WIP: Colors: Add ansi_default and make ansi_* colors actually output their ansi sequences

CHANGELOG.md

@@ -5,6 +5,14 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+
+### Added
+- Added ansi_default color which returns default terminal color https://github.com/Textualize/textual/pull/1460
+
+### Changed
+- ansi_* colors now render simple ANSI sequences https://github.com/Textualize/textual/pull/1460
+
 ## [0.9.1] - 2022-12-30
 
 ### Added
@@ -322,6 +330,7 @@ https://textual.textualize.io/blog/2022/11/08/version-040/#version-040
 - New handler system for messages that doesn't require inheritance
 - Improved traceback handling
 
+[unreleased]: https://github.com/Textualize/textual/compare/v0.9.1...HEAD
 [0.9.1]: https://github.com/Textualize/textual/compare/v0.9.0...v0.9.1
 [0.9.0]: https://github.com/Textualize/textual/compare/v0.8.2...v0.9.0
 [0.8.2]: https://github.com/Textualize/textual/compare/v0.8.1...v0.8.2

Makefile

@@ -1,3 +1,7 @@
+make:
+	python -m build --wheel --skip-dependency-check --no-isolation
+install:
+	python -m installer dist/*.whl
 test:
 	pytest --cov-report term-missing --cov=textual tests/ -vv
 unit-test:

docs/examples/styles/background.css

@@ -12,3 +12,6 @@ Static {
 #static3 {
     background: hsl(240, 100%, 50%);
 }
+#static4 {
+    background: ansi_default;
+}

docs/examples/styles/background.py

@@ -7,6 +7,7 @@ def compose(self):
         yield Static("Widget 1", id="static1")
         yield Static("Widget 2", id="static2")
         yield Static("Widget 3", id="static3")
+        yield Static("Widget 4", id="static4")
 
 
 app = BackgroundApp(css_path="background.css")

docs/examples/styles/color.css

@@ -11,3 +11,6 @@ Static {
 #static3 {
     color: hsl(240, 100%, 50%)
 }
+#static4 {
+    color: ansi_magenta;
+}

docs/examples/styles/color.py

@@ -7,6 +7,7 @@ def compose(self):
         yield Static("I'm red!", id="static1")
         yield Static("I'm rgb(0, 255, 0)!", id="static2")
         yield Static("I'm hsl(240, 100%, 50%)!", id="static3")
+        yield Static("I'm ansi_magenta!", id="static4")
 
 
 app = ColorApp(css_path="color.css")

docs/styles/background.md

@@ -32,6 +32,9 @@ This example creates three widgets and applies a different background to each.
 ## CSS
 
 ```sass
+/* Default terminal background */
+background: ansi_default;
+
 /* Blue background */
 background: blue;
 

docs/styles/color.md

@@ -32,6 +32,9 @@ This example sets a different text color to three different widgets.
 ## CSS
 
 ```sass
+/* ANSI yellow */
+color: ansi_yellow;
+
 /* Blue text */
 color: blue;
 

src/textual/_color_constants.py

@@ -1,25 +1,29 @@
 from __future__ import annotations
+from math import nan
 
 COLOR_NAME_TO_RGB: dict[str, tuple[int, int, int] | tuple[int, int, int, float]] = {
     # Let's start with a specific pseudo-color::
     "transparent": (0, 0, 0, 0),
+    "ansi_default": (1, 1, 1, nan),
     # Then, the 16 common ANSI colors:
-    "ansi_black": (0, 0, 0),
-    "ansi_red": (128, 0, 0),
-    "ansi_green": (0, 128, 0),
-    "ansi_yellow": (128, 128, 0),
-    "ansi_blue": (0, 0, 128),
-    "ansi_magenta": (128, 0, 128),
-    "ansi_cyan": (0, 128, 128),
-    "ansi_white": (192, 192, 192),
-    "ansi_bright_black": (128, 128, 128),
-    "ansi_bright_red": (255, 0, 0),
-    "ansi_bright_green": (0, 255, 0),
-    "ansi_bright_yellow": (255, 255, 0),
-    "ansi_bright_blue": (0, 0, 255),
-    "ansi_bright_magenta": (255, 0, 255),
-    "ansi_bright_cyan": (0, 255, 255),
-    "ansi_bright_white": (255, 255, 255),
+    # Values from rich._pallettes.STANDARD_PALETTE
+    # so RichColor.downgrade will return the same value
+    "ansi_black": (0, 0, 0, nan),
+    "ansi_red": (170, 0, 0, nan),
+    "ansi_green": (0, 170, 0, nan),
+    "ansi_yellow": (170, 85, 0, nan),
+    "ansi_blue": (0, 0, 170, nan),
+    "ansi_magenta": (170, 0, 170, nan),
+    "ansi_cyan": (0, 170, 170, nan),
+    "ansi_white": (170, 170, 170, nan),
+    "ansi_bright_black": (85, 85, 85, nan),
+    "ansi_bright_red": (255, 85, 85, nan),
+    "ansi_bright_green": (85, 255, 85, nan),
+    "ansi_bright_yellow": (255, 255, 85, nan),
+    "ansi_bright_blue": (85, 85, 255, nan),
+    "ansi_bright_magenta": (255, 85, 255, nan),
+    "ansi_bright_cyan": (85, 255, 255, nan),
+    "ansi_bright_white": (255, 255, 255, nan),
     # And then, Web color keywords: (up to CSS Color Module Level 4)
     "black": (0, 0, 0),
     "silver": (192, 192, 192),

