make opt-in and add harmonious

config.c

@@ -1157,8 +1157,11 @@ parse_section_main(struct context *ctx)
         return true;
     }
 
-    else if (streq(key, "generate-256-palette"))
-        return value_to_bool(ctx, &conf->generate_256_palette);
+    else if (streq(key, "palette-generate"))
+        return value_to_bool(ctx, &conf->palette_generate);
+
+    else if (streq(key, "palette-harmonious"))
+        return value_to_bool(ctx, &conf->palette_harmonious);
 
     else if (streq(key, "uppercase-regex-insert"))
         return value_to_bool(ctx, &conf->uppercase_regex_insert);
@@ -3453,39 +3456,44 @@ table_mask_is_set(const uint32_t *mask, unsigned idx)
 }
 
 static void
-generate_256_palette(uint32_t *table, const uint32_t *mask,
-                     uint32_t bg, uint32_t fg)
+generate_palette(uint32_t *table, const uint32_t *mask,
+                        uint32_t bg, uint32_t fg, bool harmonious)
 {
     /*
      * Generate colors 16-255 by interpolating in CIELAB space.
      *
      * Corner mapping for trilinear interpolation:
-     *   bg         -> (r=0, g=0, b=0)
+     *   corner0    -> (r=0, g=0, b=0)
      *   palette[1] -> (r=1, g=0, b=0)  red
      *   palette[2] -> (r=0, g=1, b=0)  green
      *   palette[3] -> (r=1, g=1, b=0)  yellow
      *   palette[4] -> (r=0, g=0, b=1)  blue
      *   palette[5] -> (r=1, g=0, b=1)  magenta
      *   palette[6] -> (r=0, g=1, b=1)  cyan
-     *   fg         -> (r=1, g=1, b=1)
+     *   corner7    -> (r=1, g=1, b=1)
      */
-    struct lab base8_lab[8];
-    for (int i = 0; i < 8; i++)
-        base8_lab[i] = lab_from_rgb(table[i]);
-
     struct lab bg_lab = lab_from_rgb(bg);
     struct lab fg_lab = lab_from_rgb(fg);
 
+    bool is_light_theme = fg_lab.l < bg_lab.l;
+    bool invert = is_light_theme && !harmonious;
+
+    struct lab base8_lab[8];
+    base8_lab[0] = invert ? fg_lab : bg_lab;
+    for (int i = 1; i < 7; i++)
+        base8_lab[i] = lab_from_rgb(table[i]);
+    base8_lab[7] = invert ? bg_lab : fg_lab;
+
     /* Colors 16-231: 6x6x6 color cube via trilinear interpolation */
     unsigned idx = 16;
     for (unsigned ri = 0; ri < 6; ri++) {
         float tr = (float)ri / 5.0f;
 
         /* Interpolate along R axis (4 edges) */
-        struct lab c0 = lab_lerp(tr, bg_lab, base8_lab[1]);
+        struct lab c0 = lab_lerp(tr, base8_lab[0], base8_lab[1]);
         struct lab c1 = lab_lerp(tr, base8_lab[2], base8_lab[3]);
         struct lab c2 = lab_lerp(tr, base8_lab[4], base8_lab[5]);
-        struct lab c3 = lab_lerp(tr, base8_lab[6], fg_lab);
+        struct lab c3 = lab_lerp(tr, base8_lab[6], base8_lab[7]);
 
         for (unsigned gi = 0; gi < 6; gi++) {
             float tg = (float)gi / 5.0f;
@@ -3505,11 +3513,11 @@ generate_256_palette(uint32_t *table, const uint32_t *mask,
         }
     }
 
-    /* Colors 232-255: grayscale ramp from bg to fg */
+    /* Colors 232-255: grayscale ramp */
     for (unsigned i = 0; i < 24; i++) {
         if (!table_mask_is_set(mask, idx)) {
             float t = (float)(i + 1) / 25.0f;
-            table[idx] = lab_to_rgb(lab_lerp(t, bg_lab, fg_lab));
+            table[idx] = lab_to_rgb(lab_lerp(t, base8_lab[0], base8_lab[7]));
         }
         idx++;
     }
@@ -3611,7 +3619,8 @@ config_load(struct config *conf, const char *conf_path,
             },
         },
         .initial_color_theme = COLOR_THEME_DARK,
-        .generate_256_palette = true,
+        .palette_generate = false,
+        .palette_harmonious = false,
         .cursor = {
             .style = CURSOR_BLOCK,
             .unfocused_style = CURSOR_UNFOCUSED_HOLLOW,
@@ -3799,13 +3808,15 @@ config_load(struct config *conf, const char *conf_path,
     if (!config_override_apply(conf, overrides, errors_are_fatal))
         ret = !errors_are_fatal;
 
-    if (conf->generate_256_palette) {
-        generate_256_palette(
+    if (conf->palette_generate) {
+        generate_palette(
             conf->colors_dark.table, conf->colors_dark.table_mask,
-            conf->colors_dark.bg, conf->colors_dark.fg);
-        generate_256_palette(
+            conf->colors_dark.bg, conf->colors_dark.fg,
+            conf->palette_harmonious);
+        generate_palette(
             conf->colors_light.table, conf->colors_light.table_mask,
-            conf->colors_light.bg, conf->colors_light.fg);
+            conf->colors_light.bg, conf->colors_light.fg,
+            conf->palette_harmonious);
     }
 
     if (ret && conf->fonts[0].count == 0) {

config.h

@@ -333,7 +333,8 @@ struct config {
     struct color_theme colors_dark;
     struct color_theme colors_light;
     enum which_color_theme initial_color_theme;
-    bool generate_256_palette;
+    bool palette_generate;
+    bool palette_harmonious;
 
     struct {
         enum cursor_style style;

doc/foot.ini.5.scd

@@ -383,7 +383,7 @@ empty string to be set, but it must be quoted: *KEY=""*)
 	
 	Default: _1_
 
-*generate-256-palette*
+*palette-generate*
 	Boolean. When enabled, the extended 256-color palette (colors
 	16-255) is generated by interpolating from the base 16 colors,
 	foreground, and background using the CIELAB color space. This
@@ -392,7 +392,14 @@ empty string to be set, but it must be quoted: *KEY=""*)
 
 	Palette entries explicitly set by the user are not overwritten.
 
-	Default: _yes_
+	Default: _no_
+
+*palette-harmonious*
+	Boolean. Whether to invert generated light theme colors (see
+	*palette-generate*). This helps give the 256-color palette more
+	semantic meaning.
+
+	Default: _no_
 
 *initial-window-size-pixels*
 	Initial window width and height in _pixels_ (subject to output

foot.ini

@@ -25,7 +25,8 @@
 # gamma-correct-blending=no
 
 # initial-color-theme=dark
-# generate-256-palette=yes
+# palette-generate=no
+# palette-harmonious=no
 # initial-window-size-pixels=700x500  # Or,
 # initial-window-size-chars=<COLSxROWS>
 # initial-window-mode=windowed