scalars in CSS

examples/basic.css

@@ -11,6 +11,7 @@ App > DockView {
   height: 1fr;
   layer: panels;
   border-right: outer #09312e;
+  offset-x: -50%;
 }
 
 #header {

examples/basic.py

@@ -16,4 +16,4 @@ class BasicApp(App):
         )
 
 
-BasicApp.run(css_file="basic.css")
+BasicApp.run(log="textual.log", css_file="basic.css")

src/textual/css/_style_properties.py

@@ -6,7 +6,14 @@ import rich.repr
 from rich.color import Color
 from rich.style import Style
 
-from .scalar import get_symbols, UNIT_SYMBOL, Unit, Scalar, ScalarParseError
+from .scalar import (
+    get_symbols,
+    UNIT_SYMBOL,
+    Unit,
+    Scalar,
+    ScalarOffset,
+    ScalarParseError,
+)
 from ..geometry import Offset, Spacing, SpacingDimensions
 from .constants import NULL_SPACING, VALID_EDGE
 from .errors import StyleTypeError, StyleValueError
@@ -42,7 +49,7 @@ class ScalarProperty:
         if value is None:
             new_value = None
         elif isinstance(value, float):
-            new_value = Scalar(value, Unit.CELLS)
+            new_value = Scalar(value, Unit.CELLS, Unit.WIDTH)
         elif isinstance(value, Scalar):
             new_value = value
         elif isinstance(value, str):
@@ -57,7 +64,7 @@ class ScalarProperty:
                 f"{self.name} units must be one of {friendly_list(get_symbols(self.units))}"
             )
         if new_value is not None and new_value.is_percent:
-            new_value = Scalar(new_value.value, self.percent_unit)
+            new_value = Scalar(new_value.value, self.percent_unit, Unit.WIDTH)
         setattr(obj, self.internal_name, new_value)
         return value
 
@@ -258,11 +265,26 @@ class OffsetProperty:
     def __set_name__(self, owner: Styles, name: str) -> None:
         self._internal_name = f"_rule_{name}"
 
-    def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> Offset:
+    def __get__(self, obj: Styles, objtype: type[Styles] | None = None) -> ScalarOffset:
-        return getattr(obj, self._internal_name) or Offset()
+        return getattr(obj, self._internal_name) or ScalarOffset(
+            Scalar.from_number(0), Scalar.from_number(0)
+        )
 
-    def __set__(self, obj: Styles, offset: tuple[int, int]) -> tuple[int, int]:
+    def __set__(
-        _offset = Offset(*offset)
+        self, obj: Styles, offset: tuple[int | str, int | str]
+    ) -> tuple[int | str, int | str]:
+        x, y = offset
+        scalar_x = (
+            Scalar.parse(x, Unit.WIDTH)
+            if isinstance(x, str)
+            else Scalar(x, Unit.CELLS, Unit.WIDTH)
+        )
+        scalar_y = (
+            Scalar.parse(y, Unit.HEIGHT)
+            if isinstance(y, str)
+            else Scalar(y, Unit.CELLS, Unit.HEIGHT)
+        )
+        _offset = ScalarOffset(scalar_x, scalar_y)
         setattr(obj, self._internal_name, _offset)
         return offset
 

src/textual/css/_styles_builder.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import cast
+from typing import cast, NoReturn
 
 import rich.repr
 from rich.color import ANSI_COLOR_NAMES, Color
@@ -11,7 +11,7 @@ from .errors import DeclarationError, StyleValueError
 from ._error_tools import friendly_list
 from ..geometry import Offset, Spacing, SpacingDimensions
 from .model import Declaration
-from .scalar import Scalar
+from .scalar import Scalar, ScalarOffset, Unit
 from .styles import DockGroup, Styles
 from .types import Edge, Display, Visibility
 from .tokenize import Token
@@ -27,7 +27,7 @@ class StylesBuilder:
     def __repr__(self) -> str:
         return "StylesBuilder()"
 
-    def error(self, name: str, token: Token, message: str) -> None:
+    def error(self, name: str, token: Token, message: str) -> NoReturn:
         raise DeclarationError(name, token, message)
 
     def add_declaration(self, declaration: Declaration) -> None:
@@ -210,13 +210,14 @@ class StylesBuilder:
             self.error(name, tokens[0], "expected two numbers in declaration")
         else:
             token1, token2 = tokens
-            if token1.name != "number":
+
-                self.error(name, token1, f"expected a number (found {token1.value!r})")
+            if token1.name != "scalar":
-            if token2.name != "number":
+                self.error(name, token1, f"expected a scalar; found {token1.value!r}")
-                self.error(name, token2, f"expected a number (found {token1.value!r})")
+            if token2.name != "scalar":
-            self.styles._rule_offset = Offset(
+                self.error(name, token2, f"expected a scalar; found {token1.value!r}")
-                int(float(token1.value)), int(float(token2.value))
+            scalar_x = Scalar.parse(token1.value, Unit.WIDTH)
-            )
+            scalar_y = Scalar.parse(token2.value, Unit.HEIGHT)
+            self.styles._rule_offset = ScalarOffset(scalar_x, scalar_y)
 
