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[PATCH 089/177] man/curs_color.3x: Revise "NOTES" section.


From: G. Branden Robinson
Subject: [PATCH 089/177] man/curs_color.3x: Revise "NOTES" section.
Date: Mon, 13 Jan 2025 11:29:01 -0600

Content:
* Relocate here some material from "PORTABILITY", such as a motivation
  for the `use_default_colors()` and `assume_default_colors()` ncurses
  extensions.
* Expand discussion of legacy IBM PC text mode color video handling.

Style:
* Set topically central literals in bold, not roman.
* Recast.

Markup:
* Favor man(7) font style macros over *roff font selection escape
  sequences, except for man page cross references (because
  man/make_sed.sh recognizes only certain patterns when rewriting such
  cross references) and terms in the "NAME" section (because the
  generated edit_man.sh script expects font selection escape sequences
  when scraping terms thence to gather names for man page aliases).
---
 man/curs_color.3x | 87 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 65 insertions(+), 22 deletions(-)

diff --git a/man/curs_color.3x b/man/curs_color.3x
index 03f82c318..ccc70b2b1 100644
--- a/man/curs_color.3x
+++ b/man/curs_color.3x
@@ -516,34 +516,77 @@ .SH RETURN VALUE
 inclusive.
 .RE
 .SH NOTES
-In the \fI\%ncurses\fP implementation,
-there is a separate color activation flag,
-color palette, color pairs table,
-and associated \fB\%COLORS\fP and \fB\%COLOR_PAIRS\fP counts
-for each screen; the \fB\%start_color\fP function only affects the current
-screen.
-The SVr4/XSI interface is not really designed with this in mind, and
+In
+.IR \%ncurses ","
+.B \%init_pair
+accepts negative foreground and background color arguments
+to support its \fB\%use_default_colors\fP(3X) extension,
+but only after the latter function has been called.
+.PP
+The assumption that
+.B \%COLOR_BLACK
+is the terminal's default background color can be overridden using
+.IR \%ncurses 's
+\fB\%assume_default_colors\fP(3X) extension.
+.PP
+In
+.IR \%ncurses ","
+each pointer passed to
+.B \%color_content
+and
+.B \%pair_content
+can be null,
+in which case the library ignores it,
+permitting the application to disregard unnecessary information.
+.PP
+In
+.IR \%ncurses ","
+each screen has a
+color activation flag,
+color palette,
+color pair table,
+and associated
+.B \%COLORS
+and
+.B \%COLOR_PAIRS
+values for each screen;
+.B \%start_color
+affects only the current screen.
+The SVr4 and X/Open Curses interface was not really designed
+with this in mind;
 historical implementations may use a single shared color palette.
 .PP
 Setting an implicit background color via a color pair affects only
 character cells that a character write operation explicitly touches.
-To change
-the background color used when parts of a window are blanked by erasing or
-scrolling operations, see \fB\%curs_bkgd\fP(3X).
+To change the background color used
+when parts of a window are blanked by erasing or scrolling operations,
+see \fB\%curs_bkgd\fP(3X).
 .PP
-Several caveats apply on older x86 machines
-(e.g., i386, i486) with VGA-compatible graphics:
-.bP
-COLOR_YELLOW is actually brown.
-To get yellow, use COLOR_YELLOW combined with the \fBA_BOLD\fP attribute.
-.bP
-The A_BLINK attribute should in theory cause the background to go bright.
-This often fails to work, and even some cards for which it mostly works
-(such as the
-Paradise and compatibles) do the wrong thing when you try to set a bright
-\*(``yellow\*('' background (you get a blinking yellow foreground instead).
+Several caveats apply to IBM PC-compatible machines
+of the 80486 era and earlier
+with CGA/EGA/VGA video.
+.bP
+.B \%COLOR_YELLOW
+is actually brown.
+To get yellow,
+combine
+.B \%COLOR_YELLOW
+with the
+.B \%A_BOLD
+attribute.
 .bP
-Color RGB values are not settable.
+The
+.B \%A_BLINK
+attribute should in theory make the background bright.
+This often fails to work,
+and even VGA controllers for which it mostly works,
+such as those from Paradise and compatibles,
+do the wrong thing
+when you try to set a bright \*(``yellow\*('' background \(em
+you get a blinking yellow foreground instead.
+.bP
+Color RGB values are not configurable on these devices
+(in text mode).
 .SH EXTENSIONS
 The functions marked as extensions were designed for
 \fB\%ncurses\fP(3X),
-- 
2.30.2

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