Add option to control using color emoji or not

kitty/config.py

@@ -291,6 +291,7 @@ type_map = {
     'active_tab_font_style': tab_font_style,
     'inactive_tab_font_style': tab_font_style,
     'url_style': url_style,
+    'prefer_color_emoji': to_bool,
 }
 
 for name in (

kitty/fontconfig.c

@@ -195,7 +195,7 @@ create_fallback_face(PyObject UNUSED *base_face, Cell* cell, bool bold, bool ita
     AP(FcPatternAddString, FC_FAMILY, (const FcChar8*)(emoji ? "emoji" : "monospace"), "family");
     if (!emoji && bold) { AP(FcPatternAddInteger, FC_WEIGHT, FC_WEIGHT_BOLD, "weight"); }
     if (!emoji && italic) { AP(FcPatternAddInteger, FC_SLANT, FC_SLANT_ITALIC, "slant"); }
-    if (emoji) { AP(FcPatternAddBool, FC_COLOR, true, "color"); }
+    if (emoji) { AP(FcPatternAddBool, FC_COLOR, OPT(prefer_color_emoji), "color"); }
     size_t num = cell_as_unicode(cell, true, char_buf, ' ');
     add_charset(pat, num);
     PyObject *d = _fc_match(pat);

kitty/kitty.conf

@@ -356,3 +356,9 @@ macos_option_as_alt yes
 # The number is a percentage of maximum volume.
 # See man XBell for details.
 x11_bell_volume 80
+
+# Prefer color emoji fonts when available. Note that this only works
+# on systems such as Linux that use fontconfig. On other OSes, the emoji
+# font used is system dependent. It can be overriden using symbol_map in the kitty
+# configuration.
+prefer_color_emoji yes

kitty/state.c

@@ -305,6 +305,7 @@ PYWRAP1(set_options) {
 #define S(name, convert) { GA(name); global_state.opts.name = convert(ret); Py_DECREF(ret); if (PyErr_Occurred()) return NULL; }
     S(visual_bell_duration, PyFloat_AsDouble);
     S(enable_audio_bell, PyObject_IsTrue);
+    S(prefer_color_emoji, PyObject_IsTrue);
     S(focus_follows_mouse, PyObject_IsTrue);
     S(cursor_blink_interval, PyFloat_AsDouble);
     S(cursor_stop_blinking_after, PyFloat_AsDouble);

kitty/state.h

@@ -21,6 +21,7 @@ typedef struct {
     double repaint_delay, input_delay;
     bool focus_follows_mouse;
     bool macos_option_as_alt, macos_hide_titlebar;
+    bool prefer_color_emoji;
     int adjust_line_height_px;
     int x11_bell_volume;
     float adjust_line_height_frac;