     def process_offset_x(self, name: str, tokens: list[Token]) -> None:
         if not tokens:
@@ -224,9 +225,12 @@ class StylesBuilder:
         if len(tokens) != 1:
             self.error(name, tokens[0], f"expected a single number")
         else:
-            x = int(float(tokens[0].value))
+            token = tokens[0]
+            if token.name != "scalar":
+                self.error(name, token, f"expected a scalar; found {token.value!r}")
+            x = Scalar.parse(token.value, Unit.WIDTH)
             y = self.styles.offset.y
-            self.styles._rule_offset = Offset(x, y)
+            self.styles._rule_offset = ScalarOffset(x, y)
 
     def process_offset_y(self, name: str, tokens: list[Token]) -> None:
         if not tokens:
@@ -234,9 +238,12 @@ class StylesBuilder:
         if len(tokens) != 1:
             self.error(name, tokens[0], f"expected a single number")
         else:
-            y = int(float(tokens[0].value))
+            token = tokens[0]
+            if token.name != "scalar":
+                self.error(name, token, f"expected a scalar; found {token.value!r}")
+            y = Scalar.parse(token.value, Unit.HEIGHT)
             x = self.styles.offset.x
-            self.styles._rule_offset = Offset(x, y)
+            self.styles._rule_offset = ScalarOffset(x, y)
 
     def process_layout(self, name: str, tokens: list[Token]) -> None:
         if tokens:
@@ -247,7 +254,10 @@ class StylesBuilder:
 
     def process_text(self, name: str, tokens: list[Token]) -> None:
         style_definition = " ".join(token.value for token in tokens)
+        try:
             style = Style.parse(style_definition)
+        except Exception as error:
+            self.error(name, tokens[0], f"failed to parse style; {error}")
         self.styles.text = style
 
     def process_text_color(self, name: str, tokens: list[Token]) -> None:

src/textual/css/scalar.py

@@ -40,15 +40,15 @@ UNIT_SYMBOL = {
 
 SYMBOL_UNIT = {v: k for k, v in UNIT_SYMBOL.items()}
 
-_MATCH_SCALAR = re.compile(r"^(\d+\.?\d*)(fr|%|w|h|vw|vh)?$").match
+_MATCH_SCALAR = re.compile(r"^(\-?\d+\.?\d*)(fr|%|w|h|vw|vh)?$").match
 
 
 RESOLVE_MAP = {
     Unit.CELLS: lambda value, size, viewport: value,
-    Unit.WIDTH: lambda value, size, viewport: size[0],
+    Unit.WIDTH: lambda value, size, viewport: size[0] * value / 100,
-    Unit.HEIGHT: lambda value, size, viewport: size[1],
+    Unit.HEIGHT: lambda value, size, viewport: size[1] * value / 100,
-    Unit.VIEW_WIDTH: lambda value, size, viewport: viewport[0],
+    Unit.VIEW_WIDTH: lambda value, size, viewport: viewport[0] * value / 100,
-    Unit.VIEW_HEIGHT: lambda value, size, viewport: viewport[1],
+    Unit.VIEW_HEIGHT: lambda value, size, viewport: viewport[1] * value / 100,
 }
 
 
@@ -69,9 +69,10 @@ class Scalar(NamedTuple):
 
     value: float
     unit: Unit
+    percent_unit: Unit
 
     def __str__(self) -> str:
-        value, _unit = self
+        value, _unit, _ = self
         return f"{int(value) if value.is_integer() else value}{self.symbol}"
 
     @property
@@ -80,12 +81,12 @@ class Scalar(NamedTuple):
 
     @property
     def cells(self) -> int | None:
-        value, unit = self
+        value, unit, _ = self
         return int(value) if unit == Unit.CELLS else None
 
     @property
     def fraction(self) -> int | None:
-        value, unit = self
+        value, unit, _ = self
         return int(value) if unit == Unit.FRACTION else None
 
     @property
@@ -93,7 +94,11 @@ class Scalar(NamedTuple):
         return UNIT_SYMBOL[self.unit]
 
     @classmethod
-    def parse(cls, token: str) -> Scalar:
+    def from_number(cls, value: float) -> Scalar:
+        return cls(value, Unit.CELLS, Unit.WIDTH)
+
+    @classmethod
+    def parse(cls, token: str, percent_unit: Unit = Unit.WIDTH) -> Scalar:
         """Parse a string in to a Scalar
 
