Option to control underline exclusion

kitty/options/definition.py

@@ -218,6 +218,14 @@ the curl will peak once per character, with dense twice.
 '''
     )
 
+opt('underline_exclusion', '1', option_type='underline_exclusion', ctype='!underline_exclusion', long_text='''
+By default kitty renders gaps in underlines when they overlap with descenders
+(the parts of letters below the baseline, such as for y, q, p etc.). This option
+controls the thickness of the gaps. It can be either a unitless number in which
+case it is a fraction of the underline thickness as specified in the font or
+it can have a suffix of :code:`px` for pixels or :code:`pt` for points.
+''')
+
 opt('text_composition_strategy', 'platform',
     ctype='!text_composition_strategy',
     long_text='''

kitty/options/parse.py

@@ -19,9 +19,9 @@ from kitty.options.utils import (
     shell_integration, store_multiple, symbol_map, tab_activity_symbol, tab_bar_edge,
     tab_bar_margin_height, tab_bar_min_tabs, tab_fade, tab_font_style, tab_separator,
     tab_title_template, titlebar_color, to_cursor_shape, to_cursor_unfocused_shape, to_font_size,
-    to_layout_names, to_modifiers, transparent_background_colors, url_prefixes, url_style,
-    visual_bell_duration, visual_window_select_characters, window_border_width, window_logo_scale,
-    window_size
+    to_layout_names, to_modifiers, transparent_background_colors, underline_exclusion, url_prefixes,
+    url_style, visual_bell_duration, visual_window_select_characters, window_border_width,
+    window_logo_scale, window_size
 )
 
 
@@ -1344,6 +1344,9 @@ class Parser:
 
     choices_for_undercurl_style = frozenset(('thin-sparse', 'thin-dense', 'thick-sparse', 'thick-dense'))
 
+    def underline_exclusion(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
+        ans['underline_exclusion'] = underline_exclusion(val)
+
     def underline_hyperlinks(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         val = val.lower()
         if val not in self.choices_for_underline_hyperlinks:

kitty/options/to-c-generated.h

@@ -83,6 +83,19 @@ convert_from_opts_undercurl_style(PyObject *py_opts, Options *opts) {
     Py_DECREF(ret);
 }
 
+static void
+convert_from_python_underline_exclusion(PyObject *val, Options *opts) {
+    underline_exclusion(val, opts);
+}
+
+static void
+convert_from_opts_underline_exclusion(PyObject *py_opts, Options *opts) {
+    PyObject *ret = PyObject_GetAttrString(py_opts, "underline_exclusion");
+    if (ret == NULL) return;
+    convert_from_python_underline_exclusion(ret, opts);
+    Py_DECREF(ret);
+}
+
 static void
 convert_from_python_text_composition_strategy(PyObject *val, Options *opts) {
     text_composition_strategy(val, opts);
@@ -1163,6 +1176,8 @@ convert_opts_from_python_opts(PyObject *py_opts, Options *opts) {
     if (PyErr_Occurred()) return false;
     convert_from_opts_undercurl_style(py_opts, opts);
     if (PyErr_Occurred()) return false;
+    convert_from_opts_underline_exclusion(py_opts, opts);
+    if (PyErr_Occurred()) return false;
     convert_from_opts_text_composition_strategy(py_opts, opts);
     if (PyErr_Occurred()) return false;
     convert_from_opts_cursor_shape(py_opts, opts);

kitty/options/to-c.h

@@ -380,6 +380,16 @@ menu_map(PyObject *entry_dict, Options *opts) {
     }
 }
 
+static inline void
+underline_exclusion(PyObject *val, Options *opts) {
+    if (!PyTuple_Check(val)) { PyErr_SetString(PyExc_TypeError, "underline_exclusion must be a tuple"); return; }
+    opts->underline_exclusion.thickness = PyFloat_AsFloat(PyTuple_GET_ITEM(val, 0));
+    if (PyUnicode_CompareWithASCIIString(PyTuple_GET_ITEM(val, 1), "%")) opts->underline_exclusion.unit = 0;
+    else if (PyUnicode_CompareWithASCIIString(PyTuple_GET_ITEM(val, 1), "px")) opts->underline_exclusion.unit = 1;
+    else if (PyUnicode_CompareWithASCIIString(PyTuple_GET_ITEM(val, 1), "pt")) opts->underline_exclusion.unit = 2;
+    else opts->underline_exclusion.unit = 0;
+}
+
 static inline void
 text_composition_strategy(PyObject *val, Options *opts) {
     if (!PyUnicode_Check(val)) { PyErr_SetString(PyExc_TypeError, "text_rendering_strategy must be a string"); return; }

kitty/options/types.py

@@ -447,6 +447,7 @@ option_names = (
     'touch_scroll_multiplier',
     'transparent_background_colors',
     'undercurl_style',
+    'underline_exclusion',
     'underline_hyperlinks',
     'update_check_interval',
     'url_color',
@@ -615,6 +616,7 @@ class Options:
     touch_scroll_multiplier: float = 1.0
     transparent_background_colors: typing.Tuple[typing.Tuple[kitty.fast_data_types.Color, float], ...] = ()
     undercurl_style: choices_for_undercurl_style = 'thin-sparse'
+    underline_exclusion: tuple[float, typing.Literal['%', 'px', 'pt']] = (1.0, '%')
     underline_hyperlinks: choices_for_underline_hyperlinks = 'hover'
     update_check_interval: float = 24.0
     url_color: Color = Color(0, 135, 189)

kitty/options/utils.py

@@ -1017,6 +1017,20 @@ def shell_integration(x: str) -> FrozenSet[str]:
     return q
 
 
+def underline_exclusion(x: str) -> tuple[float, Literal['%', 'px', 'pt']]:
+    try:
+        return float(x), '%'
+    except Exception:
+        unit: Literal['%', 'pt', 'px'] = x[-2:]  # type: ignore
+        if unit not in ('px', 'pt', '%'):
+            raise ValueError(f'Invalid underline_exclusion with unrecognized unit: {x}')
+        try:
+            val = float(x[:-2])
+        except Exception:
+            raise ValueError(f'Invalid underline_exclusion with non numberic value: {x}')
+        return val, unit
+
+
 def paste_actions(x: str) -> FrozenSet[str]:
     s = frozenset({'quote-urls-at-prompt', 'confirm', 'filter', 'confirm-if-large', 'replace-dangerous-control-codes', 'replace-newline', 'no-op'})
     q = frozenset(x.lower().split(','))