color_default Struct Reference

Data Fields
const char *	m_name
const char *	m_val

Detailed Description

The context and logic for choosing default --color screen attributes
(foreground and background colors, etc.) are the following.
   -- There are eight basic colors available, each with its own
      nominal luminosity to the human eye and foreground/background
      codes (black [0 %, 30/40], blue [11 %, 34/44], red [30 %, 31/41],
      magenta [41 %, 35/45], green [59 %, 32/42], cyan [70 %, 36/46],
      yellow [89 %, 33/43], and white [100 %, 37/47]).
   -- Sometimes, white as a background is actually implemented using
      a shade of light gray, so that a foreground white can be visible
      on top of it (but most often not).
   -- Sometimes, black as a foreground is actually implemented using
      a shade of dark gray, so that it can be visible on top of a
      background black (but most often not).
   -- Sometimes, more colors are available, as extensions.
   -- Other attributes can be selected/deselected (bold [1/22],
      underline [4/24], standout/inverse [7/27], blink [5/25], and
      invisible/hidden [8/28]).  They are sometimes implemented by
      using colors instead of what their names imply; e.g., bold is
      often achieved by using brighter colors.  In practice, only bold
      is really available to us, underline sometimes being mapped by
      the terminal to some strange color choice, and standout best
      being left for use by downstream programs such as less(1).
   -- We cannot assume that any of the extensions or special features
      are available for the purpose of choosing defaults for everyone.
   -- The most prevalent default terminal backgrounds are pure black
      and pure white, and are not necessarily the same shades of
      those as if they were selected explicitly with SGR sequences.
      Some terminals use dark or light pictures as default background,
      but those are covered over by an explicit selection of background
      color with an SGR sequence; their users will appreciate their
      background pictures not be covered like this, if possible.
   -- Some uses of colors attributes is to make some output items
      more understated (e.g., context lines); this cannot be achieved
      by changing the background color.
   -- For these reasons, the GCC color defaults should strive not
      to change the background color from its default, unless it's
      for a short item that should be highlighted, not understated.
   -- The GCC foreground color defaults (without an explicitly set
      background) should provide enough contrast to be readable on any
      terminal with either a black (dark) or white (light) background.
      This only leaves red, magenta, green, and cyan (and their bold
      counterparts) and possibly bold blue.   

Default colors. The user can overwrite them using environment
variable GCC_COLORS.   

Field Documentation

m_name

const char* color_default::m_name

m_val

const char* color_default::m_val

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The documentation for this struct was generated from the following file:

• diagnostic-color.cc