Start work on option to modify font characteristics

Implement parsing of the option

kitty/fonts/__init__.py

@@ -1,7 +1,8 @@
 try:
-    from typing import TypedDict
+    from typing import TypedDict, NamedTuple
 except ImportError:
     TypedDict = dict
+from enum import Enum, auto
 
 
 class ListedFont(TypedDict):
@@ -21,3 +22,27 @@ class FontFeature:
 
     def __repr__(self) -> str:
         return repr(self.name)
+
+
+class ModificationType(Enum):
+    underline_position = auto()
+    underline_thickness = auto()
+    strikethrough_position = auto()
+    strikethrough_thickness = auto()
+    size = auto()
+
+
+class ModificationUnit(Enum):
+    pt = auto()
+    percent = auto()
+
+
+class ModificationValue(NamedTuple):
+    val: float
+    unit: ModificationUnit
+
+
+class FontModification(NamedTuple):
+    mod_type: ModificationType
+    mod_value: ModificationValue
+    font_name: str = ''

kitty/options/definition.py

@@ -216,6 +216,20 @@ You can do this with e.g.::
 '''
     )
 
+opt('+modify_font', '',
+    option_type='modify_font',
+    add_to_default=False,
+    long_text='''
+Modify font characteristics such as the position or thickness of the underline and strikethrough.
+The modifications can be either plain numbers, in which case they are interpreted as
+pts, or percentages, in which case they are interpreted as a percentage of the original value.
+For example::
+
+    modify_font underline_position -2
+    modify_font underline_thickness 150%
+    modify_font strikethrough_thickness 50%
+''')
+
 opt('box_drawing_scale', '0.001, 1, 1.5, 2',
     option_type='box_drawing_scale',
     long_text='''

kitty/options/parse.py

@@ -12,7 +12,7 @@ from kitty.options.utils import (
     cursor_text_color, deprecated_hide_window_decorations_aliases,
     deprecated_macos_show_window_title_in_menubar_alias, deprecated_send_text, disable_ligatures,
     edge_width, env, font_features, hide_window_decorations, macos_option_as_alt, macos_titlebar_color,
-    narrow_symbols, optional_edge_width, parse_map, parse_mouse_map, paste_actions,
+    modify_font, narrow_symbols, optional_edge_width, parse_map, parse_mouse_map, paste_actions,
     resize_draw_strategy, scrollback_lines, scrollback_pager_history_size, 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,
@@ -1096,6 +1096,10 @@ class Parser:
     def mark3_foreground(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['mark3_foreground'] = to_color(val)
 
+    def modify_font(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
+        for k, v in modify_font(val):
+            ans["modify_font"][k] = v
+
     def mouse_hide_wait(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['mouse_hide_wait'] = float(val)
 
@@ -1364,6 +1368,7 @@ def create_result_dict() -> typing.Dict[str, typing.Any]:
         'exe_search_path': {},
         'font_features': {},
         'kitten_alias': {},
+        'modify_font': {},
         'narrow_symbols': {},
         'symbol_map': {},
         'watcher': {},

kitty/options/types.py

@@ -393,6 +393,7 @@ option_names = (  # {{{
  'mark2_foreground',
  'mark3_background',
  'mark3_foreground',
+ 'modify_font',
  'mouse_hide_wait',
  'mouse_map',
  'narrow_symbols',
@@ -612,6 +613,7 @@ class Options:
     exe_search_path: typing.Dict[str, str] = {}
     font_features: typing.Dict[str, typing.Tuple[kitty.fonts.FontFeature, ...]] = {}
     kitten_alias: typing.Dict[str, str] = {}
+    modify_font: typing.Dict[str, kitty.fonts.FontModification] = {}
     narrow_symbols: typing.Dict[typing.Tuple[int, int], int] = {}
     symbol_map: typing.Dict[typing.Tuple[int, int], str] = {}
     watcher: typing.Dict[str, str] = {}
@@ -731,6 +733,7 @@ defaults.env = {}
 defaults.exe_search_path = {}
 defaults.font_features = {}
 defaults.kitten_alias = {}
+defaults.modify_font = {}
 defaults.narrow_symbols = {}
 defaults.symbol_map = {}
 defaults.watcher = {}

