Visual protocol

src/textual/_border.py

@@ -271,9 +271,6 @@ def get_box(
     Returns:
         A tuple of 3 Segment triplets.
     """
-    assert isinstance(inner_style, Style)
-    assert isinstance(outer_style, Style)
-    assert isinstance(style, Style)
     _Segment = Segment
     (
         (top1, top2, top3),

src/textual/content.py

@@ -19,6 +19,7 @@
 from rich.cells import set_cell_size
 from rich.console import OverflowMethod
 from rich.segment import Segment, Segments
+from rich.style import Style as RichStyle
 from rich.terminal_theme import TerminalTheme
 from rich.text import Text
 from typing_extensions import Final, TypeAlias
@@ -27,14 +28,15 @@
 from textual._context import active_app
 from textual._loop import loop_last
 from textual.color import Color
+from textual.css.styles import RulesMap
 from textual.css.types import TextAlign
 from textual.selection import Selection
 from textual.strip import Strip
 from textual.style import Style
 from textual.visual import Visual
 
 if TYPE_CHECKING:
-    from textual.widget import Widget
+    pass
 
 
 ContentType: TypeAlias = Union["Content", str]
@@ -275,7 +277,11 @@ def __lt__(self, other: object) -> bool:
             return self.plain < other.plain
         return NotImplemented
 
-    def get_optimal_width(self, widget: Widget, container_width: int) -> int:
+    def get_optimal_width(
+        self,
+        rules: RulesMap,
+        container_width: int,
+    ) -> int:
         """Get optimal width of the visual to display its content. Part of the Textual Visual protocol.
 
         Args:
@@ -289,7 +295,7 @@ def get_optimal_width(self, widget: Widget, container_width: int) -> int:
         lines = self.without_spans.split("\n")
         return max(line.cell_length for line in lines)
 
-    def get_height(self, widget: Widget, width: int) -> int:
+    def get_height(self, rules: RulesMap, width: int) -> int:
         """Get the height of the visual if rendered with the given width. Part of the Textual Visual protocol.
 
         Args:
@@ -365,37 +371,30 @@ def get_span(y: int) -> tuple[int, int] | None:
 
     def render_strips(
         self,
-        widget: Widget,
+        rules: RulesMap,
         width: int,
         height: int | None,
         style: Style,
+        selection: Selection | None = None,
+        selection_style: Style | None = None,
     ) -> list[Strip]:
         if not width:
             return []
 
-        selection = widget.selection
-        if selection is not None:
-            selection_style = Style.from_rich_style(
-                widget.screen.get_component_rich_style("screen--selection")
-            )
-
-        else:
-            selection_style = None
-
         lines = self._wrap_and_format(
             width,
-            align=widget.styles.text_align,
+            align=rules.get("text_align", "left"),
             overflow="fold",
             no_wrap=False,
             tab_size=8,
-            selection=widget.selection,
+            selection=selection,
             selection_style=selection_style,
         )
 
         if height is not None:
             lines = lines[:height]
 
-        strip_lines = [line.to_strip(widget, style) for line in lines]
+        strip_lines = [Strip(*line.to_strip(style)) for line in lines]
         return strip_lines
 
     def __len__(self) -> int:
@@ -1128,7 +1127,7 @@ def __init__(
     def plain(self) -> str:
         return self.content.plain
 
-    def to_strip(self, widget: Widget, style: Style) -> Strip:
+    def to_strip(self, style: Style) -> tuple[list[Segment], int]:
         _Segment = Segment
         align = self.align
         width = self.width
@@ -1137,8 +1136,6 @@ def to_strip(self, widget: Widget, style: Style) -> Strip:
         x = self.x
         y = self.y
 
-        parse_style = widget.app.stylesheet.parse_style
-
         if align in ("start", "left") or (align == "justify" and self.line_end):
             pass
 
@@ -1166,9 +1163,7 @@ def to_strip(self, widget: Widget, style: Style) -> Strip:
             add_segment = segments.append
             x = self.x
             for index, word in enumerate(words):
-                for text, text_style in word.render(
-                    style, end="", parse_style=parse_style
-                ):
+                for text, text_style in word.render(style, end=""):
                     add_segment(
                         _Segment(
                             text, (style + text_style).rich_style_with_offset(x, y)
@@ -1178,16 +1173,15 @@ def to_strip(self, widget: Widget, style: Style) -> Strip:
                 if index < len(spaces) and (pad := spaces[index]):
                     add_segment(_Segment(" " * pad, (style + text_style).rich_style))
 
