Add enhanced terminal color support with fallback options

Author: shyam-ramani

rich/terminal.py

@@ -0,0 +1,124 @@
+"""Terminal color support detection and fallback options."""
+
+import os
+import sys
+from typing import Dict, Optional, Set, Tuple
+
+# ANSI color codes
+ANSI_COLORS = {
+    'black': 30,
+    'red': 31,
+    'green': 32,
+    'yellow': 33,
+    'blue': 34,
+    'magenta': 35,
+    'cyan': 36,
+    'white': 37,
+    'bright_black': 90,
+    'bright_red': 91,
+    'bright_green': 92,
+    'bright_yellow': 93,
+    'bright_blue': 94,
+    'bright_magenta': 95,
+    'bright_cyan': 96,
+    'bright_white': 97,
+}
+
+class TerminalColorSupport:
+    """Detect and manage terminal color support."""
+    
+    def __init__(self) -> None:
+        self._color_support: Optional[bool] = None
+        self._supported_colors: Set[str] = set()
+        self._fallback_colors: Dict[str, str] = {}
+        
+    def detect_color_support(self) -> bool:
+        """Detect if the terminal supports colors."""
+        if self._color_support is not None:
+            return self._color_support
+            
+        # Check environment variables
+        if 'NO_COLOR' in os.environ:
+            self._color_support = False
+            return False
+            
+        if 'FORCE_COLOR' in os.environ:
+            self._color_support = True
+            return True
+            
+        # Check if we're in a terminal
+        if not sys.stdout.isatty():
+            self._color_support = False
+            return False
+            
+        # Check terminal type
+        term = os.environ.get('TERM', '').lower()
+        if term in ('dumb', 'unknown'):
+            self._color_support = False
+            return False
+            
+        # Windows specific checks
+        if sys.platform == 'win32':
+            try:
+                import ctypes
+                kernel32 = ctypes.windll.kernel32
+                if kernel32.GetConsoleMode(kernel32.GetStdHandle(-11), None):
+                    self._color_support = True
+                    return True
+            except Exception:
+                pass
+                
+        # Default to True for modern terminals
+        self._color_support = True
+        return True
+        
+    def get_supported_colors(self) -> Set[str]:
+        """Get the set of supported colors."""
+        if not self._supported_colors:
+            if self.detect_color_support():
+                # Test each color
+                for color in ANSI_COLORS:
+                    if self._test_color(color):
+                        self._supported_colors.add(color)
+                        
+        return self._supported_colors
+        
+    def _test_color(self, color: str) -> bool:
+        """Test if a specific color is supported."""
+        # Implementation would test actual color support
+        # For now, return True for all colors if color support is enabled
+        return self.detect_color_support()
+        
+    def get_fallback_color(self, color: str) -> str:
+        """Get a fallback color if the requested color is not supported."""
+        if color in self._fallback_colors:
+            return self._fallback_colors[color]
+            
+        # Define fallback mappings
+        fallbacks = {
+            'bright_black': 'black',
+            'bright_red': 'red',
+            'bright_green': 'green',
+            'bright_yellow': 'yellow',
+            'bright_blue': 'blue',
+            'bright_magenta': 'magenta',
+            'bright_cyan': 'cyan',
+            'bright_white': 'white',
+        }
+        
+        fallback = fallbacks.get(color, 'white')
+        self._fallback_colors[color] = fallback
+        return fallback
+        
+    def get_color_code(self, color: str) -> Tuple[int, bool]:
+        """Get the ANSI color code and whether it's supported."""
+        if not self.detect_color_support():
+            return (0, False)
+            
+        if color not in self.get_supported_colors():
+            color = self.get_fallback_color(color)
+            
+        return (ANSI_COLORS[color], True)
+
+# Global instance
+terminal_color = TerminalColorSupport() 

tests/test_terminal_color.py

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+"""Tests for terminal color support."""
+
+import os
+import sys
+from unittest import mock
+
+import pytest
+
+from rich.terminal import TerminalColorSupport, terminal_color
+
+def test_color_support_detection():
+    """Test color support detection."""
+    # Test NO_COLOR environment variable
+    with mock.patch.dict(os.environ, {'NO_COLOR': '1'}):
+        assert not terminal_color.detect_color_support()
+        
+    # Test FORCE_COLOR environment variable
+    with mock.patch.dict(os.environ, {'FORCE_COLOR': '1'}):
+        assert terminal_color.detect_color_support()
+        
+    # Test dumb terminal
+    with mock.patch.dict(os.environ, {'TERM': 'dumb'}):
+        assert not terminal_color.detect_color_support()
+        
+    # Test unknown terminal
+    with mock.patch.dict(os.environ, {'TERM': 'unknown'}):
+        assert not terminal_color.detect_color_support()
+
+def test_supported_colors():
+    """Test getting supported colors."""
+    with mock.patch.object(terminal_color, 'detect_color_support', return_value=True):
+        colors = terminal_color.get_supported_colors()
+        assert isinstance(colors, set)
+        assert len(colors) > 0
+
+def test_fallback_colors():
+    """Test fallback color mapping."""
+    # Test bright color fallbacks
+    assert terminal_color.get_fallback_color('bright_red') == 'red'
+    assert terminal_color.get_fallback_color('bright_blue') == 'blue'
+    
+    # Test unknown color fallback
+    assert terminal_color.get_fallback_color('unknown_color') == 'white'
+
+def test_color_code():
+    """Test getting color codes."""
+    with mock.patch.object(terminal_color, 'detect_color_support', return_value=True):
+        code, supported = terminal_color.get_color_code('red')
+        assert code == 31  # ANSI code for red
+        assert supported is True
+        
+    with mock.patch.object(terminal_color, 'detect_color_support', return_value=False):
+        code, supported = terminal_color.get_color_code('red')
+        assert code == 0
+        assert supported is False
+
+def test_windows_specific():
+    """Test Windows-specific color support."""
+    if sys.platform == 'win32':
+        with mock.patch('ctypes.windll.kernel32.GetConsoleMode', return_value=1):
+            assert terminal_color.detect_color_support()
+            
+        with mock.patch('ctypes.windll.kernel32.GetConsoleMode', return_value=0):
+            assert not terminal_color.detect_color_support()