ZZT-style font. Code 0x00 maps to a blank
+/// space since a literal NUL is not displayable.
+const CP437: [char; 256] = [
+    // 0x00–0x0F
+    ' ', '☺', '☻', '♥', '♦', '♣', '♠', '•', '◘', '○', '◙', '♂', '♀', '♪', '♫', '☼',
+    // 0x10–0x1F
+    '►', '◄', '↕', '‼', '¶', '§', '▬', '↨', '↑', '↓', '→', '←', '∟', '↔', '▲', '▼',
+    // 0x20–0x2F  (ASCII space onward)
+    ' ', '!', '"', '#', '$', '%', '&', '\'', '(', ')', '*', '+', ',', '-', '.', '/',
+    // 0x30–0x3F
+    '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?',
+    // 0x40–0x4F
+    '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
+    // 0x50–0x5F
+    'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', '\\', ']', '^', '_',
+    // 0x60–0x6F
+    '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
+    // 0x70–0x7F
+    'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~', '⌂',
+    // 0x80–0x8F
+    'Ç', 'ü', 'é', 'â', 'ä', 'à', 'å', 'ç', 'ê', 'ë', 'è', 'ï', 'î', 'ì', 'Ä', 'Å',
+    // 0x90–0x9F
+    'É', 'æ', 'Æ', 'ô', 'ö', 'ò', 'û', 'ù', 'ÿ', 'Ö', 'Ü', '¢', '£', '¥', '₧', 'ƒ',
+    // 0xA0–0xAF
+    'á', 'í', 'ó', 'ú', 'ñ', 'Ñ', 'ª', 'º', '¿', '⌐', '¬', '½', '¼', '¡', '«', '»',
+    // 0xB0–0xBF  (shading + box drawing)
+    '░', '▒', '▓', '│', '┤', '╡', '╢', '╖', '╕', '╣', '║', '╗', '╝', '╜', '╛', '┐',
+    // 0xC0–0xCF
+    '└', '┴', '┬', '├', '─', '┼', '╞', '╟', '╚', '╔', '╩', '╦', '╠', '═', '╬', '╧',
+    // 0xD0–0xDF
+    '╨', '╤', '╥', '╙', '╘', '╒', '╓', '╫', '╪', '┘', '┌', '█', '▄', '▌', '▐', '▀',
+    // 0xE0–0xEF
+    'α', 'ß', 'Γ', 'π', 'Σ', 'σ', 'µ', 'τ', 'Φ', 'Θ', 'Ω', 'δ', '∞', 'φ', 'ε', '∩',
+    // 0xF0–0xFF
+    '≡', '±', '≥', '≤', '⌠', '⌡', '÷', '≈', '°', '∙', '·', '√', 'ⁿ', '²', '■', '\u{00A0}',
+];
+
+/// Converts a glyph tile index into a displayable character.
+///
+/// Tile indices in `0..256` use the [`CP437`] table. Larger indices (which a
+/// non-default font could in principle reference) fall back to interpreting the
+/// index as a raw Unicode scalar, then to a blank space if that is not a valid
+/// or printable character.
+pub fn tile_to_char(tile: u32) -> char {
+    if tile < 256 {
+        CP437[tile as usize]
+    } else {
+        char::from_u32(tile).unwrap_or(' ')
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn ascii_passthrough() {
+        // The printable ASCII range must map to itself.
+        assert_eq!(tile_to_char('@' as u32), '@'); // player tile 64
+        assert_eq!(tile_to_char('#' as u32), '#'); // wall tile 35
+        assert_eq!(tile_to_char(' ' as u32), ' '); // empty tile 32
+    }
+
+    #[test]
+    fn box_drawing_and_blocks() {
+        assert_eq!(tile_to_char(0xB0), '░');
+        assert_eq!(tile_to_char(0xDB), '█');
+        assert_eq!(tile_to_char(0xC4), '─');
+    }
+
+    #[test]
+    fn out_of_range_falls_back_to_space() {
+        // A surrogate code point is not a valid char → blank.
+        assert_eq!(tile_to_char(0xD800), ' ');
+    }
+}

kiln-core/src/lib.rs

@@ -2,6 +2,8 @@ mod action;
 mod archetype;
 mod board;
 mod builtin_scripts;
+/// CP437 tile-index → character mapping ([`cp437::tile_to_char`]) for the default font.
+pub mod cp437;
 /// Procedural floor generators ([`floor::FloorGenerator`]).
 pub mod floor;
 /// Core game types: [`board::Board`], [`glyph::Glyph`], [`archetype::Archetype`], etc.