-            strip = Strip(self._apply_link_style(widget, segments), width)
-            return strip
+            return segments, width
 
         segments = (
             [Segment(" " * pad_left, style.background_style.rich_style)]
             if pad_left
             else []
         )
         add_segment = segments.append
-        for text, text_style in content.render(style, end="", parse_style=parse_style):
+        for text, text_style in content.render(style, end=""):
             add_segment(
                 _Segment(text, (style + text_style).rich_style_with_offset(x, y))
             )
@@ -1197,16 +1191,13 @@ def to_strip(self, widget: Widget, style: Style) -> Strip:
             segments.append(
                 _Segment(" " * pad_right, style.background_style.rich_style)
             )
-        strip = Strip(
-            self._apply_link_style(widget, segments),
-            content.cell_length + pad_left + pad_right,
-        )
-        return strip
+
+        return (segments, content.cell_length + pad_left + pad_right)
 
     def _apply_link_style(
-        self, widget: Widget, segments: list[Segment]
+        self, link_style: RichStyle, segments: list[Segment]
     ) -> list[Segment]:
-        link_style = widget.link_style
+
         _Segment = Segment
         segments = [
             _Segment(

src/textual/css/styles.py

@@ -1,9 +1,10 @@
 from __future__ import annotations
 
+from collections import abc
 from dataclasses import dataclass, field
 from functools import partial
 from operator import attrgetter
-from typing import TYPE_CHECKING, Any, Callable, Iterable, Literal, cast
+from typing import TYPE_CHECKING, Any, Callable, Iterable, Iterator, Literal, cast
 
 import rich.repr
 from rich.style import Style
@@ -1245,7 +1246,7 @@ def css(self) -> str:
 
 
 @rich.repr.auto
-class RenderStyles(StylesBase):
+class RenderStyles(StylesBase, abc.Mapping):
     """Presents a combined view of two Styles object: a base Styles and inline Styles."""
 
     def __init__(self, node: DOMNode, base: Styles, inline_styles: Styles) -> None:
@@ -1265,6 +1266,35 @@ def __eq__(self, other: object) -> bool:
             )
         return NotImplemented
 
+    def __getitem__(self, key: str) -> object:
+        if key not in RULE_NAMES_SET:
+            raise KeyError(key)
+        return getattr(self, key)
+
+    def get(self, key: str, default: object | None = None) -> object:
+        return getattr(self, key) if key in RULE_NAMES_SET else default
+
+    def __len__(self) -> int:
+        return len(RULE_NAMES)
+
+    def __iter__(self) -> Iterator[str]:
+        return iter(RULE_NAMES)
+
+    def __contains__(self, key: object) -> bool:
+        return key in RULE_NAMES_SET
+
+    def keys(self) -> Iterable[str]:
+        return RULE_NAMES
+
+    def values(self) -> Iterable[object]:
+        for key in RULE_NAMES:
+            yield getattr(self, key)
+
+    def items(self) -> Iterable[tuple[str, object]]:
+        get_rule = self.get_rule
+        for key in RULE_NAMES:
+            yield (key, getattr(self, key))
+
     @property
     def _cache_key(self) -> int:
         """A cache key, that changes when any style is changed.

src/textual/css/tokenizer.py

@@ -130,10 +130,12 @@ def __init__(self, description: str, **tokens: str) -> None:
         self._expect_semicolon = True
 
     def expect_eof(self, eof: bool) -> Expect:
+        """Expect an end of file."""
         self._expect_eof = eof
         return self
 
     def expect_semicolon(self, semicolon: bool) -> Expect:
+        """Tokenizer expects text to be terminated with a semi-colon."""
         self._expect_semicolon = semicolon
         return self
 

src/textual/strip.py

@@ -599,6 +599,27 @@ def apply_style(self, style: Style) -> Strip:
         self._style_cache[style] = styled_strip
         return styled_strip
 
+    def _apply_link_style(self, link_style: Style) -> Strip:
+        segments = self._segments
+        _Segment = Segment
+        segments = [
+            (
+                _Segment(
+                    text,
+                    (
+                        style
+                        if style._meta is None
+                        else (style + link_style if "@click" in style.meta else style)
+                    ),
+                    control,
+                )
+                if style
+                else _Segment(text)
+            )
+            for text, style, control in segments
+        ]
+        return Strip(segments, self._cell_length)
+
     def render(self, console: Console) -> str:
         """Render the strip into terminal sequences.