src/textual/color.py

@@ -54,6 +54,8 @@
 from ._color_constants import COLOR_NAME_TO_RGB
 from .geometry import clamp
 
+import math
+
 _TRUECOLOR = ColorType.TRUECOLOR
 
 
@@ -145,7 +147,7 @@ class Color(NamedTuple):
     b: int
     """Blue component (0-255)"""
     a: float = 1.0
-    """Alpha component (0-1)"""
+    """Alpha component (0-1) or math.nan to represent ANSI color"""
 
     @classmethod
     def from_rich_color(cls, rich_color: RichColor) -> Color:
@@ -158,6 +160,10 @@ def from_rich_color(cls, rich_color: RichColor) -> Color:
             Color: A new Color.
         """
         r, g, b = rich_color.get_truecolor()
+        if rich_color.type is ColorType.STANDARD:
+            return cls(r, g, b, math.nan)
+        elif rich_color.type is ColorType.DEFAULT:
+            return cls(1, 1, 1, math.nan)
         return cls(r, g, b)
 
     @classmethod
@@ -225,10 +231,19 @@ def rich_color(self) -> RichColor:
         Returns:
             RichColor: A color object as used by Rich.
         """
-        r, g, b, _a = self
-        return RichColor(
+        r, g, b, a = self
+
+        rc = RichColor(
             f"#{r:02x}{g:02x}{b:02x}", _TRUECOLOR, None, ColorTriplet(r, g, b)
         )
+        if a is math.nan:
+            # ANSI raw colors
+            if r == 1 and g == 1 and b == 1:
+                return RichColor.default()  # ansi_default
+            # "Downgrade" color to closest ansi 16
+            return RichColor.downgrade(rc, ColorType.STANDARD)
+
+        return rc
 
     @property
     def normalized(self) -> tuple[float, float, float]:
@@ -348,15 +363,15 @@ def blend(
 
         Args:
             destination (Color): Another color.
-            factor (float): A blend factor, 0 -> 1.
+            factor (float): A blend factor, 0 -> 1, or math.nan for 1.
             alpha (float | None): New alpha for result. Defaults to None.
 
         Returns:
             Color: A new color.
         """
         if factor == 0:
             return self
-        elif factor == 1:
+        elif factor == 1 or factor is math.nan:
             return destination
         r1, g1, b1, a1 = self
         r2, g2, b2, a2 = destination

src/textual/geometry.py

@@ -29,7 +29,8 @@ def clamp(value: T, minimum: T, maximum: T) -> T:
         maximum (T): maximum value.
 
     Returns:
-        T: New value that is not less than the minimum or greater than the maximum.
+        T: New value that is not less than the minimum or greater than the maximum,
+        or the original value if that cannot be satisfied.
     """
     if minimum > maximum:
         maximum, minimum = minimum, maximum
@@ -38,6 +39,7 @@ def clamp(value: T, minimum: T, maximum: T) -> T:
     elif value > maximum:
         return maximum
     else:
+        # math.nan is an example value which is incomparable
         return value
 
 

tests/css/test_stylesheet.py

@@ -1,6 +1,7 @@
 from contextlib import nullcontext as does_not_raise
 from typing import Any
 
+import math
 import pytest
 
 from textual.color import Color
@@ -130,8 +131,8 @@ class MyWidget(Widget):
     [
         # Valid values:
         ["transparent", does_not_raise(), Color(0, 0, 0, 0)],
-        ["ansi_red", does_not_raise(), Color(128, 0, 0)],
-        ["ansi_bright_magenta", does_not_raise(), Color(255, 0, 255)],
+        ["ansi_red", does_not_raise(), Color(170, 0, 0, math.nan)],
+        ["ansi_bright_magenta", does_not_raise(), Color(255, 85, 255, math.nan)],
         ["red", does_not_raise(), Color(255, 0, 0)],
         ["lime", does_not_raise(), Color(0, 255, 0)],
         ["coral", does_not_raise(), Color(255, 127, 80)],