Fix color render path for non-emoji codepoints on color-capable faces

render_group() used has_emoji_presentation() for all codepoints, but that
only makes sense for emoji (VS15/VS16 selectors). Non-emoji codepoints now
use face_has_color() instead, and *was_colored is set from actual render
output rather than preset before rendering.

kitty/core_text.m

@@ -522,6 +522,11 @@ face_apply_scaling(PyObject *f, const FONTS_DATA_HANDLE fg) {
     return set_size_for_face(f, 0, false, fg);
 }
 
+bool
+face_has_color(PyObject *f) {
+    return CTFontSupportsColorGlyphs(((CTFace*)f)->ct_font);
+}
+
 static PyObject*
 set_size(CTFace *self, PyObject *args) {
     double font_sz_in_pts, dpi_x, dpi_y;

kitty/fonts.c

@@ -1200,7 +1200,13 @@ render_group(
         is_only_filled_boxes = true;
         for (unsigned i = 1; i < num_glyphs && is_only_filled_boxes; i++) if (global_glyph_render_scratch.glyphs[i] != box_glyph_id) is_only_filled_boxes = false;
     }
-    bool was_colored = !is_only_filled_boxes && has_emoji_presentation(cpu_cells, global_glyph_render_scratch.lc);
+    const ListOfChars *lc = global_glyph_render_scratch.lc;
+    // For emoji, honor the text/emoji presentation selectors (VS15/VS16); for a
+    // non-emoji codepoint on a color-capable face (e.g. an icon font mapped via
+    // symbol_map), use the color render path.
+    bool first_is_emoji = lc->count && char_props_for(lc->chars[0]).is_emoji;
+    bool was_colored = !is_only_filled_boxes && (
+        first_is_emoji ? has_emoji_presentation(cpu_cells, lc) : face_has_color(font->face));
     GlyphRenderInfo ri = {0};
     pixel *canvas = rendering_in_smaller_area && canvas_width != scaled_canvas_width ? scratch : fg->canvas.buf;
     if (is_only_filled_boxes) { // special case rendering of █ for tests

kitty/fonts.h

@@ -62,6 +62,7 @@ typedef void (*free_extra_data_func)(void*);
 StringCanvas render_simple_text_impl(PyObject *s, const char *text, unsigned int baseline);
 StringCanvas render_simple_text(FONTS_DATA_HANDLE fg_, const char *text);
 bool face_apply_scaling(PyObject*face, const FONTS_DATA_HANDLE fg);
+bool face_has_color(PyObject *face);
 
 bool
 add_font_name_record(PyObject *table, uint16_t platform_id, uint16_t encoding_id, uint16_t language_id, uint16_t name_id, const char *string, uint16_t string_len);

kitty/freetype.c

@@ -246,6 +246,11 @@ face_apply_scaling(PyObject *f, const FONTS_DATA_HANDLE fg) {
     return false;
 }
 
+bool
+face_has_color(PyObject *f) {
+    return ((Face*)f)->has_color;
+}
+
 static bool
 init_ft_face(Face *self, PyObject *path, int hinting, int hintstyle, long index, FONTS_DATA_HANDLE fg) {
     copy_face_metrics(self);
@@ -964,24 +969,27 @@ static const ProcessedBitmap EMPTY_PBM = {.factor = 1};
 bool
 render_glyphs_in_cells(PyObject *f, bool bold, bool italic, hb_glyph_info_t *info, hb_glyph_position_t *positions, unsigned int num_glyphs, pixel *canvas, unsigned int cell_width, unsigned int cell_height, unsigned int num_cells, unsigned int baseline, bool *was_colored, FONTS_DATA_HANDLE fg, GlyphRenderInfo *ri) {
     Face *self = (Face*)f;
-    bool is_emoji = *was_colored; *was_colored = is_emoji && self->has_color;
+    // *was_colored is an incoming hint; it is set on output to reflect whether
+    // any glyph was actually rendered as color.
+    bool want_color = *was_colored && self->has_color;
+    *was_colored = false;
     float x = 0.f, y = 0.f;
     ProcessedBitmap bm;
     unsigned int canvas_width = cell_width * num_cells;
     GlyphColorType colored;
     for (unsigned int i = 0; i < num_glyphs; i++) {
         bm = EMPTY_PBM;
+        bool colored_glyph = false;
         // dont load the space glyph since loading it fails for some fonts/sizes and it is anyway to be rendered as a blank
         if (info[i].codepoint != self->space_glyph_id) {
-            if (*was_colored && (colored = glyph_color_type(self, info[i].codepoint)) != NOT_COLORED) {
+            if (want_color && (colored = glyph_color_type(self, info[i].codepoint)) != NOT_COLORED) {
                 if (!render_color_bitmap(self, info[i].codepoint, &bm, cell_width, cell_height, num_cells, baseline)) {
                     if (PyErr_Occurred()) PyErr_Print();
                     if (!render_bitmap(self, info[i].codepoint, &bm, cell_width, cell_height, num_cells, bold, italic, true, fg)) {
                         free_processed_bitmap(&bm);
                         return false;
                     }
-                    *was_colored = false;
-                }
+                } else { colored_glyph = true; *was_colored = true; }
             } else {
                 if (!render_bitmap(self, info[i].codepoint, &bm, cell_width, cell_height, num_cells, bold, italic, true, fg)) {
                     free_processed_bitmap(&bm);
@@ -992,7 +1000,7 @@ render_glyphs_in_cells(PyObject *f, bool bold, bool italic, hb_glyph_info_t *inf
         float x_offset = x + (float)positions[i].x_offset / 64.0f;
         y = (float)positions[i].y_offset / 64.0f;
         if (debug_placement) printf("%d: x=%f canvas: %u", i, x_offset, canvas_width);
-        if ((*was_colored || self->face->glyph->metrics.width > 0) && bm.width > 0) {
+        if ((colored_glyph || self->face->glyph->metrics.width > 0) && bm.width > 0) {
             place_bitmap_in_canvas(canvas, &bm, canvas_width, cell_height, x_offset, y, baseline, i, 0xffffff, 0, 0);
         }
         if (debug_placement) printf(" adv: %f\n", (float)positions[i].x_advance / 64.0f);