terminal.py 2.45 KB
Newer Older
1 2
# Copyright (c) 2011 The Chromium OS Authors.
#
3
# SPDX-License-Identifier:	GPL-2.0+
4 5 6 7 8 9 10
#

"""Terminal utilities

This module handles terminal interaction including ANSI color codes.
"""

11 12 13 14 15 16
import os
import sys

# Selection of when we want our output to be colored
COLOR_IF_TERMINAL, COLOR_ALWAYS, COLOR_NEVER = range(3)

17
class Color(object):
18 19 20 21 22 23 24
    """Conditionally wraps text in ANSI color escape sequences."""
    BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)
    BOLD = -1
    BRIGHT_START = '\033[1;%dm'
    NORMAL_START = '\033[22;%dm'
    BOLD_START = '\033[1m'
    RESET = '\033[0m'
25

26 27
    def __init__(self, colored=COLOR_IF_TERMINAL):
        """Create a new Color object, optionally disabling color output.
28

29 30 31 32 33 34
        Args:
          enabled: True if color output should be enabled. If False then this
            class will not add color codes at all.
        """
        self._enabled = (colored == COLOR_ALWAYS or
            (colored == COLOR_IF_TERMINAL and os.isatty(sys.stdout.fileno())))
35

36 37
    def Start(self, color, bright=True):
        """Returns a start color code.
38

39 40
        Args:
          color: Color to use, .e.g BLACK, RED, etc.
41

42 43 44 45 46 47 48 49
        Returns:
          If color is enabled, returns an ANSI sequence to start the given
          color, otherwise returns empty string
        """
        if self._enabled:
            base = self.BRIGHT_START if bright else self.NORMAL_START
            return base % (color + 30)
        return ''
50

51 52
    def Stop(self):
        """Retruns a stop color code.
53

54 55 56 57 58 59 60
        Returns:
          If color is enabled, returns an ANSI color reset sequence,
          otherwise returns empty string
        """
        if self._enabled:
            return self.RESET
        return ''
61

62 63
    def Color(self, color, text, bright=True):
        """Returns text with conditionally added color escape sequences.
64

65 66 67 68
        Keyword arguments:
          color: Text color -- one of the color constants defined in this
                  class.
          text: The text to color.
69

70 71 72 73 74 75 76 77 78 79 80 81 82
        Returns:
          If self._enabled is False, returns the original text. If it's True,
          returns text with color escape sequences based on the value of
          color.
        """
        if not self._enabled:
            return text
        if color == self.BOLD:
            start = self.BOLD_START
        else:
            base = self.BRIGHT_START if bright else self.NORMAL_START
            start = base % (color + 30)
        return start + text + self.RESET