kitty/options/utils.py

@@ -20,7 +20,10 @@ from kitty.constants import is_macos
 from kitty.fast_data_types import (
     CURSOR_BEAM, CURSOR_BLOCK, CURSOR_UNDERLINE, Color
 )
-from kitty.fonts import FontFeature
+from kitty.fonts import (
+    FontFeature, FontModification, ModificationType, ModificationUnit,
+    ModificationValue
+)
 from kitty.key_names import (
     character_key_name_aliases, functional_key_name_aliases,
     get_key_name_lookup
@@ -797,6 +800,41 @@ def font_features(val: str) -> Iterable[Tuple[str, Tuple[FontFeature, ...]]]:
         yield parts[0], tuple(features)
 
 
+def modify_font(val: str) -> Iterable[Tuple[str, FontModification]]:
+    parts = val.split()
+    pos, plen = 0, len(parts)
+    if plen < 2:
+        log_error(f"Ignoring invalid modify_font: {val}")
+        return
+    mtype: Optional[ModificationType] = getattr(ModificationType, parts[pos], None)
+    if mtype is None:
+        log_error(f"Ignoring invalid modify_font with unknown modification type: {parts[pos]}")
+        return
+    pos += 1
+    font_name = ''
+    if mtype is ModificationType.size:
+        font_name = parts[pos]
+        pos += 1
+    if plen - pos < 1:
+        log_error(f"Ignoring invalid modify_font: {val}")
+        return
+    sz = parts[pos]
+    pos += 1
+    munit = ModificationUnit.pt
+    if sz.endswith('%'):
+        munit = ModificationUnit.percent
+        sz = sz[:-1]
+    try:
+        mvalue = float(sz)
+    except Exception:
+        log_error(f'Ignoring modify_font with invalid size: {sz}')
+        return
+    key = mtype.name
+    if font_name:
+        key += f':{font_name}'
+    yield key, FontModification(mtype, ModificationValue(mvalue, munit), font_name)
+
+
 def env(val: str, current_val: Dict[str, str]) -> Iterable[Tuple[str, str]]:
     val = val.strip()
     if val:

kitty_tests/options.py

@@ -23,6 +23,7 @@ class TestConfParsing(BaseTest):
         from kitty.config import load_config, defaults
         from kitty.constants import is_macos
         from kitty.options.utils import to_modifiers
+        from kitty.fonts import FontModification, ModificationType, ModificationValue, ModificationUnit
         bad_lines = []
 
         def p(*lines, bad_line_num=0):
@@ -55,6 +56,12 @@ class TestConfParsing(BaseTest):
         self.assertFalse(bad_lines)
         opts = p('pointer_shape_when_grabbed XXX', bad_line_num=1)
         self.ae(opts.pointer_shape_when_grabbed, defaults.pointer_shape_when_grabbed)
+        opts = p('modify_font underline_position -2', 'modify_font underline_thickness 150%', 'modify_font size Test -1')
+        self.ae(opts.modify_font, {
+            'underline_position': FontModification(ModificationType.underline_position, ModificationValue(-2., ModificationUnit.pt)),
+            'underline_thickness': FontModification(ModificationType.underline_thickness, ModificationValue(150, ModificationUnit.percent)),
+            'size:Test': FontModification(ModificationType.size, ModificationValue(-1., ModificationUnit.pt), 'Test'),
+        })
 
         # test the aliasing options
         opts = p('env A=1', 'env B=x$A', 'env C=', 'env D', 'clear_all_shortcuts y', 'kitten_alias a b --moo', 'map f1 kitten a arg')