         Args:
@@ -109,16 +114,11 @@ class Scalar(NamedTuple):
         if match is None:
             raise ScalarParseError(f"{token!r} is not a valid scalar")
         value, unit_name = match.groups()
-        scalar = cls(float(value), SYMBOL_UNIT[unit_name or ""])
+        scalar = cls(float(value), SYMBOL_UNIT[unit_name or ""], percent_unit)
         return scalar
 
-    def resolve(
+    def resolve(self, size: tuple[int, int], viewport: tuple[int, int]) -> float:
-        self,
+        value, unit, percent_unit = self
-        size: tuple[int, int],
-        viewport: tuple[int, int],
-        percent_unit: Unit = Unit.WIDTH,
-    ) -> float:
-        value, unit = self
         if unit == Unit.PERCENT:
             unit = percent_unit
         try:
@@ -139,8 +139,7 @@ class ScalarOffset(NamedTuple):
     def resolve(self, size: tuple[int, int], viewport: tuple[int, int]) -> Offset:
         x, y = self
         return Offset(
-            round(x.resolve(size, viewport, percent_unit=Unit.WIDTH)),
+            round(x.resolve(size, viewport)), round(y.resolve(size, viewport))
-            round(y.resolve(size, viewport, percent_unit=Unit.HEIGHT)),
         )
 
 

src/textual/css/styles.py

@@ -18,7 +18,7 @@ from .constants import (
     NULL_SPACING,
 )
 from ..geometry import NULL_OFFSET, Offset, Spacing
-from .scalar import Scalar, Unit
+from .scalar import Scalar, ScalarOffset, Unit
 from ._style_properties import (
     BorderProperty,
     BoxProperty,
@@ -63,7 +63,7 @@ class Styles:
 
     _rule_padding: Spacing | None = None
     _rule_margin: Spacing | None = None
-    _rule_offset: Offset | None = None
+    _rule_offset: ScalarOffset | None = None
 
     _rule_border_top: tuple[str, Style] | None = None
     _rule_border_right: tuple[str, Style] | None = None
@@ -144,6 +144,10 @@ class Styles:
         """Check if an outline is present."""
         return any(edge for edge, _style in self.outline)
 
+    @property
+    def has_offset(self) -> bool:
+        return self._rule_offset is not None
+
     def extract_rules(
         self, specificity: tuple[int, int, int]
     ) -> list[tuple[str, tuple[int, int, int, int], Any]]:

src/textual/css/tokenize.py

@@ -44,8 +44,7 @@ expect_declaration_content = Expect(
     declaration_end=r"\n|;",
     whitespace=r"\s+",
     comment_start=r"\/\*",
-    percentage=r"\d+\%",
+    scalar=r"\-?\d+\.?\d*(?:fr|%|w|h|vw|vh)?",
-    scalar=r"\-?\d+\.?\d*(?:fr|%)?",
     color=r"\#[0-9a-fA-F]{6}|color\([0-9]{1,3}\)|rgb\(\d{1,3}\,\s?\d{1,3}\,\s?\d{1,3}\)",
     key_value=r"[a-zA-Z_-][a-zA-Z0-9_-]*=[0-9a-zA-Z_\-\/]+",
     token="[a-zA-Z_-]+",

src/textual/layout_map.py

@@ -4,7 +4,7 @@ from __future__ import annotations
 from typing import ItemsView, KeysView, ValuesView, NamedTuple
 
 from . import log
-from .geometry import Region, Size
+from .geometry import Offset, Region, Size
 from operator import attrgetter
 from .widget import Widget
 
@@ -47,7 +47,13 @@ class LayoutMap:
         if widget in self.widgets:
             return
 
-        self.widgets[widget] = RenderRegion(region + widget.layout_offset, order, clip)
+        layout_offset = Offset(0, 0)
+        if widget.styles.has_offset:
+            log("r", region, "c", clip.size)
+            layout_offset = widget.styles.offset.resolve(region.size, clip.size)
+            log("layout_offset", layout_offset)
+
+        self.widgets[widget] = RenderRegion(region + layout_offset, order, clip)
 
         if isinstance(widget, View):
             view: View = widget

src/textual/widget.py

@@ -185,12 +185,6 @@ class Widget(DOMNode):
         assert self._animate is not None
         return self._animate
 
-    @property
-    def layout_offset(self) -> tuple[int, int]:
-        """Get the layout offset as a tuple."""
-        x, y = self.styles.offset
-        return round(x), round(y)
-
     @property
     def gutter(self) -> Spacing:
         mt, mr, mb, bl = self.margin or (0, 0, 0, 0)