On 02Mar2019 15:16, boB Stepp <robertvst...@gmail.com> wrote:
I wanted to be able to change the background screen color of a
terminal window using curses. My weak Google-Foo did not turn up a
clear example of how to do this despite much searching. The two
_obvious_curses methods to attempt this seemed to be
window.bkgdset(ch, attr) to initially set a window's background
attributes and window.bkgd(ch, attr) to change them to new values.
The thing that has puzzled me is that "ch" is a mandatory parameter to
supply.
Remember that the Python curses module is a shim for the curses (or
ncurses) C library. So "man 3 curses" gets you the main library page,
and there are distinct manual entries for the various functions.
On my machine (a Mac) the curses(3) manual entry has a section named
"Routine Name Index" thus:
Routine Name Index
The following table lists each curses routine and the name of the man‐
ual page on which it is described. Routines flagged with “*”
are ncurses-specific, not described by XPG4 or present in SVr4.
and then there's a long table of functions and the match manual entry
name. bkgdset is listed as in the curs_bkgd(3) entry, so run "man
curs_bkgd" to view that manual entry. It describes the bkgdset,
wbkgdset, bkgd, wbkgd, getbkgd functions in some detail.
Also, the curs_color manual entry talks about terminal colours in
detail. So "man curs_color".
So after a variety of experimental efforts I came up with the
following approach which seems to do what I want to do -- just change
the terminal's background color at will. But since I did *not* locate
any clear examples online on how to do this, I cannot help but wonder
if there is an easier approach to do what I want to do?
I would be inclined to call getbkgd() and then modify what it gives you
as desired, then call bkgdset(). Untested.
My code follows. As always I am open to any constructive criticism
even if it is off this email's topic, though this code is not meant to
be a polished product.
[...]
# Fill screen with spaces to color screen background:
for y in range(max_height):
try:
stdscr.addstr(y, 0, ' ' * max_width)
except curses.error as error:
if y == max_height - 1:
# Ignore error from writing to lower right-hand screen corner:
pass
else:
raise error
Is the painting of the screen with spaces actually required? I would
have thought not (again, untested). The main window (stdscr) should
start filled with spaces.
[Reads more closely...] probably you want to call bkgd() or wbkgd()
instead. "man curs_bkgd" says:
bkgd
The bkgd and wbkgd functions set the background property of the
current or specified window and then apply this setting to every
character position in that window:
· The rendition of every character on the screen is changed to
the new background rendition.
· Wherever the former background character appears, it is changed
to the new background character.
Cheers,
Cameron Simpson <c...@cskk.id.au>
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