Finish documenting the scrollbar settings

kitty/options/definition.py

@@ -7,7 +7,7 @@ import string
 
 from kitty.conf.types import Action, Definition
 from kitty.constants import website_url
-from kitty.options.utils import pointer_shape_names
+from kitty.options.utils import default_scrollbar, pointer_shape_names
 
 definition = Definition(
     'kitty',
@@ -443,8 +443,60 @@ is changed it will only affect newly created windows, not existing ones.
     )
 
 opt('scrollbar', '', option_type='scrollbar', ctype='!scrollbar',
-    long_text='''
-TODO: this writeup
+    long_text=f'''
+Control the appearance and behavior of the scrollbar that is displayed when
+scrolling through the scrollback. Accepts a number of space separated settings in key=value
+format, documented below. To have the scrollbar always visible, use:
+:code:`visible_when=always`. To disable it completely use: :code:`visible_when=never`.
+To have it be visible but not react to the mouse, use :code:`interactive=no`. For example:
+:code:`visible_when=always interactive=no`.
+
+The various settings, with their default values:
+
+**color** :code:`={default_scrollbar.color_as_string(default_scrollbar.color)}`
+    the color of the scrollbar handle. Use the special keywords: :code:`foreground` or :code:`selection_background` to use those colors.
+
+**track_color** :code:`={default_scrollbar.color_as_string(default_scrollbar.color)}`
+    the color of the scrollbar track. Use the special keywords: :code:`foreground` or :code:`selection_background` to use those colors.
+
+**opacity** :code:`={default_scrollbar.opacity}`
+    the opacity of the scrollbar handle (0 invisible to 1 fully opaque)
+
+**track_opacity** :code:`={default_scrollbar.track_opacity}`
+    the opacity of the scrollbar track
+
+**track_hover_opacity** :code:`={default_scrollbar.track_opacity}`
+    the opacity of the scrollbar track when the mouse is over it.
+
+**visible_when** :code:`=scrolled`
+    when the scrollbar is displayed.
+    :code:`scrolled` means when the scrolling backwards has started.
+    :code:`hovered` means when the mouse is hovering on the right edge of the window.
+    :code:`scrolled-and-hovered` means when the mouse is over the scrollbar region *and* scrolling backwards has started.
+    :code:`always` means whenever any scrollback is present
+    :code:`never` means disable the scrollbar.
+
+**interactive** :code:`={'yes' if default_scrollbar.interactive else 'no'}`
+    whether the scrollbar can be controlled by the mouse.
+
+**track_click** :code:`={'jump' if default_scrollbar.jump_on_track_click else 'page'}`
+    the behavior of clicking on the scrollbar track. :code:`jump` means scroll to the position of
+    the click and :code:`page` means scroll by a single screen towards the position of the click.
+
+**width** :code:`={default_scrollbar.width}`
+    the width of the scrollbar in units of cells
+
+**radius** :code:`={default_scrollbar.radius}`
+    the radius (curvature) of the scrollbar handle in units of cells
+
+**gap** :code:`={default_scrollbar.gap}`
+    the gap between the scrollbar and the window edge in units of cells
+
+**min_handle_height** :code:`={default_scrollbar.min_handle_height}`
+    the minimum height of the scrollbar handle in units of cells
+
+**hitbox_expansion** :code:`={default_scrollbar.hitbox_expansion}`
+    the extra area around the handle to allow easier grabbing of the scollbar in units of cells
 ''')
 
 opt('scrollback_pager', 'less --chop-long-lines --RAW-CONTROL-CHARS +INPUT_LINE_NUMBER',

kitty/options/types.py

@@ -588,7 +588,7 @@ class Options:
     scrollback_lines: int = 2000
     scrollback_pager: list[str] = ['less', '--chop-long-lines', '--RAW-CONTROL-CHARS', '+INPUT_LINE_NUMBER']
     scrollback_pager_history_size: int = 0
-    scrollbar: ScrollbarSettings = ScrollbarSettings(opacity=0.5, track_opacity=0, track_hover_opacity=0.1, color=0, track_color=0, interactive=True, width=0.5, radius=0.3, gap=0.25, min_handle_height=1.0, hitbox_expansion=0.25, jump_on_track_click=True, visible_when=1)
+    scrollbar: ScrollbarSettings = ScrollbarSettings(opacity=0.5, track_opacity=0, track_hover_opacity=0.1, color=0, track_color=0, interactive=True, width=0.5, radius=0.3, gap=0.1, min_handle_height=1.0, hitbox_expansion=0.25, jump_on_track_click=True, visible_when=1)
     select_by_word_characters: str = '@-./_~?&=%+#'
     select_by_word_characters_forward: str = ''
     selection_background: kitty.fast_data_types.Color | None = Color(255, 250, 205)

kitty/options/utils.py

@@ -41,7 +41,7 @@ from kitty.constants import is_macos
 from kitty.fast_data_types import CURSOR_BEAM, CURSOR_BLOCK, CURSOR_HOLLOW, CURSOR_UNDERLINE, NO_CURSOR_SHAPE, Color, Shlex, SingleKey
 from kitty.fonts import FontModification, FontSpec, ModificationType, ModificationUnit, ModificationValue
 from kitty.key_names import character_key_name_aliases, functional_key_name_aliases, get_key_name_lookup
-from kitty.rgb import color_as_int
+from kitty.rgb import color_as_int, color_from_int
 from kitty.types import FloatEdges, MouseEvent
 from kitty.utils import expandvars, log_error, resolve_abs_or_config_path, shlex_split
 
@@ -1713,12 +1713,21 @@ class ScrollbarSettings(NamedTuple):
     interactive: bool = True
     width: float = 0.5
     radius: float = 0.3
-    gap: float = 0.25
+    gap: float = 0.1
     min_handle_height: float = 1.0
     hitbox_expansion: float = 0.25
     jump_on_track_click: bool = True
     visible_when: int = 1
 
+    @classmethod
+    def color_as_string(cls, color_val: int) -> str:
+        match color_val:
+            case 0:
+                return 'foreground'
+            case 1:
+                return 'selection_background'
+        return color_from_int(color_val >> 8).as_sharp
+
     def differences(self, other: 'ScrollbarSettings') -> Iterator[str]:
         for key in self._fields:
             if getattr(self, key) != (o := getattr(other, key)):